Abstract
Narcolepsy type 1 (NT1) is a rare central disorder of hypersomnolence characterized
by excessive daytime sleepiness, cataplexy, sleep paralysis, hallucinations, and fragmented
nocturnal sleep usually arising in adolescence or young adulthood. Recently, the childhood
NT1 diagnoses have increased for improved disease awareness and for several cases
occurring after the H1N1 pandemic influenza or vaccination. As in adults, the occurrence
of NT1 in individuals with a genetic predisposition of the immune system (e.g., human
leukocyte antigen, HLA-DQB1*0602) together with the role of environmental triggers
(e.g., H1N1 influenza virus, streptococcus β hemolyticus) further supports the autoimmune
pathogenesis. Children with NT1 close to disease onset show a peculiar cataplexy phenotype
characterized by persistent hypotonia with prominent facial involvement (cataplectic
facies) and by a complex mosaic of hyperkinetic movement abnormalities that increase
during emotional stimulation. This phenotype progressively vanishes along the disease
course leading to the typical picture of cataplexy (i.e., muscle weakness exclusively
evoked by strong emotions). This possibly explains in part the misdiagnoses and diagnostic
delay. Childhood NT1 also shows behavioral abnormalities and psychiatric disorders,
encompassing depressive feelings, hyperactive/aggressive behavior, up to psychotic
features. The association with obesity and precocious puberty strikingly suggests
that NT1 arising in prepubertal children may reflect a wide hypothalamic derangement
secondary to hypocretin neuronal loss. The complexity of the childhood NT1 phenotype
claims a multidisciplinary assessment and management, taking behavioral and endocrinological
features into account. NT1 indeed is a lifelong disorder with a devastating impact
on quality of life, especially when arising across developmental age, and targeted
school programs, medicolegal and psychological supports are essential for patients
care. Controlled studies are mandatory to assess safety and efficacy of the current
symptomatic off-label medications on which also relies the treatment for children
with NT1, and hopefully future pathogenetic evidences will pave the way to better
disease prevention and therapies to modify the disease course.
Keywords
cataplexy - precocious puberty - obesity - hallucinations - hyperactivity - psychiatry
- movement disorders - polysomnography
