Dr. Lange grew up in Saratoga Springs, New York. His medical career began at New York Medical College. He served as a medical intern at Albany Medical College and completed Neurology residency at Tufts University/New England Medical Center in Boston. He returned to New York City as a fellow in neuromuscular disease at the Neurological Institute at Columbia Presbyterian Medical Center. There, he became Director of the EMG Laboratory and co-founded with Dr. Lewis P. Rowland, the Eleanor and Lou Gehrig ALS Center. Dr. Lange was then named Director of neuromuscular medicine at Mount Sinai Medical Center and Chief of Neurology at the James J. Peters VA Medical Center.

He left Mount Sinai to serve as the Chair of Neurology and the Neurologist-in-chief at Hospital for Special Surgery. In that capacity, Dr. Lange was also Professor of Neurology at Weill Cornell Medicine. At HSS, he established the neuromuscular medicine fellowship program, the ALS Clinic and the MDA clinical care center.