1. From the Departments of Neurology (Y.B.W.E.M.R., M.V.), Clinical Epidemiology and Biostatistics (M.G.W.D., R.J. d H.), and Neurosurgery (K.W.A.), Academic Medical Center, University of Amsterdam; Department of Neurosurgery (L.F.M.B.), Academic Hospital, Free University; and Department of Neurosurgery (R.J.M.G.), Slotervaart General Hospital, Amsterdam, the Netherlands.