Gale Encyclopedia of Medicine Vol 3 2nd ed pdf
The GALE
ENCYCLOPEDIA
of MEDICINE
SECOND EDITION
The GALE
ENCYCLOPEDIA
of MEDICINE
SECOND EDITION
VOLUME
3
G-M
JACQUELINE L. LONGE, EDITOR
D E I R D R E S . B L A N C H F I E L D , A S S O C I AT E E D I T O R
The GALE
ENCYCLOPEDIA
of MEDICINE
SECOND EDITION
STAFF
Jacqueline L. Longe, Project Editor
Deirdre S. Blanchfield, Associate Editor
Christine B. Jeryan, Managing Editor
Donna Olendorf, Senior Editor
Stacey Blachford, Associate Editor
Kate Kretschmann, Melissa C. McDade, Ryan
Thomason, Assistant Editors
Mark Springer, Technical Specialist
Andrea Lopeman, Programmer/Analyst
Barbara J. Yarrow, Manager, Imaging and Multimedia
Content
Robyn V. Young, Project Manager, Imaging and
Multimedia Content
Dean Dauphinais, Senior Editor, Imaging and
Multimedia Content
Kelly A. Quin, Editor, Imaging and Multimedia Content
Leitha Etheridge-Sims, Mary K. Grimes, Dave Oblender,
Image Catalogers
Pamela A. Reed, Imaging Coordinator
Randy Bassett, Imaging Supervisor
Robert Duncan, Senior Imaging Specialist
Dan Newell, Imaging Specialist
Christine O’Bryan, Graphic Specialist
Maria Franklin, Permissions Manager
Margaret A. Chamberlain, Permissions Specialist
Michelle DiMercurio, Senior Art Director
Mike Logusz, Graphic Artist
Mary Beth Trimper, Manager, Composition and
Electronic Prepress
Evi Seoud, Assistant Manager, Composition Purchasing
and Electronic Prepress
Dorothy Maki, Manufacturing Manager
Wendy Blurton, Senior Manufacturing Specialist
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Gale Group
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part in any form.
ISBN 0-7876-5489-2 (set)
0-7876-5490-6 (Vol. 1)
0-7876-5491-4 (Vol. 2)
0-7876-5492-2 (Vol. 3)
0-7876-5493-0 (Vol. 4)
0-7876-5494-9 (Vol. 5)
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
Library of Congress Cataloging-in-Publication Data
Gale encyclopedia of medicine / Jacqueline L. Longe, editor;
Deirdre S. Blanchfield, associate editor — 2nd ed.
p. cm.
Includes bibliographical references and index.
Contents: Vol. 1. A-B — v. 2. C-F — v. 3.
G-M — v. 4. N-S — v. 5. T-Z.
ISBN 0-7876-5489-2 (set: hardcover) — ISBN 0-7876-5490-6
(vol. 1) — ISBN 0-7876-5491-4 (vol. 2) — ISBN 0-7876-5492-2
(vol. 3) — ISBN 0-7876-5493-0 (vol. 4) — ISBN 0-7876-5494-9
(vol. 5)
1. Internal medicine—Encyclopedias. I. Longe, Jacqueline L.
II. Blanchfield, Deirdre S. III. Gale Research Company.
RC41.G35 2001
616’.003—dc21
2001051245
CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Advisory Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Entries
Volume 1: A-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Volume 2: C-F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Volume 3: G-M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1375
Volume 4: N-S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2307
Volume 5: T-Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3237
Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3603
General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3625
GALE ENCYCLOPEDIA OF MEDICINE 2
V
PLEASE READ—IMPORTANT INFORMATION
The Gale Encyclopedia of Medicine 2 is a medical reference product designed to inform and educate readers
about a wide variety of disorders, conditions, treatments,
and diagnostic tests. The Gale Group believes the product
to be comprehensive, but not necessarily definitive. It is
intended to supplement, not replace, consultation with a
physician or other healthcare practitioner. While the Gale
Group has made substantial efforts to provide information
that is accurate, comprehensive, and up-to-date, the Gale
Group makes no representations or warranties of any
GALE ENCYCLOPEDIA OF MEDICINE 2
kind, including without limitation, warranties of merchantability or fitness for a particular purpose, nor does it
guarantee the accuracy, comprehensiveness, or timeliness
of the information contained in this product. Readers
should be aware that the universe of medical knowledge
is constantly growing and changing, and that differences
of medical opinion exist among authorities. Readers are
also advised to seek professional diagnosis and treatment
for any medical condition, and to discuss information
obtained from this book with their health care provider.
VII
INTRODUCTION
The Gale Encyclopedia of Medicine 2 (GEM2) is a
one-stop source for medical information on nearly 1,700
common medical disorders, conditions, tests, and treatments, including high-profile diseases such as AIDS,
Alzheimer’s disease, cancer, and heart attack. This encyclopedia avoids medical jargon and uses language that
laypersons can understand, while still providing thorough coverage of each topic. The Gale Encyclopedia of
Medicine 2 fills a gap between basic consumer health
resources, such as single-volume family medical guides,
and highly technical professional materials.
SCOPE
Almost 1,700 full-length articles are included in the
Gale Encyclopedia of Medicine 2, including disorders/
conditions, tests/procedures, and treatments/therapies.
Many common drugs are also covered, with generic drug
names appearing first and brand names following in
parentheses, eg. acetaminophen (Tylenol). Throughout
the Gale Encyclopedia of Medicine 2, many prominent
individuals are highlighted as sidebar biographies that
accompany the main topical essays. Articles follow a
standardized format that provides information at a
glance. Rubrics include:
Disorders/Conditions
Tests/Treatments
Definition
Description
Causes and symptoms
Diagnosis
Treatment
Alternative treatment
Prognosis
Prevention
Resources
Key terms
Definition
Purpose
Precautions
Description
Preparation
Aftercare
Risks
Normal/Abnormal results
Resources
Key terms
In recent years there has been a resurgence of interest
in holistic medicine that emphasizes the connection
between mind and body. Aimed at achieving and maintaining good health rather than just eliminating disease,
GALE ENCYCLOPEDIA OF MEDICINE 2
this approach has come to be known as alternative medicine. The Gale Encyclopedia of Medicine 2 includes a
number of essays on alternative therapies, ranging from
traditional Chinese medicine to homeopathy and from
meditation to aromatherapy. In addition to full essays on
alternative therapies, the encyclopedia features specific
Alternative treatment sections for diseases and conditions that may be helped by complementary therapies.
INCLUSION CRITERIA
A preliminary list of diseases, disorders, tests and treatments was compiled from a wide variety of sources,
including professional medical guides and textbooks as
well as consumer guides and encyclopedias. The general
advisory board, made up of public librarians, medical
librarians and consumer health experts, evaluated the topics and made suggestions for inclusion. The list was sorted
by category and sent to GEM2 medical advisors, certified
physicians with various medical specialities, for review.
Final selection of topics to include was made by the medical advisors in conjunction with the Gale Group editor.
ABOUT THE CONTRIBUTORS
The essays were compiled by experienced medical
writers, including physicians, pharmacists, nurses, and
other health care professionals. GEM2 medical advisors
reviewed the completed essays to insure that they are
appropriate, up-to-date, and medically accurate.
HOW TO USE THIS BOOK
The Gale Encyclopedia of Medicine 2 has been
designed with ready reference in mind.
• Straight alphabetical arrangement allows users to
locate information quickly.
• Bold-faced terms function as print hyperlinks that
point the reader to related entries in the encyclopedia.
IX
Introduction
• Cross-references placed throughout the encyclopedia
direct readers to where information on subjects without entries can be found. Synonyms are also cross-referenced.
• A list of key terms are provided where appropriate to
define unfamiliar terms or concepts.
• Valuable contact information for organizations and
support groups is included with each entry. The
appendix contains an extensive list of organizations
arranged in alphabetical order.
X
• Resources section directs users to additional sources
of medical information on a topic.
• A comprehensive general index allows users to easily
target detailed aspects of any topic, including Latin
names.
GRAPHICS
The Gale Encyclopedia of Medicine 2 is enhanced
with over 675 color images, including photos, charts,
tables, and customized line drawings.
GALE ENCYCLOPEDIA OF MEDICINE 2
ADVISORY BOARD
A number of experts in the library and medical communities provided invaluable assistance in the formulation of this encyclopedia. Our advisory board performed a myriad of duties, from defining the scope of coverage to reviewing individual
entries for accuracy and accessibility. The editor would like to express her appreciation to them.
MEDICAL ADVISORS
A. Richard Adrouny, M.D.,
F.A.C.P.
Clinical Assistant Professor of
Medicine
Division of Oncology
Stanford University
Director of Medical Oncology
Community Hospital of Los GatosSaratoga
Los Gatos, CA
Laurie Barclay, M.D.
Neurological Consulting Services
Tampa, FL
Kenneth J. Berniker, M.D.
Attending Physician
Emergency Department
Kaiser Permanente Medical Center
Vallejo, CA
Rosalyn Carson-DeWitt, M.D.
Durham, NC
Robin Dipasquale, N.D.
Clinical Faculty
Bastyr University
Seattle, WA
Faye Fishman, D.O.
Randolph, NJ
J. Gary Grant, M.D.
Pacific Grove, CA
Laith F. Gulli, M.D.
M.Sc., M.Sc.(MedSci), MSA,
Msc.Psych., MRSNZ
FRSH, FRIPHH, FAIC, FZS
DAPA, DABFC, DABCI
Consultant Psychotherapist in
Private Practice
Lathrup Village, MI
L. Anne Hirschel, D.D.S.
Southfield, MI
Larry I. Lutwick M.D., F.A.C.P.
Director, Infectious Diseases
VA Medical Center
Brooklyn, NY
Ira Michelson, M.D., M.B.A.,
F.A.C.O.G.
Physician and Clinical Instructor
University of Michigan
Ann Arbor, MI
Susan Mockus, M.D.
Scientific Consultant
Seattle, WA
Ralph M. Myerson, M.D.,
F.A.C.P.
Clinical Professor of Medicine
Medical College of Pennsylvania–
Hahnemann University
Philadelphia, PA
Ronald Pies, M.D.
Clinical Professor of Psychiatry
Tufts University
School of Medicine
Boston, MA
The Permanente Medical Group
Richmond, CA
Amy B. Tuteur, M.D.
Sharon, MA
LIBRARIAN ADVISORS
Maureen O. Carleton, MLIS
Medical Reference Specialist
King County Library System
Bellevue, WA
Elizabeth Clewis Crim, MLS
Collection Specialist
Prince William Public Library, VA
Valerie J. Lawrence, MLS
Assistant Librarian
Western States Chiropractic
College
Portland, OR
Barbara J. O’Hara, MLS
Adult Services Librarian
Free Library of Philadelphia, PA
Alan M. Rees, MLS
Professor Emeritus
Case Western Reserve University
Cleveland, OH
Lecturer on Psychiatry
Harvard Medical School
Cambridge, MA
Lee A. Shratter, M.D.
Staff Radiologist
GALE ENCYCLOPEDIA OF MEDICINE 2
XI
CONTRIBUTORS
Margaret Alic, Ph.D.
Science Writer
Eastsound, WA
Donald G. Barstow, R.N.
Clincal Nurse Specialist
Oklahoma City, OK
Maury M. Breecher, Ph.D.
Health Communicator/Journalist
Northport, AL
Janet Byron Anderson
Linguist/Language Consultant
Rocky River, OH
Carin Lea Beltz, M.S.
Genetic Counselor and Program
Director
The Center for Genetic Counseling
Indianapolis, IN
Ruthan Brodsky
Medical Writer
Bloomfield Hills, MI
Lisa Andres, M.S., C.G.C.
Certified Genetic Counselor and
Medical Writer
San Jose, CA
Greg Annussek
Medical Writer/Editor
New York, NY
Bill Asenjo, M.S., C.R.C.
