α-Tocopherol protective effects on gentamicin ototoxicity: an experimental study

Gentamicin, acting as an iron chelator, activates membrane lipid peroxidation (MPL) and induces free radical formation, as observed in vitro and in vivo. Antioxidants, such as alpha-tocopherol, are able to suppress MLP, thus attenuating tissue damage. The present study was designed to investigate the possible protective effects of alpha-tocopherol on gentamicin ototoxicity. The study was carried out on albino guinea pigs (250-350 g). The animals were divided into four groups: group A (n = 4), injected with corn oil daily at a dose of 100 mg/kg body weight intramuscularly (IM); group B (n = 10), treated with corn oil at a dose of 100 mg/kg body weight and gentamicin base at a dose of 100 mg/kg body weight (IM); group C (n = 10). treated with gentamicin alone at a dose of 100 mg/kg body weight (IM); and group D (n = 10), treated with gentamicin at the same dose plus alpha-tocopherol acetate at dose of 100 mg/kg body weight (IM). Electrocochleographic recordings were made from an implanted round-window electrode. All animals were treated for 14 days. The compound action potentials (CAPs) were measured at 2-16 kHz at days 0, 10, 14 and 18 after treatment. Changes in cochlear function were characterized as CAP threshold shifts. Morphological changes were analysed by scanning electron microscopy. Gentamicin induced progressive high-frequency hearing loss of 50-60 dB SPL. alpha-Tocopherol co-therapy slowed the progression of hearing loss. The significant loss of outer hair cells (OHCs) in the cochlear basal turn in gentamicin-treated animals was not observed in the cochleas of animals protected with alpha-tocopherol. This study supports the hypothesis that alpha-tocopherol interferes with gentamicin-induced free radical formation, and suggests that this drug may be useful in protecting OHC function from aminoglycoside ototoxicity, thus reducing hearing loss.

The protective role of tiopronin in cisplatin ototoxicity in Wistar rats

The purpose of this study was to evaluate cisplatin-induced ototoxicity and the protective effects of tiopronin. Twenty-four adult Wistar rats served as subjects and were divided into three groups. Eight rats receiving only saline (group A) were used as controls. Eight rats received cisplatin (2 mg/kg) injections (group B) and eight rats received cisplatin and tiopronin (300 mg/kg) (group C) for 8 consecutive days. Both ears of all animals were tested by DPOAE before treatment and on the 4th and 9th days. Seventy-two hours after the final recording session, all animals were killed, and the left cochleas were prepared for electron microscopy and analysed. DPOAE responses were significantly reduced in group B compared to controls (p<0.05). When tiopronin was added, DPOAE responses were significantly increased compared to those obtained with the administration of cisplatin alone (p<0.05). The cochleogram showed that tiopronin had a significant protective effect in the basal half and in the lower half of the middle turn. We conclude that tiopronin, a drug effective in protecting against cisplatin nephrotoxicity, is also effective in protecting against cisplatin ototoxicity.

Protective effects of N-acetylcysteine on noise-induced hearing loss in guinea pigs

Increasing evidence suggests the involvement of oxidative stress in noise-induced hearing loss. The present study analysed, in an animal experimental model, the time course of the pathogenic mechanisms of noise-induced cochlear damage and the efficacy of the antioxidant drug N-acetylcysteine in reducing noise ototoxicity. Animals were divided into two groups, exposed to noise one treated with N-acetylcysteine for 3 days and one (the control group) with saline. Acoustic trauma was induced by a continuous pure tone of 6 kHz, at 120 dB SPL for 30 minutes. Electrocochleographic recordings were made from an implanted round window electrode and the compound action potentials were measured daily at 2-16 kHz for 7 days. Morphological changes were analysed by scanning electron microscopy. The acoustic threshold measured 1 hour after acoustic trauma was elevated in the control group to 70-90 dB in the higher frequencies of the compound action potential audiogram, with a maximum threshold elevation ranging between 12 and 16 kHz. During the first 24 h, following acoustic trauma, there was a partial recovery of compound action potential thresholds of about 20 dB to reach a final threshold elevation of about 50-70 dB; there was no further improvement over the remaining experimental week. Animals treated with N-acetylcysteine showed a similar temporary threshold shift but a clear improvement in the recovery of compound action potential thresholds, with significantly reduced permanent threshold shift and hair cell loss. These data suggest that N-acetylcysteine is able to attenuate the toxic effect of acoustic trauma and could represent an interesting molecule for preventing inner ear injuries.

