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Narcolepsy

Practice Essentials

Narcolepsy is characterized by the classic tetrad of excessive daytime sleepiness (EDS), cataplexy, hypnagogic hallucinations, and sleep paralysis. Narcolepsy is thought to result from genetic predisposition, abnormal neurotransmitter functioning and sensitivity, and abnormal immune modulation.

Signs and symptoms

Manifestations of narcolepsy are as follows:

EDS

Cataplexy (brief and sudden loss of muscle tone)

Hypnagogic/hypnopompic hallucinations

Sleep paralysis

Children rarely manifest all 4 symptoms.

Features of EDS are as follows:

EDS is the primary symptom of narcolepsy

EDS must be present for at least 3 months to justify the diagnosis

Severe EDS leads to involuntary somnolence during activities such as driving, eating, or talking

Sleepiness may be severe and constant, with paroxysms of falling asleep without warning (ie, sleep attacks)

Features of cataplexy are as follows:

If severe and generalized, cataplexy may cause a fall

More subtle forms exist with only partial loss of tone (eg, head nod, speech alteration, and knee buckling)

Respiratory and extraocular movements are preserved

Cataplexy is usually triggered by emotions (especially laughter and anger)

Features of sleep paralysis are as follows:

Usually, the patient is unable to move upon awakening

Less commonly, the patient is unable to move upon falling asleep with consciousness intact

Paralysis is often accompanied by hallucinations

Respiratory and extraocular muscles are spared

Paralysis occurs less frequently when the person sleeps in an uncomfortable position

Paralysis can be relieved by sensory stimuli (eg, touching or speaking to the person)

The following are also common features of narcolepsy:

A tendency to take short and refreshing naps during the day; these may be accompanied by dreams

Trouble sleeping at night

Nocturnal compulsive behaviors (eg, sleep-related eating disorder and nocturnal smoking

Obesity

Features of narcolepsy in children are as follows:

Restlessness and motor overactivity may 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

Motor disturbances may be negative (hypotonia) or active (eg, perioral movements, dyskinetic-dystonic, or stereotypic movements)

Motor disturbances may resolve later in the course of the disorder

Cataplectic facies is an unusual facial feature only recently described in children with narcolepsy with cataplexy, usually at disease onset. The typical manifestations of cataplectic facies include repetitive mouth opening, tongue protrusion, and ptosis. Interestingly, the usual triggering emotions, such as laughter or joking, are not always present, hampering diagnosis.

See Clinical Presentation for more detail.

Diagnosis

Sleep studies are an essential part of the evaluation of patients with possible narcolepsy. The combination of an overnight polysomnogram (PSG) followed by a multiple sleep latency test (MSLT) showing sleep latency ≤8 minutes and 2 or more sleep-onset random eye movement periods (SOREMPs) strongly suggests narcolepsy while excluding other sleep disorders. A PSG the night prior to the MSLT is required and should document at least 6 hours of sleep and should rule out other sleep disorders like obstructive sleep apnea (OSA). An alternative criterion is a cerebrospinal fluid hypocretin level of ≤110 pg/mL.

See Workup for more detail.

Management

Nonpharmacologic measures include sleep hygiene, such as the following
:

Maintaining a regular sleep schedule, usually 7.5-8 hours of sleep per night

Scheduled naps during the day, in some cases

Pharmacologic treatment of excessive somnolence in narcolepsy includes stimulants such as the following:

Methylphenidate

Modafinil

Armodafinil

Amphetamines

Solriamfetol

Codeine (in patients for whom stimulant treatment is problematic)

Pharmacologic treatment of cataplexy includes the following:

Sodium oxybate (also treats EDS)

Antidepressants (eg, clomipramine and fluoxetine; off-label use)

Histamine H3 antagonists/inverse agonists

Pitolisant is a nonscheduled therapy option indicated for excessive daytime sleepiness in adults with narcolepsy

In clinical trials, approximately 75-80% of patients had a history of cataplexy

See Treatment and Medication for more detail.

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