It is with profound sadness that we share the news of the passing of Dr. Peter James Dyck, Professor Emeritus in Neurology, on July 26, 2025, at the age of 97.

Dr. Dyck will be remembered as one of the foundational figures in the study of peripheral nerves, a dedicated physician-scientist, and a mentor to generations of neurologists. His legacy will live on through his groundbreaking research, his students, and the countless lives he touched.

Dr. Dyck was born in the Southern Caucasus, Russia, in 1927 and emigrated to Canada with his family as a young child. He earned his BA from the University of Saskatchewan in 1950 and his M.D. from the University of Toronto in 1955. Following his training in Internal Medicine, Neurology, and Neuropathology, he completed a Fellowship in Neurology at the Mayo Clinic beginning in 1959.

On July 1, 1961, Dr. Dyck joined the staff of the Mayo Clinic, where he became Full Professor of Neurology in 1973. He retired on December 31, 2024, as both the longest-serving and oldest member of the Mayo Clinic staff in its history.

Over the course of his distinguished 63-year career, Dr. Peter James Dyck made countless seminal contributions to the understanding, diagnosis, and treatment of peripheral nerve disorders. A unifying theme of his work was the drive to quantify features of peripheral neuropathies—transforming the evaluation of these conditions from subjective observation to objective, measurable science.To this end, he developed numerous tools and methodologies that remain foundational today, including quantitative sensory testing, morphometric techniques for analyzing nerve fiber size, and the Neuropathy Impairment Score to assess neuropathy severity through clinical examination.

Early in his career, Dr. Dyck founded the Peripheral Nerve Pathology Laboratory, which has since become a world-renowned center for the diagnosis and study of peripheral nerve disorders. His research provided critical clinical, electrophysiological, and pathological insights into many neuropathies. Notably, he was the first to distinguish two forms of Charcot-Marie-Tooth neuropathy—demyelinating (Type 1) and axonal (Type 2)—a classification still used today.

His contributions include defining the mechanism behind vasculitic peripheral neuropathies and introducing the now widely used term “non-systemic vasculitic peripheral neuropathy.” Dr. Dyck was also a pioneer in the identification and treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a condition he named, and for which he led some of the first controlled clinical treatment trials using prednisone, plasma exchange, and intravenous immunoglobulin.

In a landmark 20-year epidemiological study conducted in Olmsted County, Minnesota, he defined the incidence, clinical spectrum, and progression of diabetic peripheral neuropathy, producing findings that remain among the most authoritative in the field. His methodologies for diagnosing and tracking peripheral nerve disorders have been widely adopted in clinical trials, particularly for diabetic neuropathy and hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN), where they are now considered the standard of care.

Dr. Dyck authored over 460 peer-reviewed articles, 129 book chapters, 27 reviews, and editor of 9 books, including four editions of the landmark reference Peripheral Neuropathy, regarded as the most comprehensive and authoritative text on disorders of the peripheral nervous system.

In addition to his pioneering contributions to the field of peripheral nerve disorders, Dr. Dyck was a dedicated mentor to more than 150 clinical and research fellows, many of whom now lead peripheral nerve programs in Rochester, Jacksonville, and Arizona.

Dr. Dyck played a foundational role in professional societies. He was a founding member of the Peripheral Nerve Study Group, Peripheral Nerve Association, Peripheral Nerve Society, and the Quantitative Sensation Testing Society. He also served as President of the American Neurological Association and the Peripheral Nerve Society, shaping the direction of the field through leadership as well as science.

We will honor and remember Dr. Dyck as a remarkable man, physician, and mentor at the upcoming Peripheral Nerve Society (PNS) Meeting in Maastricht in 2026.