[1] Cardiff Univ, Sch Med, Cardiff, Wales
[2] Univ Ibadan, Coll Med, Ibadan, Nigeria
[3] Case Western Reserve Univ, Cleveland, OH 44106 USA
[4] Univ Texas Southwestern Med Ctr Dallas, Dallas, TX 75390 USA
[5] Vanderbilt Univ Sch Med, Nashville, TN USA
[6] Dept Hlth, North West Province, South Africa
[7] Univ KwaZulu Natal, Nelson R Mandela Sch Med, Durban, South Africa
[8] Ain Shams Univ, Fac Med, Cairo, Egypt
[9] Copperbelt Univ, Michael Chilufya Sata Sch Med, Kitwe, Zambia
[10] Univ Nairobi, Sch Med, Coll Hlth Sci, Nairobi, Kenya
[11] Glan Clwyd Gen Hosp, Bodelwyddan, Wales
[12] Philadelphia Coll Osteopath Med, Med, Philadelphia, PA USA
[13] Garki Hosp, Dept Neurosurg, Abuja, Nigeria
[14] Sheffield Teaching Hosp NHS Fdn Trust, Dept Neurosurg, Sheffield, S Yorkshire, England
[15] Univ Sheffield, Dept Neurosci, Sheffield, S Yorkshire, England