Cerebrospinal fluid hypocretin-1 levels in multiple system atrophy.

Hypocretin (orexin) cerebrospinal fluid (CSF) levels have been previously found normal or decreased in Dementia with Lewy bodies and Parkinson disease, two synucleinopathies commonly associated with excessive daytime sleepiness (EDS). We evaluated CSF hypocretin-1 levels in 15 patients with moderately severe multiple system atrophy (MSA), another synucleinopathy where sleep disorders occur frequently and EDS has been reported, performing additional electrophysiological studies in 5 of them to assess the presence of EDS and sleep onset REM (SOREM) periods. Despite relatively low sleep efficiencies in nocturnal sleep, mean sleep latencies in the Multiple Sleep Latency Test were normal with no SOREM periods. All patients had CSF hypocretin-1 levels in the normal range (>200 pg/mL) suggesting that the hypocretin system is not altered in MSA, at least in patients with a moderately severe disease.