Giant deep lobe parotid gland pleomorphic adenoma involving the parapharyngeal space. Report of three cases and review of the diagnostic and therapeutic approaches

Aim of the present report is to discuss and underline the diagnostic algorithm and the surgical approach to giant parotid pleomorphic adenomas arising in the deep lobe and growing in the parapharyngeal space. Three cases are described and a review is made of the international literature concerning giant deep lobe parotid gland pleomorphic adenoma. Diagnosis was based on imaging, computed tomography scan and magnetic resonance imaging and upon cytology, by means of fine needle aspiration biopsy. The surgical approach varied according to the location of the tumour. All patients were discharged without complications and no cases of permanent facial nerve palsy were observed. An exhaustive pre-operative diagnostic algorithm is required before approaching this lesion. Fine needle aspiration biopsy is, in our opinion, mandatory to avoid histological surprises. The surgical approach should provide excellent visibility with wide surgical exposure to secure local neurovascular structures.

Hearing loss in a family affected by Fabry disease

Fabry disease is an inborn error of metabolism due to deficient activity of the lysosomal enzyme alpha-galactosidase A. The enzyme defect leads to the systemic accumulation of neutral glycosphingolipids in tissues. Otological manifestations consist of hearing loss and mild vestibular disorders. In this report we describe a family of five members affected by Fabry disease with four subjects showing inner ear involvement.

Role of ossiculoplasty in canal wall down tympanoplasty for middle-ear cholesteatoma: hearing results

The aim of this study was to evaluate the hearing results of ossiculoplasty in canal wall down tympanoplasty in one stage middle-ear cholesteatoma surgery.

We carried out a retrospective review of a consecutive series of 142 cases which had undergone type two or three canal wall down tympanoplasty with ossicular reconstruction, between January 1995 and December 2002, due to chronic otitis media with cholesteatoma.

Pre-operative audiometric testing revealed a mean air conduction pure tone average (PTA) of 50.97 dB and a mean bone conduction PTA of 22.14 dB. The mean post-operative result for air conduction PTA was 37.62 and for bone conduction PTA was 23.37 dB. The mean pre- and post-operative air–bone gaps (ABGs) were 28.83 and 13.94 dB, respectively, with a gain of 14.89 dB. Almost 62.67 per cent of patients closed their ABGs to within 20 dB.

Our functional results are comparable with those of other authors. In the present study, we show that hearing improvement is possible following cholesteatoma surgery with canal wall down tympanoplasty and ossicular chain reconstruction.

Protective properties of idebenone in noise-induced hearing loss in the guinea pig

Idebenone is a synthetic analogue of coenzyme Q10 with antioxidant properties. The present study investigated the antioxidant activity of idebenone in the rescue of acoustic trauma. Noise-induced hearing loss was induced by exposing guinea pigs to a continuous pure tone and idebenone was injected intraperitoneally 1 h before noise exposure and once daily for 3 days. Guinea pigs treated with idebenone showed significantly smaller auditory threshold shifts than unprotected control animals. Missing and apoptotic cells were identified with scanning electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Protected animals presented a lesser extent of both apoptotic activation and hair cell loss in the organ of Corti. Our results suggest an antioxidant function of idebenone in protection from noise-induced hearing loss and provide a rationale for exploring therapeutic strategies in humans.

Vascular endothelial growth factor (VEGF) expression in noise-induced hearing loss

Noise-induced hearing loss has been associated with alterations in cochlear blood flow. Our study analyzed the expression of Vascular Endothelial Growth Factor (VEGF) and its functional receptors, Flt-1 and Flk-1, in the cochlear structures of noise-exposed and unexposed guinea pigs. VEGF is a prototypical angiogenic agent, with multiple functions on vascular biology, ranging from vascular permeability to endothelial cell migration, proliferation, differentiation, and survival. Acoustic trauma was induced by a continuous pure tone of 6 kHz, at 120 dB SPL for 30 min. Auditory function was evaluated by electrocochleographic recordings at 2-20 kHz for 7 days. Noise-induced cochlear morphological changes were studied by immunohistochemistry and scanning electron microscopy. The expression of VEGF and its receptors was examined by immunohistochemistry and western blotting analysis. The hearing threshold shift reached a level of 60 dB SPL on day 1 after trauma and underwent a partial recovery over time, reaching a value of about 20 dB SPL on day 7. Outer hair cell loss was more prominent in the area located 14-16 mm from the apex. Increased cochlear VEGF expression was observed in noise-exposed animals, in particular at the level of stria vascularis, spiral ligament, and spiral ganglion cells. No changes were observed in the expression of VEGF-receptors. Our data suggest a role for VEGF in the regulation of the vascular network in the inner ear after acoustic trauma and during auditory recovery, with potentially important clinical and therapeutic implications.

