Intratympanic gentamicin for the treatment of unilateral Meniere's disease

Consensus on intratympanic drug delivery for Menière's disease

Purpose

Intratympanic (IT) drug delivery receives attention due to its effectivity in treatment for Menière’s disease (MD). Due to the release of the consensuses and new evidence on IT drug delivery for MD have been published, the review with a view to supplementing the details of IT treatment of MD is indispensable.

Methods

The literatures on IT injection for MD treatment over the last two decades are retrieved, International consensus (ICON) on treatment of Menière’s disease (2018), Clinical Practice Guideline (2020) and European Position statement on Diagnosis and Treatment of Meniere’s Disease (2018) are taken into account for reference, and follow advice from experts from Europe, USA and China.

Results

Experts agree on the following: (1) The effectiveness of IT methylprednisolone (ITM) on vertigo control seems to be somewhat better than that of IT dexamethasone (ITD), and ITM can restore hearing in some cases. (2) Due to the ototoxicity of aminoglycosides, the application of intratympanic gentamicin (ITG) in MD patients with good hearing is conservative. However, some studies suggest that ITG with low doses has no significant effect on hearing, which needs to be further proved by clinical studies with high levels of evidence. (3) Currently, generally accepted treatment endpoint of ITG is no vertigo attack in a 12-month period or a vestibular loss in objective tests in the affected ear.

Conclusion

More studies with high level of evidence are needed to evaluate the drug type, efficacy, and therapeutic endpoint of IT therapy for MD.

Endoscopic Transcanal Labyrinthectomy for Intractable Meniere's Disease: An Alternative to Transmastoid Labyrinthectomy?

OBJECTIVE

To describe a novel approach for intractable Ménière's disease exclusively through a transcanal endoscopic ear surgery (TEES) approach.

PATIENT

A 56-year-old male with intractable Ménière's disease despite conservative treatment and chemical labyrinthectomy.

INTERVENTIONS

Transcanal endoscopic labyrinthectomy.

MAIN OUTCOME MEASURE

Subjective vertigo control, surgical morbidity.

RESULTS

The TEES approach provided a wide exposure of the oval window. This facilitated removal of stapes crura and footplate. After widening of the oval window, the perilymph was suctioned, and gentamicin was injected through the oval window. The oval window was obliterated using the perichondrium of the tragal cartilage and fibrin glue. After 2 years of follow-up, there was no recurrence of vertigo.

CONCLUSIONS

As a compelling alternative to the transmastoid approach, we propose endoscopic labyrinthectomy as an option for patients with intractable MD without functional hearing who have failed chemical labyrinthectomy. Additional studies are needed to determine the risk-benefit profile of this technique.

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

Calcium imaging in gentamicin ototoxicity: increased intracellular calcium relates to oxidative stress and late apoptosis

OBJECTIVES

To estimate intracellular calcium changes in gentamicin (GM) ototoxicity using calcium imaging. To investigate GM-induced physiologic changes in auditory cells including cell viability, apoptosis, and oxidative stress.

METHODS

Varying concentrations of GM were applied to the HEI-OC1 cochlear cell line. Calcium imaging tracked changes in intracellular calcium concentration during GM cytotoxicity. Cell viability and intracellular reactive oxygen species (ROS) levels also were measured.

RESULTS

Little change in calcium levels occurred in HEI-OC1 cells exposed to less than 35 mM GM. However, calcium rose continuously in cells exposed to more than 60 mM GM. With administration of intermediate concentrations of 40 or 50 mM GM, calcium increased variably in different cells, returning to baseline in some cases, or rising continuously in others. Upon increase of GM concentration, intracellular calcium concentration and ROS were increased, and cell viability was decreased due to late apoptosis.

CONCLUSION

This study shows that GM increased intracellular calcium, ROS, and late apoptosis of HEI-OC1 cells derived from cochlear tissue. Increase of intracellular calcium is related to GM-induced apoptosis and oxidative stress. Calcium imaging can be used to determine change of intracellular calcium concentrations and apoptosis in GM ototoxicity.

Intratympanic treatment of intractable unilateral Meniere disease: gentamicin or dexamethasone? A randomized controlled trial

OBJECTIVE

To determine the efficacy and safety of low-dose intratympanic gentamicin (ITG) compared with intratympanic dexamethasone (ITD) in patients with intractable unilateral Ménière disease (MD).

