Cis-platin ototoxicity in previously noise-exposed guinea pigs

The Relationship Between Cisplatin-related and Age-related Hearing Loss During an Extended Follow-up

OBJECTIVES

Cisplatin-related hearing loss (HL) is claimed to progress after treatment. This controlled longitudinal study with extended follow-up investigates HL in testicular cancer survivors (TCSs) after cisplatin-based chemotherapy (CBCT).

STUDY DESIGN

Controlled longitudinal study.

METHODS

Eighty-two TCSs treated with CBCT between 1980 and 1994 in Norway participated in two surveys (S1/S3), including pure-tone audiograms (0.125-8 kHz) and self-reported HL, 12 and 31 years after treatment, respectively. Hearing thresholds were age-adjusted based on age-matched hearing thresholds from the general population (controls). Hearing loss was defined as thresholds >20 dB at any frequency.

RESULTS

Between the two surveys, the prevalence of high-frequency HL (4, 6, and 8 kHz) increased from 73% to 94% but approached those of the aging general population after age adjustment. In TCSs aged >40 years at first survey, HL at the subsequent survey equaled that of controls. Self-reported HL increased from seven (9%) at S1 to 20 (26%) at S3. At S1, age-adjusted HL was identified in all (seven) TCSs reporting decreased hearing whereas at S3, hearing thresholds did not differ from controls in seven out of 20 patients reporting HL.

CONCLUSION

CBCT-related ototoxicity causes high-frequency HL, but in contrast to reports from follow-up studies from the first post-treatment decade, no major progression was found beyond the first post-treatment decade for frequencies 0.125-8 kHz. Importantly, with extended follow-up, hearing thresholds of patients approach those of the general population, possibly due to a less-than-additive effect with age-related hearing loss (ARHL) in CBCT-treated patients. Age-and sex-matching is strongly advised in long-term follow-up of CBCT-related ototoxicity. Specificity for detecting ototoxicity with self-reported questionnaires decreases with extended follow-up.

LEVEL OF EVIDENCE

3 Laryngoscope, 130:E515-E523, 2020.

Is routine audiometric evaluation necessary in gynaecologic tumour patients undergoing chemotherapy?

BACKGROUND

Our objective was to assess the auditory function of gynaecological tumour patients who had received cytotoxic agents and to determine their associated risk of ototoxicity.

PATIENTS AND METHODS

87 patients who had undergone chemotherapy for gynaecological malignancies were investigated. Of these patients, 79% had breast cancer, and 14% ovarian cancer. All of the patients had a subjective assessment of their hearing function on a visual analogue scale. Audiometric tests were performed before and at 9 weeks, 18 weeks and 3 months after completion of chemotherapy.

RESULTS

The age of the patients ranged from 32 to 71 years (mean age of 53.5 ± 10.5 years). The average subjective rating of the patients' hearing function was 83.0 ± 17.2 before and 84.8 ± 16.9 3 months after completion of chemotherapy. No significant audiometric change at either the speech hearing frequency range (0.5-2 KHz) or high frequencies was observed in the patients after chemotherapy. There was also no significant difference in the hearing threshold of the patients who had received platinum analogue-based chemotherapy compared to non-platinum analogue-based chemotherapy.

CONCLUSION

Hearing loss is uncommon in patients treated with the typical gynaecological chemotherapy protocols. Hence, routine audiometric testing in these patients is not necessary.

Distortion-product otoacoustic emission test performance for ototoxicity monitoring

INTRODUCTION

A nonbehavioral method for monitoring ototoxicity in patients treated with cisplatin is needed because patients enduring chemotherapy may not be well or cooperative enough to undergo repeated hearing tests. Distortion-product otoacoustic emissions (DPOAEs) provide a nonbehavioral measure of auditory function that is sensitive to cisplatin exposure. However, interpreting DPOAE findings in the context of ototoxicity monitoring requires that their accuracy be determined in relation to a clinically accepted gold standard test.

OBJECTIVES

Among patients receiving cisplatin for the treatment of cancer, we sought to (1) identify the combination of DPOAE metrics and ototoxicity risk factors that best classified ears with and without ototoxic-induced hearing changes; and (2) evaluate the test performance achieved by the composite measure as well as by DPOAEs alone.

DESIGN

Odds of experiencing hearing changes at a given patient visit were determined using data collected prospectively from 24 Veterans receiving cisplatin. Pure-tone thresholds were examined within an octave of each subject's high-frequency hearing limit. DPOAE were collected as a set of four response growth (input/output) functions near the highest f2 frequency that yielded a robust response at L2 = L1 = 65 dB SPL. Logistic regression modeled the risk of hearing change using several DPOAE metrics, drug treatment factors, and other patient factors as independent variables. An optimal discriminant function was derived by reducing the model so that only statistically significant variables were included. Receiver operating characteristic curve analyses were used to evaluate test performance.

RESULTS

At higher cisplatin doses, ears with better hearing at baseline were more likely to exhibit ototoxic hearing changes than those with poorer hearing. Measures of pre-exposure hearing, cumulative drug dose, and DPOAEs generated a highly accurate discriminant function with a cross-validated area under the receiver operating characteristic curve of 0.9. DPOAEs alone also provided an indication of ototoxic hearing change when measured at the highest DPOAE test frequency that yielded a robust response.

CONCLUSIONS

DPOAEs alone and especially in combination with pre-exposure hearing and cisplatin dose provide an indication of whether or not hearing has changed as a result of cisplatin administration. These promising results need to be validated in a separate sample.

The ototoxic interaction of styrene and noise

The interaction between noise and inhaled styrene on the structure and function of the auditory organ of the male Wistar rat was studied. The animals were exposed either to 600 ppm, 300 ppm or 100 ppm styrene (12 h/day, 5 days/week, for 4 weeks) alone or in combination with a simultaneous 100-105 dB industrial noise stimulant. Auditory sensitivity was tested by auditory brainstem audiometry at 1.0, 2.0, 4.0 and 8.0 kHz frequencies. Inner ear changes were studied by light microscopy. Exposure to 600 ppm styrene alone caused a 3 dB hearing loss only at the highest test frequency (8 kHz). Quantitative morphological analysis of cochlear hair cells (cytocochleograms) showed a severe outer hair cell (OHC) loss particularly in the third OHC row of the upper basal and lower middle coil. Exposure to noise alone caused only a mild hearing loss (2-9 dB), and only an occasional loss of OHCs (<1% missing). Exposure to the combination of noise and 600 ppm styrene caused a moderate flat hearing loss of 23-27 dB. The cytocochleograms showed a more severe damage of the OHCs than after exposure to 600 ppm styrene alone. The inner hair cells were found to be destroyed in some animals in the upper basal turn only after the combination exposure. Only in combination with noise exposure, the lower styrene concentrations (100 and 300 ppm) induced a hearing loss which was equivalent to that seen after exposure to noise alone. We conclude that: (1) There is an ototoxic interaction between styrene and noise. (2) Synergism is manifested only if styrene is applied in concentrations above the critical level (between 300 and 600 ppm in this study).

Combined effects of noise and cisplatin: short- and long-term follow-up

The combined effects of noise exposure and intravenous cisplatin injection on electrophysiologic hearing thresholds in guinea pigs were studied with short-term and long-term follow-up. The combined effects on the permanent threshold shift were dependent on the order of exposure. A potentiation was achieved when noise exposure preceded cisplatin injection by 30 minutes or by 3 days. Cisplatin injection 2 or 3 days before noise exposure produced no significant potentiation or inhibition. The combined effects on the temporary threshold shift were not influenced by the sequence of exposure.

Interaction of cisplatin and noise on the peripheral auditory system

The potentiation of cisplatin ototoxicity by noise was explored in the chinchilla. The effects of exposure to cisplatin alone, noise alone or concurrent exposure to both agents were compared in terms of the threshold shift of the auditory evoked potential and the amount of hair cell loss. The combination of cisplatin plus noise produced significantly more hair cell loss and hearing loss at the high frequencies than did either the noise or cisplatin alone when the noise level was 85 dB SPL or higher; no interaction was seen when the noise level was 70 dB SPL. The amount of the interaction, when present, was constant regardless of the noise level. These results indicate that moderate to high levels of noise can exacerbate cisplatin ototoxicity.

Sequence of exposure to noise and toluene can determine loss of auditory sensitivity in the rat

Rats were exposed to noise (100 dB Leq, 10 h/d, 7 d/w, 4 w), or to toluene (1,000 ppm, 16 h/d, 7 d/w, 2 w), or to noise followed by toluene. Auditory sensitivity was tested before exposure, and 1 to 4 weeks after exposure, by brainstem audiometry using a 1/3-octave filtered sine wave stimulus at the frequencies 1.6, 3.15, 6.3, 12.5 and 20.0 kHz. Some auditory impairment was observed after all exposures. The sensitivity loss after exposure to noise followed by toluene was greater than that recorded after exposure to noise alone or toluene alone, but did not exceed the summated loss caused by noise alone and toluene alone at any frequency. This result contrasts with the earlier reported effect of the same exposures in the reversed order. It is concluded that the exposure sequence can determine the extent of auditory impairment.

