Tinnitus and 2f1−f2 distortion product otoacoustic emissions following salicylate overdose

Abstract

A 22-year-old woman consumed approximately 10 g of salicylate with suicidal intent. She had a severe hearing loss and a strong tinnitus within 22 h of the overdose, and then 24 h later a subsequent hearing restoration and tinnitus abolishment. Transiently evoked otoacoustic emissions ͑TEOAEs͒ and 2 f 1Ϫ f 2 distortion product otoacoustic emissions ͑DPOAEs͒ were measured in both states. In the state of intoxication DPOAEs could be recorded well in the frequency range that corresponded to the appearance of the tinnitus despite the 50-dB hearing loss. The corresponding DPOAE I/O-functions were linearized, indicating loss of outer hair cell compression. After recovery, DPOAE level and DPOAE growth were within the normal range and showed normal physiological compression. The TEOAEs were missing in the acute state of intoxication. This case supports the hypothesis that aspirin-induced tinnitus is generated at the outer hair cell level. Whereas TEOAEs only give evidence that something might have changed in the cochlea, DPOAEs are a more useful and robust quantitative indicator of the underlying mechanism of some forms of cochlear tinnitus.A young female ͑22 years͒ who had just overdosed on salicylates was brought to our attention. She had a severe high-frequency hearing loss associated with a strong tinnitus in both ears. The patient reported that she swallowed all capsules in an aspirin box with suicidal intent. She was unable to give precise information on the dose or how many capsules she swallowed. On the assumption that she swallowed the content of a standard package of aspirin containing, 1000-mg capsules, a dose of 10 g can be estimated. Her approximate height was 165 cm, her weight 60 kg. The patient reported that she did not take additional drugs. Because aspirin-induced tinnitus is known to be reversible ͑Myers and Bernstein, 1965; McFadden and Pattsmier, 1984;Long and Tubis, 1988;Wier et al., 1988;Stypulkowski, 1990͒, the patient was not referred for any medical treatment.The clinical audiogram, measured 22 h after swallowing the aspirin capsules, revealed a sensorineural hearing loss with a 50-dB notch at 6 kHz in both ears, and the patient reported hearing a high-frequency hissing noise in both ears. She estimated the loudness of the tinnitus to be somewhat above the audiometric threshold in the high-frequency region. Forty-six hours after swallowing the aspirin capsules hearing sensitivity had been completely restored and the tinnitus had disappeared ͑see audiograms for the right ear in Fig. 1͒.Distortion product otoacoustic emissions ͑DPOAEs͒ and transiently evoked otoacoustic emissions ͑TEOAEs͒ were measured in the state of aspirin intoxication and after recovery in both ears immediately after audiogram recording.The DPOAEs were measured between f 2 ϭ488 and 8008 Hz ͑Cubedis/ER10-C instrumentation, Mimosa Acoustics/Ethymotic Research, USA͒ using a special primary tone level setting ͑L 1 ϭ0.4L 2 ϩ38 with 20ϽL 2 Ͻ65 dB SPL and f 2 / f 1 ϭ1.2, see Kummer et al., 1998͒ that accounts for the nonlinear basilar...

Level dependence of distortion-product otoacoustic emissions measured at high frequencies in humans

“…However, with OHC damage, the BM response at CF exhibits an elevated threshold, reduced compression, and a steeper slope of the I/O function. Similar findings were reported for DPOAE I/O functions following cochlear insults in animals ͑Norton and Rubel, 1990;Whitehead et al, 1992;Mills et al, 1993;Rubel, 1994͒ andin cochlear impaired human ears ͑Janssen et al, 1998;Kummer et al, 1998;Janssen et al, 2000;Dorn et al, 2001͒. However, the degree to which DPOAE level dependence reflects BM level dependence at CF remains to be established.…”

Influence of Ketamine–Xylazine Anaesthesia on Cubic and Quadratic High-Frequency Distortion-Product Otoacoustic Emissions

“…The significant increase of optimum frequency ratios during anaesthesia could be caused by endocochlear potential related deterioration of mechanical cochlear frequency tuning (Ruggero and Rich 1991) as a consequence of reduction of cochlear amplifier action. The fact that the slopes of cubic DPOAE growth functions increased strongly during anaesthesia is comparable to a steepening of DPOAE growth functions in patients with cochlear hearing loss or tinnitus (Janssen et al 1998(Janssen et al , 2000(Janssen et al , 2006. Indeed, the slopes can be used as indicator of changes in cochlear function (Neely et al 2003;Müller and Janssen 2004).…”

“…Brown and Kemp 1984;Gaskill and Brown 1990;Probst et al 1991;Brown et al 1992;Janssen et al 2000;Shera et al 2002;Boege and Janssen 2002). They provide a fast and efficient assessment of mechanical threshold sensitivity in different vertebrates and even in insects (e.g.…”

Effect of aspirin on phase gradient of 2F1–F2 distortion product otoacoustic emissions

“…However, the data do not indicate, either for amplitude or time course, clear correlations between the reduction and/or disappearance of spontaneous OAE and the loss of absolute hearing sensitivity. Studies of evoked OAE (Long and Tubis, 1988b;Janssen et al, 2000) indicate reductions in response amplitude and associated threshold elevation, corresponding with loss of absolute hearing sensitivity. The reductions in the distortion product otoacoustic emission (DPOAE) amplitude become more pronounced as the levels of the stimuli are lowered (Kujawa et al, 1992;Fitzgerald et al, 1993).…”