Narcolepsy with cataplexy is characterized by daytime sleepiness, cataplexy (sudden loss of bilateral muscle tone triggered by emotions), sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. Narcolepsy with cataplexy is most often associated with human leucocyte antigen-DQB1*0602 and is caused by the loss of hypocretin-producing neurons in the hypothalamus of likely autoimmune aetiology. Noting that children with narcolepsy often display complex abnormal motor behaviours close to disease onset that do not meet the classical definition of cataplexy, we systematically analysed motor features in 39 children with narcolepsy with cataplexy in comparison with 25 age- and sex-matched healthy controls. We found that patients with narcolepsy with cataplexy displayed a complex array of ‘negative’ (hypotonia) and ‘active’ (ranging from perioral movements to dyskinetic–dystonic movements or stereotypies) motor disturbances. ‘Active’ and ‘negative’ motor scores correlated positively with the presence of hypotonic features at neurological examination and negatively with disease duration, whereas ‘negative’ motor scores also correlated negatively with age at disease onset. These observations suggest that paediatric narcolepsy with cataplexy often co-occurs with a complex movement disorder at disease onset, a phenomenon that may vanish later in the course of the disease. Further studies are warranted to assess clinical course and whether the associated movement disorder is also caused by hypocretin deficiency or by additional neurochemical abnormalities.

INTRODUCTIONNarcolepsy with cataplexy (NC) is a central nervous system hypersomnia, characterized by excessive daytime sleepiness (EDS), cataplexy (transient loss of muscle tone triggered by emotions), sleep paralysis, hypnagogic hallucinations, and disrupted nocturnal sleep. 1 It is caused by the selective loss of hypothalamic neurons 2 producing hypocretin-1 and 2 (or orexin-A and B), 3,4 two related peptides involved in regulation of sleep-wake transition, energy homeostasis, feeding behavior, and reward systems.5 Accordingly, low/undetectable cerebrospinal (CSF) hypocretin-1 (hrct-1) is observed in almost all cases of NC.Sleep-related eating disorder (SRED) is a NREM parasomnia, characterized by recurrent episodes of involuntary eating and drinking during arousals from the main sleep period. It involves nocturnal consumption of food or toxic substances, dis- [Bdi]). Measurements and Results: NC patients showed a higher prevalence of sRed (32% vs 3%, P = 0.00001), Ns (21% vs 0%, P = 0.00006), and Rls (18% vs 5%, P = 0.013) than controls. Moreover, NC patients presented more frequently with an eating-related pathological profile on the edi-2 (80% vs 46%, P = 0.00006) and had a higher prevalence of depressed mood on the Bdi (41% vs 18%, P = 0.004). in comparison to patients without sRed, NC patients with sRed were more frequently women (71% vs 39%, P = 0.013), had higher "bulimic" (29% vs 2%, P = 0.004) and "social insecurity" (48% vs 18%, P = 0.013) traits on the edi-2, had higher obsessive-compulsiveness on the MoCi (29% vs 4%, P = 0.009), and were more depressed on the Bdi (67% vs 29%, P = 0.005). NC patients with Ns showed more frequent pathological profiles on the edi-2 (100% vs 75%, P = 0.035), including the "bulimic" (29% vs 6%, P = 0.015), "perfectionism" (43% vs 14%, P = 0.016), and "social insecurity" (50% vs 22, P = 0.035) profiles. Conclusion: our study shows a strong association of the compulsive nocturnal behaviors sRed and Ns with adult NC. NARCOLEPSY WITH CATAPLEXY AND NOCTURNAL COMPULSIVE BEHAVIORS

Catathrenia should be considered a possible side effect in NC patients under SO treatment and should be accurately identified to prevent unnecessary SO withdrawal.