Audiologic threshold monitoring of patients receiving ototoxic drugs. Preliminary report

An effort was made to determine the efficacy of auditory threshold monitoring of patients receiving ototoxic drugs. Forty-four patients treated with either tobramycin or vancomycin for osteomyelitis were tested at the beginning of treatment, following treatment, and twice weekly during treatment when possible. All patients had renal function carefully monitored. Peak and trough drug levels were kept out of the toxic range throughout the study. In no patient did indisputable ototoxicity occur, and therefore, no conclusion about the most efficacious schedule for auditory monitoring of patients receiving ototoxic drugs was made, and what constitutes a significant intratherapeutic threshold shift is still in question. Until further data are collected, monitoring of renal function and peak and trough drug levels, as well as patient counseling, is recommended. Pretherapy and posttherapy auditory monitoring and intratherapeutic monitoring of high-risk patients and those who develop aural symptoms may prove beneficial.

The ototoxic effect of cisplatin on guinea pigs in relation to dosage

The effect on the electrophysiological hearing thresholds and the endocochlear DC potential (EP) was studied in four groups of guinea pigs receiving different doses of cisplatin. By multiple low-dose intraperitoneal injections a permanent hearing loss was produced without a permanent decrease of the EP. On the other hand, when cisplatin was given as a single high-dose intravenous injection, there was an impairment of the electrophysiological hearing thresholds and EP, depending upon the level of cisplatin dose. It is concluded that cisplatin-induced hearing loss is not necessarily a sequela to a loss of EP.

The combined effect of cisplatin and furosemide on hearing function in guinea pigs

The effect of the combined administration of cisplatin and furosemide on the electrophysiological hearing thresholds and endocochlear DC potential (EP) was studied in guinea pigs. A lack of interaction was found in animals given repeated intraperitoneal injections of a low dose of cisplatin with a pharmacological dose of furosemide. An ototoxic interaction occurred when a moderately high dose of cisplatin was administered intravenously at a time when the strial function was most affected by a very high dose of furosemide. The interaction was seen both as a decreased EP and a pronounced shift of auditory thresholds. It is concluded that the stria vascularis plays a role in the ototoxic mechanism of cisplatin.

Synergistic interactions of gentamicin and pure tones causing cochlear hair cell loss in pigmented guinea pigs

The effects of single and repeated combinations of gentamicin and sound on Preyer reflex and cochlear hair cells in pigmented guinea pigs have been examined. Gentamicin at 50 mg/kg for 10 days and an 8 kHz pure tone (116 dB for 60 min) cause little or no hair cell loss when given alone. In combination, hair cell loss occurs with the gentamicin and sound acting synergistically. If the pure tone is given on the first of a 10-day gentamicin course there is considerable loss of hair cells in the basal coil; if given on the 10th day the loss is several times less. Repeating the treatments after 3 weeks increases the hair cell loss and the synergistic effect. A possible explanation for the differential synergistic effect is discussed.

Effect of interaction between noise and toluene on auditory function in the rat

Rats were exposed to toluene (1000 ppm, 16 h/d, 5 d/w, 2 w), or noise (100 dB Leq, 10 h/d, 7 d/w, 4 w) or toluene followed by noise. Auditory function was tested by brainstem audiometry using a 1/3 octave filtered sine wave stimulus at the frequencies 1.6, 3.15, 6.3, 12.5 and 20.0 kHz. A high-frequency auditory impairment was observed after exposure to toluene alone and noise alone. A slight recovery was recorded 1 and 6 months after the toluene exposure. Toluene followed by noise resulted in a higher threshold at all frequencies. A slight recovery was recorded 6 months post-exposure. The threshold shift exceeded the summated loss caused by toluene alone and by noise alone, particularly at 3.15 and 6.3 kHz. The latencies varied only slightly. The results indicate that the major cause of the auditory impairment was cochlear damage and that only minor injury was caused to the auditory pathways.

Ototoxicity of cisplatin in gynaecological cancer patients

The ototoxic side effect of a moderate dose of cisplatin was studied by regular audiometric investigations in 186 women with gynaecologic cancer. Cisplatin was given in a dose of 50 mg/m2 body surface by intravenous infusion every 4 weeks. High-frequency hearing loss occurred in 40 patients (22%), but in no single case was a significant change observed in the frequency range of 0.5-2 kHz. Older patients showed a statistically significant greater incidence of audiometric changes, but the pretreatment audiogram was not a predictor for ototoxic changes. It is concluded that a moderate dose of cisplatin does not effect the ability to communicate.

Ototoxicity of cisplatin

Ototoxicity is one of the unwanted side effects of cisplatin treatment. The first sign of hearing loss usually appears 3-4 days after the drug administration and occurs primarily in the higher frequencies. One hundred and eighty-six women treated with a moderate dose of cisplatin (50 mg/m2 every 4 weeks) for gynaecological cancer were studied. No significant loss of hearing was detected in the speech frequency range. Since the cisplatin concentration in the inner ear is highest after a single high dose injection, systemic audiometric monitoring is advisable during cisplatin therapy with single high dose regimen.