[1] Inst Neurosci Kolkata, Dept Pain Management, Kolkata 700017, W Bengal, India
[2] Inst Neurosci Kolkata, Dept Neurosurg, Kolkata 700017, W Bengal, India
[3] Sree Chitra Tirunal Inst Med Sci & Technol, Neuroanesthesiol Div, Dept Anesthesiol, Thiruvananthapuram, Kerala, India
[4] Rabindranath Tagore Int Inst Cardiac Sci, Dept Emergency Med, Kolkata, W Bengal, India