Successful treatment of cataplexy in patients with early-infantile Niemann–Pick disease type C: Use of tricyclic antidepressants

Cataplexy is a brief episode of bilateral loss of muscle tone with intact consciousness, triggered by a variety of strong emotions such as anger, laugh, humor or surprise and it is considered to represent the physiologic atonia of rapid eye movement sleep. On the other hand, Niemann–Pick Type C is a neurodegenerative lysosomal storage disease, characterized by the accumulation of cholesterol and glycosphingolipids. Cataplexy is a relatively specific and common neurologic sign seen in almost 50% of all patients with Niemann–Pick Type C. The aim of this report is to demonstrate the successful treatment of cataplexy with the use of a tricyclic antidepressant imipiramine, in two patients between the ages 6–9, with mild to moderate mental retardation, molecularly diagnosed as Niemann–Pick Type C 1 and currently under miglustat treatment and to discuss the possible mechanisms of drug action in the light of cataplexy and Niemann–Pick Type C pathophysiology.