M O-N Nnadi1, O B Bankole2, S O Arigbabu2. 1. Division of Neurosurgery, Department of Surgery, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria. nnadimon@yahoo.com. 2. Neurosurgical Unit, Department of Surgery, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria.