The association of saccadic abnormalities with rem sleep in patients with Huntington's disease.

Background: Huntington's disease (HD) is a progressive neurodegenerative disorder characterised by chorea, cognitive impairment, psychiatric and behavioral disturbances. Sleep disturbances including reduced REM sleep have been observed in HD.

Objectives: The aim of the study was to study the polysomnography findings in HD and to assess whether oculomotor abnormalities are associated with poor REM sleep.

Methods: Twenty-nine genetically confirmed HD patients underwent clinical evaluation including extraocular movement and OKN examination. Twenty-six patients and 15 controls underwent overnight video polysomnography (VPSG).

Results: VPSG of 23 HD patients and 13 controls were considered for analysis. Compared to controls, HD patients had higher median wake period and higher WASO percentage (p = 0.005). REM sleep percentage was reduced significantly in HD in comparison to controls (p < 0.001). Out of 23 patients, only two patients had REM sleep above 20% while 14 patients had REM sleep percentage less than 15%. Poor horizontal OKN (grades 2 and 3) was associated with the presence of low REM sleep percentage (REM sleep less than 15%) (p = 0.02). Low REM sleep was also associated with severe illness (UHDRS) (p = 0.038).

Conclusion: An association between decreased REM sleep and OKN abnormalities indicate that EOM abnormalities seen in HD could lead to errors in scoring REM sleep. To understand the actual degree of decreased REM sleep percentage will require additional parameters in AASM guidelines to score REM sleep in patients with EOM abnormalities like that seen in HD.