1. Department of Neurosurgery, Inkosi Albert Luthuli Central Hospital, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
2. Department of Interventional Neuro-radiology, Lahey Hospital and Medical Center, Tufts University, School of Medicine, Medford, Massachusetts
3. Bio-statistics Unit, Centre for Evidence Based Health Care, Faculty of Health Sci-ences, Stellenbosch University, Stellen-bosch, South Africa