Resident Physician Duke Head and Neck Surgery & Communication Science Duke University Durham, North Carolina
Objective: To determine if corrective saccade patterns during video head impulse testing (vHIT) may provide a biomarker for physiologic compensation relative to rotary chair findings in patients with unilateral vestibular hypofunction (UVH).
Study Design: Retrospective cohort study
Setting: Tertiary referral center, academic hospital
Patients: 229 Adults >18 years old with evidence for UVH (defined by >25% caloric asymmetry) who also underwent rotary chair and vHIT testing.
Interventions: Vestibular laboratory results were extracted. Patients were characterized as demonstrating evidence for physiologic compensation of eye movements if there was no asymmetry during rotary chair testing, in addition to, an absence of spontaneous and positional nystagmus.
Main Outcome Measures: Corrective saccade parameters (latency, amplitudes, clustering scores)
Results: 36 patients were identified as having an uncompensated UVH, while 193 showed evidence for compensation on rotary chair. Compensated UVH patients had lower dizziness handicap scores relative to uncompensated UVH (F=4.83, p=0.029). Among patients with corrective saccades during vHIT, there was a difference in overt saccade latency (F=7.74, p=0.006), and in percent of impulses generating overt corrective saccades (F=1.50, p=0.001) between uncompensated and compensated patients. Trends toward differences in amplitudes of corrective saccades (covert & overt) and average VOR gain did not reach significance. No differences were seen between group for any covert corrective saccade parameters.
Conclusions: Patients characterized as having a compensated UVH showed statistically significant differences in overt compensatory saccade patterns compared to those with an uncompensated UVH. This may provide evidence for vHIT saccades as a biomarker for compensation status.
*Professional Practice Gap & Educational Need: The role of corrective saccades as a marker of compensation has not been systematically compared to other measures of compensation in the vestibular laboratory test battery in a large cohort of patients with unilateral vestibular hypofunction.
*Learning Objective:Describe vHIT corrective saccade patterns based on classification of compensation status using standard clinical laboratory measures.
*Desired Result: Identification of an objective biomarker of physiologic compensation in UVH on vestibular laboratory testing that is more accessible than rotary chair.