Science Writer
Iowa City, IA
Sharon A. Aufox, M.S., C.G.C.
Genetic Counselor
Rockford Memorial Hospital
Rockford, IL
Linda K. Bennington, C.N.S.
Science Writer
Virginia Beach, VA
Issac R. Berniker
Medical Writer
Vallejo, CA
Kathleen Berrisford, M.S.V.
Science Writer
Bethanne Black
Medical Writer
Atlanta, GA
Sandra Bain Cushman
Massage Therapist, Alexander
Technique Practitioner
Charlottesville, VA
Jennifer Bowjanowski, M.S.,
C.G.C.
Genetic Counselor
Children’s Hospital Oakland
Oakland, CA
Howard Baker
Medical Writer
North York, Ontario
Michelle Q. Bosworth, M.S., C.G.C.
Genetic Counselor
Eugene, OR
Laurie Barclay, M.D.
Neurological Consulting Services
Tampa, FL
Barbara Boughton
Health and Medical Writer
El Cerrito, CA
Jeanine Barone
Nutritionist, Exercise Physiologist
New York, NY
Cheryl Branche, M.D.
Retired General Practitioner
Jackson, MS
Julia R. Barrett
Science Writer
Madison, WI
Michelle Lee Brandt
Medical Writer
San Francisco, CA
GALE ENCYCLOPEDIA OF MEDICINE 2
Tom Brody, Ph.D.
Science Writer
Berkeley, CA
Leonard C. Bruno, Ph.D.
Medical Writer
Chevy Chase, MD
Diane Calbrese
Medical Sciences and Technology
Writer
Silver Spring, Maryland
Richard H. Camer
Editor
International Medical News Group
Silver Spring, MD
Rosalyn Carson-DeWitt, M.D.
Medical Writer
Durham, NC
Lata Cherath, Ph.D.
Science Writing Intern
Cancer Research Institute
New York, NY
Linda Chrisman
Massage Therapist and Educator
Oakland, CA
Lisa Christenson, Ph.D.
Science Writer
Hamden, CT
Geoffrey N. Clark, D.V.M.
Editor
Canine Sports Medicine Update
Newmarket, NH
XIII
Contributors
Rhonda Cloos, R.N.
Medical Writer
Austin, TX
Gloria Cooksey, C.N.E
Medical Writer
Sacramento, CA
Amy Cooper, M.A., M.S.I.
Medical Writer
Vermillion, SD
David A. Cramer, M.D.
Medical Writer
Chicago, IL
Esther Csapo Rastega, R.N., B.S.N.
Medical Writer
Holbrook, MA
Arnold Cua, M.D.
Physician
Brooklyn, NY
Tish Davidson, A.M.
Medical Writer
Fremont, California
Dominic De Bellis, Ph.D.
Medical Writer/Editor
Mahopac, NY
Lori De Milto
Medical Writer
Sicklerville, NJ
Robert S. Dinsmoor
Medical Writer
South Hamilton, MA
Thomas Scott Eagan
Student Researcher
University of Arizona
Tucson, AZ
Altha Roberts Edgren
Medical Writer
Medical Ink
St. Paul, MN
Karen Ericson, R.N.
Medical Writer
Estes Park, CO
L. Fleming Fallon Jr., M.D.,
Dr.PH
Associate Professor of Public
Health
Bowling Green State University
Bowling Green, OH
Julie A. Gelderloos
Biomedical Writer
Playa del Rey, CA
Gary Gilles, M.A.
Medical Writer
Wauconda, IL
Harry W. Golden
Medical Writer
Shoreline Medical Writers
Old Lyme, CT
Debra Gordon
Medical Writer
Nazareth, PA
Megan Gourley
Writer
Germantown, MD
Faye Fishman, D.O.
Physician
Randolph, NJ
Jill Granger, M.S.
Senior Research Associate
University of Michigan
Ann Arbor, MI
Janis Flores
Medical Writer
Lexikon Communications
Sebastopol, CA
Alison Grant
Medical Writer
Averill Park, NY
Risa Flynn
Medical Writer
Culver City, CA
Paula Ford-Martin
Medical Writer
Chaplin, MN
Stephanie Dionne, B.S.
Medical Writer
Ann Arbor, MI
Janie F. Franz
Writer
Grand Forks, ND
Martin W. Dodge, Ph.D.
Technical Writer/Editor
Centinela Hospital and Medical
Center
Inglewood, CA
Sallie Freeman, Ph.D., B.S.N.
Medical Writer
Atlanta, GA
Elliot Greene, M.A.
former president, American
Massage Therapy Association
Massage Therapist
Silver Spring, MD
Peter Gregutt
Writer
Asheville, NC
Laith F. Gulli, M.D.
M.Sc., M.Sc.(MedSci), M.S.A.,
Msc.Psych, MRSNZ
FRSH, FRIPHH, FAIC, FZS
DAPA, DABFC, DABCI
Consultant Psychotherapist in
Private Practice
Lathrup Village, MI
David Doermann
Medical Writer
Salt Lake City, UT
Rebecca J. Frey, Ph.D.
Research and Administrative
Associate
East Rock Institute
New Haven, CT
Stefanie B. N. Dugan, M.S.
Genetic Counselor
Milwaukee, WI
Cynthia L. Frozena, R.N.
Nurse, Medical Writer
Manitowoc, WI
Maureen Haggerty
Medical Writer
Ambler, PA
Doug Dupler, M.A.
Science Writer
Boulder, CO
Ron Gasbarro, Pharm.D.
Medical Writer
New Milford, PA
Clare Hanrahan
Medical Writer
Asheville, NC
XIV
Kapil Gupta, M.D.
Medical Writer
Winston-Salem, NC
GALE ENCYCLOPEDIA OF MEDICINE 2
Judy C. Hawkins, M.S.
Genetic Counselor
The University of Texas Medical
Branch
Galveston, TX
Caroline Helwick
Medical Writer
New Orleans, LA
David Helwig
Medical Writer
London, Ontario
Lisette Hilton
Medical Writer
Boca Raton, FL
Katherine S. Hunt, M.S.
Genetic Counselor
University of New Mexico Health
Sciences Center
Albuquerque, NM
Kevin Hwang, M.D.
Medical Writer
Morristown, NJ
Holly Ann Ishmael, M.S., C.G.C.
Genetic Counselor
The Children’s Mercy Hospital
Kansas City, MO
West Chester, PA
Beth A. Kapes
Medical Writer
Bay Village, OH
Christine Kuehn Kelly
Medical Writer
Havertown, PA
Bob Kirsch
Medical Writer
Ossining, NY
Joseph Knight, P.A.
Medical Writer
Winton, CA
Melissa Knopper
Medical Writer
Chicago, IL
Karen Krajewski, M.S., C.G.C.
Genetic Counselor
Assistant Professor of Neurology
Wayne State University
Detroit, MI
Jeanne Krob, M.D., F.A.C.S.
Physician, writer
Pittsburgh, PA
Jennifer Lamb
Medical Writer
Spokane, WA
John T. Lohr, Ph.D.
Assistant Director, Biotechnology
Center
Utah State University
Logan, UT
Larry Lutwick, M.D., F.A.C.P.
Director, Infectious Diseases
VA Medical Center
Brooklyn, NY
Suzanne M. Lutwick
Medical Writer
Brooklyn, NY
Nicole Mallory, M.S.
Medical Student
Wayne State University
Detroit, MI
Warren Maltzman, Ph.D.
Consultant, Molecular Pathology
Demarest, NJ
Adrienne Massel, R.N.
Medical Writer
Beloit, WI
Ruth E. Mawyer, R.N.
Medical Writer
Charlottesville, VA
Richard H. Lampert
Senior Medical Editor
W.B. Saunders Co.
Philadelphia, PA
Richard A. McCartney M.D.
Fellow, American College of
Surgeons
Diplomat American Board of
Surgery
Richland, WA
Jeffrey P. Larson, R.P.T.
Physical Therapist
Sabin, MN
Bonny McClain, Ph.D.
Medical Writer
Greensboro, NC
Jill Lasker
Medical Writer
Midlothian, VA
Sally C. McFarlane-Parrott
Medical Writer
Ann Arbor, MI
Paul A. Johnson, Ed.M.
Medical Writer
San Diego, CA
Kristy Layman
Music Therapist
East Lansing, MI
Mercedes McLaughlin
Medical Writer
Phoenixville, CA
Cindy L. A. Jones, Ph.D.
Biomedical Writer
Sagescript Communications
Lakewood, CO
Victor Leipzig, Ph.D.
Biological Consultant
Huntington Beach, CA
Alison McTavish, M.Sc.
Medical Writer and Editor
Montreal, Quebec
Lorraine Lica, Ph.D.
Medical Writer
San Diego, CA
Liz Meszaros
Medical Writer
Lakewood, OH
Dawn A. Jacob, M.S.
Genetic Counselor
Obstetrix Medical Group of Texas
Fort Worth, TX
Sally J. Jacobs, Ed.D.
Medical Writer
Los Angeles, CA
Michelle L. Johnson, M.S., J.D.
Patent Attorney and Medical Writer
Portland, OR
David Kaminstein, M.D.
Medical Writer
GALE ENCYCLOPEDIA OF MEDICINE 2
XV
Contributors
Ann M. Haren
Science Writer
Madison, CT
Contributors
Betty Mishkin
Medical Writer
Skokie, IL
J. Ricker Polsdorfer, M.D.
Medical Writer
Phoenix, AZ
Belinda Rowland, Ph.D.
Medical Writer
Voorheesville, NY
Barbara J. Mitchell
Medical Writer
Hallstead, PA
Scott Polzin, M.S., C.G.C.
Medical Writer
Buffalo Grove, IL
Andrea Ruskin, M.D.
Whittingham Cancer Center
Norwalk, CT
Mark A. Mitchell, M.D.
Medical Writer
Seattle, WA
Elizabeth J. Pulcini, M.S.
Medical Writer
Phoenix, Arizona
Susan J. Montgomery
Medical Writer
Milwaukee, WI
Laura Ruth, Ph.D.
Medical, Science, & Technology
Writer
Los Angeles, CA
Nada Quercia, M.S., C.C.G.C.
Genetic Counselor
Division of Clinical and Metabolic
Genetics
The Hospital for Sick Children
Toronto, ON, Canada
Louann W. Murray, PhD
Medical Writer
Huntington Beach, CA
Bilal Nasser, M.Sc.
Senior Medical Student
Universidad Iberoamericana
Santo Domingo, Domincan
Republic
Ann Quigley
Medical Writer
New York, NY
Laura Ninger
Medical Writer
Weehawken, NJ
Robert Ramirez, B.S.
Medical Student
University of Medicine & Dentistry
of New Jersey
Stratford, NJ
Nancy J. Nordenson
Medical Writer
Minneapolis, MN
Kulbir Rangi, D.O.
Medical Doctor and Writer
New York, NY
Teresa Norris, R.N.
Medical Writer
Ute Park, NM
Esther Csapo Rastegari, Ed.M.,
R.N./B.S.N.
Registered Nurse, Medical Writer
Holbrook, MA
Lisa Papp, R.N.
Medical Writer
Cherry Hill, NJ
Patience Paradox
Medical Writer
Bainbridge Island, WA
Barbara J. Pettersen
Genetic Counselor
Genetic Counseling of Central
Oregon
Bend, OR
Genevieve Pham-Kanter, M.S.
Medical Writer
Chicago, IL
Collette Placek
Medical Writer
Wheaton, IL
XVI
Toni Rizzo
Medical Writer
Salt Lake City, UT
Martha Robbins
Medical Writer
Evanston, IL
Richard Robinson
Medical Writer
Tucson, AZ
Nancy Ross-Flanigan
Science Writer
Belleville, MI
Anna Rovid Spickler, D.V.M.,
Ph.D.