STUDY DESIGN

Open prospective randomized controlled study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Sixty patients affected by definite unilateral MD were enrolled between January 1, 2007, and June 30, 2008. Thirty-two patients were treated with a buffered gentamicin solution injected in the middle ear (maximum of 2 injections); 28 patients were treated with ITD (4 mg/mL, 3 injections at intervals of 1 every 3 days). Mean outcome measurements consisted of control of vertigo attacks, pure tone average (PTA), speech discrimination score, functional disability score, and statistical analysis using repeated measures analysis of variance.

RESULTS

In the ITG group at 2-year follow-up, complete control of vertigo (class A) was achieved in 26 patients (81%) and substantial control of vertigo (class B) in 4 patients (12.5%). In the ITD group, class A was achieved in 12 (43%), and class B in 5 (18%) patients. In the gentamicin group, 4 patients showed a reduction in PTA of ≥10 dB. In the ITD group, PTA was unchanged or slightly improved in 16 patients (belonging to class A-B) and worse in 12.

CONCLUSIONS

Low-dose ITG achieved better outcome than ITD in the control of vertigo attacks in patients suffering from unilateral MD, with a very low incidence of hearing deterioration. ITD offers poorer vertigo control rate, and hearing preservation is achieved only in cases with no vertigo recurrences.

New developments in aminoglycoside therapy and ototoxicity

After almost seven decades in clinical use, aminoglycoside antibiotics still remain indispensible drugs for acute infections and specific indications such as tuberculosis or the containment of pseudomonas bacteria in patients with cystic fibrosis. The review will describe the pathology and pathophysiology of aminoglycoside-induced auditory and vestibular toxicity in humans and experimental animals and explore contemporary views of the mechanisms of cell death. It will also outline the current state of protective therapy and recent advances in the development of aminoglycoside derivatives with low toxicity profiles for antimicrobial treatment and for stop-codon suppression in the attenuation of genetic disorders.

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.

Evidence-based modification of intratympanic gentamicin injections in patients with intractable vertigo

OBJECTIVES

To compare the cochlear distribution of low-dose fluorescent gentamicin after intra-tympanic administration in guinea pig (GPs) with clinical data of low dose intra-tympanic gentamicin in patients with intractable vertigo.

MATERIALS AND METHODS

Purified gentamicin-Texas Red (GTTR) was injected intratympanically into GPs and the cochlear distribution and time course of GTTR fluorescence in outer hair cells (OHCs) was determined using confocal microscopy.

RESULTS

GTTR was rapidly taken up by OHCs, particularly in the subcuticular zone. GTTR was distributed in the cochlea in a decreasing baso-apical gradient, and was retained within OHCs without significant decrease in fluorescence until 4 weeks after injection.

CONCLUSION

OHCs rapidly take up GTTR after intra-tympanic administration with slow clearance.

CLINICAL APPLICATION

A modified low-dose titration intratympanic approach was applied to patients with intractable Ménière's Disease (MD) based on our animal data and the clinical outcome was followed. After the modified intratympanic injections for MD patients, vertigo control was achieved in 89% patients, with hearing deterioration identified in 16% patients. The 3-week interval titration injection technique thereby had a relatively high vertigo control rate with a low risk of hearing loss, and is a viable alternative to other intratympanic injection protocols.

Middle ear exploration in patients with Ménière's disease who have failed outpatient intratympanic gentamicin therapy

OBJECTIVE

Treatment of medically refractory Ménière's disease (MD) with intratympanic (IT) gentamicin has now become a standard therapy. This procedure is effective in controlling vertigo attacks, but approximately 10% of patients do not have an adequate response. The objective of the current study was to evaluate the option of middle ear exploration with direct application of gentamicin to the round window (MEE-G) in patients with persistent MD after transtympanic injection of gentamicin.

STUDY DESIGN

A retrospective chart review of 191 patients with MD treated with IT gentamicin revealed 16 who failed to have symptomatic relief after transtympanic injection. Options discussed with these patients included labyrinthectomy, vestibular nerve section, and MEE-G.

SETTING

Tertiary referral center.

