Share this site with others using one of these sharing tools.
To link to this article, paste this block of HTML code onto your webpage.
Guidelines for sites linking to mayoclinic.org
Medical College of Pennsylvania, Philadelphia, PA
Montreal General Hospital , Montreal, Quebec, Canada
Internal Medicine, Royal Victoria Hospital, Montreal, Quebec, Canada
Neurology, Massachusetts General Hospital, Boston, MA
Neuro-Ophthalmology, Bascom-Palmer Eye Institute, University of Miami, Miami, FL
American Board of Psychiatry and Neurology
American College of Physicians
Royal College of Physicians and Surgeons of Canada
American Board of Internal Medicine
Assistant Professor of Neurology
See a listing of publications on PubMed, a service of the National Library of medicine.
Learn about treatment of diseases and becoming a patient. Read more about medical services.
.
Find Mayo Clinic on