The Effect of Increasing Intracranial Pressure on Ocular Vestibular-Evoked Myogenic Potential Frequency Tuning.

The Effect of Increasing Intracranial Pressure on Ocular Vestibular-Evoked Myogenic Potential Frequency Tuning.

Ear Hear. 2015 Nov-Dec;36(6):e336-e341

Authors: Jerin C, Wakili R, Kalla R, Gürkov R

Abstract
OBJECTIVE: Ocular vestibular-evoked myogenic potentials (oVEMPs) represent extraocular muscle activity in response to vestibular stimulation. The authors sought to investigate whether posture-induced increase of the intracranial pressure (ICP) modulated oVEMP frequency tuning, that is, the amplitude ratio between 500-Hz and 1000-Hz stimuli.
DESIGN: Ten healthy subjects were enrolled in this study. The subjects were positioned in the horizontal plane (0 degree) and in a 30-degree head-downwards position to elevate the ICP. In both positions, oVEMPs were recorded using 500-Hz and 1000-Hz air-conducted tone bursts.
RESULTS: When tilting the subject from the horizontal plane to the 30-degree head-down position, oVEMP amplitudes in response to 500-Hz tone bursts distinctly decreased (3.40 μV versus 2.06 μV; p < 0.001), whereas amplitudes to 1000 Hz were only slightly diminished (2.74 μV versus 2.48 μV; p = 0.251). Correspondingly, the 500/1000-Hz amplitude ratio significantly decreased when tilting the subjects from 0- to 30-degree inclination (1.59 versus 1.05; p = 0.029). Latencies were not modulated by head-down position.
CONCLUSIONS: Increasing ICP systematically alters oVEMPs in terms of absolute amplitudes and frequency tuning characteristics. oVEMPs are therefore in principle suited for noninvasive ICP monitoring.

PMID: 26502192 [PubMed - as supplied by publisher]

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