Professor and Head of the Department of Stereotactic and Functional Neurosurgery at the University of Illinois College of Medicine. He is a former president of the American Society for Stereotactic and Functional Neurosurgery and current vice-president of the World Society for Stereotactic and Functional Neurosurgery. His specialties include aneurysms, brain surgery, brain tumors, cerebrovascular disorders, craniotomy, dystonias, essential tremors, facial nerve pain, facial pain, glioblastomas, headache disorders, laminectomy, lower back pain, movement disorders, multiple sclerosis, neck pain, neurosurgery, neurosurgical procedures, pain, Parkinson’s disease, spinal cord injuries, and stroke.