Polysomnographic and actigraphic characteristics of patients with H1N1-vaccine-related and sporadic narcolepsy.

OBJECTIVE: After the pandemic H1N1 influenza ASO3-adjuvanted vaccine, Pandemrix©, was used in late 2009 and early 2010, the incidence of narcolepsy increased in many European countries. This incidence mainly increased in children and adolescents and, to a lesser degree, in adults. PATIENTS/
METHODS: 125 unmedicated patients, aged 4 to 61 years, were included in this case-series study. Of these, 69 were diagnosed to have an H1N1-vaccine-related narcolepsy and 57 had sporadic narcolepsy. Most of these patients had: an actigraphy recording of 1-2 weeks, polysomnography, a Multiple Sleep Latency Test (MSLT), and cerebrospinal fluid hypocretin-1 concentration analysis.
RESULTS: Patients with H1N1-vaccine-related narcolepsy had shorter diagnostic delays, lower periodic leg movement index during sleep, earlier sleep-wake rhythm, and were younger in age at diagnosis, compared with sporadic cases. They also had shorter sleep latency and more sleep onset REM periods in MSLT, but these results were strongly age-dependent. Actigraphy showed quantitatively less sleep and more sleep fragmentation than polysomnography.
CONCLUSION: Regarding polysomnographic and actigraphic characteristics, there were no dramatic deviations between H1N1-vaccine-related and sporadic narcolepsy. Circadian rhythms indicated some interesting new findings with respect to the H1N1-vaccine-related disease. An actigraphy recording of 1-2 weeks is useful when studying the nocturnal aspects of narcolepsy and sleep-wake rhythms of narcoleptic patients.