1. San Francisco Headache Clinic
2. San Francisco, CA, USA; Bristol-Myers Squibb Company
3. Hillside, NJ, USA; Oklahoma University Neurological Center
4. Oklahoma City, OK, USA; Neurological Associates of Tulsa
5. Tulsa, OK, USA; and Albert Einstein College of Medicine, Montefiore Headache Unit, Bronx, NY and Innovative Medical Research, Stamford, CT, USA