PATIENTS

Eight patients opted for MEE-G.

INTERVENTION

Patients were taken to the operating room for MEE-G. After removal of the round window obstruction, gentamicin-soaked pledgets were placed for at least 30 minutes.

MAIN OUTCOME MEASURES

Control of MD-related vertigo and need for additional therapy.

RESULTS

At the time of MEE-G, all 8 patients were found to have adhesions, bone dust blocking the round window, or a thickened round window membrane. In 6 of these patients, vertigo symptoms due to MD either resolved with no further therapy (4 patients) or with subsequent IT gentamicin injections in clinic (2 patients). The remaining 2 patients underwent a vestibular nerve section, which resolved MD symptoms in each case.

CONCLUSION

Anatomic barriers to the round window membrane may be a significant cause of IT gentamicin failure, and MEE-G can be considered before ablative therapy in this subset of patients with Ménière's disease.

Dependence of hearing changes on the dose of intratympanically applied gentamicin: a meta-analysis using mathematical simulations of clinical drug delivery protocols

OBJECTIVES/HYPOTHESIS

To establish safe dosing protocols for the treatment of patients with Meniere's disease with intratympanic gentamicin.

STUDY DESIGN

A validated computer model of gentamicin dispersion in the inner ear fluids was used to calculate cochlear drug levels resulting from specific clinical delivery protocols. Dosing in the cochlea was compared with changes of hearing sensitivity for 568 patients reported in 19 publications.

METHODS

Cochlear drug levels were calculated based on the concentration and volume of gentamicin applied, the time the drug remained in the middle ear, and on the specific timing of injections. Time courses were quantified in terms of the maximum concentration (Cmax) and the area under the curve of the drug at specific cochlear locations.

RESULTS

Drug levels resulting from single, "one-shot" injections were typically lower than those from repeated or continuous application protocols. Comparison of hearing sensitivity changes with gentamicin dosing revealed a flat curve with a near-zero mean for lower doses, suggesting that hearing changes with doses over this range were probably unrelated to the applied drug. Higher intracochlear doses were generated with repeated or continuous delivery protocols, which in some cases caused substantial hearing losses and an increased incidence of deafened ears.

CONCLUSIONS

One-shot application protocols produce gentamicin doses in the cochlea that have minimal risk to hearing at the frequencies tested. Repeated or continuous application protocols result in higher doses that in some cases damage hearing. The high variability of hearing changes, even with low gentamicin doses, calls into question the rationale for using individual hearing changes to titrate the applied dose.

Effects of a single intratympanic gentamicin injection on Meniere's disease

CONCLUSION

Both single and multiple injections of ITGM were effective in vertigo control and functional improvement. However, the risk of sensorineural hearing loss was much lower for a single injection than for multiple injections.

OBJECTIVES

While intratympanic gentamicin injection (ITGM) has been established as treatment option for intractable Meniere's disease, several injection protocols have been introduced. The risk of sensorineural hearing loss (SNHL) has been reported to be variable for each protocol. Among the protocols, the single injection protocol is an easy to administer, well-tolerated and cost effective technique, as compared with others. We compared the clinical efficacy of ITGM with regard to the vertigo control rate and the incidence of SNHL between two different protocols: the use of single and multiple injections.

MATERIALS AND METHODS

A retrospective review was conducted for 30 subjects who were treated with ITGM with intractable unilateral Meniere's disease from May 1997 through February 2005. The patients were divided into two groups according to the protocol utilized: the multiple injection group (n =10) and the single injection group (n =20). Treatment efficacy was evaluated by using the AAO-HNS Committee on Hearing and Equilibrium guidelines (1995).

RESULTS

Effective vertigo control (Class A and B) were accomplished in 90% of patients in the multiple injection group and in 90% of patients in the single injection group. Functional status was also markedly improved in both groups. However, a significant hearing loss occurred more frequently in the multiple injection group (71%) than in the single injection group (5%). The rate of caloric loss was not different for the two groups (88% for the multiple injection group vs. 85% for the single injection group).

Intratympanic gentamicin: a 1-day protocol treatment for unilateral Meniere's disease

PURPOSE

The objective of this study was to assess the usefulness of low-dose intratympanic gentamicin administration in patients with Meniere's disease (MD).