Medical Writer
Moorehead, KY
Karen Sandrick
Medical Writer
Chicago, IL
Kausalya Santhanam, Ph.D.
Technical Writer
Branford, CT
Jason S. Schliesser, D.C.
Chiropractor
Holland Chiropractic, Inc.
Holland, OH
Joan Schonbeck
Medical Writer
Nursing
Massachusetts Department of
Mental Health
Marlborough, MA
Laurie Heron Seaver, M.D.
Clinical Geneticist
Greenwood Genetic Center
Greenwood, SC
Catherine Seeley
Medical Writer
Kristen Mahoney Shannon, M.S.,
C.G.C.
Genetic Counselor
Center for Cancer Risk Analysis
Massachusetts General Hospital
Boston, MA
Kim A. Sharp, M.Ln.
Writer
Richmond, TX
Judith Sims, M.S.
Medical Writer
Logan, UT
Joyce S. Siok, R.N.
Medical Writer
South Windsor, CT
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Liz Swain
Medical Writer
San Diego, CA
Patricia Skinner
Medical Writer
Amman, Jordan
Deanna M. Swartout-Corbeil,
R.N.
Medical Writer
Thompsons Station, TN
Genevieve Slomski, Ph.D.
Medical Writer
New Britain, CT
Stephanie Slon
Medical Writer
Portland, OR
Linda Wasmer Smith
Medical Writer
Albuquerque, NM
Java O. Solis, M.S.
Medical Writer
Decatur, GA
Elaine Souder, PhD
Medical Writer
Little Rock, AR
Jane E. Spehar
Medical Writer
Canton, OH
Lorraine Steefel, R.N.
Medical Writer
Morganville, NJ
Kurt Sternlof
Science Writer
New Rochelle, NY
Roger E. Stevenson, M.D.
Director
Greenwood Genetic Center
Greenwood, SC
Dorothy Stonely
Medical Writer
Los Gatos, CA
Keith Tatarelli, J.D.
Medical Writer
Mary Jane Tenerelli, M.S.
Medical Writer
East Northport, NY
Amy Vance, M.S., C.G.C.
Genetic Counselor
GeneSage, Inc.
San Francisco, CA
Michael Sherwin Walston
Student Researcher
University of Arizona
Tucson, AZ
Ronald Watson, Ph.D.
Science Writer
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Catherine L. Tesla, M.S., C.G.C.
Senior Associate, Faculty
Dept. of Pediatrics, Division of
Medical Genetics
Emory University School of
Medicine
Atlanta, GA
Ellen S. Weber, M.S.N.
Medical Writer
Fort Wayne, IN
Bethany Thivierge
Biotechnical Writer/Editor
Technicality Resources
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Science Writer
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Mai Tran, Pharm.D.
Medical Writer
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Medical Writer
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Judith Turner, B.S.
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Ken R. Wells
Freelance Writer
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Kathleen D. Wright, R.N.
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Medical Advisor
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GALE ENCYCLOPEDIA OF MEDICINE 2
Contributors
Jennifer Sisk
Medical Writer
Havertown, PA
XVII
G
Galactorrhea
Definition
Galactorrhea is the secretion of breast milk in men,
or in women who are not breastfeeding an infant.
Description
Lactation, or the production of breast milk, is a normal condition occurring in women after delivery of a
baby. Many women who have had children may even be
able to express a small amount of breast milk from the
nipple up to two years after childbirth. Galactorrhea, or
hyperlactation, however, is a rare condition that can
occur in both men and women, where a white or grayish
fluid is secreted by the nipples of both breasts. While this
condition is not serious in itself, galactorrhea can indicate more serious conditions, including hormone imbalances or the presence of tumors.
Causes and symptoms
Causes
Galactorrhea is associated with a number of conditions. The normal production of breast milk is controlled
by a hormone called prolactin, which is secreted by the
pituitary gland in the brain. Any condition that upsets the
balance of hormones in the blood or the production of
hormones by the pituitary gland or sexual organs can
stimulate the production of prolactin.
Often, a patient with galactorrhea will have a high
level of prolactin in the blood. A tumor in the pituitary
gland can cause this overproduction of prolactin. At least
30% of women with galactorrhea, menstrual abnormalities, and high prolactin levels have a pituitary gland tumor.
Other types of brain tumors, head injuries, or encephalitis
(an infection of the brain) can also cause galactorrhea.
Tumors or growths in the ovaries or other reproductive organs in women, or in the testicles or related sexual
GALE ENCYCLOPEDIA OF MEDICINE 2
organs of men, can also stimulate the production of prolactin. Any discharge of fluid from the breast after a
woman has passed menopause may indicate breast cancer. However, most often the discharge associated with
breast cancer will be from one breast only. In galactorrhea both breasts are usually involved. The presence of
blood in the fluid discharged from the breast could indicate a benign growth in the breast tissue itself. In approximately 10–15% of patients with blood in the fluid, carcinoma of the breast tissue is present.
A number of medications and drugs can also cause
galactorrhea as a side-effect. Hormonal therapies (like
oral contraceptives), drugs for treatment of depression
or other psychiatric conditions, tranquilizers, morphine,
heroin, and some medications for high blood pressure
can cause galactorrhea.
Several normal physiologic situations can cause production of breast milk. Nipple stimulation in men or
women during sexual intercourse may induce lactation,
for women particularly during or just after pregnancy.
Even after extensive testing, no specific cause can be
determined for some patients with galactorrhea.
Symptoms
The primary symptom of galactorrhea is the discharge of milky fluid from both breasts. In women,
galactorrhea may be associated with infertility, menstrual cycle irregularities, hot flushes, or amenorrhea—a
condition where menstruation stops completely. Men
may experience loss of sexual interest and impotence.
Headaches and visual disturbances have also been associated with some cases of galactorrhea.
Diagnosis
Galactorrhea is generally considered a symptom that
may indicate a more serious problem. Collection of a
thorough medical history, including pregnancies, surgeries, and consumption of drugs and medications is a
1375
Galactosemia
Prognosis
KEY TERMS
Amenorrhea—Abnormal cessation of menstruation.
Bromocriptine—Also known as Parlodel, the main
drug used to treat galactorrhea by reducing levels
of the hormone prolactin.
Hyperlactation—Another term for galactorrhea.
Lactation—The production of breast milk.
first step in diagnosing the cause of galactorrhea. A
physical examination, along with a breast examination,
will usually be conducted. Blood and urine samples may
be taken to determine levels of various hormones in the
body, including prolactin and compounds related to thyroid function.
A mammogram (an x ray of the breast) or an ultrasound scan (using high frequency sound waves) might be
used to determine if there are any tumors or cysts present
in the breasts themselves. If a tumor of the pituitary
gland is suspected, a series of computer assisted x rays
called a computed tomography scan (CT scan) may be
done. Another procedure that may be useful is a magnetic resonance imaging (MRI) scan to locate tumors or
abnormalities in tissues.
Treatment with bromocriptine is usually effective in
stopping milk secretion, however, symptoms may recur if
drug therapy is discontinued. Surgical removal or radiation treatment may correct the problem permanently if it
is related to a tumor. Frequent monitoring of hormone
status and tumor size may be recommended.
Prevention
There is no way to prevent galactorrhea. If the condition is caused by the use of a particular drug, a patient
may be able to switch to a different drug that does not
have the side-effect of galactorrhea.
Resources
BOOKS
Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. Philadelphia: W. B. Saunders Co., 1996.
“Galactorrhea.” In Current Medical Diagnosis & Treatment,
1998. 37th ed. Stamford: Appleton & Lange, 1997.
“Galactorrhea (Hyperprolactinemia).” In Professional Guide to
Diseases. 5th ed. Springhouse, PA: Springhouse Corporation, 1995.
“Galactorrhea.” In The Merck Manual of Diagnosis and Therapy. 16th ed. Ed. Robert Berkow. Rahway, NJ: Merck
Research Laboratories, 1992.
Altha Roberts Edgren
Treatment
Treatment for galactorrhea will depend on the cause
of the condition and the symptoms. The drug bromocriptine is often prescribed first to reduce the secretion of
prolactin and to decrease the size of pituitary tumors.
This drug will control galactorrhea symptoms and in
many cases may be the only therapy necessary. Oral
estrogen and progestins (hormone pills, like birth control
pills) may control symptoms of galactorrhea for some
women. Surgery to remove a tumor may be required for
patients who have more serious symptoms of headache
and vision loss, or if the tumor shows signs of enlargement despite drug treatment. Radiation therapy has also
been used to reduce tumor size when surgery is not possible or not totally successful. A combination of drug,
surgery, and radiation treatment can also be used.
Galactorrhea is more of a nuisance than a real threat
to health. While it is important to find the cause of the
condition, even if a tumor is discovered in the pituitary
gland, it may not require treatment. With very small,
slow-growing tumors, some physicians may suggest a
“wait and see” approach.
1376
Galactosemia
Definition
Galactosemia is an inherited disease in which the
transformation of galactose to glucose is blocked, allowing galactose to increase to toxic levels in the body. If
galactosemia is untreated, high levels of galactose cause
vomiting, diarrhea, lethargy, low blood sugar, brain
damage, jaundice, liver enlargement, cataracts, susceptibility to infection, and death.
Description
Galactosemia is a rare but potentially life-threatening disease that results from the inability to metabolize
galactose. Serious consequences from galactosemia can
be prevented by screening newborns at birth with a simple blood test.
Galactosemia is an inborn error of metabolism.
“Metabolism” refers to all chemical reactions that take
GALE ENCYCLOPEDIA OF MEDICINE 2
Sugars are sometimes called “the energy molecules,” and galactose and glucose are both sugars. For
galactose to be utilized for energy, it must be transformed into something that can enter the metabolic pathway that converts glucose into energy (plus water and
carbon dioxide). This is important for infants because
they typically get most of their nutrient energy from
milk, which contains a high level of galactose. Each
molecule of lactose, the major sugar constituent of milk,
is made up of a molecule of galactose and a molecule of
glucose, and so galactose makes up 20% of the energy
source of a typical infant’s diet.
Three enzymes are required to convert galactose into
glucose-1-phosphate (a phosphorylated glucose that can
enter the metabolic pathway that turns glucose into energy). Each of these three enzymes is encoded by a separate gene. If any of these enzymes fail to function, galactose build-up and galactosemia result. Thus, there are
three types of galactosemia with a different gene responsible for each.
Every cell in a person’s body has two copies of
each gene. Each of the forms of galactosemia is inherited as a recessive trait, which means that galactosemia is
only present in individuals with two mutated copies of
one of the three genes. This also means that carriers,
with only one copy of a gene mutation, will not be
aware that they are carrying a mutation (unless they
have had a genetic test), as it is masked by the normal
gene they also carry and they have no symptoms of the
disease. For each step in the conversion of galactose to
glucose, if only one of the two copies of the gene controlling that step is normal (i.e. for carriers), enough
functional enzyme is made so that the pathway is not
blocked at that step. If a person has galactosemia, both
copies of the gene coding for one of the enzymes
required to convert glucose to galactose are defective
and the pathway becomes blocked. If two carriers of the
same defective gene have children, the chance of any of
their children getting galactosemia (the chance of a
child getting two copies of the defective gene) is 25%
(one in four) for each pregnancy.
Classic galactosemia occurs in the United States
about one in every 50,000–70,000 live births.
GALE ENCYCLOPEDIA OF MEDICINE 2
Causes and symptoms
Galactosemia I
Galactosemia I (also called classic galactosemia),
the first form to be discovered, is caused by defects in
both copies of the gene that codes for an enzyme called
galactose-1-phosphate uridyl transferase (GALT). There
are 30 known different mutations in this gene that cause
GALT to malfunction.
