1. Department of Otolaryngology, University of Freiburg Medical School, Freiburg i. Br., FRG. Current address: Department of Otolaryngology-Head and Neck Surgery, Tulane Medical Center, New Orleans, LA 70112-2699
2. Department of Otolaryngology, University of Freiburg Medical School, Freiburg i. Br., FRG. Current address: Department of Otolaryngology, Joachim Gutenberg University, Mainz, FRG
3. Department of Neurosurgery, University of Freiburg Medical School, Freiburg i. Br., FRG