1 Department of General Medicine, Burdwan Medical College and Hospital, Burdwan, West Bengal, India.
2 Section of Clinical Neurophysiology, Department of Neurology, University Hospital "La Paz", Madrid, Spain.
3 Department of Neuromedicine, Bangur Institute of Neurosciences, Institute of Post Graduate Medical Education and Research & SSKM Hospital, Kolkata, West Bengal, India.
4 Department of Neurology, University Hospital "12 de Octubre", Madrid, Spain.
5 Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
6 Department of Medicine, Complutense University, Madrid, Spain.