Newborns with galactosemia I appear normal at
birth, but begin to develop symptoms after they are given
milk for the first time. Symptoms include vomiting, diarrhea, lethargy (sluggishness or fatigue), low blood glucose, jaundice (a yellowing of the skin and eyes),
enlarged liver, protein and amino acids in the urine, and
susceptibility to infection, especially from gram negative
bacteria. Cataracts (a grayish white film on the eye lens)
can appear within a few days after birth. People with
galactosemia frequently have symptoms as they grow
older even though they have been given a galactose-free
diet. These symptoms include speech disorders,
cataracts, ovarian atrophy and infertility in females,
learning disabilities, and behavioral problems.
Galactosemia II
Galactosemia II is caused by defects in both copies
of the gene that codes for an enzyme called galactokinase
(GALK). The frequency of occurrence of galactosemia II
is about one in 100,000–155,000 births.
Galactosemia II is less harmful than galactosemia I.
Babies born with galactosemia II will develop cataracts
at an early age unless they are given a galactose-free diet.
They do not generally suffer from liver damage or neurologic disturbances.
Galactosemia III
Galactosemia III is caused by defects in the gene
that codes for an enzyme called uridyl diphosphogalactose-4-epimerase (GALE). This form of galactosemia is
very rare.
There are two forms of galactosemia III, a severe
form, which is exceedingly rare, and a benign form. The
benign form has no symptoms and requires no special
diet. However, newborns with galactosemia III, including
the benign form, have high levels of galactose-1-phosphate that show up on the initial screenings for elevated
galactose and galactose-1-phosphate. This situation illustrates one aspect of the importance of follow-up enzyme
function tests. Tests showing normal levels of GALT and
GALK allow people affected by the benign form of
galactosemia III to enjoy a normal diet.
1377
Galactosemia
place in living organisms. A metabolic pathway is a series
of reactions where the product of each step in the series is
the starting material for the next step. Enzymes are the
chemicals that help the reactions occur. Their ability to
function depends on their structure, and their structure is
determined by the deoxyribonucleic acid (DNA)
sequence of the genes that encode them. Inborn errors of
metabolism are caused by mutations in these genes which
do not allow the enzymes to function properly.
Galactosemia
KEY TERMS
Casein hydrolysate—A preparation made from the
milk protein casein, which is hydrolyzed to break
it down into its constituent amino acids. Amino
acids are the building blocks of proteins.
Catalyst—A substance that changes the rate of a
chemical reaction, but is not physically changed
by the process.
Enzyme—A protein that catalyzes a biochemical
reaction or change without changing its own
structure or function.
Galactose—One of the two simple sugars, together with glucose, that makes up the protein, lactose, found in milk. Galactose can be toxic in high
levels.
Glucose—One of the two simple sugars, together
with galactose, that makes up the protein, lactose,
found in milk. Glucose is the form of sugar that is
usable by the body to generate energy.
Lactose—A sugar made up of of glucose and
galactose. It is the primary sugar in milk.
Metabolic pathway—A sequence of chemical
reactions that lead from some precursor to a product, where the product of each step in the series is
the starting material for the next step.
Metabolism—The total combination of all of the
chemical processes that occur within cells and tissues of a living body.
Recessive trait—An inherited trait or characteristic
that is outwardly obvious only when two copies of
the gene for that trait are present.
The severe form has symptoms similar to those of
galactosemia I, but with more severe neurological problems, including seizures. Only two cases of this rare form
had been reported as of 1997.
Diagnosis
The newborn screening test for classic galactosemia
is quick and straightforward; all but three states require
testing on all newborns. Blood from a baby who is two to
three days old is usually first screened for high levels of
galactose and galactose-1-phosphate. If either of these
compounds is elevated, further tests are performed to
find out which enzymes (GALT, GALK, or GALE) are
present or missing. DNA testing may also be performed
to confirm the diagnosis.
1378
If there is a strong suspicion that a baby has galactosemia, galactose is removed from their diet right away.
In this case, an initial screen for galactose or galactose-1phosphate will be meaningless. In the absence of galactose in the diet, this test will be negative whether the
baby has galactosemia or not. In this case, tests to measure enzyme levels must be given to find out if the suspected baby is indeed galactosemic.
In addition, galactosemic babies who are refusing
milk or vomiting will not have elevated levels of galactose or galactose phosphate, and their condition will not
be detected by the initial screen. Any baby with symptoms of galactosemia (for example, vomiting) should be
given enzyme tests.
Treatment
Galactosemia I and II are treated by removing galactose from the diet. Since galactose is a break-down product of lactose, the primary sugar constituent of milk, this
means all milk and foods containing milk products must
be totally eliminated. Other foods like legumes, organ
meats, and processed meats also contain considerable
galactose and must be avoided. Pills that use lactose as a
filler must also be avoided. Soy-based and casein
hydrolysate-based formulas are recommended for infants
with galactosemia.
Treatment of the severe form of galactosemia III
with a galactose-restricted diet has been tried, but this
disorder is so rare that the long-term effects of this treatment are unknown.
Prognosis
Early detection in the newborn period is the key to
controlling symptoms. Long-term effects in untreated
babies include severe mental retardation, cirrhosis of
the liver, and death. About 75% of the untreated babies
die within the first two weeks of life. On the other hand,
with treatment, a significant proportion of people with
galactosemia I can lead nearly normal lives, although
speech defects, learning disabilities, and behavioral
problems are common. In addition, cataracts due to
galactosemia II can be completely prevented by a galactose-free diet.
Prevention
Since galactosemia is a recessive genetic disease, the
disease is usually detected on a newborn screening test,
since most people are unaware that they are carriers of a
gene mutation causing the disease. For couples with a
previous child with galactosemia, prenatal diagnosis is
available to determine whether a pregnancy is similarly
GALE ENCYCLOPEDIA OF MEDICINE 2
Demographics
About 5,000 people are diagnosed with gallbladder
cancer each year in the United States, making it the fifth
most common gastrointestinal cancer. It is more common
in females than males and most patients are elderly.
Southwest American Indians have a particularly high
incidence—six times that of the general population.
Causes and symptoms
Resources
BOOKS
Ng, Won G., Thomas F. Roe, and George N. Donnell. “Carbohydrate Metabolism.” In Emery and Rimoin’s Principles
and Practice of Medical Genetics, edited by David L.
Rimoin, J. Michael Connor, and Reed E. Pyeritz. 3rd. ed.
New York: Churchill Livingstone, 1998.
ORGANIZATIONS
Association for Neuro-Metabolic Disorders. 5223 Brookfield
Lane, Sylvania, OH 43560. (419) 885-1497.
Metabolic Information Network. PO Box 670847, Dallas, TX
75367-0847. (214) 696-2188 or (800) 945-2188.
Parents of Galactosemic Children, Inc. 2148 Bryton Dr., Powell OH 43065. .
OTHER
“GeneCards: Human Genes, Proteins and Diseases.” .
“Vermont Newborn Screening Program: Galactosemia.” .
Amy Vance, MS, CGC
Gallbladder cancer
Definition
Cancer of the gallbladder is cancer of the pearshaped organ that lies on the undersurface of the liver.
Description
Bile from the liver is funneled into the gallbladder
by way of the cystic duct. Between meals, the gallbladder stores a large amount of bile. To do this, it must
absorb much of the water and electrolytes from the bile.
In fact, the inner surface of the gallbladder is the most
absorptive surface in the body. After a meal, the gallbladder’s muscular walls contract to deliver the bile back
through the cystic duct and eventually into the small
intestine, where the bile can help digest food.
GALE ENCYCLOPEDIA OF MEDICINE 2
Gallstones are the most significant risk factor for
the development of gallbladder cancer. Roughly 75 to 90
percent of patients with gallbladder cancer also have
gallstones. Larger gallstones are associated with a higher
chance of developing gallbladder cancer. Chronic
inflammation of the gallbladder from infection also
increases the risk for gallbladder cancer.
Unfortunately, sometimes cancer of the gallbladder
does not produce symptoms until late in the disease.
When symptoms are evident, the most common is pain
in the upper right portion of the abdomen, underneath the
right ribcage. Patients with gallbladder cancer may also
report symptoms such as nausea, vomiting, weakness,
jaundice, skin itching, fever, chills, poor appetite, and
weight loss.
Diagnosis
Gallbladder cancer is often misdiagnosed because it
mimics other more common conditions, such as gallstones, cholecystitis, and pancreatitis. But the imaging
tests that are utilized to evaluate these other conditions
can also detect gallbladder cancer. For example, ultrasound is a quick, noninvasive imaging test that reliably
diagnoses gallstones and cholecystitis. It can also detect
the presence of gallbladder cancer as well as show how
far the cancer has spread. If cancer is suspected, a computed tomography scan is useful in confirming the presence of an abnormal mass and further demonstrating the
size and extent of the tumor. Cholangiography, usually
performed to evaluate a patient with jaundice, can also
detect gallbladder cancer.
There are no specific laboratory tests for gallbladder
cancer. Tumors can obstruct the normal flow of bile from
the liver to the small intestine. Bilirubin, a component of
bile, builds up within the liver and is absorbed into the
bloodstream in excess amounts. This can be detected in a
blood test, but it can also manifest clinically as jaundice.
Elevated bilirubin levels and clinical jaundice can also
occur with other conditions, such as gallstones.
On occasion, gallbladder cancer is diagnosed incidentally. About one percent of all patients who have their
gallbladder removed for symptomatic gallstones are
1379
Gallbladder cancer
affected. Families in which a child has been diagnosed
with galactosemia can have DNA testing which can
enable other more distant relatives to determine their carrier status. Prospective parents can then use that information to conduct family planning or to prepare for a child
with special circumstances. Children born with galactosemia should be put on a special diet right away, to
reduce the symptoms and complications of the disease.
Gallbladder cancer
KEY TERMS
Cholangiography—Radiographic examination of
the bile ducts after injection with a special dye
Cholecystitis—Inflammation of the gallbladder,
usually due to infection
Computed tomography—A radiology test by
which images of cross-sectional planes of the
body are obtained
Jaundice—Yellowish staining of the skin and eyes
due to excess bilirubin in the bloodstream
Metastasis—The spread of tumor cells from one
part of the body to another through blood vessels
or lymphatic vessels
Pancreatitis—Inflammation of the pancreas
Stent—Slender hollow catheter or rod placed
within a vessel or duct to provide support or maintain patency
Ultrasound—A radiology test utilizing high frequency sound waves
found to have gallbladder cancer. The cancer is found
either by the surgeon or by the pathologist who inspects
the gallbladder with a microscope.
Treatment
Staging of gallbladder cancer is determined by the
how far the cancer has spread. The effectiveness of
treatment declines as the stage progresses. Stage I cancer is confined to the wall of the gallbladder. Approximately 25% of cancers are at this stage at the time of
diagnosis. Stage II cancer has penetrated the full thickness of the wall, but has not spread to nearby lymph
nodes or invaded adjacent organs. Stage III cancer has
spread to nearby lymph nodes or has invaded the liver,
stomach, colon, small intestine, or large intestine. Stage
IV disease has invaded very deeply into two or more
adjacent organs or has spread to distant lymph nodes or
organs by way of metastasis.
Early Stage I cancers involving only the innermost
layer of the gallbladder wall can be cured by simple
removal of the gallbladder. Cancers at this stage are
sometimes found incidentally when the gallbladder is
removed in the treatment of gallstones or cholecystitis.
The majority of patients have good survival rates. Late
Stage I cancers, which involve the outer muscular layers
of the gallbladder wall, are generally treated in the same
way as Stage II or III cancers. Removal of the gallblad1380
der is not sufficient for these stages. The surgeon also
removes nearby lymph nodes as well as a portion of the
adjacent liver (radical surgery). Survival rates for these
patients are considerably worse than for those with early
Stage I disease. Patients with early Stage IV disease may
benefit from radical surgery, but the issue is controversial. Late Stage IV cancer has spread too extensively to
allow complete excision. Surgery is not an option for
these patients.
