[1] Univ Coll London NHS Hosp Trust, Natl Inst Neurol & Neurosurg, London, England
[2] Sree Chitra Tirunal Inst Med Sci, Thiruvananthapuram, Kerala, India
[3] All India Inst Med Sci, New Delhi, India
[4] Univ Oxford, Neuroanesthesia & Neurocrit Care, Oxford, England
[5] Sree Chitra Tirunal Inst Med Sci & Technol, Div Neuroanesthesia & Crit Care, Trivandrum, India