He specializes in cranial neurosurgery and has extensive experience in the neurosurgical management of brain tumors, cerebrovascular neurosurgery and microvascular decompression. Dr. Dempsey is an internationally recognized expert on teaching neurosurgery.

Currently, Dr. Dempsey has multiple NIH-funded research projects with a focus on cerebral ischemia and the repair of the injured brain. He has published more than 300 scientific articles on these subjects. He has been a principal investigator of grants from the National Institutes of Health, Veterans Administration and the American Heart Association, leading a group of neurosurgeons and scientists dedicated to improving patient care.