Extracranial internal carotid artery aneurysm presenting as pharyngeal mass with dysphagia

Aneurysms of the extracranial portion of the internal carotid artery are rare. Generally, they occur just at the level of, or above, the bifurcation. Here we report a case of a left internal carotid artery aneurysm presenting as an oropharyngeal mass causing dysphagia.

New techniques and technology to repair cerebrospinal fluid rhinorrhea

Cerebrospinal fluid rhinorrhea occurs as a result of abnormal communication between the subarachnoid space and the pneumatized portion of the skull base, the paranasal sinuses and the middle ear. Conservative measures may be sufficient in the management of cerebrospinal fluid rhinorrhea, but, in some cases, surgical treatment may be required. Transnasal endoscopic techniques are constantly being used in preference to the intra- and extracranial approaches. Recently, image guidance systems have been adopted in neurosurgery, skull base and paranasal sinus surgery. The present report refers to 4 cases of nasal cerebrospinal fluid rhinorrhea leak successfully treated with a transnasal endoscopic approach using various techniques and materials to close the bone defect, in 2 of which, the navigation system (Stealth Station Treon ENT Image Guidance System with Landmark X, Software, Medtronic, XOMED, Jacksonville, FL, USA) was also used. In all cases, correct localization and repair of the leak was achieved and no major complications occurred. Following a review of the literature, the Authors conclude that, at present, transnasal endoscopic repair of cerebrospinal fluid rhinorrhea is the surgical treatment of choice when the techniques and materials are correctly used. Furthermore, preliminary findings indicate that it is possible to make routine use of the navigation systems and that this technology may be usefully employed, above all, in the management of cerebrospinal fluid leaks.

Protective effects of alpha-tocopherol and tiopronin against cisplatin-induced ototoxicity

OBJECTIVE

To investigate the possible protective effects of alpha-tocopherol and tiopronin against cisplatin-induced cochlear damage. Cisplatin ototoxicity and nephrotoxicity seem to result from the inhibition of cochlear antioxidant defences, causing an increase in the amount of reactive oxygen species. Antioxidants, such as alpha-tocopherol and tiopronin, are able to suppress lipid peroxidation, thus attenuating tissue damage.

MATERIAL AND METHODS

Hartley albino guinea pigs were used. The animals were treated for 7 consecutive days with either (I) cisplatin alone, (II) cisplatin+alpha-tocopherol acetate, (III) cisplatin+tiopronin, (IV) cisplatin+alpha-tocopherol acetate+tiopronin, (V) alpha-tocopherol acetate alone or (VI) tiopronin alone. Changes in cochlear function were characterized by means of compound action potential threshold shifts. After the functional testing, tympanic bullae were removed and processed for morphological examination of the sensorineural epithelium. Renal function was evaluated by measuring serum blood urea nitrogen and creatinine levels.

RESULTS

Cisplatin induced progressive high-frequency hearing loss of 40-50 dB SPL. Alpha-tocopherol and tiopronin co-therapy significantly slowed the progression of hearing loss. Treatment with alpha-tocopherol acetate or tiopronin alone was less effective. Morphological observations showed an important loss of outer hair cells and degeneration of the organ of Corti in the basal and middle turns. Injection of both alpha-tocopherol and tiopronin reduced cochlear outer hair cell loss more than treatment with a single drug. Beneficial effects of alpha-tocopherol and tiopronin on cisplatin-induced nephrotoxicity were observed.

CONCLUSION

This study supports the hypothesis that alpha-tocopherol and tiopronin interfere with cisplatin-induced damage, and suggests that concurrent treatment with the two drugs can be useful in protecting against hearing loss.

