Teaching video neuroimages: gelastic cataplexy as the first neurologic manifestation of Niemann-Pick disease type C.

A 10-year-old boy presented to our hospital with a 3-year history of fall attacks triggered by laughing, leading to a generalized loss of muscle tone without loss of consciousness (video). One year later, motor delayed skills started. Examination showed ataxia, moderate cognitive impairment, and vertical gaze palsy. EEG revealed diffuse slowing and disorganization of background rhythms. Molecular analysis disclosed heterozygosis p.P1007A and p.A1035V mutations, diagnostic of Niemann-Pick disease type C (NPC).