Measurement of the vestibulo-ocular reflex by magnetometry during active head movement.
A new method of measuring the vestibulo-ocular reflex (VOR) during active head movements is presented. Subjects sat and attempted to maintain their gaze upon a fixed point whilst turning their heads from side to side in response to an auditory cue, to attain frequencies of head rotation that increased from 1 Hz to 4 Hz during a 24 s period. Head movements were monitored by a small magnetic field detector worn on the subject's forehead and positioned a set distance from a magnetic field transmitter coil. Eye movements were monitored using the corneo-retinal potential. Gain (eye angle/head angle) and phase difference (eye phase-head phase) were calculated to define the VOR. Three repeat measurements were made on 20 normal subjects. Gain decreased significantly (P < 0.0001) with increasing frequency whilst the phase difference remained unchanged. The 95% prediction intervals were narrow for both gain (+/- 0.28) and phase (+/- 11 degrees). These data, together with the speed and ease of performance of the test, suggest that the test can provide valuable information on the performance of the vestibular system.
Aldren
C P
CP
Department of Otolaryngology, Freeman Hospital, Newcastle upon Tyne.
FitzGerald
J E
JE
Kelly
P
P
Birchall
J P
JP
Murray
A
A
D000328:Adult; D005133:Eye Movements; D006257:Head / Q000502:physiology*; D006801:Humans; D008280:Magnetics; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*