The role of antioxidants in protection from ototoxic drugs

A number of studies have shown that cisplatin and gentamicin ototoxic effects may result from free radical-mediated damage due to the reduction of antioxidant substances and an increased lipid peroxidation. The authors summarize the results obtained evaluating the auditory and vestibular functions and the inner ear hair cell morphology and survival after administration of antioxidant agents against cisplatin and gentamicin. In the first experiment, albino guinea pigs were treated with gentamicin (100 mg/kg per day, i.m.) alone or gentamicin (100 mg/kg per day, i.m.) plus alpha-tocopherol (100 mg/kg per day, i.m.) for 2 weeks. In a second experiment, albino guinea pigs were injected with cisplatin (2.5 mg/kg per day) or cisplatin (2.5 mg/kg per day) plus tiopronin (300 mg/kg) for 6 days. Electrocochleographic recordings were made from an implanted round window electrode. In all experiments compound action potentials (CAPs) were measured at 2-16 kHz. Changes in cochlear function were characterized as CAP threshold shifts. To evaluate vestibular function, the animals underwent sinusoidal oscillations in the dark about their vertical and longitudinal axes to evoke horizontal and vertical vestibulo-ocular reflexes (VOR). Frequency stimulation parameters ranged from 0.02 to 0.4 Hz and peak-to-peak amplitude was 20 degrees. Morphological changes were analysed by light microscopy and scanning electron microscopy. Both hearing loss and vestibular dysfunction induced by gentamicin were significantly attenuated by alpha-tocopherol. However, tiopronin co-therapy slowed the progression of hearing loss in cisplatin-treated animals and significantly attenuated the final threshold shifts. Cisplatin had little effect on the hair cells of cristae ampullares and maculae. Vestibular function was completely preserved in tiopronin co-treated animals. In conclusion, antioxidants such as alpha-tocopherol or tiopronin interfere with gentamicin and cisplatin damage and this suggests that they may be useful in preventing oto-vestibulotoxicity. Therefore, it is important to develop protective strategies that permit the avoidance of the toxic side effects of these drugs without interfering with their therapeutic effects.

The role of antioxidants in protection from ototoxic drugs

A number of studies have shown that cisplatin and gentamicin ototoxic effects may result from free radical-mediated damage due to the reduction of antioxidant substances and an increased lipid peroxidation. The authors summarize the results obtained evaluating the auditory and vestibular functions and the inner ear hair cell morphology and survival after administration of antioxidant agents against cisplatin and gentamicin. In the first experiment, albino guinea pigs were treated with gentamicin (100 mg/kg per day, i.m.) alone or gentamicin (100 mg/kg per day, i.m.) plus α-tocopherol (100 mg/kg per day, i.m.) for 2 weeks. In a second experiment, albino guinea pigs were injected with cisplatin (2.5 mg/kg per day) or cisplatin (2.5 mg/kg per day) plus tiopronin (300 mg/kg) for 6 days. Electrocochleographic recordings were made from an implanted round window electrode. In all experiments compound action potentials (CAPs) were measured at 2-16 kHz. Changes in cochlear function were characterized as CAP threshold shifts. To evaluate vestibular function, the animals underwent sinusoidal oscillations in the dark about their vertical and longitudinal axes to evoke horizontal and vertical vestibulo-ocular reflexes (VOR). Frequency stimulation parameters ranged from 0.02 to 0.4 Hz and peak-to-peak amplitude was 20°. Morphological changes were analysed by light microscopy and scanning electron microscopy. Both hearing loss and vestibular dysfunction induced by gentamicin were significantly attenuated by α-tocopherol. However, tiopronin co-therapy slowed the progression of hearing loss in cisplatin-treated animals and significantly attenuated the final threshold shifts. Cisplatin had little effect on the hair cells of cristae ampullares and maculae. Vestibular function was completely preserved in tiopronin co-treated animals. In conclusion, antioxidants such as α-tocopherol or tiopronin interfere with gentamicin and cisplatin damage and this suggests that they may be useful in preventing oto-vestibulotoxicity. Therefore, it is important to develop protective strategies that permit the avoidance of the toxic side effects of these drugs without interfering with their therapeutic effects.

Multiple treatment of gas gangrene at a rare anatomic location. Case report

The authors report a clinical case of gas gangrene in a rare anatomic location in a 79-year-old woman, admitted because 3 days earlier she had developed a painful swelling with erythematous cutis in her right iliac fossa and suffered from a seriously increasing fever. The physical examination showed a large area of gas gangrene. In accordance with international literature, excellent results have been obtained by adopting an early multiple therapy (including surgical debridement, intensive therapy, antibiotic treatment and hyperbaric oxygen treatment).

