The prevalence of sensorineural hearing loss, measured by pure tone audiometry, was determined in 66 patients with chronic renal failure and threshold changes following haemodialysis were measured in 31 patients. The incidence of hearing loss was 41% in the low, 15% in the middle and 53% in the high frequency ranges respectively. No correlations with weight changes, haematocrit, metabolic bone disease or ototoxic drug history were found. Of 62 ears studied, 38% had a decrease in low frequency threshold after dialysis and 9% had an increase. Threshold in 22/31 ears with pre-existing low frequency loss altered after dialysis with little change in other frequencies and no correlation with weight changes. In conclusion, we find a high incidence of low and high frequency hearing losses in chronic renal failure patients. Fluctuation in low frequencies with dialysis is common. Possible mechanisms include treatment induced changes in fluid and electrolyte composition of endolymph.

Hearing loss in chronic renal failure-hearing threshold changes following haemodialysis.

The incidence of sensorineural hearing loss among patients with chronic renal failure (CRF) is considerably higher than in the general population. Bazzi et al. [1] found an incidence of 77% including patients with mild and very mild hearing loss. Ozturan and Lam [2] found a moderate to severe hearing loss in 46% of the tested patients. The general consensus in audiometric findings among patients with CRF claims a high frequency hearing loss [3,4] with a notch at 6 kHz [2]. Presence of hearing loss and estimation of type and degree constitute one of the most common methods used to investigate the effects of renal disease on the auditory system. Degree of hearing loss may give an indication of the extent of damage to auditory function, whereas the type of hearing loss may distinguish between lesions in the outer and middle ear (conductive hearing loss) or the cochlea and the neural pathways (sensorineural hearing loss). In addition to these indicators, the reports to be reviewed in the following sections have also described auditory function in CRF with methods such as otoacoustic emissions (OAEs) (namely transient evoked OAEs, TEOAEs and distorion product OAEs, DPOAEs), and auditory evoked potentials (AEPs). OAEs are low level sounds emitted by the cochlea in the process of receiving the sound vibrations and transforming them to cellular and neural stimulation. Recording of OAEs implies a functioning cochlea and healthy middle ear mechanism. TEOAEs are produced by the action of the hair cells, and they reflect special characteristics of the stimulus. DPOAEs are produced when the ear is stimulated with a combination of pure tones that are close in frequency (the primary tones). DPOAEs reflect non-linear processes of hair cell motion. Both TEOAEs and DPOAEs are generated by the active cochlear mechanisms responsible for enhancing basilar membrane vibration; this is known as the ‘cochlear amplifier’ [5]. AEPs represent neural activity related to auditory stimulation. They show summated neural energy at the various synaptic levels of the auditory pathway; this activity is generated by specific stimuli and extracted from the ongoing EEG activity by specialized technical manipulation. AEPs are recorded from the scalp representing activity in the cochlea and brainstem, thalamus and cortical areas. They are distinguished in early, middle and late evoked potentials, respectively. AEPs recorded from the cochlea include the cochlear microphonic (CM), the summating potential (SP) and the auditory nerve action potential (AP). The CM originates in the outer hair cells and mirrors the incoming signal. The SP also reflects hair cell function. The auditory nerve AP represents the sum of synchronous responses of auditory nerve fibers at the level of the cochlea. The largest component of the AP is the N1, a characteristic wave that constitutes also the first identifiable component of the auditory brainstem response (ABR). The ABR is also an ‘early’ evoked response, as it reflects neural function along the ascending auditory pathway, from the cochlea to the inferior colliculus. The five distinct waves of the normal ABR waveform are mainly generated by successive nuclei in the ascending auditory pathway: waves I and II originate from the distal and proximal portions of the auditory nerve, respectively, wave III originates from the cochlear nucleus, wave IV originates from the superior olivary complex and wave V originates from the lateral lemniscus/inferior colliculus. Each higher level order wave receives contributions from lower levels of the pathway [6]. The AEP reflecting function from auditory cortical areas is the Auditory Late Response (ALR). Major identifiable waves of the ALR are the N1 and P2 waves. ALR measurements reflect higher-level auditory function [7]. In general, latency of AEP waves indicates speed of neural function, whereas amplitude is a variable indicator of response robustness. The cochlea and kidney have similar physiological mechanisms, namely the active transport of fluid Correspondence and offprint requests to: Dr Chryssoula ThodiPetrou Cyprus, Audiology Center, Kallipoleos and 1Damaskinos Str, 1070, P.O. Box 20739, 1663 Nicosia, Cyprus. Email: DrC@cyprusaudiologycenter.com Nephrol Dial Transplant (2006) 21: 3023–3030

