[1] Alfried Krupp Hosp Essen, Dept Neurol, Essen, Germany
[2] Ruhr Univ Bochum, St Josef Hosp, Dept Neurol, Bochum, Germany
[3] Univ Duisburg Essen, Dept Neurol, Essen, Germany
[4] Univ Duisburg Essen, Headache Ctr, Univ Hosp Essen, Essen, Germany
[5] Evangel Hosp Unna, Dept Neurol, Essen, Germany
[6] Asklepios Hosp Schildautal, Ctr Neurol, Seesen, Germany