Other therapies
When long-term survival is not likely, the focus of
therapy shifts to improving quality of life. Jaundice and
blockage of the stomach are two problems faced by
patients with advanced cancer of the gallbladder. These
can be treated with surgery, or alternatively, by special
interventional techniques employed by the gastroenterologist or radiologist. A stent can be placed across the bile
ducts in order to re-establish the flow of bile and relieve
jaundice. A small feeding tube can be placed in the small
intestine to allow feeding when the stomach is blocked.
Pain may be treated with conventional pain medicines or
a celiac ganglion nerve block.
Current chemotherapy or radiation therapy cannot cure gallbladder cancer, but they may offer some
benefit in certain patients. For cancer that is too
advanced for surgical cure, treatment with chemotherapeutic agents such as 5-fluorouracil may lengthen survival for a few months. The limited benefit of chemotherapy must be weighed carefully against its side effects.
Radiation therapy is sometimes used after attempted surgical resection of the cancer to extend survival for a few
months or relieve jaundice.
Resources
BOOKS
Ahrendt, Steven A. and Henry
ENCYCLOPEDIA
of MEDICINE
SECOND EDITION
The GALE
ENCYCLOPEDIA
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SECOND EDITION
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G-M
JACQUELINE L. LONGE, EDITOR
D E I R D R E S . B L A N C H F I E L D , A S S O C I AT E E D I T O R
The GALE
ENCYCLOPEDIA
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CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Advisory Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Entries
Volume 1: A-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Volume 2: C-F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Volume 3: G-M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1375
Volume 4: N-S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2307
Volume 5: T-Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3237
Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3603
General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3625
GALE ENCYCLOPEDIA OF MEDICINE 2
V
PLEASE READ—IMPORTANT INFORMATION
The Gale Encyclopedia of Medicine 2 is a medical reference product designed to inform and educate readers
about a wide variety of disorders, conditions, treatments,
and diagnostic tests. The Gale Group believes the product
to be comprehensive, but not necessarily definitive. It is
intended to supplement, not replace, consultation with a
physician or other healthcare practitioner. While the Gale
Group has made substantial efforts to provide information
that is accurate, comprehensive, and up-to-date, the Gale
Group makes no representations or warranties of any
GALE ENCYCLOPEDIA OF MEDICINE 2
kind, including without limitation, warranties of merchantability or fitness for a particular purpose, nor does it
guarantee the accuracy, comprehensiveness, or timeliness
of the information contained in this product. Readers
should be aware that the universe of medical knowledge
is constantly growing and changing, and that differences
of medical opinion exist among authorities. Readers are
also advised to seek professional diagnosis and treatment
for any medical condition, and to discuss information
obtained from this book with their health care provider.
VII
INTRODUCTION
The Gale Encyclopedia of Medicine 2 (GEM2) is a
one-stop source for medical information on nearly 1,700
common medical disorders, conditions, tests, and treatments, including high-profile diseases such as AIDS,
Alzheimer’s disease, cancer, and heart attack. This encyclopedia avoids medical jargon and uses language that
laypersons can understand, while still providing thorough coverage of each topic. The Gale Encyclopedia of
Medicine 2 fills a gap between basic consumer health
resources, such as single-volume family medical guides,
and highly technical professional materials.
SCOPE
Almost 1,700 full-length articles are included in the
Gale Encyclopedia of Medicine 2, including disorders/
conditions, tests/procedures, and treatments/therapies.
Many common drugs are also covered, with generic drug
names appearing first and brand names following in
parentheses, eg. acetaminophen (Tylenol). Throughout
the Gale Encyclopedia of Medicine 2, many prominent
individuals are highlighted as sidebar biographies that
accompany the main topical essays. Articles follow a
standardized format that provides information at a
glance. Rubrics include:
Disorders/Conditions
Tests/Treatments
Definition
Description
Causes and symptoms
Diagnosis
Treatment
Alternative treatment
Prognosis
Prevention
Resources
Key terms
Definition
Purpose
Precautions
Description
Preparation
Aftercare
Risks
Normal/Abnormal results
Resources
Key terms
In recent years there has been a resurgence of interest
in holistic medicine that emphasizes the connection
between mind and body. Aimed at achieving and maintaining good health rather than just eliminating disease,
GALE ENCYCLOPEDIA OF MEDICINE 2
this approach has come to be known as alternative medicine. The Gale Encyclopedia of Medicine 2 includes a
number of essays on alternative therapies, ranging from
traditional Chinese medicine to homeopathy and from
meditation to aromatherapy. In addition to full essays on
alternative therapies, the encyclopedia features specific
Alternative treatment sections for diseases and conditions that may be helped by complementary therapies.
INCLUSION CRITERIA
A preliminary list of diseases, disorders, tests and treatments was compiled from a wide variety of sources,
including professional medical guides and textbooks as
well as consumer guides and encyclopedias. The general
advisory board, made up of public librarians, medical
librarians and consumer health experts, evaluated the topics and made suggestions for inclusion. The list was sorted
by category and sent to GEM2 medical advisors, certified
physicians with various medical specialities, for review.
Final selection of topics to include was made by the medical advisors in conjunction with the Gale Group editor.
ABOUT THE CONTRIBUTORS
The essays were compiled by experienced medical
writers, including physicians, pharmacists, nurses, and
other health care professionals. GEM2 medical advisors
reviewed the completed essays to insure that they are
appropriate, up-to-date, and medically accurate.
HOW TO USE THIS BOOK
The Gale Encyclopedia of Medicine 2 has been
designed with ready reference in mind.
• Straight alphabetical arrangement allows users to
locate information quickly.
• Bold-faced terms function as print hyperlinks that
point the reader to related entries in the encyclopedia.
IX
Introduction
• Cross-references placed throughout the encyclopedia
direct readers to where information on subjects without entries can be found. Synonyms are also cross-referenced.
• A list of key terms are provided where appropriate to
define unfamiliar terms or concepts.
• Valuable contact information for organizations and
support groups is included with each entry. The
appendix contains an extensive list of organizations
arranged in alphabetical order.
X
• Resources section directs users to additional sources
of medical information on a topic.
• A comprehensive general index allows users to easily
target detailed aspects of any topic, including Latin
names.
GRAPHICS
The Gale Encyclopedia of Medicine 2 is enhanced
with over 675 color images, including photos, charts,
tables, and customized line drawings.
GALE ENCYCLOPEDIA OF MEDICINE 2
ADVISORY BOARD
A number of experts in the library and medical communities provided invaluable assistance in the formulation of this encyclopedia. Our advisory board performed a myriad of duties, from defining the scope of coverage to reviewing individual
entries for accuracy and accessibility. The editor would like to express her appreciation to them.
MEDICAL ADVISORS
A. Richard Adrouny, M.D.,
F.A.C.P.
Clinical Assistant Professor of
Medicine
Division of Oncology
Stanford University
Director of Medical Oncology
Community Hospital of Los GatosSaratoga
Los Gatos, CA
Laurie Barclay, M.D.
Neurological Consulting Services
Tampa, FL
Kenneth J. Berniker, M.D.
Attending Physician
Emergency Department
Kaiser Permanente Medical Center
Vallejo, CA
Rosalyn Carson-DeWitt, M.D.
Durham, NC
Robin Dipasquale, N.D.
Clinical Faculty
Bastyr University
Seattle, WA
Faye Fishman, D.O.
Randolph, NJ
J. Gary Grant, M.D.
Pacific Grove, CA
Laith F. Gulli, M.D.
M.Sc., M.Sc.(MedSci), MSA,
Msc.Psych., MRSNZ
FRSH, FRIPHH, FAIC, FZS
DAPA, DABFC, DABCI
Consultant Psychotherapist in
Private Practice
Lathrup Village, MI
L. Anne Hirschel, D.D.S.
Southfield, MI
Larry I. Lutwick M.D., F.A.C.P.
Director, Infectious Diseases
VA Medical Center
Brooklyn, NY
Ira Michelson, M.D., M.B.A.,
F.A.C.O.G.
Physician and Clinical Instructor
University of Michigan
Ann Arbor, MI
Susan Mockus, M.D.
Scientific Consultant
Seattle, WA
Ralph M. Myerson, M.D.,
F.A.C.P.
Clinical Professor of Medicine
Medical College of Pennsylvania–
Hahnemann University
Philadelphia, PA
Ronald Pies, M.D.
Clinical Professor of Psychiatry
Tufts University
School of Medicine
Boston, MA
The Permanente Medical Group
Richmond, CA
Amy B. Tuteur, M.D.
Sharon, MA
LIBRARIAN ADVISORS
Maureen O. Carleton, MLIS
Medical Reference Specialist
King County Library System
Bellevue, WA
Elizabeth Clewis Crim, MLS
Collection Specialist
Prince William Public Library, VA
Valerie J. Lawrence, MLS
Assistant Librarian
Western States Chiropractic
College
Portland, OR
Barbara J. O’Hara, MLS
Adult Services Librarian
Free Library of Philadelphia, PA
Alan M. Rees, MLS
Professor Emeritus
Case Western Reserve University
Cleveland, OH
Lecturer on Psychiatry
Harvard Medical School
Cambridge, MA
Lee A. Shratter, M.D.
Staff Radiologist
GALE ENCYCLOPEDIA OF MEDICINE 2
XI
CONTRIBUTORS
Margaret Alic, Ph.D.
Science Writer
Eastsound, WA
Donald G. Barstow, R.N.
Clincal Nurse Specialist
Oklahoma City, OK
Maury M. Breecher, Ph.D.
Health Communicator/Journalist
Northport, AL
Janet Byron Anderson
Linguist/Language Consultant
Rocky River, OH
Carin Lea Beltz, M.S.
Genetic Counselor and Program
Director
The Center for Genetic Counseling
Indianapolis, IN
Ruthan Brodsky
Medical Writer
Bloomfield Hills, MI
Lisa Andres, M.S., C.G.C.
Certified Genetic Counselor and
Medical Writer
San Jose, CA
Greg Annussek
Medical Writer/Editor
New York, NY
Bill Asenjo, M.S., C.R.C.
Science Writer
Iowa City, IA
Sharon A. Aufox, M.S., C.G.C.
Genetic Counselor
Rockford Memorial Hospital
Rockford, IL
Linda K. Bennington, C.N.S.
Science Writer
Virginia Beach, VA
Issac R. Berniker
Medical Writer
Vallejo, CA
Kathleen Berrisford, M.S.V.
Science Writer
Bethanne Black
Medical Writer
Atlanta, GA
Sandra Bain Cushman
Massage Therapist, Alexander
Technique Practitioner
Charlottesville, VA
Jennifer Bowjanowski, M.S.,
C.G.C.
Genetic Counselor
Children’s Hospital Oakland
Oakland, CA
Howard Baker
Medical Writer
North York, Ontario
Michelle Q. Bosworth, M.S., C.G.C.
Genetic Counselor
Eugene, OR
Laurie Barclay, M.D.
Neurological Consulting Services
Tampa, FL
Barbara Boughton
Health and Medical Writer
El Cerrito, CA
Jeanine Barone
Nutritionist, Exercise Physiologist
New York, NY
Cheryl Branche, M.D.
Retired General Practitioner
Jackson, MS
Julia R. Barrett
Science Writer
Madison, WI
Michelle Lee Brandt
Medical Writer
San Francisco, CA
GALE ENCYCLOPEDIA OF MEDICINE 2
Tom Brody, Ph.D.
Science Writer
Berkeley, CA
Leonard C. Bruno, Ph.D.
Medical Writer
Chevy Chase, MD
Diane Calbrese
Medical Sciences and Technology
Writer
Silver Spring, Maryland
Richard H. Camer
Editor
International Medical News Group
Silver Spring, MD
Rosalyn Carson-DeWitt, M.D.
Medical Writer
Durham, NC
Lata Cherath, Ph.D.
