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Phase difference of vestibulo-ocular reflex in head autorotation test
T P Hirvonen1, H Aalto, I Pyykkö
1Department of Otorhinolaryngology, University Central Hospital of Helsinki, Finland. timo.hirvonen@helsinki.fi
Acta Oto-Laryngologica. Supplementum
|January 1, 1997
Summary
Phase, a measure of eye-head movement timing, is a valuable tool for assessing the vestibulo-ocular reflex (VOR). This study found significant phase differences in elderly individuals and vestibular schwannoma patients, highlighting its diagnostic potential.
Area of Science:
- Neuroscience
- Ophthalmology
- Audiology
Background:
- The vestibulo-ocular reflex (VOR) is crucial for stabilizing gaze during head movements.
- Gain is the standard metric for VOR assessment using the head autorotation test (HART).
- The role of phase, representing timing differences between eye and head motion, in VOR evaluation is less understood.
Purpose of the Study:
- To investigate the clinical relevance of VOR phase in differentiating between healthy individuals and patient groups.
- To analyze VOR phase across different age groups and vestibular pathologies.
Main Methods:
- Head autorotation test (HART) was performed on 4 groups: healthy adults, elderly subjects, vestibular schwannoma (VS) patients, and Meniere's disease (MD) patients.
- VOR phase was quantified in degrees and milliseconds across 5 frequency bands.
- Statistical analysis was used to compare phase differences between groups.
Main Results:
- Healthy adults and MD patients exhibited near-zero phase at 3-4 Hz.
- Elderly subjects demonstrated a consistent phase lead (5.0–15.5 ms).
- VS patients showed a significant phase lag (-4.2 to -7.6 ms) at frequencies above 2 Hz.
- Statistically significant differences in phase were observed between elderly, VS, and healthy groups at specific frequencies.
Conclusions:
- VOR phase is a valuable parameter, complementing gain, for evaluating vestibular function.
- Age-related changes and permanent vestibular lesions (like VS) are associated with distinct alterations in VOR phase.
- Phase analysis offers potential for improved diagnostic capabilities in vestibular disorders.