Video-oculography for enhancing the diagnostic accuracy of early oculomotor dysfunction in Progressive Supranuclear Palsy.

Background: Oculomotor impairment is an important diagnostic feature of Progressive Supranuclear Palsy (PSP) and PSP subtypes.

Objectives: We assessed the role of video oculography (VOG) in confirming clinically suspected slow saccades in PSP and differentiating PSP from Parkinson's disease (PD). We also measured the correlation of both saccadic velocity and latency in PSP with scores in PSP rating scale, Montreal Cognitive Assessment (MoCA) and Frontal assessment battery (FAB). We assessed the frequency of apraxia of eyelid opening (ALO) and reflex blepharospasm in PSP and PD.

Method: 112 PSP cases with slow saccades but not gaze palsy, 50 PD and 50 healthy controls (HC) were recruited. MDS task force-PSP and PD criteria were used respectively, for the diagnoses. All subjects underwent VOG.

Result: Horizontal and vertical saccadic velocities and latencies differentiated PSP from PD and HC (p<0.001). Vertical saccadic velocity and latency accurately differentiated PSP-P from PD (p<0.001 and 0.003 respectively). Vertical and horizontal saccadic velocities differentiated PSP- RS and PSP- P (p=0.026 and 0.036 respectively). In vertical gaze, the mean velocity cut-off showed good sensitivity and specificity in differentiating PSP from HC and PD. Prolonged horizontal gaze latency was associated with more severe PSP and worse global cognitive and frontal dysfunction. ALO and reflex blepharospasm were only seen in PSP.

Conclusion: VOG is useful for confirming slow saccades in PSP-RS and PSP-P and in differentiating PSP-P from PD. Prolonged horizontal gaze latency was associated with more severe PSP and worse cognitive dysfunction. ALO and reflex blepharospasm were seen only in PSP.