Noise-induced vestibular dysfunction in rats: longitudinal assessment using cVEMP and behavioral testing after...

High-intensity noise exposure is a well-established risk factor for auditory dysfunction; however, its effects on the vestibular system remain poorly understood. This is an important question due to the anatomical proximity and shared vulnerability of cochlear and vestibular structures. This study aims to determine the longitudinal effects of prolonged low-frequency noise (LFN) exposure at two different sound intensities (110- and 120-dB SPL) on vestibular function in Sprague-Dawley rats using behavioral and electrophysiological assessments.

Adult male Sprague-Dawley rats (3-months-old) were exposed to LFN (0.5-4.0 kHz) at either 110- or 120-dB SPL for 6 h and monitored over 21 days. Cervical vestibular-evoked myogenic potentials (cVEMPs), auditory brainstem responses (ABRs), and balance-related behaviors were evaluated at baseline and different times after exposure.

Exposure to 120 dB SPL resulted in significant and permanent vestibular dysfunction, evidenced by elevated cVEMP thresholds and reduced cVEMP P1-N1 suprathreshold amplitudes. These parameters partially recovered over 21 days but did not return to baseline levels. As expected for this noise exposure, large ABR thresholds increases and peak I amplitudes reductions were observed. In addition, behavioral tests showed impaired motor coordination over 21 days. In contrast, 110 dB SPL exposure only caused temporary cVEMP P1-N1 amplitude decreases and much smaller ABR threshold increases.

These results show that, similar to the auditory system, LFN exposure has an intensity-dependent effect on vestibular function and highlight the importance of including vestibular evaluations for a comprehensive assessment of noise-induced health conditions.