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Updated: Feb 4, 2026

A Unified Methodological Framework for Vestibular Schwannoma Research
Published on: June 20, 2017
Ocular torsion responses to electrical vestibular stimulation in vestibular schwannoma
Stuart W Mackenzie1, Richard Irving2, Peter Monksfield2
1University of Birmingham, School of Sport, Exercise & Rehabilitation Sciences, UK.
Objectives:
We determined if eye movements evoked by Electrical Vestibular Stimulation (EVS) can be used to detect vestibular dysfunction in patients with unilateral vestibular schwannoma (VS).
Methods:
Ocular torsion responses to monaural sinusoidal EVS currents (±2 mA, 2 Hz) were measured in 25 patients with tumours ranging in size from Koos grade 1-3. For comparative purposes we also measured postural sway response to EVS, and additionally assessed vestibular function with the lateral Head Impulse Test (HIT). Patient responses were compared to age-matched healthy control subjects.
Results:
Patients exhibited smaller ocular responses to ipsilesional versus contralesional EVS, and showed a larger asymmetry ratio (AR) than control subjects (19.4 vs. 3.3%, p < 0.05). EVS-evoked sway responses were also smaller in ipsilesional ear, but exhibited slightly more variability than the eye movement response, along with marginally lower discriminatory power (patients vs. controls: AR = 16.6 vs 2.6%, p < 0.05). The HIT test exhibited no significant difference between groups.
Conclusions:
These results demonstrate significant deficits in the ocular torsion response to EVS in VS patients.
Significance:
The fast, convenient and non-invasive nature of the test are well suited to clinical use.
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