MATERIALS AND METHODS

We carried out a retrospective review of the charts of 55 patients with definite MD in accordance with the AAO-HNS (American Academy of Otolaryngology-Head and Neck Surgery) Diagnostic Scale who were treated at Gruppo Otologico (Piacenza, Rome, Italy). The treatment protocol consisted of 3 intratympanic injections of gentamicin at a 12-hour interval between each administration.

RESULTS

Results were resumed in accordance with AAO-HNS criteria and showed complete control of vertigo spells in 60% (class A), good control in 16% (class B), moderate control in 4% (class C), poor control in 16% (class D), and no control in 4% (class E) of the patients. Audiological assessment showed unchanged thresholds in 61%, improvement in 22%, and worsening in 17% of the cases.

CONCLUSION

Administration of gentamicin is a good alternative to medical and surgical procedures in the treatment of intractable MD. One-day treatment allows for adequate control of vertigo attacks without compromising hearing and quality of life and with reduced costs.

Intratympanic gentamicin therapy for intractable Ménière's disease

CONCLUSIONS

Intratympanic gentamicin treatment using a low dose of gentamicin (approximately 21-24 mg per injection) applied at intervals of a minimum of 27 days, has been shown to be a successful treatment of vertigo.

OBJECTIVES

The objective of this analysis was to evaluate the efficacy and side effects of intratympanic injections of gentamicin as treatment of intractable unilateral Ménière's disease.

PATIENTS AND METHODS

This was a retrospective study in which 57 patients treated with intratympanic gentamicin for Ménière's disease were analysed. Patients received between 1 and 10 intratympanic injections of gentamicin in an outpatient setting.

RESULTS

Six months after treatment, overall complete or substantial vertigo control was reported by 80.7% of our patients (VCC class A, 61.4%; class B, 19.3%). Unilateral caloric weakness increased from 50.1% to 79.8% after treatment, and complete caloric areflexia (30 degrees C and 44 degrees C) was induced in 38.6%. In this study hearing worsened (> 10 dB = SNHL) in only 15.8% of our patients (range 10-29 dB) and loss of word recognition (WR) scores worsened (>15%) in 31% of the patients. Only 1 injection was necessary in 49.1% of the patients, the remaining 50.9% needed 2, 3, 4, 6 or 10 injections, always with a time interval of a minimum of 27 days.

Outcome-based assessment of endolymphatic sac decompression for Ménière's disease using the Ménière's disease outcome questionnaire: a review of 90 patients

OBJECTIVE

To evaluate the quality of life (QOL) of patients treated by endolymphatic sac decompression (ELSD) for Ménière's disease (MD) with a dedicated questionnaire, while recording the results of this surgery on vertigo attacks using the American Academy of Otolaryngology-Head and Neck Surgery criteria.

STUDY DESIGN

Retrospective case review in a tertiary referral care center.

MATERIAL AND METHODS

Ninety patients who have MD were treated by ELSD at our institution between 1986 and 2004. They were sent a 40-question Ménière's Disease QOL dedicated questionnaire (Ménière's Disease Outcome Questionnaire) concerning physical, mental, and social well-being. Five scores out of 100 were calculated (S1-S5): S3 for preoperative QOL score, S4 for postoperative QOL score, S5 for change in QOL score (S5 = S4 - S3), and S1 and S2 representing the answers to two other paired questions about the "overall" feeling of the patients. In parallel, results of ELSD on vertigo attacks and hearing were evaluated using the Academy of Otolaryngology-Head and Neck Surgery criteria.

RESULTS

Fifty-nine interpretable answers (65.6%) to the Ménière's Disease Outcome Questionnaire were obtained from 28 men and 31 women (mean age, 56 yr and 9 mo), all suffering from "definite" MD. The mean S3 was 32.5 (range, 9.7-84.7), and the mean S4 was 60.8 (range, 0-98.6). Consecutively, S5 score was 28.3 (range, -34.7 to 77.4). QOL improved in 81.4% of cases with an average duration of follow-up of 57.5 months (range, 4-156 mo) (p < 0.001), worsened in 11.9% and was stable in 6.8%. There was no statistically significant difference as a function of sex (p = 0.7) or length of follow-up (p = 0.6). There was a significant correlation between S1 and S3 (p < 0.0001), and S2 and S4 (p < 0.0001), validating the whole questionnaire. In addition, 71% of satisfactory control of vertigo at 2 years postoperatively was noted. Hearing was improved or unchanged in 79% of cases at 3 months postoperatively.

CONCLUSION

These results show that ELSD significantly improves the health of patients. It represents a first-line procedure that preserves the vestibular and afferent structures, unlike vestibular neurotomy and chemical labyrinthectomy, which may be indicated as a second line.

Factors Relating to the Vertigo Control and Hearing Changes Following Intratympanic Gentamicin for Intractable Ménière's Disease

OBJECTIVE

To look for factors relating to the vertigo control and hearing changes after intratympanic injections of gentamicin (GM).

STUDY DESIGN

Prospective.

SETTING

Tertiary referral medical center.

PATIENTS

Twenty-eight patients with intractable Ménière's disease.

INTERVENTIONS

Three intratympanic injections of GM (once per day for three consecutive days).

MAIN OUTCOME MEASURES

Although five patients needed further GM injections or vestibular neurectomy because of poor control (Group I), 23 patients had their vertigo controlled for more than two years without further treatment (Group II). The number of vertigo spells per month, pure-tone audiometry, electrocochleography, caloric response, post-head shake nystagmus, and plasma vasopressin as a stress marker were examined.

RESULTS

Before GM injections, there was no difference in the number of vertigo spells per month between Groups I and II. However, the hearing thresholds were higher in Group I. Hearing improvement, increase in percentage of canal paresis and induction of post-head shake nystagmus were observed after GM injections only in Group II. Even in the 11 patients who showed an improvement in hearing of more than 10 dB (hearing improvement group), percentage of canal paresis was increased after GM. More, premedication plasma vasopressin levels were lower in the hearing improvement group as compared with the hearing loss/no changes group. Four of eight patients became negative for dominant negative summating potential in electrocochleography after GM injections in the hearing improvement group.

CONCLUSION

Our data indicate that the frequency of vertigo is not a key factor in the vertigo control after GM injections, that induction of vestibular damage in the injected ear is essential for the control of vertigo and this effect is mostly pronounced in patients with milder hearing loss, and that hearing improvement is not only a consequence of good vertigo control but also affected by the stress level before treatment.

Revision Surgery for Vertigo

When confronted with vertigo after an otologic procedure, a surgeon first must identify the functional status of the inner ear by performing auditory and vestibular testing. Using this information in conjunction with knowledge of the primary disease process for which the initial procedure was performed, the surgeon can make a rational selection of the procedure required to eliminate vertigo. This article outlines a systematic approach to the selection of the appropriate revision procedure and discusses the specific advantages and disadvantages of these procedures used to control vertigo.

Angular vestibulo-ocular reflex gains correlate with vertigo control after intratympanic gentamicin treatment for Meniere's disease

OBJECTIVES

The objective of our study was to determine whether angular vestibulo-ocular reflex (aVOR) gains correlated with vertigo control after intratympanic gentamicin treatment for Meniere's disease.

METHODS

We conducted a prospective study of 18 subjects with unilateral Meniere's disease treated with intratympanic gentamicin injection and followed all subjects for 1 year. We measured the gain of the aVOR elicited by rapid rotary head thrusts in each of the canal planes for each subject before and after treatment with intratympanic gentamicin by using magnetic search coils to record eye movements.

RESULTS

During the follow-up period, 11 subjects ("single-treatment group"; 61%) had control of their vertigo with a single gentamicin injection. The remaining 7 subjects ("multiple-treatment group"; 39%) experienced recurrent vertigo that required a second injection of gentamicin at a mean of 6 months after the first treatment. The 11 subjects in the single-treatment group had significantly greater reduction of labyrinthine function after the first treatment, as measured by change in ipsilateral horizontal canal gain, than did the 7 subjects with vertigo recurrence. Changes in caloric asymmetry did not correlate with vertigo control.

CONCLUSIONS

Our results suggest that successful treatment of Meniere's disease is closely related to attenuation of semicircular canal function as measured by horizontal canal aVOR gains.

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 Menière's Disease: a Meta-Analysis

OBJECTIVES

To systematically review the published experience on intratympanic gentamicin treatment for intractable Menière's disease.

STUDY DESIGN

Meta-analysis using a random effect model.

METHODS

A comprehensive literature search was performed for articles using intratympanic gentamicin as a sole treatment modality with reporting of results according to the American Academy of Otolaryngology Head and Neck Surgery (AAO-HNS) guidelines for Menière's disease. Two reviewers independently assessed trial quality and extracted data.

RESULTS

Fifteen trials with 627 patients met the inclusion criteria. All trials reported "before-after" outcome measures, using patients as their own controls. No double-blind or blinded prospective control trials were identified. Complete (class A) vertigo control was achieved in 74.7% (confidence interval [CI]95% 67.8-81.5%) of patients, and complete or substantial (class B) control was achieved in 92.7% (CI95% 89.5-96.0%). The success rate was not affected by gentamicin treatment regimen (fixed vs. titration). Hearing level and word recognition were not adversely affected, regardless of gentamicin treatment regimen. Analysis of functional level was not performed because of lack of data in the selected articles.

CONCLUSIONS

Intratympanic gentamicin treatment for intractable Menière's disease appears to be effective in the relief of vertigo. Cochleotoxicity and ototoxicity is unlikely to be a major side effect. However, the level of evidence reflected from the eligible articles is insufficient, especially because of relatively poor study design. Therefore, it is prudent that patients eligible for this type of treatment should be selected carefully and titrated with low-dose gentamicin. Further investigation with this treatment modality with control subjects is warranted.

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 status of the contralateral ear in established unilateral Menière's disease

OBJECTIVES/HYPOTHESIS

To determine the incidence of measurable audiometric changes in the contralateral ear and clinical bilateral Menière's disease in individuals with longstanding established unilateral Menière's disease.

STUDY DESIGN

Analysis of data in an ongoing prospective study.

METHODS

One hundred and one patients who were treated with intratympanic gentamicin installation for disabling unilateral Menière's disease were followed up for a minimum of 2 years. The mean follow-up time between the initial diagnosis to the last audiogram conducted was 12 +/- 7 (range 2-45) years, and the mean follow-up between the first and last audiograms conducted in our clinic was 5 +/- 3 (range 2-15) years. The incidence of Menière's disease (clinical diagnosis) as compared with audiometric changes in the contralateral ear was analyzed.

RESULTS

Compared with several published reports, the development of bilateral Menière's disease in our series within the described observation period was much lower (5%). The incidence of contralateral isolated hearing loss in the low frequencies was 16% (average threshold of .25 and .5 kHz of 25 dB or more). The time interval between the initial diagnosis and the onset of contralateral findings ranged from 0 to 26 years.

CONCLUSION

In our experience, individuals with disabling longstanding unilateral disease are not likely to develop bilateral disease. However, a small but significant percentage of patients have audiometric changes in the low frequencies of the contralateral ear (.25, .5 kHz).

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.

Vestibular nerve section versus intratympanic gentamicin for Meniere's disease

OBJECTIVES/HYPOTHESIS

Vestibular nerve section and transtympanic gentamicin administration are procedures with proven efficacy in the treatment of vertigo associated with Meniere's disease refractory to medical management. Hearing loss is a known complication of each of these procedures; however, there has not been a report of hearing results of both treatments from a single institution.

STUDY DESIGN

Retrospective review.

METHODS

Review was made of 25 patients undergoing gentamicin injection and 39 patients undergoing vestibular nerve section for Meniere's disease. Rate of vertigo control and pretreatment and post-treatment pure-tone average values and speech discrimination scores were reported.

RESULTS

The mean preoperative pure-tone average for patients having vestibular nerve section was 47.2 dB, with a speech discrimination score of 75.4%. In these patients, the postoperative pure-tone average was 49.1 dB and the speech discrimination score was 75%. Patients undergoing gentamicin injection had a mean pretreatment pure-tone average of 55.9 dB and a speech discrimination score of 62%. The post-treatment pure-tone average and speech discrimination score for the gentamicin group were 68.8 dB and 49.3%, respectively. Five of 25 patients (20%) in the gentamicin treatment group and 1 of 39 (3%) in the vestibular nerve section treatment group had an increase in bone-conduction threshold greater than 30 dB. The amount of postprocedure hearing loss was significantly greater in the gentamicin treatment group (P =.006). Control of vertigo was good to excellent in 95% of the patients treated with vestibular nerve section and in 80% of the patients treated with gentamicin.

