Cataplexy leading to the diagnosis of Niemann-Pick disease type C.

Cataplexy in childhood is a rare and often misdiagnosed symptom. It is described as a brief episode of bilateral loss of muscle tone with intact consciousness, triggered by a variety of strong emotions and in particular with unexpected laughter. This report presents a 9-year old male with progressive cerebellar and pyramidal symptoms and a cognitive decline since the age of 4. His recently developed "drop attacks" on laughter were recognized as cataplexy and led to the diagnosis of Niemann-Pick type C disease. With biochemical studies this diagnosis, a lysosomal storage disease, was confirmed. With cataplexy narcolepsy, Niemann-Pick type C disease, Norrie disease, Prader-Willi syndrome, and Coffin-Lowry syndrome are associated disorders. Recognition of cataplexy in children with concomitant neurologic symptoms may lead to an early and straight diagnosis of one of these disorders.