Oculomotor abnormalities and its association with sleep stages in progressive supranuclear palsy

Oculomotor abnormalities are one of the cardinal clinical features of progressive supranuclear palsy (PSP). Vertical saccadic slowing is an early sign of PSP. The association between oculomotor abnormalities and sleep architecture has not been studied so far.

To study the association of oculomotor abnormalities of PSP with the sleep stages by using video polysomnography (vPSG).

This was a cross-sectional single-center study. Twenty-two patients with PSP and 15 age and gender-matched controls were recruited. Saccades, vestibulo-ocular reflex, and optokinetic nystagmus were assessed and graded clinically in all patients and one overnight vPSG was done in all cases.

Vertical saccades, upward more than downwards, were affected in all cases. While horizontal saccades were normal only in 41% of cases. Vertical optokinetic nystagmus (OKN) was affected in all cases. Horizontal OKN was normal in 36% of patients. The vertical upward saccades had a negative correlation with N1% and duration (r = -0.418; p = 0.05, r = -0.457; p = 0.03), N3% and duration (r = -0.486; p = 0.02, r = -0.510; p = 0.01), REM% (r = -0.449; p = 0.04), total sleep time (r = -0.487; p = 0.02) and sleep efficiency (r = -0.444; p = 0.04). There was a positive correlation between horizontal OKN and sleep onset latency (r = 0.432; p = 0.05).

Vertical saccadic restriction in PSP has significant negative correlation with total sleep time and sleep efficiency. The oculomotor and sleep abnormalities in PSP are probably interlinked and their assessment is useful in determining the characteristics of the disease.