1. Department of Pharmacy and Pharmacology, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa
2. Department of Neurology, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa
3. Department of Neurosurgery, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa