Effect of acute inner ear pressure changes on low-level distortion product otoacoustic emissions in the guinea pig

Abstract

Objective—To determine a relation between acute inner ear pressure changes and cochlear function as measured by low-level 2f₁–f₂ distortion product otoacoustic emissions (DPOAEs).

Material and Methods—During and after a change in inner ear pressure induced by injection or aspiration of perilymph, the 2f₁–f₂ DPOAE at 4.5 kHz generated by low-level primaries was recorded in the guinea pig.

Results—Large changes in overall inner ear pressure produced only small changes in the 2f₁–f₂ amplitude and phase. During injection of 0.5 μl of artificial perilymph into the scala tympani over a 10-s period, the mean inner ear pressure increased by ≈500 Pa, with an accompanying mean increase in the 2f₁–f₂ amplitude of 0.7 dB. During aspiration of 0.5 μl of perilymph over a 10-s period, the mean inner ear pressure decreased by ≈700 Pa, with an accompanying mean decrease in the 2f₁–f₂ amplitude of 0.9 dB. Changes in DPOAE amplitude followed inner ear pressure changes with a delay of 1–2 s. The magnitude and sign of the amplitude changes can (partly) be explained by a change in oval window stiffness. No explanation was found for the measured delay.

Conclusion—Clinically, these experiments can be of value in gaining insight into the pathophysiological mechanisms of pathological pressure changes as seen in Ménière's disease and perilymphatic fistulae.

• aspiration
• cochlear aqueduct
• guinea pig
• injection
• inner ear pressure
• Ménière's disease
• otoacoustic emissions
• perilymph
• perilymphatic fistula

Valk WL, Wit HP, Albers FWJ. Effect of acute inner ear pressure changes on low-level distortion product otoacoustic emissions in the guinea pig. Acta Otolaryngol 2004; 124: 929–936.

Valk WL, Wit HP, Albers FWJ. Effect of acute inner ear pressure changes on low-level distortion product otoacoustic emissions in the guinea pig. Acta Otolaryngol 2004; 124: 929–936.