Auditory and vestibular findings in Fabry disease: a study of hemizygous males and heterozygous females

AIM

This study aimed to evaluate audiological and vestibular involvement in Fabry disease and the early effects of enzyme replacement therapy with human alpha-galactosidase A.

METHODS

Fourteen patients (10 males, 4 females) aged 14-57 years were studied. Each patient underwent a clinical (history of otological and vestibular aspects, otoscopy) and instrumental (pure tone and speech audiometry, impedance, auditory brainstem response and oto-acoustic emission recordings, vestibular caloric tests, electronystagmography during acceleratory stimulation, dynamic posturography) evaluation before starting enzyme replacement therapy.

RESULTS

Fifty per cent of patients complained of hearing symptoms (hearing loss, tinnitus, ear fullness). Subjective hearing loss was present in six cases and in three cases it was the first reported symptom of Fabry disease. In six of the seven cases the onset and/or progression of hearing symptoms were sudden. Vertigo or dizziness was reported by four patients and in two cases was associated with hearing symptoms. Audiological evaluation showed sensorineural hearing loss in eight patients (5 males, 3 females). Hearing loss was unilateral in six cases and bilateral in the remaining two cases. The hearing loss (HL) ranged from 30 to 80 dB HL (mean, 43 dB HL) and the lesion was always cochlear. Vestibular examination showed abnormalities in four patients (bilateral weak/abolished response in three cases, side prevalence in one case), which were not related to either the audiological results or the history of vertigo/dizziness.

CONCLUSION

Involvement of the inner ear is common in men and women with Fabry disease. We found a high incidence of cochlear hearing loss, which was typically unilateral and showed onset and/or progression by sudden episodes. Vascular or hydropic mechanisms could be hypothesized to explain audiological findings. Vestibular involvement had a lower incidence and showed a different pattern, thus suggesting that several pathophysiological mechanisms could play a role in determining inner ear damage in Fabry disease. Our preliminary results show that enzyme replacement therapy may stabilize hearing function; however, further follow-up is required.

Bile reflux as possible risk factor in laryngopharyngeal inflammatory and neoplastic lesions

Laryngopharyngeal reflux is now of major interest as an aetiologic factor in chronic inflammatory and neoplastic lesions of upper digestive tract. However, reports in the literature refer only to the irritating action of the acid component of reflux, while possible damaging action of other reflux components remains unknown. Aim of this study was to verify the hypothesis that alkaline-bile reflux could also be involved in onset of inflammatory, precancerous and neoplastic laryngeal lesions. A total of 40 consecutive gastrectomized patients coming to our Clinic from Gastroenterology Outpatient Unit for an anamnestic and clinical evaluation with videolaryngoscopy of upper digestive airways, entered the study. All presented bile or alkaline reflux as a direct consequence of gastroduodenal anastomosis (Billroth I) and gastrojejunal anastomosis (Billroth II) performed over a time span > 20 years. Oesophagogastroduodenoscopy revealed the presence of bile in the residual gastric cavity in all operated patients objectively confirming duodenogastric reflux. Examination of data showed that 3 patients (7.5%) had undergone CO2 laser cordectomy in the 3 years prior to the study for squamous cell laryngeal carcinoma, 3 patients (7.5%) had leukoplakia, 8 (20%) vocal cord chronic oedema with signs of chronic diffuse laryngitis, 6 (15%) posterior laryngitis, 8 (20%) interarytenoid oedema while only 12 (30%) showed no ENT lesions. Statistical analysis revealed a significant correlation between incidence of inflammatory and neoplastic laryngeal lesions and type of surgery (Billroth II and total gastrectomy) with respect to other types of gastric resection. There was also a significant increase in presence and severity of laryngopharyngeal lesions in relation to time elapsed after surgery. These results, although preliminary, seem to confirm that some components of reflux (duodenal content), other than the acid component, play a damaging role involved in the onset of multiple clinical signs and symptoms of laryngopharyngeal reflux disease. It is concluded that systematic use of bile measurement, together with 24-hour pH monitoring, is advisable in subjects with clinical signs and symptoms of laryngopharyngeal reflux, but unresponsive to classic medical treatment, and in gastrectomized patients in order to confirm, on larger series, this fascinating aetiopathogenetic hypothesis.

