Hearing loss in renal disease: clinical and pathological studies

The multifaceted links between hearing loss and chronic kidney disease

Hearing loss affects nearly 1.6 billion people and is the third-leading cause of disability worldwide. Chronic kidney disease (CKD) is also a common condition that is associated with adverse clinical outcomes and high health-care costs. From a developmental perspective, the structures responsible for hearing have a common morphogenetic origin with the kidney, and genetic abnormalities that cause familial forms of hearing loss can also lead to kidney disease. On a cellular level, normal kidney and cochlea function both depend on cilial activities at the apical surface, and kidney tubular cells and sensory epithelial cells of the inner ear use similar transport mechanisms to modify luminal fluid. The two organs also share the same collagen IV basement membrane network. Thus, strong developmental and physiological links exist between hearing and kidney function. These theoretical considerations are supported by epidemiological data demonstrating that CKD is associated with a graded and independent excess risk of sensorineural hearing loss. In addition to developmental and physiological links between kidney and cochlear function, hearing loss in patients with CKD may be driven by specific medications or treatments, including haemodialysis. The associations between these two common conditions are not commonly appreciated, yet have important implications for research and clinical practice.

Association Between Sensorineural Hearing Loss and Various Stages of Chronic Kidney Disease

Objectives To compare the proportion of sensorineural hearing impairment (SHI) among patients of chronic kidney disease (CKD) stages 3&4 with CKD stage 5.

Materials and Methods This is a cross-sectional study of 30 patients with CKD stages 3 and 4 and 30 patients in stage 5. All patients had an audiological evaluation with pure tone audiometry.

Results Our study had 49 males (82%) and 11 females (18%), with the age ranging from 20 to 60 years (mean: 45.13 years). The mean SHI values in stage 3&4 were 28.44 dB and in CKD stage 5 was 31.22 dB. In the right ear, the mean hearing loss in stage 3, stage 4, and stage 5 was 28.17 dB, 28.67 dB, and 31.84 dB, respectively. In the left ear, the mean SHI values in stage 3, stage 4, and stage 5 were 27.05 dB, 31.89 dB, and 30.61 dB, respectively.

The mean SHI in stage 3&4 for age group 20 to 30 years was 13.66 dB, for 31 to 40 years was 26.33 dB, for 41 to 50 years was 35.18 dB, for 51 to 60 years was 37.12 dB. The mean SHI in stage 5 for the age group of 20 to 30 years was 16.48 dB, for 31 to 40 years was 28.29 dB, for 41 to 50 years was 31.82 dB, for 51 to 60 years was 34.35 dB. There was a significant correlation between hearing loss and CKD with respect to age (p < 0.001). The duration of renal illness and associated comorbidities was not a significant contributor to hearing loss in our study (p > 0.05).

Conclusion As per our study, with progression in the stage of chronic kidney disease, the hearing loss also increased indicating a possible link between the two. We also noted that the hearing loss increased with the increasing age.

Acute sensorineural hearing loss in hemodialysis patients

Background: Approximately, 30-40% of patients experienced hearing loss under regular hemodialysis.Objective: This study reviewed our experience on treating acute hearing loss in patients under regular hemodialysis over the past two decades.Methods: Twenty-six patients having acute hearing loss under hemodialysis were divided into two groups based on their etiologies. Sixteen patients (16 ears) with sudden sensorineural hearing loss (SSHL) were assigned to Group A and 10 patients (13 ears) with endolymphatic hydrops (EH) were assigned to Group B.Results: No significant difference was noted between Groups A and B, regardless of hemodialysis duration, clinical manifestation, underlying systemic diseases, blood examination, and vestibular test battery. In contrast, serum osmolality was significantly lower in Group B (292 ± 11 mOsm/kg) than in Group A (310 ± 11 mOsm/kg). Furthermore, Group B (40 ± 14 dB) had better mean hearing level than Group A (87 ± 21 dB) in the initial audiogram, and a higher hearing improvement rate (69%) than Group A (19%).Conclusions and significance: Both SSHL and EH are major causes for precipitating acute hearing loss in hemodialysis patients. Compared to SSHL, the less deteriorated MHL and lower serum osmolality in EH provide two clues for differentiating acute hearing loss in hemodialysis patients.