CONCLUSION

Although vestibular nerve section and transtympanic gentamicin are both acceptable treatment options for vertigo associated with Meniere's disease, gentamicin causes a higher level of hearing loss related to treatment and vestibular nerve section has higher vertigo control rates.

Results of vestibular autorotation testing at the end of intratympanic gentamicin treatment for Ménière's disease

OBJECTIVE

The vestibular autorotation test (VAT) examines the ocular response to voluntary horizontal and vertical head movements at frequencies for which the vestibular system is the main source for eye stabilization. The purpose of this study was to analyse the VAT results in patients with disabling Ménière's disease and to evaluate the change in VAT values once treatment with intratympanic gentamicin had terminated and clinical signs of vestibular hypofunction could be observed.

MATERIAL AND METHODS

The 30 study subjects were patients diagnosed with definitive unilateral Ménière's disease that could not be controlled with medication. The vestibulo-ocular reflexes of each patient were evaluated by means of the VAT before the first injection of gentamicin and after the last injection.

RESULTS

The pattern of abnormalities found in this population conformed to the selection criteria and the findings reflected a severe disabling process, with major modifications in the vestibulo-ocular reflex. At the end of treatment there was a reduction in the peak frequency of head oscillation. Furthermore, we commonly found that, in the horizontal VAT, gain and phase were reduced while in the vertical VAT some subjects registered a normal response. The phase in the horizontal and vertical VATs was most significantly reduced for oscillation frequencies of 2-3.7 Hz.

CONCLUSION

This study provides further evidence that effective control of vertigo in patients with Ménière's disease can be achieved by administering intratympanic gentamicin.

Long-term hearing outcome in patients receiving intratympanic gentamicin for Ménière's disease

OBJECTIVE

To determine the long-term hearing outcome in patients with intractable vertigo caused by unilateral Ménière's disease who were treated with intratympanic injection of gentamicin.

STUDY DESIGN

The study was a longitudinal analysis of hearing and control of vertigo in patients with unilateral Ménière's disease who received intratympanic gentamicin.

METHODS

Pure-tone thresholds and speech discrimination scores on audiometry were analyzed, along with the control of vertigo. Criteria described in 1995 by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) were used. Patients treated with intratympanic gentamicin had "definite" Ménière's disease and had intractable vertigo despite optimal medical therapy, no symptoms suggestive of Ménière's disease in the contralateral ear, and serviceable hearing in the contralateral ear. The study analyzed the outcomes of 34 patients for whom follow-up data were available for periods greater than 24 months after intratympanic gentamicin.

RESULTS

Complete control of vertigo (AAOHNS Class A) was obtained in 90% of the patients. Profound sensorineural hearing loss occurred as a result of gentamicin injection in 1 of the 34 patients (3%). When data from all patients were grouped together, hearing was improved in 5 (15%), unchanged in 23 (68%), and worse in 6 (17%) patients. This distribution of hearing outcome is similar to that in patients whose symptoms of Ménière's disease were managed with medical measures. Recurrent vertigo developed in 10 patients (29%) at an interval of 4 to 15 months after initially complete control. Treatment with additional intratympanic injection(s) of gentamicin did not result in a change in hearing.

CONCLUSION

The risk of hearing loss in patients treated with infrequent intratympanic injection(s) of gentamicin is low.

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.

Gentamicin perfusion vestibular response and hearing loss

OBJECTIVE

To compare hearing results as a function of vestibular ablation in the treatment of Ménière's Disease, using gentamicin perfusion.

STUDY DESIGN

A retrospective review of patients with Ménière's Disease treated by gentamicin perfusion of the inner ear via the MicroWick device.

SETTING

A tertiary otologic referral center.

PATIENTS AND INTERVENTIONS

The charts of patients treated with gentamicin perfusion via the MicroWick between the years 1998 and 2000 were reviewed. The results for patients with functional hearing in the affected ear were analyzed and were compared with the results in patients without functional hearing.

