Narcolepsy is characterised by the classic tetrad of excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. Note that this tetrad is seen only rarely in children. The term “narcolepsy” is derived from Greek, “seized by somnolence.” Gelineau was the first to delineate the syndrome in 1880.
Narcolepsy frequently is unrecognised, with a typical delay of 10 years between onset and diagnosis. Approximately 50% of adults with the disorder retrospectively report symptoms beginning in their teenage years. This disorder may lead to impairment of social and academic performance in otherwise intellectually normal children. The implications of the disease are often misunderstood by patients, parents, teachers, and health care professionals.
Narcolepsy is treatable. However, a multimodal approach is required for the most favourable outcome.
Narcolepsy is thought to result from genetic predisposition, abnormal neurotransmitter functioning and sensitivity, and abnormal immune modulation. Current data implicate certain human leukocyte antigen (HLA) subtypes and abnormalities in monoamine synaptic transmission, particularly in the pontine reticular activating system.
Understanding of the neurochemistry of narcolepsy stems primarily from research involving narcoleptic dogs (eg, special laboratory-bred Dobermans and Labradors ). In these animal models, the disorder is transmitted in an autosomal recessive fashion with full penetrance and is characterised mainly by cataplexy.Excessive daytime sleepiness (EDS) is the primary symptom of narcolepsy.
Cataplexy (Latin, “to strike down with fear”) is an abrupt attack of muscle weakness.
Sleep paralysis is the inability to move upon falling asleep or awakening with consciousness intact.
The classic picture of narcolepsy may be somewhat different in young children.
In one study of 51 prepubertal patients with narcolepsy, the following initial complaints were noted: