1. Department of Neurosurgery , Desert Regional Medical Center , 1150 N. Indian Canyon Drive , Palm Springs , CA 92262 , USA
2. Department of Physical Medicine & Rehabilitation , Spaulding Rehabilitation Hospital, Harvard Medical School , Boston , MA , USA
3. Liaquat National Hospital and Medical College , Karachi , Pakistan
4. Department of Neurology , University of New Mexico , Albuquerque , NM , USA
5. Department of Neurology , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA