10 years of experience with intratympanally applied streptomycin (gentamycin) in the therapy of Morbus Menière

Intratympanic gentamycine for Ménière's disease: is there a selective vestibulotoxic effect?

Purpose

The aim of our study is to investigate the effectiveness and safety of the treatment, based on vertigo diaries and pure tone audiograms.

Methods

The complete medical documentation of 105 definite patients suffering from Ménière’s disease was analyzed. In the studied group, nine patients were treated with intratympanic gentamycine. Long-term follow-up of the patients was carried out, using vertigo diaries, medical letters, anamnestic data, and pure tone audiograms. Audiometric results and vertigo complaints before and after treatment were contrasted using IBM SPSS V24 software.

Results

Based on our analysis, vertigo attacks appeared significantly less often after gentamycine treatment [p < 0.001; Odds ratio 0.003 (95% CI 0.001–0.012)], which confirms the efficacy of the therapy. Pure tone stages before and after the application of gentamycine were contrasted using the Mann–Whitney U test. When comparing the audiometric results of long-term follow-ups by using the logistic regression, a statistically significant difference was observed between the treated and not treated groups [p = 0.001; Odds ratio 0.141 (95% CI 0.064–0.313)], and based on the survivorship curve hearing impairment was more common in the not treated group which also supports our results. Based on the non-parametric test, there was no significant difference (p = 0.84) between the pure-tone stages of the control group and of those treated with gentamycine.

Conclusion

Our results indicate that intratympanic gentamycine is effective in controlling vertigo attacks, and there is no higher risk for hearing loss than in case of spontaneous progression of the disorder.

Long-term Vertigo Control and Vestibular Function After Low-dose On-demand Transtympanic Gentamicin for Refractory Menière's Disease

OBJECTIVE

To describe the long-term clinical vertigo control along with measured lateral canal vestibular function in patients with unilateral refractory Menière's disease (MD) treated with gentamicin transtympanic injections (TTI).

STUDY DESIGN

Retrospective analytic study.

SETTING

Tertiary referral center.

PATIENTS

Thirty-eight patients treated by TTI for medically refractory unilateral MD, defined by the 1995 AAO-HNS criteria, between May 2006 and December 2012.

INTERVENTION(S)

One-year course of treatment with gentamicin TTI following a low dose on-demand protocol. TTI were repeated in new courses of treatment when MD recurrence occurred.

MAIN OUTCOME MEASURE(S)

AAO-HNS class of control, caloric tests (CalT), recurrence rate.

RESULTS

After an average clinical follow-up of 71 months, all patients entered a class of control A (78%) or B (22%), with an average of 2.3 TTI received. The mean maximal obtained deficit was 88.5%, and the mean long-term deficit was 85.5%. Ten (26%) patients had disease recurrence requiring a new course of treatment. A value of the first CalT in the 3 months following the first TTI strictly higher than 78% was significantly associated with disease control and the absence of symptom recurrence (p≤0.01). In the "recurrence" group, four patients had a significantly lower mean value of all CalT performed after the first TTI when compared with other patients (p≤0.001), indicating gentamicin resistance CONCLUSION:: Achieving a sustainable vestibular deficit on caloric testing is key for MD symptom control after gentamicin TTI. Gentamicin resistance must be diagnosed early to adapt therapeutic strategies.

Intratympanic Therapies in Ménière Disease: Evaluation of Outcomes and Early Vertigo Control

OBJECTIVE

To evaluate outcomes of intratympanic (IT) dexamethasone and gentamicin in Ménière Disease (MD).

METHODS

Charts of adult patients with unilateral definite MD receiving IT gentamicin or dexamethasone from 2005 to 2017 were retrospectively reviewed. All patients had at least 6 months follow-up. Failure in each group was defined as the need for more aggressive therapy. Prior to 2011, all patient received IT gentamicin, administered as primary therapy after failure of conservative treatment measures. Gentamicin was administered every 2 weeks, up to three injections, until vertigo control was achieved. Beginning in 2011, the treatment protocol shifted to IT dexamethasone as initial treatment, with gentamicin used for dexamethasone failures. Dexamethasone was administered weekly for up to three injections. Treatments could be repeated if symptoms recurred.

RESULTS

Thirty-three patients received IT dexamethasone, and 70 patients received IT gentamicin. Dexamethasone patients received a mean of 3.3 injections compared to 2.7 in the gentamicin group (P = 0.011). There were 12 (38%) failures in the dexamethasone group and only seven (10%) gentamicin failures (P = 0.025). No patients failed both treatments. The mean time to failure in the dexamethasone group was 5 months, whereas in the gentamicin group it was 27 months. Change in pure tone audiometry from baseline was not different between treatment groups (P = 0.30).

CONCLUSION

Subjects receiving IT gentamicin required fewer injections and had a significantly longer time to failure than IT dexamethasone. Audiometric outcomes were similar between the groups. The use of IT gentamicin as initial therapy for early and long-term control of MD is safe and effective.

LEVEL OF EVIDENCE

3 Laryngoscope, 129:216-221, 2019.

Low Concentration Intra-Tympanic Gentamicin Treatment for Menière's Disease: A Long-Term Follow Up

BACKGROUND

Intra-tympanic injections of gentamicin (ITG), a known ototoxic agent, have been proven to be effective in controlling Menière's disease (MD) symptoms, in patients who did not respond to conservative therapy, although its safety was questionable.

OBJECTIVES

To study whether low-concentration ITG, in refractory MD, had an effect on the ipsilateral hearing, in comparison to the contralateral ear, and to study the effectiveness of such treatment.

METHODS

A comparative, retrospective cohort study was conducted between 2003 and 2015, and compared the change in the hearing level between the injected ear and the contralateral, untreated ear.

OUTCOMES

In 20 of 27 patients (74.1%), one course of ITG treatment was considered as successful. In the short-term, there was improvement of hearing level at 1000 Hz (p = 0.014), and deterioration of hearing level at 8000 Hz (p = 0.039), both in comparison to the control ear. In the long-term and after confounders adjustment, we found there were no differences in the hearing levels between the treated ear and the untreated contralateral ear.

CONCLUSIONS

A high success rates of treating vertigo attacks with low concentration ITG in refractory unilateral MD patients is herein reported, while a significant difference was not observed in the hearing threshold compared with the healthy contralateral ear.

Intratympanic (IT) Therapies for Menière's Disease: Some Consensus Among the Confusion

Purpose of Review

Aminoglycosides and corticosteroids are commonly used to treat Menière's disease. Intratympanic (IT) administration of these medications allows high inner ear concentrations without significant adverse systemic effects. As a direct result, IT therapy has grown in popularity. Recent studies have compared patient outcomes between IT aminoglycosides and corticosteroids. This review summarizes these findings.

