Dr. Claassen is a Professor of Neurology and the Director of Critical Care Neurology at Columbia University. He is an Associate Attending Physician at NewYork-Presbyterian/Columbia University Irving Medical Center and the Medical Director of the Neurocritical Care Unit. Dr. Claassen received his medical degree from the University of Hamburg, Germany, and completed residency training in Neurology, and Fellowship training in Neurocritical Care and Epilepsy at Columbia University. He is board certified in Neurology and Neurocritical Care.

Dr Claassen is a nationally and internationally recognized expert in the treatment of neurological intensive care. He is an expert in coma, status epilepticus and brain hemorrhages. He served on the board of directors and as the co-chair for guidelines development for the Neurocritical Care Society. He has championed the use of innovative brain monitoring techniques including continuous EEG monitoring. His sits on the editorial board of Annals of Neurology and Neurocritical Care.

Dr Claassen's research characterizes physiologic changes following acute brain injury, focusing on novel treatment approaches to potentially improve patient outcomes. He is a widely recognized expert on disorders of consciousness. He has published more than 300 journal articles, book chapters, and reviews. He is the co-editor of the seminal monograph Plum and Posner's: Diagnosis and Treatment of Stupor and Coma. His research is supported by federal R01 and foundation grants