Narcolepsy is a disorder of impaired expression of wakefulness and rapid-eye-movement (REM) sleep. This manifests as excessive daytime sleepiness and expression of individual physiological correlates of REM sleep that include cataplexy and sleep paralysis (REM sleep atonia intruding into wakefulness), impaired maintenance of REM sleep atonia (e.g. REM sleep behaviour disorder [RBD]), and dream imagery intruding into wakefulness (e.g. hypnagogic and hypnopompic hallucinations). Excessive sleepiness typically begins in the second or third decade followed by expression of auxiliary symptoms.
ICSD-1 criteria: minimal criteria for diagnosis = B plus C, or A plus D plus E plus G.
A. The patient complains of excessive daytime sleepiness (EDS) or sudden muscle weakness.
B. Recurrent daytime naps or lapses into sleep occur almost daily for at least 3 months.
C. Sudden bilateral loss of postural muscle tone occurs in association with intense emotion (cataplexy).
D. Associated features include:
- Sleep paralysis
- Hypnagogic hallucinations
- Automatic behaviours
- Disrupted major sleep episode.
E. Polysomnography (PSG) demonstrates one or more of the following:
- Sleep latency <8 minutes
- Rapid eye movement (REM) sleep latency <20 minutes
- A multiple sleep latency test (MSLT) that demonstrates a mean sleep latency of <5 minutes
- Two or more sleep-onset REM (SOREM) periods.
F. HLA typing demonstrates DQB1*0602 or DR2 positivity.
G. No medical or mental disorder accounts for the symptoms.
H. Other sleep disorders (e.g., periodic limb movement disorder or central sleep apnoea syndrome) may be present but are not the primary cause of the symptoms.
Narcolepsy with cataplexy:
- EDS daily for >3 months
- Definite history of cataplexy – sudden and transient episodes of loss of motor tone triggered by emotions
- Diagnosis of narcolepsy should, whenever possible, be confirmed by PSG followed by MSLT, the latter showing sleep latency </= 8 minutes and >/= 2 SOREMs. Alternatively, hypocretin cerebrospinal fluid levels </=110 picograms/mL
- Hypersomnia is not better explained by another sleep, neurological, mental, or medical condition, medicine or substance use.
Narcolepsy without cataplexy:
- EDS daily for >3 months
- Typical cataplexy is not present
- Diagnosis of narcolepsy MUST be confirmed by PSG followed by MSLT, the latter showing: sleep latency </= 8 minutes and >/= 2 SOREMs
- Hypersomnia is not better explained by another sleep, neurological, mental or medical condition, medicine or substance use.
- Vignatelli L, Plazzi G, Bassein L, Barbato A, De Vincentiis A, Lugaresi E, D’Alessandro R; GIN-SEN. Gruppo Italiano Narcolessia-Studio Epidemiologico Nazionale. ICSD diagnostic criteria for narcolepsy: interobserver reliability. Intemational Classification of Sleep Disorders. Sleep. 2002 Mar 15;25(2):193-6. [Medline]
- Billiard M. Diagnosis of narcolepsy and idiopathic hypersomnia. An update based on the International classification of sleep disorders, 2nd edition. Sleep Med Rev. 2007 Oct;11(5):377-88. [Medline]
Created Jul 5, 2011.