Recent Findings

Trials comparing IT corticosteroids to IT placebo or oral therapy have had conflicting results. Most recently, Lambert et al. investigated the effect of IT dexamethasone in a sustained-release formulation compared to placebo. Their findings demonstrated improvement in some secondary measures of vertigo with the sustained-release formulation.IT gentamicin is known to be effective in controlling vertigo in Menière's disease. In a recent study from 2016, Patel et al compared IT gentamicin and IT methylprednisolone in a double-blind, randomized controlled trial and identified no significant differences between the two in vertigo control.

Summary

IT injections of aminoglycosides and corticosteroids can improve vertigo control. Hearing and vestibular loss however may result with IT aminoglycosides. Corticosteroids demonstrate limited hearing loss but may not have the same efficacy in controlling vertigo. Further investigation in the etiology of Menière's disease is needed to tailor the proposed treatment to suit the disease mechanism.

Labyrinthectomy and Vestibular Neurectomy for Intractable Vertiginous Symptoms

Introduction Labyrinthectomy and vestibular neurectomy are considered the surgical procedures with the highest possibility of controlling medically untreatable incapacitating vertigo. Ironically, after 100 years of the introduction of both transmastoid labyrinthectomy and vestibular neurectomy, the choice of which procedure to use rests primarily on the evaluation of the hearing and of the surgical morbidity.

Objective To review surgical labyrinthectomy and vestibular neurectomy for the treatment of incapacitating vestibular disorders.

Data Sources PubMed, MD consult and Ovid-SP databases.

Data Synthesis In this review we describe and compare surgical labyrinthectomy and vestibular neurectomy. A contrast between surgical and chemical labyrinthectomy is also examined. Proper candidate selection, success in vertigo control and complication rates are discussed on the basis of a literature review.

Conclusions Vestibular nerve section and labyrinthectomy achieve high and comparable rates of vertigo control. Even though vestibular neurectomy is considered a hearing sparing surgery, since it is an intradural procedure, it carries a greater risk of complications than transmastoid labyrinthectomy. Furthermore, since many patients whose hearing is preserved with vestibular nerve section may ultimately lose that hearing, the long-term value of hearing preservation is not well established. Although the combination of both procedures, in the form of a translabyrinthine vestibular nerve section, is the most certain way to ablate vestibular function for patients with no useful hearing and disabling vertigo, some advocate for transmastoid labyrinthectomy alone, considering that avoiding opening the subarachnoid space minimizes the possible intracranial complications. Chemical labyrinthectomy may be considered a safer alternative, but the risks of hearing loss when hearing preservation is desired are also high.

Transtympanic Gentamicin and Fibrin Tissue Adhesive for Treatment of Unilateral Menière's Disease: Effects on Vestibular Function

OBJECTIVE: To determine the effects of transtympanic injections, with a mixture composed of gentamicin and fibrin tissue adhesive (FTA), on vestibular function of patients with intractable unilateral Menière's disease.

STUDY DESIGN: This was an open, prospective study.

SETTING AND PATIENTS: The study was performed at 2 tertiary referral centers. Twenty-six patients affected by “definite” unilateral Menière's disease, unresponsive to medical therapy for at least 6 months, were enrolled.

INTERVENTION: A buffered gentamicin solution mixed with FTA was injected in the middle ear until the development of bedside vestibular hypofunction signs and/or caloric weakness in the treated ear.

MAIN OUTCOME MEASURE: Vestibular function was evaluated by 3 bedside vestibular tests (observation of spontaneous nystagmus, head shaking test, and head thrust test) and by a caloric test. Tests were performed on days 10 and 30 after completion of treatment. Tests were also performed 3, 6, and 12 months from completion of the gentamicin-FTA protocol. The effects of treatment were also assessed in terms of hearing levels, control of vertigo, and disability status.

RESULTS: In 22 of the 26 patients, only 1 gentamicin-FTA injection was necessary to obtain 1 or more signs indicating a reduction of the vestibular function in the treated ear. Four patients needed another treatment because of the persistence of their incapacitating symptoms during the follow-up. Four patients needed more than 1 injection to obtain a vestibular hypofunction. None of the patients who received 1 or 2 injections presented hearing loss in direct temporal relationship to the treatment.

CONCLUSIONS: A mixture of gentamicin and fibrin glue makes it possible to considerably reduce the number of administrations in patients with intractable unilateral Menière's disease. Spontaneous nystagmus, post head shaking nystagmus, and a head thrust sign are the clinical signs that indicate onset or progression of unilateral vestibular hypofunction. These signs were obtained with only 1 injection in 81% of patients.

EBM RATING: C

Is low-dose intratympanic gentamicin an effective treatment for Ménière's disease: the Birmingham experience

BACKGROUND

Since the development of intratympanic aminoglycoside in the 1950s, otologists have been able to chemically ablate the vestibule. We present the results of using low-dose intratympanic gentamicin to treat Ménière's disease.

METHOD

A retrospective review was performed of all patients who underwent low-dose intratympanic gentamicin therapy over seven years. Data on gender, age, number of procedures, pure tone audiometry and symptom control were analysed.

RESULTS

In all, 38 patients underwent low-dose intratympanic gentamicin therapy. These comprised 25 females and 13 males, with an average age of 58.4 years. Hearing was preserved in 87.5 per cent of patients, with no significant difference before and after treatment (p = 0.744). In all, 85.7 per cent of patients had complete or substantial symptom control (classes A and B, respectively).

CONCLUSION

Low-dose intratympanic gentamicin therapy was effective in controlling the symptoms of Ménière's disease patients, while preserving hearing.

Longitudinal results of intratympanic injection of budesonide for otitis media with effusion in children over 12 years and adults

OBJECTIVE

To assess the longitudinal curative effect and improvement of subjective symptoms by using intratympanic injection of Budesonide(BUD) for otitis media with effusion (OME) patients older than 12 years and adults.

STUDY DESIGN

A single-blind, randomized, parallel-controlled prospective study.

SETTING

Hospital, outpatient.

PATIENTS

Ninety patients (112 ears) who were diagnosed as having OME were recruited and then randomized to BUD, dexamethasone (DEX), and sodium chloride (NS) groups, the latter two served as controls.

INTERVENTIONS

The randomly allocated patients received intratympanic injection of BUD (0.5 mg/1 ml), DEX (2 mg/1 ml), or 0.9% NS solution (1 ml) once a week.

MAIN OUTCOME MEASURES

Survival analysis was applied to compare the longitudinal curative effects among the 3 groups. Meanwhile, the 6 main subjective symptoms were scored by 10-point visual scale, and physician's evaluations were preformed during treatment and follow-up.