Sudden sensorineural hearing loss with end-stage renal disease: a report of 32 cases

Background: Patients with end-stage renal disease (ESRD) have a higher risk of suffering sudden sensorineural hearing loss (SSNHL), but little is known about this population. Aims and objectives: To investigate the clinical characteristics, treatment and recovery of SSNHL patients with ESRD. Materials and methods: Records of 32 SSNHL patients with ESRD were reviewed, including clinical characteristics and hearing recovery. Patients were divided into intratympanic steroid (ITS) group and oral steroid (OS) group, and hearing recovery was compared between two groups. Results: Twenty-six patients (81.3%) exhibited tinnitus, and 18 patients (56.3%) suffered vertigo. Mean pure-tone threshold at the initial presentation was 73.2 ± 19.4 dB, and the audiogram configuration was ascending in 9.4%, descending in 9.4%, flat in 34.4% and profound in 46.9% cases. At 3-month follow-up, percentages of patients in complete recovery, partial recovery, slight recovery, and no improvement were 18.8%, 31.3%, 21.9% and 28.1%, respectively. Furthermore, the overall recovery rate, complete recovery rate and hearing improvement were significantly higher in the ITS group than those in the OS group. Conclusion: SSNHL patient with ESRD often suffered a severe hearing loss with a high rate of accompanying tinnitus and vertigo. ITS may provide better audiological results for SSNHL with ESRD than OS.

Audiovestibular functions in chronic kidney disease in relation to haemodialysis

Background

Several studies have reported that the audiovestibular system is affected in patients with chronic kidney disease.

Objective

This study aimed to investigate how the audiovestibular system is affected in patients with various stages of chronic kidney disease.

Methods

Sixty participants were divided into three groups: group 1 – controls; group 2 – chronic kidney disease patients receiving conservative treatment; and group 3 – chronic kidney disease patients undergoing regular haemodialysis. Assessments included: standard and high-frequency audiometry and otoacoustic emissions testing, oculomotor tests, and combined vestibular-evoked myogenic potentials testing.

Results

Fifty per cent of group 2 and 60 per cent of group 3 had bilateral sensorineural hearing loss. High-frequency pure tone audiometry showed reduced detectability and higher thresholds at 12 kHz and 16 kHz in patients than in controls. Otoacoustic emissions, tracking, optokinetic and combined vestibular-evoked myogenic potential tests showed abnormal results in chronic kidney disease cases.

Conclusion

Both the auditory and vestibular pathways are affected in different stages of chronic kidney disease. High-frequency pure tone audiometry, otoacoustic emissions and combined vestibular-evoked myogenic potentials could be performed routinely in patients with chronic kidney disease, regardless of the disease stage.

Achados audiológicos em pacientes submetidos ao transplante renal

OBJETIVO: Investigar o comportamento auditivo de pacientes com insuficiência renal crônica submetidos ao transplante renal. MÉTODOS: Foram avaliados 30 pacientes, 10 do gênero feminino e 20 do gênero masculino, na faixa etária de 13 a 26 anos (média de idade 16,97 anos). Os sujeitos foram submetidos a anamnese, avaliação otorrinolaringológica, avaliação audiológica convencional e de altas frequências, medidas de imitância acústica e avaliação do processamento auditivo central. Para os resultados da audiometria de altas frequências foi utilizado um grupo controle. RESULTADOS: Os sujeitos não apresentaram queixas auditivas na anamnese. Os resultados da audiometria convencional demonstraram predomínio da normalidade; na audiometria de altas frequências, os pacientes apresentaram resultados piores do que os sujeitos do grupo controle. Na imitanciometria houve predomínio de curva tipo A bilateral. Na avaliação do processamento auditivo central, 14 sujeitos (46,67%) apresentaram resultados alterados no Staggered Spondaic Word Test (SSW). Houve diferença significativa entre a variável idade e o resultado da audiometria tonal limiar: quanto maior a idade, menor a sensibilidade auditiva nos limiares de 250 Hz a 8 kHz. Houve relação entre o tipo de doador (cadáver ou vivo) e o resultado do teste SSW: os índices de resultados alterados foram maiores quando o doador era cadáver, em comparação com casos de doador vivo. CONCLUSÃO: Houve alterações na avaliação audiológica convencional e de altas frequências e no processamento auditivo central de sujeitos com insuficiência renal crônica submetidos ao transplante renal, sugerindo a necessidade de orientação à equipe envolvida quanto aos cuidados, prevenção e identificação precoce de acometimentos audiológicos.

Increased risk of getting sudden sensorineural hearing loss in patients with chronic kidney disease: a population-based cohort study

OBJECTIVES/HYPOTHESIS

To examine the risk of getting Sudden Sensorineural Hearing Loss (SSHL) among patients with chronic kidney disease (CKD).

STUDY DESIGN

A retrospective cohort study.

METHODS

Population-based representative insurance claims data were used to examine the risk of getting SSHL among patients with chronic kidney disease. Data extracted from the Taiwan National Health Insurance Research Database yielded 37,421 patients with newly diagnosed renal insufficiency and 37,421 subjects without renal insufficiency from between 2000 and 2004.

RESULTS

The incidence of SSHL at the end of 2009 was determined. The incidence of SSHL was 1.57 times higher in the CKD-carrying group compared to the incidence in the non-CKD group (10.24 vs. 6.52 per 10,000 person-years), with adjusted hazard ratio (HR) of 1.46 (95% CI = 1.194-1.787) using Cox proportional hazard regressions. Age was an independent risk factor of getting SSHL, with adjusted HRs of 2.01, 3.178, and 2.285 for age ranges of 35 ≈ 49, 50 ≈ 64 and ≥ 65 compared with age range of 0 ≈ 35. Diabetes Mellitus was another independent risk factor with HR of 1.31 (95% CI = 1.003-1.711).

CONCLUSIONS

Present results suggested a significant association between CKD and increased risk of getting SSHL. Comorbidity of diabetes in patients with CKD appeared to be associated with increased risk of getting SSHL, especially for the patients who are 35 years of age and older.

Hearing loss in patients of chronic renal failure: a study of 100 cases

The purpose of our study was to determine the incidence of hearing loss and to describe the hearing impairment and the possible contributing factors, responsible for sensori neural hearing loss in chronic renal failure (CRF) patients. This was a prospective study carried out on 50 cases of CRF attending otorhinolaryngological services for hearing disturbance and on 50 healthy volunteers for control study, having the same inclusion criteria except (does not suffering with CRF) having normal renal function tests. These volunteers attended the ENT OPD, for oto-rhino-laryngological services but not for hearing problems. 14 (28%) out of 50 cases of CRF had sensori neural hearing loss of moderate to severe degree in the high frequency range which was bilateral and symmetrical, while in control group the incidence of sensorineural hearing loss was only 6%.

The hearing status in 12 female and 15 male Japanese Fabry patients

OBJECTIVE

Fabry disease (FD) is an x-linked inherited disease that causes a lack of a lysosomal enzyme, alpha-galactosidaseA, leading to cellular accumulation of glycosphingolipids of the whole body. This accumulation in the inner ear causes hearing loss also. However, FD is rare, and the frequency is lower in females than in males. Thus, there have been few comparative studies between women and men for hearing loss in FD. Accordingly, we examined the hearing status of both male and female FD patients and elucidated the similarities and differences. We also analyzed for correlations between the hearing status and renal and heart disorders.

METHODS

12 women and 15 men were studied by means of pure tone audiometry, the relationships between the hearing status and the renal and cardiac functions.

RESULTS

The audiogram type was the flat type in a majority of both women and men, followed by the high type and low type, while the U-shaped type was rare. Examination of the thresholds average showed abnormality in one woman and four men. Comparison to threshold for each age bracket of normal subjects showed abnormality in three women and nine men. No correlations were found between the hearing loss and either the renal or cardiac function. All the patients with renal dysfunction had abnormal hearing.

CONCLUSIONS

The frequency of hearing loss in FD was higher in men than in women. Also, there may be some relationship between renal function and hearing loss in FD.

Sudden Sensorineural Hearing Loss and Hemodialysis

The etiology of sensorineural hearing loss (SNHL) associated with renal failure and hemodialysis is controversial. Possible mechanisms include a shared antigenicity between the kidney and the labyrinths, osmotic alteration caused by hemodialysis, and the ototoxic effect of diuretics. We present 2 cases of SNHL associated with renal failure and its treatment. One patient was a 35-year-old man who developed profound SNHL after 5 sessions of hemodialysis, and the other was a 36-year-old woman who developed severe to profound SNHL after 7 sessions. It is our impression that both hearing losses might have been attributable to osmotic disequilibrium in the labyrinth or to an acute labyrinthine injury caused by contamination of the blood by the degraded product of an old cellulose acetate hemodialyzer membrane; the hemodialyzer had been in use for 15 years.

Low endolymph calcium concentrations in deafwaddler2J mice suggest that PMCA2 contributes to endolymph calcium maintenance

In vertebrates, transduction of sound into an electrochemical signal is carried out by hair cells that rely on calcium to perform specialized functions. The apical surfaces of hair cells are surrounded by endolymphatic fluid containing calcium at concentrations that must be maintained by active transport. The mechanism of this transport is unknown, but an ATP-dependent pump is believed to participate. Mutation of the Atp2b2 gene that encodes plasma membrane calcium ATPase type 2 (PMCA2) produces the deaf, ataxic mouse: deafwaddler2J (dfw2J). We hypothesized that PMCA2 might transport calcium into the endolymph and that dfw2J mice would have low endolymph calcium concentrations, possibly contributing to their deafness and ataxia. First, using immunocytochemistry, we demonstrated that PMCA2 is present in control mice inner and outer hair cell stereocilia where it could pump calcium into the endolymph and that PMCA2 is absent in dfw2J stereocilia. Second, using an aspirating microelectrode and calcium-sensitive fluorescent dye, we found that dfw2J mice endolymph calcium concentrations are significantly lower than those of control mice. These findings suggest that PMCA2, located in hair cell stereocilia, contributes significantly to endolymph calcium maintenance.

A study of otorhinolaryngological manifestations in patients of chronic renal failure

The present study was carried out on 50 patients of Chronic renal failure (CRF), Majority of CRF patients had high frequency hearing loss, but inner ear changes were found to be irreversible even after dialysis. All cases had cochlear lesion. No relationship could be established between the level of blood urea, creatinine, serum potassium, serum calcium and blood pressure with the severity of the impaired hearing. A direct correlation was seen between increasing hyponatraemia and impaired hearing. No direct relationship could be made between blood pressure and epistaxis, but all the cases had raised blood urea.

Reversible uremic deafness: is it correlated with the degree of anemia?

Hearing loss is a common finding in patients with end-stage renal failure. Uremic toxins, ototoxins, and axonal uremic neuropathy appear to be likely pathogenic factors. We analyzed whether an improvement in hearing capacity can be achieved with an improvement of anemia by erythropoietin (EPO) administration. Fifty patients on long-term hemodialysis in a single center were examined audiologically by otoscopy, tympanometry, pure tone audiometry, and the short increment sensitivity index. Twenty-five patients were treated with EPO in a dose of 120 U/kg per week over a period of 5 to 8 months, and the remaining 25 patients were not treated with EPO (controls). Both groups were reexamined audiologically after the study period, and the results were compared. In the group treated with EPO, the hemoglobin level increased from 7 +/- 0.9 to 11 +/- 0.8 g/dL, as against the control group, whose hemoglobin increased from 7.1 +/- 0.9 to 8 +/- g/dL. The audiologic tests were repeated at the end of the study period, and a significant improvement of hearing was found in the patients treated with EPO as compared with the control group (p < .001). Our study suggests that improvement of anemia in patients on long-term hemodialysis by administration of EPO is associated with an improvement in hearing capacity in a significant number of patients. Thus, anemia seems to be an important factor responsible for hearing disorders in patients with end-stage renal failure. Studies with larger numbers of patients are required to confirm this observation.

Sensorineural hearing loss in patients reaching chronic renal failure in childhood

The incidence of sensorineural hearing loss (SNHL) was investigated in 68 patients who reached chronic renal failure (CRF) in childhood with the aim of identifying possible risk factors. Tests were carried out by means of pure-tone and impedance audiometry. SNHL was found in 29% of patients on conservative treatment, 28% of patients on hemodialysis, and 47% after renal transplantation. Differences among groups were not significant. A significant correlation was found with the administration of ototoxic drugs (aminoglycosides and furosemide). We hypothesize that SNHL may be reduced in patients with CRF or on renal replacement therapy by strictly monitoring ototoxic therapy.

Evoked potentials in children with chronic renal failure, treated conservatively or by continuous ambulatory peritoneal dialysis

Children with chronic renal failure (CRF) show developmental, intellectual and motor disturbances. It is questionable if an early start of renal replacement therapy may prevent or delay these disturbances. We studied the neurological and intellectual development of children < 5 years suffering from CRF (creatinine clearance < 20% of normal) prospectively, over a period of 3 years. As part of the neurological study, brainstem auditory evoked potentials (BAEP) and somatosensory evoked potentials (SSEP) were recorded. Measurements were performed in a group of 22 children every 6 months. In 18 of these children CRF was present from birth. Sufficient data were available for analysis in 19 (BAEP) and 22 (SSEP), respectively. A delay of peak I of BAEP gave indications for peripheral conduction disturbances, possibly due to cochlear dysfunction. Brainstem conduction was normal. There were no differences between the children treated conservatively (n = 9) and those treated with continuous ambulatory peritoneal dialysis (CAPD) (n = 10). In children < 2.5 years SSEP showed a delayed thalamocortical conduction, which was not observed in older children. This might indicate a delayed myelination in young children with CRF. No differences were found between the children treated conservatively (n = 10) and those treated with CAPD (n = 12).

Stria vascularis in Ménière's disease: a quantitative histopathological study

To investigate the role of pathology of the stria vascularis in Ménière's disease, the vascularity and the cross-sectional area of the stria vascularis in a midmodiolar section of the cochlea were examined by histological observation and a computer-aided planimetric, respectively, in eight temporal bones from individuals with Ménière's disease and eight age-matched normal temporal bones. The number of vessels in the stria vascularis was significantly smaller in most of the cochlear turns in ears with Ménière's disease than in control ears, and the cross-sectional area of the stria vascularis in the same sections was significantly smaller in all the cochlear turns in ears with Ménière's disease than in controls. Furthermore, vascularity correlated significantly with the cross-sectional area of the stria vascularis in all the temporal bones examined. From these results it appears that poor vascularity of the stria vascularis is closely related to strial atrophy, and that these pathological findings might be important factors in the pathophysiology of Ménière's disease.

The hearing of the patients treated with hemodialysis: a long term follow-up study

Sensorineural hearing loss is frequently found in the patients under the treatment with hemodialysis, but the responsible etiological factor(s) still remains controversial. The purpose of the present study was to determine by a long term follow-up study whether hemodialysis per se or other factors induce sensorineural hearing loss. Thirty-seven patients with the observation periods of 4 years or longer were selected for the analysis. Hearing tests were performed soon after the initiation of hemodialysis and every 3 to 12 months thereafter. Significant hearing loss was found in 16 cases (31 ears) at the first test. Although 3 cases (5 ears) of the initially normal group and one case (2 ears) of the group with already existing hearing loss exhibited significant hearing loss, the change in the hearing level was quite minimal in remaining 67 ears during the observation period. Although the cochlea in patients under the treatment with hemodialysis is susceptible to various insults, we conclude that hemodialysis per se does no harm to the cochlea and the hearing can be maintained at the pre-hemodialysis level in the majority of the cases.

Audiological findings in elderly patients with chronic 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.

A new syndrome: hearing loss and familial salivary gland insensitivity to aldosterone in two brothers

Two male siblings presented in infancy with hyponatremia. The levels of plasma renin activity and aldosterone were elevated. Sodium supplement was necessary to maintain normal sodium balance. The salivary sodium concentrations were markedly elevated, with sweat sodium levels being in the upper normal range. Urinary sodium concentration and renal epithelial exchange between sodium and potassium were normal. This was felt to be due to an autosomal recessive disorder. Both siblings were later diagnosed as having a bilateral moderate to severe sensorineural hearing loss with intermittent conductive overlay due to middle ear fluid. The sensorineural loss was also felt to be autosomal recessive in origin, but the possibility of a disturbance of sodium balance in the inner ear has been questioned.

Hearing loss in a uraemic patient: indications of involvement of the VIIIth nerve

A case of acute renal failure associated with severe uraemic hearing loss is presented. Audiometric site-of-lesion testing revealed cochlear as well as neural involvement. After therapy hearing recovered up to an almost normal level, with normal auditory nerve conduction velocities. This case report supports the suggestion that the improvement of hearing after renal transplantation or dialysis might be correlated with the influences of these forms of therapy upon the peripheral neuropathy.

Human cochlear pathology in aminoglycoside ototoxicity--a review

The pathological findings due to aminoglycoside ototoxicity in man, as reported in the literature, is reviewed. 21 cases (40 ears) have been studied after serial sectioning, 8 cases (12 ears) have been investigated by the microdissection and surface preparation technique. The combination of both methods provides maximal information. OHCs are primarily affected, followed by IHC loss. Degeneration starts at the basal coil and proceeds towards the apex. The stria vascularis becomes involved in all turns. It is not clear whether stria degeneration is primary or secondary. Supporting cells, nerve fibres and ganglion cells degenerate secondary to hair cell loss. In some cases ingrowth of myelinated nerve fibres in areas with complete destruction of the organ of Corti has been observed. Ototoxic lesions can be asymmetric. Attention is drawn to the audiometric Z-curve in moderate lesions.

Basophilic deposits in the stria vascularis. A clinicopathological update

Basophilic deposits in the stria vascularis have been found in association with a multitude of disease entities. Their true significance and nature remain obscure. In the temporal bone collection at the Massachusetts Eye and Ear Infirmary are 22 cases with basophilic deposits in the stria vascularis. The ages of the subjects studied ranged from two days to 83 years. Atrophy of the stria vascularis was the main pathology seen in their temporal bones. The deposits were found in both ears in 82% of cases. They tend to show a striking polymorphism. Special histochemical stains suggest they contain glycogen. Hypertension and uremia were two health problems most of the subjects were suffering from during life. A theory is advanced as to the immune complex nature of these deposits. A review of the literature concerning this subject is also offered.

Hearing loss in end-stage renal disease - effect of dialysis

Hearing sensitivity was determined in 23 patients with end-stage renal disease shortly before and 1-5 years after the institution of maintenance hemodialysis. Normal or only slightly abnormal hearing sensitivity was found in 9 of our 23 patients while the remaining 14 patients had marked hearing abnormalities at the onset of dialysis treatment. Neither group showed any significant change in their audiographic findings during the study period. It thus appears that chronic hemodialysis may have no effect on hearing abnormalities associated with end-stage renal disease.

Reversal of deafness after renal transplantation in Alport's syndrome

Six patients (five men and one woman) with Alport's syndrome underwent successful renal transplantation (four received kidneys from cadaver donors and two received allografts from living, related donors). One patient who had received a cadaver kidney had substantial hearing improvement and the others had stabilization of hearing. Hearing loss in Alport's syndrome is progressive. The reversal of deafness in one of our patients and stabilization in the others made us wonder whether an inherited enzymopathy had been reversed, which then mitigated the deafness.

Effect of renal transplantation on uremic deafness: a long-term study

In order to investigate the influence of a functioning transplant on uremic hearing loss, audiometrical controls were performed on 13 patients before and after renal transplantation. During renal dialysis treatment there was a marked hearing loss for the higher frequencies between 2 000 and 8 000 Hz. Hearing capacity improved to normal after transplantation, the best audiometric results being obtained 21.4 (8-42) months after surgery. There was a significant improvement in hearing especially for middle- and high-tone frequencies. It is assumed that uremic toxins, possibly responsible for sensorineural hearing loss in patients with chronic renal failure may be sufficiently removed by a functioning transplant.

Hearing loss in patients with dialysis and renal transplants

Hearing loss in renal dialysis and renal transplant patients occurs quite frequently. An assessment of the likely etiological factors is nearly impossible in a retrospective analysis of any one patient because many factors exist simultaneously. In a prospective study of a large series of patients an identification of factors contributing to the hearing loss was possible in the majority of patients. During the study it became increasingly apparent that what was observed at any one time was the combined effect of many factors. Although one factor seemed to precipitate the hearing loss it was inadvisable to attribute total responsibility to that agent or circumstance. Further, this combined effect was not a simple addition of effects but potentiation. The serious implications of this phenomenon are discussed.

Hearing function and chronic renal failure

In order to evaluate the degree and type of hearing loss in patients with chronic renal failure, 61 patients undergoing chronic hemodialysis were examined. Hearing threshold levels, adjusted for age and sex, demonstrated a significant high frequency deficit, which in some patients was noted early in the course of hemodialysis. Fluctuations in hearing were noted over single dialysis events but were transient and apparently independent of corresponding changes in Na, K, Ca, BUN, creatinine, glucose, mean blood pressure, and weight. Preliminary attempts to evaluate hyperlipidemia as a possible cause of hearing loss did not reveal any hearing deficit or gain as related to triglyceride or cholesterol levels. The data suggested other possible causes of observed auditory loss.

Permanent deafness associated with furosemide administration

Six cases of hearing impairment have been presented. Furosemide was administered to all of these patients at the time of the alleged onset of the deafness. None of the known or suspected causes of deafness occurring in transplant patients was evident in these cases. With the experimental evidence that furosemide does induce stria damage and the absence of other recognized causes of deafness in this series of patients, furosemide must be considered the etiologic agent responsible for the permanent sensorineural hearing loss. A characteristic audiometric pattern of hearing impairment emerged and a possible explanation for these features has been given. Certain precautionary steps in the use of ototoxic drugs are suggested.