Narcolepsy
It is characterized 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 unrecognized, 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.
In patients with narcolepsy, severe EDS leads to involuntary somnolence during more active conditions such as eating and talking. Sleepiness in narcolepsy may be severe and constant, with paroxysms during which patients may fall asleep without warning (i.e., sleep attacks). Patients with narcolepsy tend to take short and refreshing naps (i.e., REM type naps) during the day. Cataplexy (Latin, "to strike down with fear") is an abrupt attack of muscle weakness. If severe and generalized, it may cause a fall. More subtle forms exist with only partial loss of tone (e.g., head nod). The most characteristic feature of cataplexy is that it usually is triggered by emotions (usually laughter and danger). Sleep paralysis is the inability to move upon falling asleep or awakening with consciousness intact. It often is accompanied by hallucinations. Sleep paralysis occurs during REM sleep in healthy subjects. Sleep-related hallucinations may occur at sleep onset (i.e., hypnagogic) or awakening (i.e., hypnopompic) and are usually vivid (dreamlike) visual, auditory, or tactile in nature.
The classic picture of narcolepsy may be somewhat different in young children. Children may deny EDS because of embarrassment. Sometimes restlessness and motor over activity may predominate. Academic deterioration, inattentiveness, and emotional liability are common. Children younger than 5 years presented with unexplained falls and "drop attacks," aggressive behavior, abrupt irritability, sleep terrors, and abrupt dropping of objects. In children aged 5-10 years, the most common initial complaint was repetitive sleepiness, followed by difficulty with morning arousal associated with aggressive behavior and abrupt falls in school. These children often were misdiagnosed as having attention deficit hyperactivity disorder (ADHD), learning disability, or another neurological disorder.
In children aged 10-12 years, poor academic performance was a common complaint. Other presenting symptoms included inappropriate low level of alertness, falling asleep in class, and inability to wake up in the morning.