RESULTS

After adjustment for course of disease, volume, and characters of effusion, the relative risk (RR) of BUD is 0.139 (95% CI, 0.054-0.358) when compared with NS. Survival curve demonstrated that the rank of longitudinal therapeutic efficacy was BUD, DEX, and NS (p < 0.05). Both BUD and DEX showed improvements in subjective symptoms and quality of life compared with NS (p < 0.05). In the aspect of improving the symptom of stuffy ear, BUD showed advantage over both DEX and NS. During and after treatment, no serious complications or sequelae were observed.

CONCLUSION

Intratympanic injection with BUD for OME patients showed advantages in improving long-term therapeutic efficacy, it was a safe and effective intervention for adolescents and adults with OME.

Gentamicin concentration gradients in scala tympani perilymph following systemic applications

It has been shown in prior studies that round window membrane (RWM) application of gentamicin produced a robust basal-apical concentration gradient in the perilymph of scala tympani (ST) with peak concentrations in the basal turn of ST. These gradients potentially contribute to the clinical efficacy and safety of intratympanic gentamicin applications for the treatment of Ménière's disease. The present study aimed to establish the distribution of gentamicin along ST perilymph after systemic applications. Gentamicin sulfate was applied intravenously in the amounts of 100, 300 and 600 mg/kg body weight (BW) over a period of 3 h or as a 300 mg/kg BW subcutaneous bolus injection. At 3 and 5 h after the start of the application perilymph of ST was aspirated from the cochlea apex of the right and left cochlea, respectively, and 10 sequential 1-µl perilymph samples from the apex of each cochlea were quantitatively analyzed using a fluorescence polarization immunoassay. In contrast to local RWM delivery, systemic application of gentamicin resulted in the highest perilymph levels in the apex of the cochlea with decreasing concentrations towards the basal regions of ST. The absolute gentamicin concentrations increased with the amount of drug applied and time before sampling. While it is likely that the basal-apical gradient measured after local drug applications to the round window niche is the result of the direct uptake of drugs into the perilymph of the ST, distribution by diffusion and a very low perilymph flow towards the cochlear apex, computer simulations suggested that the apical-basal gradient observed with these systemic applications can be explained by higher entry rates of gentamicin in the apex compared to the basal turns of the cochlea. It is also possible that gentamicin enters perilymph indirectly from the blood via the endolymph. In this case the faster kinetics in apical turns could be due to the smaller cross-sectional area of ST relative to endolymph in the apical turns.

Distribution of gentamicin in inner ear after local administration via a chitosan glycerophosphate hydrogel delivery system

OBJECTIVES

We examined the distribution of gentamicin sulfate in the inner ear after delivery via a chitosan glycerophosphate (CGP) hydrogel system and examined the change in morphology of the hair cells so as to determine how gentamicin affected the function of the inner ear.

METHODS

A matrix of CGP hydrogel loaded with gentamicin conjugated with Texas Red (GTTR) was injected into the round window niche of the left ear of C57/BL6 mice. The mice were painlessly killed on day 1 or day 7 after injection. Confocal fluorescence microscopy was used to locate the gentamicin in the cochlear and vestibular systems.

RESULTS

In the vestibule, the intensity of GTTR staining in the hair cells of the macula of the saccule on day 1 was significantly stronger than that on day 7, and the number of hair cell bundles on top of the cuticular plate on day 7 was obviously decreased in comparison to that on day 1. In the cochlea, the intensity of GTTR staining in the basal turn was significantly stronger than that in the medial turn on both day 1 and day 7. Negligible fluorescence was observed in the apical turn on both day 1 and day 7. Less-intense GTTR staining was detected on day 7 than on day 1 in both the basal turn and the medial turn. There was some outer hair cell loss in the basal turn on day 7, and no hair cell loss in the medial and apical turns at any time point.

CONCLUSIONS

Gentamicin is distributed in the inner ear via the CGP hydrogel delivery system in a time-dependent and basal-to-apical manner. This finding implies that the vestibule and the basal turn may retain more gentamicin for a longer period than do other sites in the inner ear. These two characteristics may account for the high-frequency hearing loss and vestibular dysfunction seen with use of this system to deliver gentamicin into the inner ear.

Combined intratympanic and systemic use of steroids for idiopathic sudden sensorineural hearing loss

OBJECTIVE

To compare hearing results in idiopathic sudden hearing loss patients treated with systemic steroids alone or combined intratympanic and steroids.

STUDY DESIGN

Prospective.

SETTING

Tertiary referral hospital.

PATIENTS

Idiopathic sudden sensorineural hearing loss patients.

INTERVENTIONS

The patients in the systemic therapy group received consecutive administration of 100 mg intravenous methylprednisolone in the first day, 80 mg/day oral prednisolone in 3 divided doses for the next 2 days, and continued with oral administration of steroids by tapering the dose 20 mg in every 2 days. The patients in the combined treatment group received intratympanic injection of methylprednisolone (an approximate dose of 0.5 ml of 125 mg/ml). A total of 5 injections on alternate days were performed.

MAIN OUTCOME MEASURES

The mean and median PTA gains of systemic corticosteroid therapy (SCT) group were 7.5 and 5 dB at 5th day, 12.1 and 7.5 dB at 10th day, and 13.0 and 8.8 dB at 15th day. The mean and median PTA gains for combined treatment (CT) group were 12.5 and 7.5, 17.8 and 13.8, 21.8 and 20.0 dB, respectively.

RESULTS

Both the mean and the median PTA gains were statistically significantly different between SCT and CT groups. According to improved hearing results (more than 10 dB gain), there was statistically significant difference between SCT and CT groups. None of the patients had an important complication.

CONCLUSION

The results of this study suggest that adding intratympanic methylprednisolone to systemic therapy increases the probability of hearing recovery in ISSHL patients.

Intratympanic gentamicin in Ménière's disease: our experience

Aims:

To analyse intratympanic gentamicin injection as a treatment option in patients with monolateral Ménière's disease resistant to medical treatment.

Material and methods:

Longitudinal, prospective, descriptive study of response to gentamicin treatment in 71 patients diagnosed with Ménière's disease and treated medically for more than a year, unsuccessfully. American Academy of Otolaryngology-Head and Neck Surgery criteria were used for diagnosis and follow up.

Results:

Complete vertigo control was obtained in 65.6 per cent of patients, and complete or substantial control in 84.37 per cent. Thirteen patients (18.3 per cent) suffered significant hearing loss.

Conclusion:

This intratympanic gentamicin injection protocol enabled effective vertigo control in most patients, and represents a good alternative to more aggressive techniques for the treatment of Ménière's disease which does not respond to medical treatment.

Round window perfusion dynamics: implications for intracochlear therapy

PURPOSE OF REVIEW

The treatments for inner ear diseases are evolving as the systemic administration of medication is replaced by novel intratympanic and intracochlear drug delivery. The current review explores the background and recent developments in this field.

RECENT FINDINGS

Although still in various stages of clinical development, novel drug delivery techniques such as the Silverstein MicroWick, the round window microcatheter, biodegradable hydrogels, biopolymers, nanoparticles, newly designed cochlear implant arrays, osmotic mini/micro pumps, and reciprocating perfusion systems hold significant promise. Animal data suggest that sustained delivery systems have more reliable inner ear pharmacokinetics than both systemic administration and intratympanic injections.

SUMMARY

As research scientists advance technologies for treating inner ear diseases, drug delivery techniques must keep pace. Viable treatment options for sensorineural hearing loss, tinnitus, and vestibular disorders are on the horizon and may usher in a new golden age for otology.

Audiovestibular testing in patients with Meniere's disease

In this article, the present state of the art with respect to audiovestibular testing for Meniere's disease (MD) is reviewed. There is no gold standard for MD diagnosis, and the classic dictum is that even the "best" tests yield positive results in only two-thirds of patients with MD. Still, we advocate the use and further investigation of advanced audiovestibular testing in patients with MD in an attempt to answer the questions that confront any clinician who cares for patients with audiovestibular symptoms.

Intratympanic gentamicin injections for the treatment of Ménière's disease

Objective

To assess the success rate and complications of treatment with injections of intratympanic gentamicin to the middle ear of patients with Ménière's disease.

Study Design

Case series with chart review.

Setting

A tertiary otologic private ENT clinic.

Subjects and Methods

Patients with Ménière's disease, who had not responded to medical treatment. Included in the sample were patients with Ménière's disease who had been treated with injections of gentamicin into the middle ear. After each gentamicin application, patients were monitored for their symptoms and hearing. If symptoms persisted, they received another intratympanic injection of gentamicin. This method is referred to as the variable titration method. A retrospective chart review was performed, and questionnaires were used to assess hearing, functional status, tinnitus, ear fullness sensation, and the control of vertigo attacks in response to treatment.

Results

Nineteen patients were sampled. Eighteen patients (94%) had complete or substantial control of vertigo. Five patients (26%) had worse hearing results on their post-treatment audiogram, averaging 13 dB hearing loss (range, 5-25 dB). In response to the questionnaires, all patients reported a significant improvement in the quality of life after treatment.

Conclusion

The treatment was found to be highly effective. The variable titration method of injection prevents unnecessary injections for patients whose symptoms have already subsided.

Drug delivery for treatment of inner ear disease: current state of knowledge

Delivery of medications to the inner ear has been an area of considerable growth in both the research and clinical realms during the past several decades. Systemic delivery of medication destined for treatment of the inner ear is the foundation on which newer delivery techniques have been developed. Because of systemic side effects, investigators and clinicians have begun developing and using techniques to deliver therapeutic agents locally. Alongside the now commonplace use of intratympanic gentamicin for Meniere's disease and the emerging use of intratympanic steroids for sudden sensorineural hearing loss, novel technologies, such as hydrogels and nanoparticles, are being explored. At the horizon of inner ear drug-delivery techniques, intracochlear devices that leverage recent advances in microsystems technology are being developed to apply medications directly into the inner ear. Potential uses for such devices include neurotrophic factor and steroid delivery with cochlear implantation, RNA interference technologies, and stem-cell therapy. The historical, current, and future delivery techniques and uses of drug delivery for treatment of inner ear disease serve as the basis for this review.

[Endolymph homeostasis and Menière's disease: fundamentals, pathological changes, aminoglycosides]

Although low dose intratympanal gentamicin has empirically been very effective in treating Menière's disease, the mechanisms of elimination or amelioration of vertigo are still insufficiently understood. Most animal studies investigating the effect of aminoglycosides used high doses that damage or kill hair cells and many other cell types of the inner ear. Additional studies are needed to investigate the effects of low dose gentamicin to elucidate the mechanisms affecting vertigo. In this article it will be explained how disturbances of endolymph homeostasis lead to endolymphatic hydrops and finally to leakage of K(+) from the endolymph into the perilymphatic space. This can lead to a non-physiological activation of vestibular nerve fibres thus causing vertigo.

Gene transfer into guinea pig cochlea using adeno-associated virus vectors

BACKGROUND

Several genes are candidates for treating inner ear diseases. For clinical applications, minimally invasive approaches to the inner ear are desirable along with minimal side-effects.

METHODS

Adeno-associated virus (AAV) was used as a vector into the guinea pig inner ear. Six AAV-cytomegalovirus hybrids (AAV-2/1, -2/2, -2/5, -2/7, -2/8 and -2/9) were infused into perilymph of the cochlea basal turn, an approach that could be used in cochlear implant surgery. At 7 days after injection, distribution of gene expression, hearing and morphology were evaluated. Adenoviral vector was also used to compare distributions of gene expression. Moreover, distribution of cell surface receptors of AAV in the cochlea was examined using immunohistochemistry.

RESULTS

Using the perilymphatic approach, adenovirus could be transferred to mesothelial cells lining the perilymph, but not sensory cells. Conversely, all AAV serotypes displayed tissue tropism to inner hair cells, with AAV-2/2 showing particularly efficient transfer to sensory cells. This tissue tropism of AAV could not be explained by the distribution of AAV receptors. Hearing and morphology were largely unaffected.

CONCLUSIONS

Our results indicate that AAV vector can be safely applied to the inner ear and AAV-2/2 offers a good tool for transferring transgenes into sensory cells of the inner ear efficiently without toxicity.

Triple semicircular canal occlusion for the treatment of Ménière's disease

CONCLUSION

Triple semicircular canal occlusion (TSCO) controls vertigo, is easy to perform, and could be used as an alternative procedure for the treatment of Meniere's disease in selected patients who complain mainly of intractable vertigo.

OBJECTIVE

To seek an effective alternative surgical procedure for treating Ménière's disease in selected patients with intolerant rotational vertigo.

PATIENTS AND METHODS

Three patients with Ménière's disease who underwent unsuccessful endolymphatic sac decompression or mastoid shunt, then underwent TSCO. Vertigo control and vestibular and auditory function were measured.

RESULTS

The early vestibular symptoms caused by surgery resolved quickly and no hearing deterioration occurred after surgery. At the end of the follow-up period, based on the AAO-HNS criteria, two cases had complete control of vertigo (class A) and the other had substantial control of vertigo attacks (class B). Hearing was similar to the preoperative level at the end of the follow-up period.

Auditory results after vestibular nerve section and intratympanic gentamicin for Ménière's disease

OBJECTIVE

Hearing loss is a possible complication of vestibular neurectomy and intratympanic gentamicin administration in Ménière's disease. The aim of this study was to compare the incidence of this complication with the two treatments.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

The initial study population reviewed consisted of 24 patients receiving gentamicin injections and 209 patients undergoing vestibular nerve section. Comparison of data was performed among all 24 intratympanic gentamicin patients and the last 24 vestibular neurectomy patients operated on via the retrosigmoid approach.

INTERVENTIONS

Intratympanic gentamicin administration (26-156 mg) and retrosigmoid vestibular neurectomy.

MAIN OUTCOME MEASURE

Auditory and vertigo results were evaluated according to the American Academy of Otolaryngology 1995 criteria.

RESULTS

The mean preoperative pure-tone average for patients undergoing vestibular nerve section was 48.5 dB, with a speech discrimination score of 85%. In these patients, the postoperative pure-tone average was 50.3 dB, and the speech discrimination score was 82%. Patients undergoing gentamicin injection had a mean pretreatment pure-tone average of 50.1 dB and a speech discrimination score of 87%. The posttreatment pure-tone average and discrimination score for the gentamicin group were 74.7 dB and 65%, respectively. The amount of postprocedure hearing loss was significantly greater in the gentamicin group (p = 0.03). Excellent control of vertigo (classes A and B) was obtained in 95.8% of the patients treated with vestibular nerve section and in 75% of the patients in the gentamicin group.

CONCLUSION

Gentamicin administration and vestibular neurectomy are both effective for relieving vertigo in Ménière's disease. The incidence of hearing loss is significantly higher after gentamicin injection.

Intratympanic gentamicin in monolateral Meniere’s disease: our experience

The aim of this study was to verify the efficacy of a modified Odkvist titration protocol of intratympanic gentamicin application in the control of vertigo attacks and the effects on the auditory and vestibular function in a group of 71 patients affected by monolateral MD resistant to medical therapy. All the patients underwent an intratympanic administration of a 1-ml solution containing 26.6 mg of gentamicin sulfate. The treatment protocol provided one to three injections for a total amount of gentamicin varying from 26.6 to 80 mg. Five days after the first gentamicin administration, cochlear and vestibular function tests were performed. The worsening of the PTA greater than 15 dB, the appearance of clinical signs of vestibulotoxicity such as imbalance or persistent spontaneous nystagmus beating away from the injected ear or of a "curative vertigo" were the criteria taken into consideration to stop the treatment. In the absence of any sign, a second and third injection were performed. The presence of an unchanged frequency of the attacks at least 3 months after the previous cycle was the parameter considered to perform a second or third cycle. Seventeen (24%) patients were submitted to a second cycle of therapy and two (3%) to a third cycle. After a mean follow-up period of 20.3 months (range: 3 to 48) all 71 patients experienced good control of the vertigo attacks: grade A in 46 cases and grade B in 25 cases according to the AAO-HNS CoHE criteria. The pure tone average (PTA) hearing threshold (500-3,000 Hz) worsened in 19 patients, improved in 5 and was unchanged in 47. On the basis of the experience acquired during the treatment, we progressively decreased the number of injections from 3/cycle to a 1-2/cycle of therapy. Moreover, in the later phase of the study re-injections were administered 1 or 2 weeks after the previous application and avoided in the presence of signs of depression of the vestibular and/or cochlear function. A residual caloric excitability was found in 30% of the cases. Vertigo control doesn't seem to be linked to the achievement of vestibular inexcitability. The marker of successful gentamicin treatment at short-term is the appearance of signs of curative vertigo and/or vestibular imbalance, and at long-term the disappearance of vertigo attacks.

Intratympanic gentamicin for the treatment of Ménière's disease and other forms of peripheral vertigo

Titration therapy with intratympanic gentamicin offers class A or B control of vertigo in 87% (range, 75%-100%) of patients with unilateral Ménière's disease. The risk of additional hearing loss is about 21% (range,0-37%). Vertigo may recur, however, in nearly one third of patients over time. These recurrences can also be treated by intratympanic gentamicin with a similar risk of hearing loss. The salient effect of intratympanic gentamicin is probably the reduction of vestibular function through damage to hair cells, but a complete ablation of function does not seem to be necessary for vertigo control.

The history of intratympanic drug therapy in otology

The application of drugs through the eardrum and into the middle ear to treat various otologic disorders has recently gained wide-spread popularity. Despite the relatively recent interest in this technique, if one considers any application of medication into the middle ear as intratympanic therapy, the roots of this method can really be considered to date back to antiquity. This article presents the development of intratympanic drug therapy from early times through the nineteenth century.

Sustained-release devices in inner ear medical therapy

Inner ear medical therapy has been gaining increasing popularity during the last 2 decades. Despite the increased use of this therapy,basic questions regarding this type of treatment have not been answered. The authors have used a variety of sustained-release devices in the laboratory to begin to answer some of these basic questions. This article discusses the results of this work and the application and use of sustained-release devices in patients.

Transtympanic perfusion: indications and limitations

PURPOSE OF REVIEW

To review the most recent literature regarding the application of transtympanic inner ear perfusion in the treatment of inner ear disorders including Meniere disease, sudden sensorineural hearing loss, and autoimmune inner ear disease.

RECENT FINDINGS

The use of gentamicin perfusion in the management of Meniere disease with intractable vertigo has been demonstrated to have a very high rate of success, and is much less invasive than alternative surgical procedures such as vestibular nerve section or labyrinthectomy. The technique for achieving the highest rate of success while still minimizing the risk of cochleotoxicity continues to be investigated. Sustained delivery techniques such as the Silverstein MicroWick appear to achieve the best pharmacokinetic profile within the inner ear fluids. The end point of treatment does not necessarily require complete vestibular ablation to cure the patient, and shorter courses of treatment may help to reduce the risk of hearing loss. Cochlear Meniere disease can be treated with dexamethasone 4 mg/cc perfusion of the inner ear, which may improve the hearing, tinnitus, and pressure in the ear. Sudden sensorineural hearing loss has been managed with transtympanic steroid delivery, and this appears to be beneficial for some patients who have failed to respond to oral steroids, or have medical contraindications to systemic steroids.

SUMMARY

Inner ear perfusion via transtympanic delivery is an emerging technique in the management of inner ear disease. Improved results are expected over time as research in this area answers questions about dosage and delivery techniques, as well as identifying new applications and pharmaceuticals.

Intratympanic perfusion for the treatment of tinnitus

Intratympanic treatment of tinnitus with corticosteroids or gentamicin should be considered as an option of treatment in selected tinnitus patients, alone or in combination with standard modalities of management such as tinnitus retraining therapy, masking, and hearing aid amplification. Review of the literature and the authors' experience suggest the following points regarding intratympanic treatment for tinnitus: 1. Lidocaine, although effective in decreasing tinnitus, has been largely abandoned because of its severe side-effect profile and need for inpatient administration. 2. Corticosteroids have been associated with few if any side effects. 3. The good results reported in the literature with intratympanic steroids for treating tinnitus of various causes should be viewed with caution,because most are retrospective and uncontrolled studies. 4. Some Meniere's disease patients with tinnitus may experience tinnitus improvement following intratympanic steroids. This treatment may be considered in such patients, especially for those with good hearing. 5. Gentamicin is effective in eliminating or reducing tinnitus in a significant number of patients with Meniere's disease and may be considered especially for those with nonserviceable hearing. 6. Further prospective, randomized, and controlled studies to evaluate the effect of intratympanic perfusion for the treatment of tinnitus are warranted.

Intratympanic Gentamicin Therapy for Ménière’s Disease: A Meta-analysis

OBJECTIVE

This study compared the effectiveness of five different techniques of intratympanic gentamicin administration for Ménière's disease.

DATA SOURCES

A MEDLINE search of the English language literature from 1978 to 2002 was performed using the key words "intratympanic," "gentamicin," "therapy," "Ménière's," and "disease."

STUDY SELECTION

Inclusion criteria to select articles for meta-analysis were clear description of gentamicin delivery technique, clearly reported vertigo control results, and report of hearing loss posttreatment. Seven studies (n = 218) describing the multiple daily dosing technique (delivery three times per day for >or=4 d), two studies (n = 84) describing the weekly dosing technique (weekly injections for four total doses), eight studies (n = 253) of the low-dose technique (one to two injections with retreatment for recurrent vertigo), four studies (n =156) of continuous microcatheter delivery, and six studies (n =269) of the titration technique (daily or weekly doses until onset of vestibular symptoms, change in vertigo, or hearing loss) were entered into the model.

DATA EXTRACTION

Vertigo control results were stratified into complete, substantial, or poor control. Hearing results were separated by profound, partial, or no hearing loss. Individuals undergoing caloric testing were separated by degree of vestibular ablation (complete versus partial) and analyzed for vertigo control (n = 301) and hearing loss (n = 333) after treatment.

DATA SYNTHESIS

Comparisons between the rates of complete vertigo control, effective vertigo control (complete plus substantial control), overall hearing loss (partial plus profound), and profound hearing loss by delivery method were based on a parametric empirical Bayes analysis using binomial generalized linear models and backward variable selection (joining). Relative risk for vertigo control and hearing loss by partial or complete ablation was examined study by study using residual maximum likelihood to carry out a parametric empirical Bayes analysis.

CONCLUSION

The titration method of gentamicin delivery demonstrated significantly better complete (81.7%, p = 0.001) and effective (96.3%, p < 0.05) vertigo control compared with other methods. The low-dose method of delivery demonstrated significantly worse complete vertigo control (66.7%, p < 0.001) and trends toward worse effective vertigo control (86.8%, p = 0.05) compared with other methods. The weekly method of delivery trends toward less overall hearing loss (13.1%, p = 0.08), and the multiple daily method demonstrated significantly more overall hearing loss (34.7%, p < 0.01) compared with other groups. No significant difference in profound hearing loss was found between groups. Degree of vestibular ablation after gentamicin therapy is not significantly correlated with the resulting vertigo control or hearing loss status.

Selective vestibular ablation by intratympanic gentamicin in patients with unilateral active Ménière's disease: a prospective, double-blind, placebo-controlled, randomized clinical trial

OBJECTIVE

To establish the efficacy of intratympanic gentamicin treatment in patients with unilateral Ménière's disease.

MATERIAL AND METHODS

This was a prospective, double-blind, randomized clinical trial of intratympanic gentamicin versus intratympanic buffer solution (placebo) in patients with established active Ménière's disease in the affected ear. Outcome measures included the number of vertiginous spells, degree of sensorineural hearing loss, labyrinthine function and labyrinthine asymmetry.

RESULTS

Topical gentamicin provided a significant reduction in the number of vertiginous spells, although a "placebo effect" was also observed. Sensorineural hearing loss did not occur in the gentamicin group, although some deterioration occurred in the placebo group.

CONCLUSIONS

Intratympanic gentamicin is a safe and efficient treatment for the vertiginous spells associated with Ménière's disease. When applied early in the course of the disease, it may prevent some of the sensorineural hearing deterioration associated with it.

Gentamicina intratimpánica para la enfermedad de ménière: análisis de la técnica

OBJECTIVE

The aim of this paper is to analyze the peculiarities of a protocol for treatment with intratympanic gentamicin in patients with Ménière's disease.

MATERIAL AND METHODS

71 patients with unilateral disabling Ménière's disease were followed for a period longer than two years after concluding the treatment. AAO-HNS criteria for reporting treatment results was followed. Gentamicin was applied weekly until of symptoms or signs of vestibular hypofunction were noticed.

RESULTS

Control of vertigo was obtained in 83% of the patients while in 24% a second course was needed beacuse of vertigo recurrence. 66% of the patients developed a typical syndrome of unilateral vestibular hypofunction in the ear treated.

CONCLUSIONS

Ending weekly injections of gentamicin for the treatment of patients with Ménière's disease when signs of vestibular hypofunction appear warrants a control of vertigo similar to that obtained in other series.

Inner ear perfusion: indications and applications

PURPOSE OF REVIEW

To examine the indications and applications of inner ear perfusion in the treatment of common otologic diseases, including Meniere disease, sudden sensorineural hearing loss, and autoimmune inner ear disease.

RECENT FINDINGS

The number of surgical procedures, including vestibular neurectomy, labyrinthectomy, and endolymphatic sac surgery, decreased during the 1990s. Intratympanic gentamicin therapy has become the most frequently performed invasive procedure for treatment of Meniere disease. Reports on successful control of vertigo in patients with Meniere disease have ranged from 71.4 to 100%. There is a correlation between the degree of vestibular ablation in transtympanic gentamicin, the control of vertigo, and the risk of hearing loss. Patients with less than 75% ice-reduced vestibular response had a statistically lower risk of hearing loss, but they had a higher rate of persistent vertigo than patients with 100% reduced vestibular response. One hundred percent reduced vestibular response may not be indicative of complete vestibular ablation and may not be necessary for control of vertigo symptoms. In preliminary studies, inner ear perfusion of methylprednisolone in patients with severe, profound sudden sensorineural hearing loss who fail to respond to standard treatment is beneficial, with improvement in hearing thresholds of 16 to 25 dB and dramatic improvement in speech discrimination scores. No immunosuppressive medication has been found effective in suppressing inner ear inflammatory infiltrates or reducing hearing loss in an animal model.

SUMMARY

Transtympanic chemical perfusion of the inner ear is safe, inexpensive, and easily performed by an otologic surgeon. With inner ear perfusion, high inner ear concentrations of medication can be achieved, and systemic side effects are minimized.

Intratympanic gentamicin for unilateral Meniere's disease: results of therapy

Patients with Meniere's disease that remains refractory to conservative treatment have traditionally been subjected to ablative surgery. The purpose of this prospective study was to evaluate the use of intratympanic gentamicin in eliminating incapacitating vertigo, while preserving hearing. Over the past 8 years, 83 patients have received between 1 and 6 intratympanic injections of gentamicin in an out-patient setting, with duration of therapy titrated to individual symptom response and effect on hearing. Using established AAO-HNS guidelines, we present data on 50 patients who have a minimum of 2 years follow-up. Control or significant improvement of definitive Meniere's attacks was achieved in 92% of patients and hearing preserved or improved in 76%. Only one patient experienced profound sensorineural hearing loss. We feel this treatment option should be considered and offered to patients in whom medical treatment has failed.

Pharmacologic Manipulation of the Labyrinth with Novel and Traditional Agents Delivered to the Inner Ear

We describe the methodology and rationale behind the delivery of therapeutic medicines to the inner ear. The inner ear has long been impervious to pharmacologic manipulation. This is most likely the result of a protective mechanism called the blood-labyrinth barrier, whose function closely resembles that of the blood-brain barrier. This protective barrier impedes the clinician's ability to treat inner ear diseases with systemically administered medications. Since 1935, otolaryngologists have attempted to manipulate the inner ear with transtympanically injected medicines. Success has varied widely, but medicinal ablation of vestibular function can be achieved in this manner. Unfortunately, the auditory system is also at great risk from any medicine that is delivered to the inner ear via the middle ear. Over the past 10 years, significant improvements in drug delivery have allowed for more “titratable” treatment, which has reduced (but not eliminated) the risk of permanent hearing loss. In this article, we discuss both novel and time-tested methods of delivering medicines to the inner ear. We also review the classes of medications that alter inner ear function and the attendant risks of such treatments.

Transtympanic management of tinnitus

Transtympanic therapy is becoming and important treatment modality for many inner ear disorders. The current therapies aimed at Meniere's disease, sudden sensorineural hearing loss, noise-induced hearing loss, and the tinnitus associated with these disorders and idiopathic tinnitus, however, represents simply an evolutionary step in this treatment modality and must be validated by further scientific study. A number of promising developments including newer more targeted neuroactive medicines, a better understanding of medicine delivery, and the knowledge of the site, origin, and pathophysiology of the symptoms complex will make this therapy more effective. In the future it is possible that many inner ear disorders will be amenable to inner ear medical therapy. Ideally in the future with knowledge of the disease and its etiology the physician will simply pick the established medicine, the established dose, and the established route of administration and achieve a relatively predictable result.

Intratympanic gentamicin for intractable Meniere's disease

OBJECTIVE

The study aimed to analyze the results of the intratympanic injection of gentamicin as a treatment option for patients with unilateral Meniere's disease who were refractory to medical treatment.

STUDY DESIGN

Prospective study in the setting of a tertiary care medical center.

METHODS

Seventy-one patients with unilateral Meniere's disease according to 1995 American Academy of Otolaryngology-Head and Neck Surgery 1995 guidelines who had been unresponsive to medical therapy for at least 1 year were studied. Intratympanic injections of a prepared concentration of 27 mg/mL gentamicin were performed at weekly intervals until the development of symptoms and signs indicative of vestibular hypofunction in the treated ear. As the main outcome measure, the 1995 American Academy of Otolaryngology-Head and Neck Surgery criteria for reporting treatment outcome in Meniere's disease were used. The results of treatment were expressed in terms of control of vertigo, disability status (functional level and degree of overall impairment evaluated by the Dizziness Handicap Inventory and the University of California Los Angeles Dizziness Questionnaire), hearing level, and quantitative measurement of vestibular function.

RESULTS

Vertigo was controlled in 83.1% of the 71 patients. Recurrence of vertigo spells after initially complete control was noted in 17 patients. In 13 of these patients, this was cured by another course of intratympanic injections of gentamicin. Functional level and measures of self-reported handicap were significantly and promptly lowered after treatment in the patients who attained control of vertigo. Hearing level as pure-tone average was unchanged 2 years after treatment, but hearing loss as a result of gentamicin injections occurred in 23 patients at the end of treatment and in 9 and 11 patients at 3 months and 2 years after the treatment, respectively. Vestibular function was kept normal or reduced in 49.3% of the patients, whereas in the rest of the patients vestibular areflexia was observed. Control of vertigo did not depend on the amount of vestibular damage.

CONCLUSIONS

Ending weekly intratympanic injections when clinical signs of vestibular deafferentation appear can control vertigo in the majority of patients, and it is a useful alternative, together with other surgical options, for the treatment of patients with Meniere's disease who do not respond to medical treatment.

Changing Trends in the Surgical Treatment of Ménière's Disease: Results of a 10-year Survey

In order to discern trends in surgical procedures used to treat Ménière's disease in the United States during the 1990s, we mailed a questionnaire to 700 members of the American Otological Society and the American Neurotology Society. These physicians were asked about the frequency, results, and complications of surgical procedures for Ménière's disease that they had performed between Jan. 1, 1990, and Dec. 31, 1999. Questionnaires were returned by 137 surgeons (19.6%). Their responses indicated that the number of vestibular neurectomies, labyrinthectomies, and endolymphatic sac surgeries all decreased during 1999. Meanwhile, the use of office-administered intratympanic gentamicin therapy increased rapidly throughout the entire 10-year period, and by 1999 it had become the most frequently used invasive treatment for Ménière's disease. Surgeons now seem to reserve inpatient procedures for cases where intratympanic gentamicin fails to control vertigo.

Middle ear instillation of gentamicin and streptomycin in chinchillas: electrophysiological appraisal of selective ototoxicity

The purpose of this study was to investigate selective vestibular ototoxicity of gentamicin and streptomycin in the chinchilla model. In total, 10 chinchillas underwent left middle ear instillation of one of three agents: gentamicin, streptomycin and saline. Electrophysiological data (otoacoustic emissions (OAEs), auditory brainstem evoked response (ABRs), and ice-water electronystagmography were recorded before and after instillation. Animals were sacrificed for temporal bone studies using scanning electron microscopy. Morphological changes in the cochlear and vestibular neuroepithelia were correlated with electrophysiological changes. Widespread ipsilateral cochlear and vestibular neuroepithelial injuries were observed and correlated with loss of OAEs, ABRs and ice-water caloric response. This study provides no evidence of selective vestibular ototoxicity of gentamicin or streptomycin. Morphological damage correlates with, but precedes loss of electrophysiological parameters. Chinchillas, like other small mammals, may not be an ideal model for the study of human ototoxicity.