Science Writing Intern
Cancer Research Institute
New York, NY
Linda Chrisman
Massage Therapist and Educator
Oakland, CA
Lisa Christenson, Ph.D.
Science Writer
Hamden, CT
Geoffrey N. Clark, D.V.M.
Editor
Canine Sports Medicine Update
Newmarket, NH
XIII
Contributors
Rhonda Cloos, R.N.
Medical Writer
Austin, TX
Gloria Cooksey, C.N.E
Medical Writer
Sacramento, CA
Amy Cooper, M.A., M.S.I.
Medical Writer
Vermillion, SD
David A. Cramer, M.D.
Medical Writer
Chicago, IL
Esther Csapo Rastega, R.N., B.S.N.
Medical Writer
Holbrook, MA
Arnold Cua, M.D.
Physician
Brooklyn, NY
Tish Davidson, A.M.
Medical Writer
Fremont, California
Dominic De Bellis, Ph.D.
Medical Writer/Editor
Mahopac, NY
Lori De Milto
Medical Writer
Sicklerville, NJ
Robert S. Dinsmoor
Medical Writer
South Hamilton, MA
Thomas Scott Eagan
Student Researcher
University of Arizona
Tucson, AZ
Altha Roberts Edgren
Medical Writer
Medical Ink
St. Paul, MN
Karen Ericson, R.N.
Medical Writer
Estes Park, CO
L. Fleming Fallon Jr., M.D.,
Dr.PH
Associate Professor of Public
Health
Bowling Green State University
Bowling Green, OH
Julie A. Gelderloos
Biomedical Writer
Playa del Rey, CA
Gary Gilles, M.A.
Medical Writer
Wauconda, IL
Harry W. Golden
Medical Writer
Shoreline Medical Writers
Old Lyme, CT
Debra Gordon
Medical Writer
Nazareth, PA
Megan Gourley
Writer
Germantown, MD
Faye Fishman, D.O.
Physician
Randolph, NJ
Jill Granger, M.S.
Senior Research Associate
University of Michigan
Ann Arbor, MI
Janis Flores
Medical Writer
Lexikon Communications
Sebastopol, CA
Alison Grant
Medical Writer
Averill Park, NY
Risa Flynn
Medical Writer
Culver City, CA
Paula Ford-Martin
Medical Writer
Chaplin, MN
Stephanie Dionne, B.S.
Medical Writer
Ann Arbor, MI
Janie F. Franz
Writer
Grand Forks, ND
Martin W. Dodge, Ph.D.
Technical Writer/Editor
Centinela Hospital and Medical
Center
Inglewood, CA
Sallie Freeman, Ph.D., B.S.N.
Medical Writer
Atlanta, GA
Elliot Greene, M.A.
former president, American
Massage Therapy Association
Massage Therapist
Silver Spring, MD
Peter Gregutt
Writer
Asheville, NC
Laith F. Gulli, M.D.
M.Sc., M.Sc.(MedSci), M.S.A.,
Msc.Psych, MRSNZ
FRSH, FRIPHH, FAIC, FZS
DAPA, DABFC, DABCI
Consultant Psychotherapist in
Private Practice
Lathrup Village, MI
David Doermann
Medical Writer
Salt Lake City, UT
Rebecca J. Frey, Ph.D.
Research and Administrative
Associate
East Rock Institute
New Haven, CT
Stefanie B. N. Dugan, M.S.
Genetic Counselor
Milwaukee, WI
Cynthia L. Frozena, R.N.
Nurse, Medical Writer
Manitowoc, WI
Maureen Haggerty
Medical Writer
Ambler, PA
Doug Dupler, M.A.
Science Writer
Boulder, CO
Ron Gasbarro, Pharm.D.
Medical Writer
New Milford, PA
Clare Hanrahan
Medical Writer
Asheville, NC
XIV
Kapil Gupta, M.D.
Medical Writer
Winston-Salem, NC
GALE ENCYCLOPEDIA OF MEDICINE 2
Judy C. Hawkins, M.S.
Genetic Counselor
The University of Texas Medical
Branch
Galveston, TX
Caroline Helwick
Medical Writer
New Orleans, LA
David Helwig
Medical Writer
London, Ontario
Lisette Hilton
Medical Writer
Boca Raton, FL
Katherine S. Hunt, M.S.
Genetic Counselor
University of New Mexico Health
Sciences Center
Albuquerque, NM
Kevin Hwang, M.D.
Medical Writer
Morristown, NJ
Holly Ann Ishmael, M.S., C.G.C.
Genetic Counselor
The Children’s Mercy Hospital
Kansas City, MO
West Chester, PA
Beth A. Kapes
Medical Writer
Bay Village, OH
Christine Kuehn Kelly
Medical Writer
Havertown, PA
Bob Kirsch
Medical Writer
Ossining, NY
Joseph Knight, P.A.
Medical Writer
Winton, CA
Melissa Knopper
Medical Writer
Chicago, IL
Karen Krajewski, M.S., C.G.C.
Genetic Counselor
Assistant Professor of Neurology
Wayne State University
Detroit, MI
Jeanne Krob, M.D., F.A.C.S.
Physician, writer
Pittsburgh, PA
Jennifer Lamb
Medical Writer
Spokane, WA
John T. Lohr, Ph.D.
Assistant Director, Biotechnology
Center
Utah State University
Logan, UT
Larry Lutwick, M.D., F.A.C.P.
Director, Infectious Diseases
VA Medical Center
Brooklyn, NY
Suzanne M. Lutwick
Medical Writer
Brooklyn, NY
Nicole Mallory, M.S.
Medical Student
Wayne State University
Detroit, MI
Warren Maltzman, Ph.D.
Consultant, Molecular Pathology
Demarest, NJ
Adrienne Massel, R.N.
Medical Writer
Beloit, WI
Ruth E. Mawyer, R.N.
Medical Writer
Charlottesville, VA
Richard H. Lampert
Senior Medical Editor
W.B. Saunders Co.
Philadelphia, PA
Richard A. McCartney M.D.
Fellow, American College of
Surgeons
Diplomat American Board of
Surgery
Richland, WA
Jeffrey P. Larson, R.P.T.
Physical Therapist
Sabin, MN
Bonny McClain, Ph.D.
Medical Writer
Greensboro, NC
Jill Lasker
Medical Writer
Midlothian, VA
Sally C. McFarlane-Parrott
Medical Writer
Ann Arbor, MI
Paul A. Johnson, Ed.M.
Medical Writer
San Diego, CA
Kristy Layman
Music Therapist
East Lansing, MI
Mercedes McLaughlin
Medical Writer
Phoenixville, CA
Cindy L. A. Jones, Ph.D.
Biomedical Writer
Sagescript Communications
Lakewood, CO
Victor Leipzig, Ph.D.
Biological Consultant
Huntington Beach, CA
Alison McTavish, M.Sc.
Medical Writer and Editor
Montreal, Quebec
Lorraine Lica, Ph.D.
Medical Writer
San Diego, CA
Liz Meszaros
Medical Writer
Lakewood, OH
Dawn A. Jacob, M.S.
Genetic Counselor
Obstetrix Medical Group of Texas
Fort Worth, TX
Sally J. Jacobs, Ed.D.
Medical Writer
Los Angeles, CA
Michelle L. Johnson, M.S., J.D.
Patent Attorney and Medical Writer
Portland, OR
David Kaminstein, M.D.
Medical Writer
GALE ENCYCLOPEDIA OF MEDICINE 2
XV
Contributors
Ann M. Haren
Science Writer
Madison, CT
Contributors
Betty Mishkin
Medical Writer
Skokie, IL
J. Ricker Polsdorfer, M.D.
Medical Writer
Phoenix, AZ
Belinda Rowland, Ph.D.
Medical Writer
Voorheesville, NY
Barbara J. Mitchell
Medical Writer
Hallstead, PA
Scott Polzin, M.S., C.G.C.
Medical Writer
Buffalo Grove, IL
Andrea Ruskin, M.D.
Whittingham Cancer Center
Norwalk, CT
Mark A. Mitchell, M.D.
Medical Writer
Seattle, WA
Elizabeth J. Pulcini, M.S.
Medical Writer
Phoenix, Arizona
Susan J. Montgomery
Medical Writer
Milwaukee, WI
Laura Ruth, Ph.D.
Medical, Science, & Technology
Writer
Los Angeles, CA
Nada Quercia, M.S., C.C.G.C.
Genetic Counselor
Division of Clinical and Metabolic
Genetics
The Hospital for Sick Children
Toronto, ON, Canada
Louann W. Murray, PhD
Medical Writer
Huntington Beach, CA
Bilal Nasser, M.Sc.
Senior Medical Student
Universidad Iberoamericana
Santo Domingo, Domincan
Republic
Ann Quigley
Medical Writer
New York, NY
Laura Ninger
Medical Writer
Weehawken, NJ
Robert Ramirez, B.S.
Medical Student
University of Medicine & Dentistry
of New Jersey
Stratford, NJ
Nancy J. Nordenson
Medical Writer
Minneapolis, MN
Kulbir Rangi, D.O.
Medical Doctor and Writer
New York, NY
Teresa Norris, R.N.
Medical Writer
Ute Park, NM
Esther Csapo Rastegari, Ed.M.,
R.N./B.S.N.
Registered Nurse, Medical Writer
Holbrook, MA
Lisa Papp, R.N.
Medical Writer
Cherry Hill, NJ
Patience Paradox
Medical Writer
Bainbridge Island, WA
Barbara J. Pettersen
Genetic Counselor
Genetic Counseling of Central
Oregon
Bend, OR
Genevieve Pham-Kanter, M.S.
Medical Writer
Chicago, IL
Collette Placek
Medical Writer
Wheaton, IL
XVI
Toni Rizzo
Medical Writer
Salt Lake City, UT
Martha Robbins
Medical Writer
Evanston, IL
Richard Robinson
Medical Writer
Tucson, AZ
Nancy Ross-Flanigan
Science Writer
Belleville, MI
Anna Rovid Spickler, D.V.M.,
Ph.D.
Medical Writer
Moorehead, KY
Karen Sandrick
Medical Writer
Chicago, IL
Kausalya Santhanam, Ph.D.
Technical Writer
Branford, CT
Jason S. Schliesser, D.C.
Chiropractor
Holland Chiropractic, Inc.
Holland, OH
Joan Schonbeck
Medical Writer
Nursing
Massachusetts Department of
Mental Health
Marlborough, MA
Laurie Heron Seaver, M.D.
Clinical Geneticist
Greenwood Genetic Center
Greenwood, SC
Catherine Seeley
Medical Writer
Kristen Mahoney Shannon, M.S.,
C.G.C.
Genetic Counselor
Center for Cancer Risk Analysis
Massachusetts General Hospital
Boston, MA
Kim A. Sharp, M.Ln.
Writer
Richmond, TX
Judith Sims, M.S.
Medical Writer
Logan, UT
Joyce S. Siok, R.N.
Medical Writer
South Windsor, CT
GALE ENCYCLOPEDIA OF MEDICINE 2
Liz Swain
Medical Writer
San Diego, CA
Patricia Skinner
Medical Writer
Amman, Jordan
Deanna M. Swartout-Corbeil,
R.N.
Medical Writer
Thompsons Station, TN
Genevieve Slomski, Ph.D.
Medical Writer
New Britain, CT
Stephanie Slon
Medical Writer
Portland, OR
Linda Wasmer Smith
Medical Writer
Albuquerque, NM
Java O. Solis, M.S.
Medical Writer
Decatur, GA
Elaine Souder, PhD
Medical Writer
Little Rock, AR
Jane E. Spehar
Medical Writer
Canton, OH
Lorraine Steefel, R.N.
Medical Writer
Morganville, NJ
Kurt Sternlof
Science Writer
New Rochelle, NY
Roger E. Stevenson, M.D.
