[1] Norwegian Univ Sci & Technol NTNU, Dept Clin Neurosci, Norwegian Natl Headache Ctr, St Olavs Hosp, N-7006 Trondheim, Norway
[2] Univ London Imperial Coll Sci Technol & Med, London, England
[3] WHO, CH-1211 Geneva, Switzerland
[4] Michigan State Univ, E Lansing, MI 48824 USA
[5] Chikankata Hlth Serv, Mazabuka, Zambia
[6] Univ Copenhagen, Glostrup Hosp, Danish Headache Ctr, Copenhagen, Denmark
[7] Univ Essen Gesamthsch, Essen, Germany
[8] Univ Roma La Sapienza, Rome, Italy