Abstract Details

Title High Frequency Vestibulo-ocular Reflex in Spinocerebellar Ataxias with Slow Saccades

Topic Neuro-ophthalmology/Neuro-otology

Presentation(s) S14 - Neuro-ophthalmology/Neuro-otology (11:39 AM-11:51 AM)

Poster/Presentation
Number 003

Background vHIT assesses the VOR by measuring gain and compensatory CS. However, some SCA subtypes exhibit impaired saccade generation, making the presence of CS less reliable. This study explores the role of CS in patients with slow saccades.

Objective To evaluate the clinical significance of compensatory catch-up saccades (CS) in spinocerebellar ataxia (SCA) patients with slow saccades, using the video head impulse test (vHIT), which measures the vestibulo-ocular reflex (VOR) gain and the presence of CS.

Design/Methods Seventeen genetically confirmed SCA patients (9 males, mean age 29; SCA2=8, SCA7=9) were enrolled. All participants underwent vHIT (GN Otometrics, Taastrup, Denmark) to assess VOR gain and the presence of CS. Video-oculography (SLMED, Seoul, Korea) was used to analyze saccadic function and other ocular motor findings.

Results Saccadic slowing was found in 15 of 17 patients (88.2%; SCA2=7, SCA7=8). Of these, 7 patients (46.7%; SCA2=1, SCA7=6) had abnormally decreased VOR gain in at least one canal plane. VOR gain impairment was more common in vertical planes (7/7, 100%) and less frequent in the horizontal plane (2/7, 28.6%). Only one SCA7 patient exhibited compensatory CS in the horizontal plane, and no CS were observed in the vertical planes despite frequent VOR impairments.

Conclusions In SCA patients with slow saccades, particularly in SCA7, VOR gain impairments do not consistently result in compensatory CS, especially in the vertical canal planes. This suggests that quantitative analysis of VOR gain using vHIT is essential, as relying solely on bedside HIT with naked eye observation of CS may be insufficient in these cases.

Authors/Disclosures
Seung-Han Lee, MD, PhD (Chonnam National University Hospital) PRESENTER	Dr. Lee has nothing to disclose.
Jae-Myung Kim, MD, PhD	Prof. Kim has nothing to disclose.

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