Director
Greenwood Genetic Center
Greenwood, SC
Dorothy Stonely
Medical Writer
Los Gatos, CA
Keith Tatarelli, J.D.
Medical Writer
Mary Jane Tenerelli, M.S.
Medical Writer
East Northport, NY
Amy Vance, M.S., C.G.C.
Genetic Counselor
GeneSage, Inc.
San Francisco, CA
Michael Sherwin Walston
Student Researcher
University of Arizona
Tucson, AZ
Ronald Watson, Ph.D.
Science Writer
Tucson, AZ
Catherine L. Tesla, M.S., C.G.C.
Senior Associate, Faculty
Dept. of Pediatrics, Division of
Medical Genetics
Emory University School of
Medicine
Atlanta, GA
Ellen S. Weber, M.S.N.
Medical Writer
Fort Wayne, IN
Bethany Thivierge
Biotechnical Writer/Editor
Technicality Resources
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Jennifer F. Wilson, M.S.
Science Writer
Haddonfield, NJ
Mai Tran, Pharm.D.
Medical Writer
Troy, MI
Carol Turkington
Medical Writer
Lancaster, PA
Judith Turner, B.S.
Medical Writer
Sandy, UT
Ken R. Wells
Freelance Writer
Laguna Hills, CA
Kathleen D. Wright, R.N.
Medical Writer
Delmar, DE
Jennifer Wurges
Medical Writer
Rochester Hills, MI
Mary Zoll, Ph.D.
Science Writer
Newton Center, MA
Amy B. Tuteur, M.D.
Medical Advisor
Sharon, MA
Jon Zonderman
Medical Writer
Orange, CA
Samuel Uretsky, Pharm.D.
Medical Writer
Wantagh, NY
Michael V. Zuck, Ph.D.
Medical Writer
Boulder, CO
GALE ENCYCLOPEDIA OF MEDICINE 2
Contributors
Jennifer Sisk
Medical Writer
Havertown, PA
XVII
G
Galactorrhea
Definition
Galactorrhea is the secretion of breast milk in men,
or in women who are not breastfeeding an infant.
Description
Lactation, or the production of breast milk, is a normal condition occurring in women after delivery of a
baby. Many women who have had children may even be
able to express a small amount of breast milk from the
nipple up to two years after childbirth. Galactorrhea, or
hyperlactation, however, is a rare condition that can
occur in both men and women, where a white or grayish
fluid is secreted by the nipples of both breasts. While this
condition is not serious in itself, galactorrhea can indicate more serious conditions, including hormone imbalances or the presence of tumors.
Causes and symptoms
Causes
Galactorrhea is associated with a number of conditions. The normal production of breast milk is controlled
by a hormone called prolactin, which is secreted by the
pituitary gland in the brain. Any condition that upsets the
balance of hormones in the blood or the production of
hormones by the pituitary gland or sexual organs can
stimulate the production of prolactin.
Often, a patient with galactorrhea will have a high
level of prolactin in the blood. A tumor in the pituitary
gland can cause this overproduction of prolactin. At least
30% of women with galactorrhea, menstrual abnormalities, and high prolactin levels have a pituitary gland tumor.
Other types of brain tumors, head injuries, or encephalitis
(an infection of the brain) can also cause galactorrhea.
Tumors or growths in the ovaries or other reproductive organs in women, or in the testicles or related sexual
GALE ENCYCLOPEDIA OF MEDICINE 2
organs of men, can also stimulate the production of prolactin. Any discharge of fluid from the breast after a
woman has passed menopause may indicate breast cancer. However, most often the discharge associated with
breast cancer will be from one breast only. In galactorrhea both breasts are usually involved. The presence of
blood in the fluid discharged from the breast could indicate a benign growth in the breast tissue itself. In approximately 10–15% of patients with blood in the fluid, carcinoma of the breast tissue is present.
A number of medications and drugs can also cause
galactorrhea as a side-effect. Hormonal therapies (like
oral contraceptives), drugs for treatment of depression
or other psychiatric conditions, tranquilizers, morphine,
heroin, and some medications for high blood pressure
can cause galactorrhea.
Several normal physiologic situations can cause production of breast milk. Nipple stimulation in men or
women during sexual intercourse may induce lactation,
for women particularly during or just after pregnancy.
Even after extensive testing, no specific cause can be
determined for some patients with galactorrhea.
Symptoms
The primary symptom of galactorrhea is the discharge of milky fluid from both breasts. In women,
galactorrhea may be associated with infertility, menstrual cycle irregularities, hot flushes, or amenorrhea—a
condition where menstruation stops completely. Men
may experience loss of sexual interest and impotence.
Headaches and visual disturbances have also been associated with some cases of galactorrhea.
Diagnosis
Galactorrhea is generally considered a symptom that
may indicate a more serious problem. Collection of a
thorough medical history, including pregnancies, surgeries, and consumption of drugs and medications is a
1375
Galactosemia
Prognosis
KEY TERMS
Amenorrhea—Abnormal cessation of menstruation.
Bromocriptine—Also known as Parlodel, the main
drug used to treat galactorrhea by reducing levels
of the hormone prolactin.
Hyperlactation—Another term for galactorrhea.
Lactation—The production of breast milk.
first step in diagnosing the cause of galactorrhea. A
physical examination, along with a breast examination,
will usually be conducted. Blood and urine samples may
be taken to determine levels of various hormones in the
body, including prolactin and compounds related to thyroid function.
A mammogram (an x ray of the breast) or an ultrasound scan (using high frequency sound waves) might be
used to determine if there are any tumors or cysts present
in the breasts themselves. If a tumor of the pituitary
gland is suspected, a series of computer assisted x rays
called a computed tomography scan (CT scan) may be
done. Another procedure that may be useful is a magnetic resonance imaging (MRI) scan to locate tumors or
abnormalities in tissues.
Treatment with bromocriptine is usually effective in
stopping milk secretion, however, symptoms may recur if
drug therapy is discontinued. Surgical removal or radiation treatment may correct the problem permanently if it
is related to a tumor. Frequent monitoring of hormone
status and tumor size may be recommended.
Prevention
There is no way to prevent galactorrhea. If the condition is caused by the use of a particular drug, a patient
may be able to switch to a different drug that does not
have the side-effect of galactorrhea.
Resources
BOOKS
Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. Philadelphia: W. B. Saunders Co., 1996.
“Galactorrhea.” In Current Medical Diagnosis & Treatment,
1998. 37th ed. Stamford: Appleton & Lange, 1997.
“Galactorrhea (Hyperprolactinemia).” In Professional Guide to
Diseases. 5th ed. Springhouse, PA: Springhouse Corporation, 1995.
“Galactorrhea.” In The Merck Manual of Diagnosis and Therapy. 16th ed. Ed. Robert Berkow. Rahway, NJ: Merck
Research Laboratories, 1992.
Altha Roberts Edgren
Treatment
Treatment for galactorrhea will depend on the cause
of the condition and the symptoms. The drug bromocriptine is often prescribed first to reduce the secretion of
prolactin and to decrease the size of pituitary tumors.
This drug will control galactorrhea symptoms and in
many cases may be the only therapy necessary. Oral
estrogen and progestins (hormone pills, like birth control
pills) may control symptoms of galactorrhea for some
women. Surgery to remove a tumor may be required for
patients who have more serious symptoms of headache
and vision loss, or if the tumor shows signs of enlargement despite drug treatment. Radiation therapy has also
been used to reduce tumor size when surgery is not possible or not totally successful. A combination of drug,
surgery, and radiation treatment can also be used.
Galactorrhea is more of a nuisance than a real threat
to health. While it is important to find the cause of the
condition, even if a tumor is discovered in the pituitary
gland, it may not require treatment. With very small,
slow-growing tumors, some physicians may suggest a
“wait and see” approach.
1376
Galactosemia
Definition
Galactosemia is an inherited disease in which the
transformation of galactose to glucose is blocked, allowing galactose to increase to toxic levels in the body. If
galactosemia is untreated, high levels of galactose cause
vomiting, diarrhea, lethargy, low blood sugar, brain
damage, jaundice, liver enlargement, cataracts, susceptibility to infection, and death.
Description
Galactosemia is a rare but potentially life-threatening disease that results from the inability to metabolize
galactose. Serious consequences from galactosemia can
be prevented by screening newborns at birth with a simple blood test.
Galactosemia is an inborn error of metabolism.
“Metabolism” refers to all chemical reactions that take
GALE ENCYCLOPEDIA OF MEDICINE 2
Sugars are sometimes called “the energy molecules,” and galactose and glucose are both sugars. For
galactose to be utilized for energy, it must be transformed into something that can enter the metabolic pathway that converts glucose into energy (plus water and
carbon dioxide). This is important for infants because
they typically get most of their nutrient energy from
milk, which contains a high level of galactose. Each
molecule of lactose, the major sugar constituent of milk,
is made up of a molecule of galactose and a molecule of
glucose, and so galactose makes up 20% of the energy
source of a typical infant’s diet.
Three enzymes are required to convert galactose into
glucose-1-phosphate (a phosphorylated glucose that can
enter the metabolic pathway that turns glucose into energy). Each of these three enzymes is encoded by a separate gene. If any of these enzymes fail to function, galactose build-up and galactosemia result. Thus, there are
three types of galactosemia with a different gene responsible for each.
Every cell in a person’s body has two copies of
each gene. Each of the forms of galactosemia is inherited as a recessive trait, which means that galactosemia is
only present in individuals with two mutated copies of
one of the three genes. This also means that carriers,
with only one copy of a gene mutation, will not be
aware that they are carrying a mutation (unless they
have had a genetic test), as it is masked by the normal
gene they also carry and they have no symptoms of the
disease. For each step in the conversion of galactose to
glucose, if only one of the two copies of the gene controlling that step is normal (i.e. for carriers), enough
functional enzyme is made so that the pathway is not
blocked at that step. If a person has galactosemia, both
copies of the gene coding for one of the enzymes
required to convert glucose to galactose are defective
and the pathway becomes blocked. If two carriers of the
same defective gene have children, the chance of any of
their children getting galactosemia (the chance of a
child getting two copies of the defective gene) is 25%
(one in four) for each pregnancy.
Classic galactosemia occurs in the United States
about one in every 50,000–70,000 live births.
GALE ENCYCLOPEDIA OF MEDICINE 2
Causes and symptoms
Galactosemia I
Galactosemia I (also called classic galactosemia),
the first form to be discovered, is caused by defects in
both copies of the gene that codes for an enzyme called
galactose-1-phosphate uridyl transferase (GALT). There
are 30 known different mutations in this gene that cause
GALT to malfunction.
Newborns with galactosemia I appear normal at
birth, but begin to develop symptoms after they are given
milk for the first time. Symptoms include vomiting, diarrhea, lethargy (sluggishness or fatigue), low blood glucose, jaundice (a yellowing of the skin and eyes),
enlarged liver, protein and amino acids in the urine, and
susceptibility to infection, especially from gram negative
bacteria. Cataracts (a grayish white film on the eye lens)
can appear within a few days after birth. People with
galactosemia frequently have symptoms as they grow
older even though they have been given a galactose-free
diet. These symptoms include speech disorders,
cataracts, ovarian atrophy and infertility in females,
learning disabilities, and behavioral problems.
Galactosemia II
Galactosemia II is caused by defects in both copies
of the gene that codes for an enzyme called galactokinase
(GALK). The frequency of occurrence of galactosemia II
is about one in 100,000–155,000 births.
Galactosemia II is less harmful than galactosemia I.
Babies born with galactosemia II will develop cataracts
at an early age unless they are given a galactose-free diet.
They do not generally suffer from liver damage or neurologic disturbances.
Galactosemia III
Galactosemia III is caused by defects in the gene
that codes for an enzyme called uridyl diphosphogalactose-4-epimerase (GALE). This form of galactosemia is
very rare.