Correlation between fine needle aspiration biopsy and histologic findings in parotid masses. Personal experience

Pre-operative fine-needle aspiration biopsy findings have been compared with those of post-operative histopathology in 146 patients with parotid masses. Post-operative histology showed 124 benign and 22 malignant lesions: pre-operative fine-needle aspiration biopsy correctly identified 118/124 (95.1%) benign masses with an accurate classification of the tumour in 111/118 cases (94%). Fine-needle aspiration biopsy identified malignancy in 12/22 cases (>50%). In the remaining 7 cases (six benign lesions and one malignant), cytology was not diagnostic. There were no false positive cases. In the present study, the accuracy, sensitivity and specificity of cytologic findings were, respectively, 94%, 57.2% and 100%. The accuracy of fine-needle aspiration biopsy was seen to be higher in benign than in malignant lesions. Fine-needle aspiration biopsy represents a first choice diagnostic tool for the study of palpable head and neck masses excluding abscesses and vascular neoplasms. However, for a correct diagnosis, great skill is required and cytology does not always reach the sensitivity and specificity of post-operative histology. Therefore, in the presence of a palpable head and neck mass, resistant to medical treatment, surgery is still strongly indicated and cytology is very useful in planning the surgical approach.

Cisplatin ototoxicity in the guinea pig: vestibular and cochlear damage

The aim of the present study was to investigate both vestibular and cochlear cisplatin toxicity. Twelve albino guinea pigs were divided into an experimental (n=8) and a control saline group (n=4) and were treated with cisplatin at a daily dose of 2.5 mg/kg for 6 consecutive days. Vestibular dysfunction was evaluated by computing the gain of the vestibular ocular reflex (VOR) evoked by stimulation in the horizontal (HVOR) and vertical (VVOR) planes. Changes in cochlear function were characterised as compound action potential threshold shifts. After the functional testing, tympanic bullae were removed and processed for morphological examination of the sensorineural epithelium. The onset of vestibular functional impairment was observed on the third day, although the VOR gain decrease was not significant. The impairment of the vestibular function progressed until the sixth day becoming statistically significant particularly at VVOR mid frequencies of stimulation. At these frequencies both macula and crista ampullaris functions are involved. Concomitantly a progressive auditory threshold shift was observed at all stimulus frequencies. The decline of the auditory function was statistically significant from the third day of treatment and it was more evident at high frequencies. Morphological observations showed a massive loss of outer hair cells and a degeneration of the organ of Corti in the basal/middle turns and only a slight loss of hair cells of the cristae ampullares and maculae. In conclusion, functional and morphological data provide evidence that the toxic effect of cisplatin is more pronounced in the organ of Corti than in the vestibular epithelium.

Protective effects of alpha-tocopherol against gentamicin-induced Oto-vestibulo toxicity: an experimental study

OBJECTIVE

Free radicals are involved in gentamicin ototoxicity and vestibular dysfunction and it has been demonstrated that free radical scavengers, such as alpha-tocopherol, are able to inactive free radicals, attenuating tissue damage This study was designed to investigate the possible protective effects of alpha-tocopherol against gentamicin-induced oto-vestibulo toxicity.

MATERIAL AND METHODS

Adult albino guinea pigs were divided into four groups and were treated for 2 weeks as follows: Group A, controls; Group B, gentamicin plus corn oil; Group C, gentamicin only; and Group D, gentamicin plus alpha-tocopherol. To evaluate vestibular function, the animals underwent sinusoidal oscillations in the dark about their vertical and longitudinal axes to evoke horizontal and vertical vestibulo-ocular reflexes (VORs), respectively. Electrocochleographic recordings were performed using an implanted round window electrode. The compound action potentials (CAPs) at 2, 4, 8 and 16 kHz were measured every 5 days Morphological changes were analysed by means of scanning electron microscopy.

RESULTS

Gentamicin induced a consistent reduction in VOR responses and a progressive high-frequency hearing loss of 50-60 dB sound pressure level. Alpha-Tocopherol co-therapy slowed the progression of hearing loss and significantly attenuated the final threshold shifts The impairment of vestibular function was reduced, as evidenced by an increased VOR gain. The massive loss of outer hair cells in the cochlear basal turn and of cristae ampullaris stereocilia in gentamicin-treated animals was not observed in the cochlea of animals protected with alpha-tocopherol.

CONCLUSION

This study supports the hypothesis that alpha-tocopherol interferes with gentamicin-induced free radical formation, and suggests that this drug may be useful in preventing aminoglycoside oto-vestibulo toxicity.