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.