MAIN OUTCOME MEASURES

Audiologic and vestibular test results as well as subjective symptoms.

RESULTS

There were 45 patients who met the inclusion criteria. The averages for speech discrimination score and pure tone average before treatment were 92% and 38 dB, and after treatment were 82% and 47 dB. Patients were divided into two groups: Group 1 (20 patients), less than 75% ice air caloric reduced vestibular response (RVR); Group 2 (25 patients), those who reached greater than 75% ice air caloric RVR. There were 8 patients (17.6%) with persistent vertigo; 7 were from Group 1, and 1 was from Group 2, which was statistically significant (p = 0.007)wwww. The pure tone average dropped an average of 3 dB for Group 1 and 15 dB for Group 2. The difference in hearing loss between the two groups was statistically significant (p = 0.01).

CONCLUSION

This study suggests that there is a correlation between the degree of vestibular ablation, the control of vertigo, and the risk of hearing loss. Patients with functional hearing seem to have a similar success rate for vertigo control, compared with patients who already had lost functional hearing before treatment. Future investigation may determine if less than 100% RVR, but greater than 75% RVR, is an alternative end point with adequate vertigo control and reduced risk of hearing loss.

Gentamicin tympanoclysis: effects on the labyrinthine sensory cells

OBJECTIVES

The objective of the study was to determine whether a selective vestibular hair cell toxicity with sparing of the cochlear hair cells could be achieved by infusing different concentrations of gentamicin into the middle ears of adult cats.

STUDY DESIGN

Prospective experimental animal study treating only the left ear of each cat, the right ear serving as individual control.

METHODS

Gentamicin solution at concentrations of either 30 or 3 mg/mL was infused daily into the left middle ear of adult cats until overt ataxia occurred. After 1 month or 6 months, each cat was killed and its temporal bones prepared for optical microscopy.

RESULTS

Animals treated with 30 mg/mL gentamicin until ataxic required a median of five daily doses. These animals had clear-cut cochlear basal turn hair cell losses accompanying toxic lesions in the utricle and cristae. In contrast, animals treated with 3 mg/mL gentamicin until ataxic required an average of 19 daily doses. These animals had lesions restricted to the utricle and cristae with sparing of the cochlea hair cells. Animals that failed to develop ataxia manifested neither lesions of the cochlear nor vestibular hair cells.

CONCLUSION

Gentamicin tympanoclysis in the cat animal model, using a dilute solution and continued once daily until clinical ataxia occurs, is capable of producing selective vestibular hair cell toxicity while sparing cochlea hair cells.

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.

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.

Continuous gentamicin therapy using an IntraEAR microcatheter for Meniere's disease: a retrospective study

OBJECTIVES

The study goals were to evaluate the safety and effectiveness of continuous gentamicin therapy (CGT) in the treatment of Meniere's disease and to evaluate the effect of flow rate.

STUDY DESIGN

In a retrospective study, physicians who were known to have used CGT in the treatment of Meniere's disease were asked to report patient information on a standardized data collection form.

RESULTS

In patients treated with low-flow CGT, vertigo was eliminated or substantially controlled in 90%, tinnitus was improved in 69%, pressure was improved in 77%, hearing was worse in 23%, and vestibular function was ablated in only 14% of patients.

CONCLUSION

On the basis of an average 10-month follow-up period, of the methods currently available to treat Meniere's patients with gentamicin, low-flow CGT seems to provide an excellent combination of vertigo control and tinnitus and pressure improvement, with a relatively low risk to hearing and vestibular function.

SIGNIFICANCE

The clinical use of low-flow CGT appears to be justified based on these data.

Peripheral vestibular disorders with acute onset of vertigo

Disorders of the vestibular nerve and end organs are the most common causes of vertigo. The advances in recognizing different forms of canalolithiasis and cupulolithiasis, which sometimes present with continuous positional nystagmus, have revealed a peripheral vestibular aetiology in which central nervous system lesions were previously suspected. Treatments using repositioning manoeuvres are also successful in cases in which nystagmus does not appear, and when administered by less specialized physicians. In acute vestibulopathy, suspicions of the activation of herpes virus infections as a causative agent are increasing, but no reports on the treatment of such infections are yet available. New treatments are in development for use in Ménière's disease.