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.