Moderate: Cataplexy once daily or every few days, disturbed nocturnal sleep, and need for multiple naps daily.
Severe: Drug-resistant cataplexy with multiple attacks daily, nearly constant sleepi- ness, and disturbed nocturnal sleep (i.e., movements, insomnia, and vivid dreaming).
In narcolepsy without cataplexy but with hypocretin deficiency, unclear ”cataplexy-like” symptoms may be reported (e.g., the symptoms are not triggered by emotions and are un- usually long lasting). In extremely rare cases, cerebrospinal ﬂuid (CSF) levels of hypocre— tin-1 are low, and polysomnographic/multiple sleep latency test (MSLT) results are negative: repeating the test is advised before establishing the subtype diagnosis. In narco- lepsy with cataplexy but without hypocretin deficiency, test results for human leukocyte antigen (HLA) DQBl‘06202 may be negative. Seizures, falls of other origin, and conversion disorder (functional neurological symptom disorder) should be excluded. In narcolepsy secondary to infectious (e.g., Whipple’s disease, sarcoidosis), traumatic, or tumoral de- struction of hypocretin neurons, test results for HLA DQB1‘06202 may be positive and may result from the insult triggering the autoimmune process. In other cases, the destruction of hypocretin neurons may be secondary to trauma or hypothalamic surgery. Head trauma or infections of the central nervous system can, however, produce transitory decreases in
CSF hypocretin-l levels without hypocretin cell loss, complicating the diagnosis.
The essential features of sleepiness in narcolepsy are recurrent daytime naps or lapses into sleep. Sleepiness typically occurs daily but must occur at a minimum three times a week for at least 3 months (Criterion A). Narcolepsy generally produces cataplexy, which most commonly presents as brief episodes (seconds to minutes) of sudden, bilateral loss of mus- cle tone precipitated by emotions, typically laughing and joking. Muscles affected may include those of the neck, jaw, arms, legs, or whole body, resulting in head bobbing, jaw dropping, or complete falls. Individuals are awake and aware during cataplexy. To meet
Criterion B1(a), cataplexy must be triggered by laughter or joking and must occur at least a few times per month when the condition is untreated or in the past.
Cataplexy should not be confused with ”weakness” occurring in the context of athletic activities (physiological) or exclusively after unusual emotional triggers such as stress or anxiety (suggesting possible psychopathology). Episodes lasting hours or days, or those not triggered by emotions, are unlikely to be cataplexy, nor is rolling on the ﬂoor while laugh- ing hysterically.
In children close to onset, genuine cataplexy can be atypical, affecting primarily the face, causing grimaces or jaw opening with tongue thrusting (”cataplectic faces”). Alter- natively, cataplexy may present as low-grade continuous hypotonia, yielding a wobbling walk. In these cases, Criterion Bl (b) can be met in children or in individuals within 6 months of a rapid onset.