The French neurologist Jean-Marie Charcot (1825-1893) is acclaimed for his studies on the motor system and unifying previously disparate entities into 1 disorder, amyotrophic lateral sclerosis (ALS). His careful work correlating neurological signs with anatomy led to the concept that a spectrum of neurological disorders, including progressive muscular atrophy, progressive bulbar palsy, and primary lateral sclerosis, represented a single entity, ALS. Charcot summarized his ideas in a frequently cited review in 1874 that has dominated medical nosology for 140 years.1