There are two forms of galactosemia III, a severe
form, which is exceedingly rare, and a benign form. The
benign form has no symptoms and requires no special
diet. However, newborns with galactosemia III, including
the benign form, have high levels of galactose-1-phosphate that show up on the initial screenings for elevated
galactose and galactose-1-phosphate. This situation illustrates one aspect of the importance of follow-up enzyme
function tests. Tests showing normal levels of GALT and
GALK allow people affected by the benign form of
galactosemia III to enjoy a normal diet.
1377
Galactosemia
place in living organisms. A metabolic pathway is a series
of reactions where the product of each step in the series is
the starting material for the next step. Enzymes are the
chemicals that help the reactions occur. Their ability to
function depends on their structure, and their structure is
determined by the deoxyribonucleic acid (DNA)
sequence of the genes that encode them. Inborn errors of
metabolism are caused by mutations in these genes which
do not allow the enzymes to function properly.
Galactosemia
KEY TERMS
Casein hydrolysate—A preparation made from the
milk protein casein, which is hydrolyzed to break
it down into its constituent amino acids. Amino
acids are the building blocks of proteins.
Catalyst—A substance that changes the rate of a
chemical reaction, but is not physically changed
by the process.
Enzyme—A protein that catalyzes a biochemical
reaction or change without changing its own
structure or function.
Galactose—One of the two simple sugars, together with glucose, that makes up the protein, lactose, found in milk. Galactose can be toxic in high
levels.
Glucose—One of the two simple sugars, together
with galactose, that makes up the protein, lactose,
found in milk. Glucose is the form of sugar that is
usable by the body to generate energy.
Lactose—A sugar made up of of glucose and
galactose. It is the primary sugar in milk.
Metabolic pathway—A sequence of chemical
reactions that lead from some precursor to a product, where the product of each step in the series is
the starting material for the next step.
Metabolism—The total combination of all of the
chemical processes that occur within cells and tissues of a living body.
Recessive trait—An inherited trait or characteristic
that is outwardly obvious only when two copies of
the gene for that trait are present.
The severe form has symptoms similar to those of
galactosemia I, but with more severe neurological problems, including seizures. Only two cases of this rare form
had been reported as of 1997.
Diagnosis
The newborn screening test for classic galactosemia
is quick and straightforward; all but three states require
testing on all newborns. Blood from a baby who is two to
three days old is usually first screened for high levels of
galactose and galactose-1-phosphate. If either of these
compounds is elevated, further tests are performed to
find out which enzymes (GALT, GALK, or GALE) are
present or missing. DNA testing may also be performed
to confirm the diagnosis.
1378
If there is a strong suspicion that a baby has galactosemia, galactose is removed from their diet right away.
In this case, an initial screen for galactose or galactose-1phosphate will be meaningless. In the absence of galactose in the diet, this test will be negative whether the
baby has galactosemia or not. In this case, tests to measure enzyme levels must be given to find out if the suspected baby is indeed galactosemic.
In addition, galactosemic babies who are refusing
milk or vomiting will not have elevated levels of galactose or galactose phosphate, and their condition will not
be detected by the initial screen. Any baby with symptoms of galactosemia (for example, vomiting) should be
given enzyme tests.
Treatment
Galactosemia I and II are treated by removing galactose from the diet. Since galactose is a break-down product of lactose, the primary sugar constituent of milk, this
means all milk and foods containing milk products must
be totally eliminated. Other foods like legumes, organ
meats, and processed meats also contain considerable
galactose and must be avoided. Pills that use lactose as a
filler must also be avoided. Soy-based and casein
hydrolysate-based formulas are recommended for infants
with galactosemia.
Treatment of the severe form of galactosemia III
with a galactose-restricted diet has been tried, but this
disorder is so rare that the long-term effects of this treatment are unknown.
Prognosis
Early detection in the newborn period is the key to
controlling symptoms. Long-term effects in untreated
babies include severe mental retardation, cirrhosis of
the liver, and death. About 75% of the untreated babies
die within the first two weeks of life. On the other hand,
with treatment, a significant proportion of people with
galactosemia I can lead nearly normal lives, although
speech defects, learning disabilities, and behavioral
problems are common. In addition, cataracts due to
galactosemia II can be completely prevented by a galactose-free diet.
Prevention
Since galactosemia is a recessive genetic disease, the
disease is usually detected on a newborn screening test,
since most people are unaware that they are carriers of a
gene mutation causing the disease. For couples with a
previous child with galactosemia, prenatal diagnosis is
available to determine whether a pregnancy is similarly
GALE ENCYCLOPEDIA OF MEDICINE 2
Demographics
About 5,000 people are diagnosed with gallbladder
cancer each year in the United States, making it the fifth
most common gastrointestinal cancer. It is more common
in females than males and most patients are elderly.
Southwest American Indians have a particularly high
incidence—six times that of the general population.
Causes and symptoms
Resources
BOOKS
Ng, Won G., Thomas F. Roe, and George N. Donnell. “Carbohydrate Metabolism.” In Emery and Rimoin’s Principles
and Practice of Medical Genetics, edited by David L.
Rimoin, J. Michael Connor, and Reed E. Pyeritz. 3rd. ed.
New York: Churchill Livingstone, 1998.
ORGANIZATIONS
Association for Neuro-Metabolic Disorders. 5223 Brookfield
Lane, Sylvania, OH 43560. (419) 885-1497.
Metabolic Information Network. PO Box 670847, Dallas, TX
75367-0847. (214) 696-2188 or (800) 945-2188.
Parents of Galactosemic Children, Inc. 2148 Bryton Dr., Powell OH 43065. .
OTHER
“GeneCards: Human Genes, Proteins and Diseases.” .
“Vermont Newborn Screening Program: Galactosemia.” .
Amy Vance, MS, CGC
Gallbladder cancer
Definition
Cancer of the gallbladder is cancer of the pearshaped organ that lies on the undersurface of the liver.
Description
Bile from the liver is funneled into the gallbladder
by way of the cystic duct. Between meals, the gallbladder stores a large amount of bile. To do this, it must
absorb much of the water and electrolytes from the bile.
In fact, the inner surface of the gallbladder is the most
absorptive surface in the body. After a meal, the gallbladder’s muscular walls contract to deliver the bile back
through the cystic duct and eventually into the small
intestine, where the bile can help digest food.
GALE ENCYCLOPEDIA OF MEDICINE 2
Gallstones are the most significant risk factor for
the development of gallbladder cancer. Roughly 75 to 90
percent of patients with gallbladder cancer also have
gallstones. Larger gallstones are associated with a higher
chance of developing gallbladder cancer. Chronic
inflammation of the gallbladder from infection also
increases the risk for gallbladder cancer.
Unfortunately, sometimes cancer of the gallbladder
does not produce symptoms until late in the disease.
When symptoms are evident, the most common is pain
in the upper right portion of the abdomen, underneath the
right ribcage. Patients with gallbladder cancer may also
report symptoms such as nausea, vomiting, weakness,
jaundice, skin itching, fever, chills, poor appetite, and
weight loss.
Diagnosis
Gallbladder cancer is often misdiagnosed because it
mimics other more common conditions, such as gallstones, cholecystitis, and pancreatitis. But the imaging
tests that are utilized to evaluate these other conditions
can also detect gallbladder cancer. For example, ultrasound is a quick, noninvasive imaging test that reliably
diagnoses gallstones and cholecystitis. It can also detect
the presence of gallbladder cancer as well as show how
far the cancer has spread. If cancer is suspected, a computed tomography scan is useful in confirming the presence of an abnormal mass and further demonstrating the
size and extent of the tumor. Cholangiography, usually
performed to evaluate a patient with jaundice, can also
detect gallbladder cancer.
There are no specific laboratory tests for gallbladder
cancer. Tumors can obstruct the normal flow of bile from
the liver to the small intestine. Bilirubin, a component of
bile, builds up within the liver and is absorbed into the
bloodstream in excess amounts. This can be detected in a
blood test, but it can also manifest clinically as jaundice.
Elevated bilirubin levels and clinical jaundice can also
occur with other conditions, such as gallstones.
On occasion, gallbladder cancer is diagnosed incidentally. About one percent of all patients who have their
gallbladder removed for symptomatic gallstones are
1379
Gallbladder cancer
affected. Families in which a child has been diagnosed
with galactosemia can have DNA testing which can
enable other more distant relatives to determine their carrier status. Prospective parents can then use that information to conduct family planning or to prepare for a child
with special circumstances. Children born with galactosemia should be put on a special diet right away, to
reduce the symptoms and complications of the disease.
Gallbladder cancer
KEY TERMS
Cholangiography—Radiographic examination of
the bile ducts after injection with a special dye
Cholecystitis—Inflammation of the gallbladder,
usually due to infection
Computed tomography—A radiology test by
which images of cross-sectional planes of the
body are obtained
Jaundice—Yellowish staining of the skin and eyes
due to excess bilirubin in the bloodstream
Metastasis—The spread of tumor cells from one
part of the body to another through blood vessels
or lymphatic vessels
Pancreatitis—Inflammation of the pancreas
Stent—Slender hollow catheter or rod placed
within a vessel or duct to provide support or maintain patency
Ultrasound—A radiology test utilizing high frequency sound waves
found to have gallbladder cancer. The cancer is found
either by the surgeon or by the pathologist who inspects
the gallbladder with a microscope.
Treatment
Staging of gallbladder cancer is determined by the
how far the cancer has spread. The effectiveness of
treatment declines as the stage progresses. Stage I cancer is confined to the wall of the gallbladder. Approximately 25% of cancers are at this stage at the time of
diagnosis. Stage II cancer has penetrated the full thickness of the wall, but has not spread to nearby lymph
nodes or invaded adjacent organs. Stage III cancer has
spread to nearby lymph nodes or has invaded the liver,
stomach, colon, small intestine, or large intestine. Stage
IV disease has invaded very deeply into two or more
adjacent organs or has spread to distant lymph nodes or
organs by way of metastasis.
Early Stage I cancers involving only the innermost
layer of the gallbladder wall can be cured by simple
removal of the gallbladder. Cancers at this stage are
sometimes found incidentally when the gallbladder is
removed in the treatment of gallstones or cholecystitis.
The majority of patients have good survival rates. Late
Stage I cancers, which involve the outer muscular layers
of the gallbladder wall, are generally treated in the same
way as Stage II or III cancers. Removal of the gallblad1380
der is not sufficient for these stages. The surgeon also
removes nearby lymph nodes as well as a portion of the
adjacent liver (radical surgery). Survival rates for these
patients are considerably worse than for those with early
Stage I disease. Patients with early Stage IV disease may
benefit from radical surgery, but the issue is controversial. Late Stage IV cancer has spread too extensively to
allow complete excision. Surgery is not an option for
these patients.
Other therapies
When long-term survival is not likely, the focus of
therapy shifts to improving quality of life. Jaundice and
blockage of the stomach are two problems faced by
patients with advanced cancer of the gallbladder. These
can be treated with surgery, or alternatively, by special
interventional techniques employed by the gastroenterologist or radiologist. A stent can be placed across the bile
ducts in order to re-establish the flow of bile and relieve
jaundice. A small feeding tube can be placed in the small
intestine to allow feeding when the stomach is blocked.
Pain may be treated with conventional pain medicines or
a celiac ganglion nerve block.
Current chemotherapy or radiation therapy cannot cure gallbladder cancer, but they may offer some
benefit in certain patients. For cancer that is too
advanced for surgical cure, treatment with chemotherapeutic agents such as 5-fluorouracil may lengthen survival for a few months. The limited benefit of chemotherapy must be weighed carefully against its side effects.
Radiation therapy is sometimes used after attempted surgical resection of the cancer to extend survival for a few
months or relieve jaundice.
Resources
BOOKS
Ahrendt, Steven A. and Henry