Department of Neurology, Amrita Institute of Medical Sciences, Amrita Visvavidyapeetham, Amrita University, Kochi, Kerala, 682041, India. sudheerank@aims.amrita.edu. Neuroimmunology Laboratory, Amrita Institute of Medical Sciences, Amrita Visvavidyapeetham, Amrita University, Kochi, Kerala, 682041, India. sudheerank@aims.amrita.edu. Department of Neurology, Amrita Institute of Medical Sciences, Amrita Visvavidyapeetham, Amrita University, Kochi, Kerala, 682041, India. Neuroimmunology Laboratory, Amrita Institute of Medical Sciences, Amrita Visvavidyapeetham, Amrita University, Kochi, Kerala, 682041, India.