1 Department of Neurosurgery, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
Address for correspondence Rob J. M. Groen, MD, PhD, Department of Neurosurgery, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands, (e-mail: [email protected]; [email protected]).
received September 16, 2013
accepted after revision November 6, 2013
published online February 25, 2014
