Dr. Brannagan is the director of the Peripheral Neuropathy Center and co-director of the EMG laboratory at Columbia University Medical Center. He graduated from the University of Virginia and also received his medical degree from the University of Virginia in Charlottesville. He completed his Neurology residency training at the Neurological Institute of Columbia Presbyterian Medical Center between 1991 and 1994. He subsequently did a Neuromuscular EMG fellowship at Columbia, followed by a Neuroimmunology fellowship in the laboratory of Dr. Norman Latov. Prior to returning to Columbia, Dr. Brannagan was the director of the Diabetic Neuropathy Research center at Cornell University in New York City.

He is a member of the American Academy of Neurology, the American Neurological Association, as well as the American Association of Electrodiagnostic Medicine. He is also a member of the International Society of Amyloidosis and the Peripheral Nerve Society.

He currently sees patients with peripheral neuropathies and does electrodiagnostic studies, as well as conducts clinical research and clinical trials for new treatments for peripheral neuropathy, with a special interest in hereditary transthyretin amyloid polyneuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP).