Dr. Grenell was educated at Queens College of the City University of New York (CUNY) and Rutgers Medical School (now Robert Wood Johnson School of Medicine). He completed residencies in internal medicine and neurology at Montefiore Medical Center/Albert Einstein College of Medicine, where he was chief resident in neurology. At Montefiore, Dr. Grenell was the neurology head of the Comprehensive Pain Program. He is a neurohospitalist with an interest in stroke, pain, and headache. Dr. Grenell brings particular expertise in managing spinal stimulators and intrathecal pump systems for opioids and baclofen. He is based at NewYork-Presbyterian/Lawrence Hospital.