1. From the Department of Neurology, Epidemiology, and Social Medicine, Albert Einstein College of Medicine, Montefiore Headache Unit, New York, NY
2. Innovative Medical Research Inc, Stamford, Conn and Towson, Md
3. Johns Hopkins School of Hygiene and Public Health, Baltimore, Md
4. Zeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire, UK
5. Department of Medicine, Sunnybrook Health Science Centre, Toronto, Canada