Hearing in renal failure

The audiological results of 46 patients (m/f 27/19, mean age; 57.4 +/- 11.1) with chronic renal failure (CRF) undergoing dialysis were compared with those of an age- and gender-matched control group (n = 25). Mean pure tone average from 0.5 to 8 kHz was about 15 dB higher in CRF patients than in control subjects. The ABR parameters of the test group were then contrasted with those recorded in a second control group (n = 47, m/f 26/21, mean age: 56.1 +/- 11.4) matched by age, gender and degree of hearing loss (HL). After assessing the normality of the groups by the usual criteria, using the data of a sample of normal young adults, the ABR were found to be abnormal in 23.9% of the controls and in the 39.13% of the CRF patients. Wave V, I-III, III-V and I-V delays were significantly shorter in the females of the control group; in the CRF group, only the V and the I-V delays were shorter in females. The only age-dependent effect was found in the CRF sample, in which older patients had significantly longer I-III IPLD. The degree of HL influenced the latency of the waves in both groups but only the I-V IPLD was longer in CRF patients with pronounced high tone loss. The most distinguishing feature between the effects of CRF plus ageing and those of normal ageing was the lengthening of the I-III IPLD in the test group. This finding is likely to reflect a subclinical disorder of the VIII nerve function that is a part of the axonal uremic neuropathy.

Audiological findings in elderly patients with chronic renal failure.

Sensorineural hearing loss is frequently reported in young patients with chronic renal failure having haemodialysis. The effect of a single session of haemodialysis on hearing acuity was assessed prospectively in nine children with end-stage renal disease using pure-tone audiometry (PTA) and distortion-product otoacoustic emissions (DPOAEs). Results were compared with those obtained from nine audiologically normal healthy children also tested with PTA and DPOAEs twice during a 4-h interval. Sensorineural hearing loss of unknown aetiology was found in 55.5% of renal patients, mainly in the higher frequencies. Patients on HD had mean PTA thresholds significantly poorer than those of the control group in the frequency range 1000-12 000Hz (P 1184 Hz (P 0.05). Changes in PTA thresholds or DPOAE amplitudes were not significantly different than those in the control group (P > 0.05). In conclusion, sensorineural hearing loss of unknown origin, especially in high frequencies, is frequent in young renal patients under HD and single HD sessions do not seem to alter the hearing acuity of these patients. DPOAEs seem to be more sensitive to incipient cochlear damage than behaviour thresholds in monitoring renal patients.

Hearing evaluation with distortion-product otoacoustic emissions in young patients undergoing haemodialysis.

• A 47-year-old man with normal hearing had chronic progressive renal failure. He experienced hearing loss in additive increments with peritoneal dialysis and hemodialysis, until he was profoundly deaf in both ears. Postmortem studies showed collapse of the endolymphatic system and edema and atrophy of most of the specialized cell types of the auditory and vestibular sense organs. It is our interpretation that the alterations were caused by osmotic disequilibrium associated with hemodialysis. ( Arch Otolaryngol 106:751-756, 1980)

Ronald L. Wathen

Papers

Effects of hemodialysis on hearing threshold.