Efficacy of increased gentamicin concentration for intratympanic injection therapy in Ménière's disease

OBJECTIVES

Update of ongoing case series of intratympanic gentamicin use in intractable Ménière's disease. Comparison of the treatment results of two gentamicin concentrations: 30 mg/ml and 40 mg/ml.

STUDY DESIGN

Retrospective case-matched review of an ongoing protocol.

SETTING

Ambulatory visits in an office setting.

PATIENTS

Eighty-seven patients were included in this study according to the 1995 guidelines of the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) for reporting treatment results of Ménière's disease.

INTERVENTION

Intratympanic injection of a buffered gentamicin solution (30 mg/ml) was used in 44 patients (Group 1) in years 1992 to 1995. Stock gentamicin solution (40 mg/ml) was used in 43 patients (Group 2) in years 1996 to 1999. Treatment was titrated for each patient, and the hearing was strictly monitored. The endpoint of treatment was the complete cessation of vertigo spells.

MAIN OUTCOME MEASURES

Hearing results, vertigo control scores, and ice water caloric testing responses were analyzed after 24 months of follow-up. Thirty-two patients from each group were selected for case-matched statistical analysis.

RESULTS

Four or fewer gentamicin injections were used in 70% of Group 1 patients and 96% of Group 2 patients. In Group 1, vertigo control was achieved in 81% of patients, and the hearing remained the same or was improved in 68% of patients. In Group 2, vertigo control was achieved in 72% of patients, and the hearing remained the same or was improved in 81% of patients. Treatment was aborted in four patients of Group 2 for early reversible hearing loss, and 31 of 39 patients (79%) who completed the protocol experienced lasting vertigo control. There was a trend for longer-lasting vertigo control in the Group 2 patients.

CONCLUSION

It was concluded that increasing the gentamicin concentration to 40 mg/ml probably produces similar rates of vertigo control as those of the lower dose, at least initially, but requires fewer injections. The higher dose did not increase the risk of hearing loss if treatment was stopped at the first indication of injury. A larger study is needed to confirm the trend of improved long-term hearing results in patients treated with the 40 mg/ml solution.

Low-dose intratympanic gentamicin treatment of Menière's disease

To control attacks of vertigo while preserving both hearing and labyrinthine function, low doses of gentamicin were instilled intratympanically in nine patients with intractable unilateral Meniere's disease. Each patient received six instillations of antibiotic of 4 mg each (total dose, 24 mg). Patients were then followed for 2-4 years. Long-term results of treatment are reported according to the American Academy of Otolaryngology-Head and Neck Surgery 1985 criteria. Of the nine cases, three experienced complete control of vertiginous attacks, while six received substantial control. Post-treatment hearing acuity was unaffected, although disability following treatment became worse in one patient, a 66-year-old man. Caloric responses after therapy were absent or severely reduced in three ears, moderately reduced in two ears and unchanged in four ears. In three patients, labyrinthine function was found damaged 4-8 days after administration of the last dose of drug. Overall, intratympanic instillations of low doses of gentamicin in patients with intractable Meniere's disease were found to control vertiginous attacks with less damage to the inner ear function than that reported in the literature.

Chemical perfusion of the inner ear

In general, chemical perfusion therapy of inner ear disease is safe, inexpensive, and easy to perform. High inner ear medication concentrations can be achieved while minimizing systemic side effects. Most delivery methods are minimally invasive and can be performed in the office. The treatment is usually well accepted by patients. Vertigo control rates for Meniere's disease have been excellent--rivaling other prominent surgical treatments--allowing intratympanic therapy to become the most prominent first-line treatment for Meniere's disease. Side effects of ototoxicity occurring in approximately 30% of patients remain as one of the primary hurdles to overcome. Most patients who experience hearing loss, however, do not complain of the loss and are simply happy to be free of their vertigo attacks. The use of oral steroids to rescue and preserve hearing during gentamicin perfusion remain promising, and complete recovery and even hearing improvement have been observed [30]. Steroid perfusion of the inner ear also is variably effective for the treatment of SSHL, and is particularly indicated when oral steroids fail or are contraindicated due to other health reasons. Many inner ear perfusion methods and philosophies of treatment exist. Each technique has its associated advantages and disadvantages, and the individual surgeon must decide which technique to use in concordance with the patient's disease and expectations. In the future, new medications likely will be developed to treat certain types of inner ear disease, including SSHL, tinnitus, and various forms of vertigo. These medications can be administered by direct chemical perfusion of the inner ear.

Intentional ablation of vestibular function using commercially available topical gentamicin-betamethasone eardrops in patients with Meniere's disease: further evidence for topical eardrop ototoxicity

OBJECTIVE

To determine whether the controversial findings of suspected ototoxicity from commercially available gentamicin sulfate and betamethasone sodium phosphate eardrops can be used in a therapeutic fashion to ablate (or attenuate) vestibular function in patients with unilateral Meniere's disease.

STUDY DESIGN

Prospective case review.

METHODS

At a tertiary care dizziness unit at the University Health Network, Toronto General Hospital, University of Toronto (Toronto, Ontario, Canada), adults with unilateral Meniere's disease undergoing intratympanic ablation therapy were studied. After insertion of a tympanostomy tube with the patient under local anesthesia, patients instilled gentamicin containing eardrops three times daily until they became vertiginous for longer than 24 hours and then for an additional 2 days longer or for 1 month, whichever came first. Electronystagmographic caloric test responses were measured before treatment using bithermal water caloric and after treatment using air caloric tests. Main outcome measures included clinical titration of drops to the onset of prolonged vertigo. As well, post-treatment findings on electronystagmography and audiometry were compared with pretreatment testing.

RESULTS

Twenty patients were available for review. Fifteen patients had a significant reduction in caloric test responses compared with pretreatment values; among them, 10 patients had absent air caloric test responses on the treated side. In 10 patients hearing worsened according to the 1995 American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium Guidelines for reporting in Meniere's disease.

CONCLUSIONS

Topical gentamicin-betamethasone eardrops can pass through a tube into the middle ear, where they may prove primarily vestibulo-ototoxic patients with Meniere's disease. The study further confirms clinical observations that gentamicin-containing eardrops might prove ototoxic, especially in noninflamed ears with a tympanic membrane defect.