Childhood narcolepsy with cataplexy: comparison between post-H1N1 vaccination and sporadic cases

We aimed to compare post-Pandemrix vaccination (postvaccine) childhood narcolepsy with cataplexy (NC) vs. sporadic pre-H1N1 pandemic (pre-H1N1) cases.Clinical, anthropometric, polysomnographic, and cerebrospinal hypocretin 1 (hcrt-1) measurements were collected together with the video recordings of cataplexy in 27 Finnish patients with NC onset after H1N1 Pandemrix vaccination (mean age, 12±4 years; 52\% boys) and 42 Italian NC patients with NC onset before the H1N1 pandemic (mean age, 11±3 years; 48\% boys). All subjects carried the HLA-DQB1*0602 allele.Postvaccine subjects were older at NC onset (12±3 vs. 9±3 years; P=.008) and displayed a shorter mean sleep latency in multiple sleep latency tests (MSLT) (2.3±2.2 vs. 3.7±2.9 min; P=.026) compared to pre-H1N1 cases. Anthropometric, clinical (core NC symptoms), hcrt-1 deficiency, and polysomnographic data did not differ among groups, but higher disrupted nocturnal sleep was observed in postvaccine subjects. Comparison of cataplexy features at video assessment showed an overlapping picture with the exception for hyperkinetic movements which appeared to be more evident in pre-H1N1 subjects.The clinical picture of childhood NC was similar in postvaccine and pre-H1N1 children.