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The Effect of Noise Exposure in the Presence of Canal Fenestration on the Amplitude of Short-Latency Vestibular Evoked Potentials
Adi Biron, MD;
Sharon Freeman, PhD;
Jean-Yves Sichel, MD;
Haim Sohmer, PhD
Arch Otolaryngol Head Neck Surg. 2002;128:544-548.
Background Exposure to high-intensity noise causes little, if any, reduction in
vestibular function in normal animals as shown by short-latency vestibular
evoked potentials (VsEPs).
Objective To investigate the effect of noise exposure on VsEPs following fenestration
of the horizontal semicircular canal.
Design and Methods Psammomys obesus (fat sand rat) underwent labyrinthectomy
in 1 ear, while the lateral semicircular canal in the other ear was fenestrated.
Control VsEPs to linear acceleration (approximately 3g;
rise time, approximately 1-2 milliseconds) were recorded immediately after
the operation. The experimental group animals were then subjected to loud
white noise (113-dB sound pressure level) for 1 hour. Immediately after the
noise exposure in the experimental group animals, VsEPs were once more recorded.
Results The VsEPs in the experimental group animals were significantly reduced
immediately following the noise exposure, while there was no change in the
recordings from the control group animals (fenestrated but not noise exposed;
noise exposed but not fenestrated), even though the noise exposure induced
a mean 47-dB threshold elevation of the auditory brainstem response.
Conclusions The presence of the fenestration caused the vestibular end organs to
become vulnerable to noise exposure. The fenestration may create a pathway
enabling pressure release through the vestibular end organs during noise exposure,
thus increasing the possibility of damage to the vestibular end organs. This
did not occur in the intact, nonfenestrated animals.
From the Departments of Otolaryngology–Head & Neck Surgery
(Drs Biron and Sichel) and Physiology (Drs Freeman and Sohmer), Hebrew University–Hadassah
Medical Center, Jerusalem, Israel.
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