Criteria

International classification of sleep disorders (ICSD), American Academy of Sleep Medicine​​​​[1]​​

Narcolepsy is subdivided in the ICSD-3-TR into type 1 (with hypocretin deficiency) or type 2 (without hypocretin deficiency). This classification replaces the old categorization of narcolepsy with cataplexy and narcolepsy without cataplexy. The ICSD-3-TR also recognizes two pathophysiologic subtypes - narcolepsy type 1 due to a medical condition, and narcolepsy type 2 due to a medical condition.

Narcolepsy type 1 - all 3 of the following criteria must be met:

  1. The patient has daily periods of irrepressible need to sleep or daytime lapses into drowsiness or sleep.

  2. The presence of one or both of the following:

    1. Cataplexy and either:

      Mean sleep latency ≤8 minutes and 2 or more sleep-onset rapid eye movement periods (SOREMPs) on a multiple sleep latency test (MSLT) performed in accordance with current recommended protocols.

      OR

      A SOREMP (within 15 minutes of sleep onset) on nocturnal polysomnogram.

    2. Cerebrospinal fluid (CSF) hypocretin-1 concentration, measured by

      radioimmunoassay is ≤110 picograms/mL (using a Stanford reference sample) or less than one third of mean values obtained in normal subjects with the same standardized assay.

  3. The symptoms and signs are not better explained by chronic insufficient sleep, a circadian rhythm sleep-wake disorder or other current sleep disorder, mental disorder, or the medication/substances or withdrawal.

Narcolepsy type 1 due to a medical condition:

In these cases, the condition is presumably caused by another central nervous system disorder, for example, an autoimmune or paraneoplastic disorder associated with anti-Ma-2 or anti-aquaporin-4 antibodies, or tumors or other lesions of the hypothalamus. Some genetic disorders such as Niemann-Pick type C, Norrie disease, and Prader-Willi syndrome can have a narcolepsy-type phenotype (typically with pediatric onset). Narcolepsy type 1 phenotype can be observed in individuals with DNMT1 mutations. However, hypocretin levels are not always decreased in these disorders, suggesting different etiologies for these phenotypes. In addition, undetectable hypocretin-1 levels have been reported in association with sleepiness after severe head trauma.

The condition must fulfill the criteria for narcolepsy type 1 and be attributable to another medical disorder.

Narcolepsy type 2 - all 5 of the following criteria must be met:

  1. The patient has daily periods of irrepressible need to sleep or daytime lapses into drowsiness or sleep occurring for at least 3 months.

  2. A mean sleep latency of ≤8 minutes and 2 or more SOREMPs on a MSLT performed in accordance with current recommended protocols. A SOREMP (within 15 minutes of sleep onset) on the preceding nocturnal PSG may replace one of the SOREMPs on the MSLT.

  3. Cataplexy is absent.

  4. If CSF hypocretin-1 concentration is measured by radioimmunoassay, it is either >110 picograms/mL or more than one third of mean values obtained in normal subjects with the same standardized assay.

  5. The symptoms and signs are not better explained by chronic insufficient sleep, a circadian rhythm sleep-wake disorder or other current sleep disorder, mental disorder, or medication/substance use or their withdrawal.

Narcolepsy type 2 due to a medical condition:

  • This condition fulfills the criteria for narcolepsy type 2 and is attributable to another medical disorder. Neurologic disorders associated with narcolepsy type 2 include tumors or sarcoidosis of the hypothalamus, autoimmune or paraneoplastic disorders associated with anti-Ma-2 or anti-aquaporin-4 antibodies, multiple sclerosis, myotonic dystrophy, Prader-Willi syndrome, Parkinson’s disease, and head trauma. In disorders associated with both obstructive sleep apnea (OSA) and narcolepsy type 2, such as myotonic dystrophy or Prader-Willi syndrome, the diagnosis of narcolepsy type 2 should only be made if the abnormal MSLT findings persist after OSA is adequately treated, and sleep insufficiency is excluded as a cause of symptoms. In all cases, especially with complex problems such as head trauma, clinical judgment should be used to determine if the development of narcolepsy was a mere coincidence or was triggered by the event or disorder.

Diagnostic and statistical manual of mental disorders, 5th edition Text Revision (DSM-5-TR)[2]

Recurrent periods of an irrepressible need to sleep, lapsing into sleep, or napping, occurring within the same day. Periods must have occurred at least 3 times per week over the past 3 months in association with at least one of the following:

  • Cataplexy

  • CSF hypocretin-1 deficiency

  • Rapid eye movement sleep latency ≤15 minutes on nocturnal polysomnography

  • Mean sleep latency ≤8 minutes on MSLT with ≥2 sleep-onset REM periods.

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