Narcolepsy Clinical Presentation

Updated: May 09, 2017
  • Author: Sagarika Nallu, MD; Chief Editor: Selim R Benbadis, MD  more...
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Presentation

History

The classic tetrad of narcolepsy consists of excessive daytime sleepiness (EDS), cataplexy, hypnagogic hallucinations, and sleep paralysis. Children rarely manifest all 4 symptoms. [1] EDS is the primary symptom of narcolepsy and must be present for at least 3 months to justify the diagnosis.

Sleepiness is a normal experience that cycles and invariably occurs after prolonged wakefulness. In healthy persons, mild sleepiness is apparent only during boring, sedentary situations (eg, falling asleep while watching television). In persons with narcolepsy, severe EDS leads to involuntary somnolence during activities that normally engage attention, such as driving, eating, or talking. Sleepiness in narcolepsy may be severe and constant, with paroxysms during which patients may fall asleep without warning (ie, sleep attacks).

Patients with narcolepsy tend to take short and refreshing naps (ie, rapid eye movement [REM]-type naps) during the day. Their daytime naps may be accompanied by dreams.

A significant number of narcolepsy patients have trouble sleeping at night. [2] In addition, patients may have nocturnal compulsive behaviors, including sleep-related eating disorder and nocturnal smoking. [3]

Obesity is another common feature of narcolepsy. The combination of narcolepsy and obesity may promote the development of obstructive sleep apnea.

Cataplexy

Cataplexy is a brief and sudden loss of muscle tone and represents REM sleep intrusion during wakefulness. If severe and generalized, it may cause a fall. More subtle forms may cause only partial loss of tone (eg, head nod and knee buckling). Case reports of facial muscle involvement, especially in children with narcolepsy, have been reported. [43] Respiratory and extraocular movements are preserved. The most characteristic feature of cataplexy is that it usually is triggered by emotions (especially laughter and anger).

Cataplexy is seen in about 70% of patients with narcolepsy. Its presence in conjunction with EDS strongly suggests the diagnosis of narcolepsy.

Sleep disturbances

Patients with narcolepsy may experience sleep paralysis, which is the inability to move upon awakening—or, less commonly, upon falling asleep with consciousness intact. It often is accompanied by hallucinations. Respiratory and extraocular muscles are spared. Sleep paralysis occurs less frequently when patients sleep in uncomfortable positions. It can be relieved by sensory stimuli, such as touching or speaking to the person.

Sleep-related hallucinations may be either hypnagogic (ie, occurring at sleep onset) or hypnopompic (ie, occurring at awakening). These hallucinations are usually vivid (dreamlike) visual, auditory, or tactile in nature.

Disrupted nocturnal sleep is also a common feature of narcolepsy. Consequently, because of daytime naps, total sleep time in 24 hours is essentially unchanged in narcoleptic patients.

Young children

The classic picture of narcolepsy may be somewhat different in young children. Children may deny EDS because of embarrassment. In some cases, restlessness and motor overactivity predominate. Academic deterioration, inattentiveness, and emotional lability are common.

At disease onset, children with narcolepsy and cataplexy may display a wide range of motor disturbances that do not meet the classic definition of cataplexy. These motor disturbances, which may be negative (hypotonia) or active (eg, perioral movements, dyskinetic-dystonic movements, or stereotypic movements), may resolve later in the course of the disorder. [4]

In a study of 51 prepubertal patients with narcolepsy, the initial complaints, as well as the typical misdiagnoses, varied by age. [44] Children younger than 5 years presented with unexplained falls and “drop attacks,” aggressive behavior, sudden irritability, and abrupt dropping of objects. Atonic seizures were the most common misdiagnosis in this age group.

In children aged 5-10 years, the most common initial complaint was inattentiveness, followed by repetitive sleepiness and then by difficulty with morning arousal associated with aggressive behavior and abrupt falls in school. [44] These children often were misdiagnosed as having attention deficit hyperactivity disorder (ADHD), learning disability, depression, or another neurologic disorder.

In children aged 10-12 years, poor academic performance was a common complaint. [44] Other presenting symptoms included inappropriate low level of alertness, falling asleep in class, and inability to wake up in the morning.

Questionnaires

Several questionnaires are available for evaluating sleepiness. Of these, the most commonly used is the 8-question Epworth Sleepiness Scale. Patients respond to each question with a numerical score ranging from 0 (not at all likely to fall asleep) to 3 (very likely to fall asleep); thus, the lowest possible total score is 0, and the highest possible score is 24. Although there is some controversy as to precisely what score constitutes abnormal sleepiness, it is generally considered that total scores higher than 10 warrant investigation.

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Physical Examination

Physical examination findings are normal in patients with narcolepsy. A careful neurologic examination should be performed to exclude other causes of the patient’s condition, including an underlying structural abnormality. There are no specific physical findings that suggest narcolepsy, though obesity may be associated with the disorder. During an episode of cataplexy, patients typically demonstrate atonia of muscles of the limbs and neck and loss of deep tendon reflexes.

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