1

Introduction

Ménière’s disease (MD) was characterized in 1861 by Prosper Ménière and includes episodic vertigo, fluctuating hearing loss, aural fullness, and tinnitus . The relationship between MD and endolymphatic hydrops was established in 1938 and has subsequently been confirmed in many animal and human studies . The diagnosis of MD is primarily based on clinical history, audiometric findings, and the exclusion of other lesions that could mimic its non-specific symptoms or cause secondary endolymphatic hydrops .

The clinical course of MD is highly variable with the majority of patients having symptomatic improvement over time. Spontaneous resolution of vertigo has been reported in 71% of patients after 8-years . Still a subset of patients have progressive disease with debilitating vertigo, hearing loss, and possibly bilateral involvement . The inability to predict disease progression remains a source of frustration for both patients and clinicians. This prolonged disease course underlies the importance of following these patients for many years, but also complicates analysis of MD treatment outcomes.

The treatment of MD is aimed at symptom management and can be divided into destructive and non-destructive options. Medical management remains first-line therapy and includes avoidance of triggers, low-sodium diet, hydration, and diuretics. Betahistine is utilized in many parts of the world but is not FDA approved in the United States. Meniett device, allergy control, and vestibular suppressants may also have a role . Corticosteroids, via oral or intratympanic (IT) routes, are useful to treat exacerbations and may rescue an acute decline in hearing . A destructive medical option is IT gentamicin, while destructive surgical options include vestibular nerve section and labyrinthectomy. A recent randomized, double-blinded study found IT steroids to be as effective as IT gentamicin for management of refractory MD .

Endolymphatic sac procedures have a growing profile of safety and efficacy as a non-destructive surgical option for MD. The exact mechanism of its benefit is unknown and variations of the procedure continue to be reported. The goal of this study is to describe a modification of the endolymphatic sac decompression with shunt placement in which intraoperative steroids are delivered into the inner ear via round window absorption and direct instillation into the endolymphatic sac. The hypothesis is that steroid delivery directly into the inner ear during shunt placement will improve long-term (> 18-month follow-up) audiometric and vertigo outcomes. Additionally, a patient survey was used to report long-term functional levels.

2

Methods

This is a retrospective case series of patients surgically treated with endolymphatic sac decompression and shunt placement at University Hospitals Cleveland Medical Center between 2002 and 2013. All patients met criteria for definite or probable MD according to the 1995 American Academy of Otolaryngology — Head and Neck Surgery (AAO-HNS) guideline on MD . Patients with possible MD or cochlear hydrops were excluded from the study. Additional inclusion criteria were adult age (18 years old or greater) and failure of medical management consisting of low-sodium diet, hydration, avoidance of triggers, and a diuretic. Patients were also offered IT steroids for disease exacerbations. Endolymphatic sac procedures were offered only after failure of medical management and with persistent severe vertigo, progressive hearing loss, or widely fluctuant hearing. Endolymphatic decompression and shunt placement is not utilized as first-line therapy. Intratympanic gentamicin is offered to patients that decline an endolymphatic sac procedure or are poor surgical candidates. Revision procedures were excluded. There were no bilateral cases. Patients also had to have clinical follow-up of at least 18-months.

Chart review, data collection, and questionnaire mailings were done in compliance with the University Hospitals Cleveland Medical Center Institutional Review Board (IRB #08-12-40). The data inquiry sought to stratify patients’ preoperative and postoperative functional level, hearing stage, and vertigo control class as defined by the 1995 AAO-HNS guideline . Hearing stage is defined by the four-tone average with stage 1 being < 25 dB (dB), stage 2 between 25 and 40 dB, stage 3 between 41 and 70 dB, and stage 4 > 70 dB. Vertigo control class A is complete vertigo control, class B represents a 60% or greater reduction in vertigo attacks, and class C represents a 20 to 59% reduction in attacks. Classes D and E are limited vertigo control and class F indicates additional treatment was required to help with vertigo symptoms. Both classes A and B are considered successful vertigo control. The functional level scale also conformed to the 1995 AAO-HNS guideline ( Appendix 1 ) .

Preoperative data included patient demographics, medical comorbidities, medical management, vertigo frequency, hearing status, and functional level. The worst preoperative audiogram in the 6-months before surgery was used as the audiometric baseline. Pure tone average (PTA) was based on thresholds at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. Speech discrimination score (SDS) were also collected, although these are not factored into the 1995 AAO-HNS hearing stages. Postoperative data included vertigo frequency, functional level, and hearing status based on the most recent audiogram and clinical documentation.

The patient questionnaire assisted clinical documentation for the functional level calculation. The questionnaire responses were also analyzed independently. Patients were asked about their preoperative, postoperative (18–24 months), and long-term (> 24 months) symptoms, specifically tinnitus, aural fullness, subjective hearing, and quality of life ( Appendix 1 ). The symptoms were graded as better, worse, or the same since the surgery. This study and questionnaire design were meant to parallel the methods used by Brinson et al. . Questionnaire data is reported separately. Length of follow-up refers to the last clinical examination.

The senior authors, C.A.M. and M.T.S., performed all surgeries. Operative data was reviewed including technique, confirmation of shunt placement and method of steroid delivery. All procedures involved a mastoidectomy with wide decompression of the posterior fossa plate, incision of the endolymphatic sac, and placement of a T-shaped silastic stent. Patients were stratified into three cohorts based on the method of steroid delivery. This variation reflects the evolution of the senior authors operative technique. The cohorts include: Group A did not receive any local steroid administration; Group B received IT dexamethasone prior to the postauricular incision; Group C received dexamethasone via both IT injection and direct instillation into the endolymphatic sac during silastic shunt placement. The concentration of dexamethasone varied between 4 mg/ml and 10 mg/ml. The amount of steroid administration was difficult to quantify because the mastoid cavity was often filled with the steroid solution and steroid soaked gel-foam were placed around the open endolymphatic sac. Intravenous steroids were not accounted for, but per anesthesia protocol patients received a 10 mg intraoperative dose of intravenous dexamethasone.

Vertigo class control was analyzed using a Chi-square test of independence. Functional level was analyzed with a one-way analysis of variance (ANOVA). A value of p < 0.05 was considered statistically significant. In accordance with 1995 AAO-HNS guideline, hearing results were considered significant if the PTA changed by 10 dB or the SDS changed by 15-percentage points . Confidence intervals (CI), standard deviation (SD), or ranges were reported when relevant. Changes in PTA and SDS were also analyzed using non-parametric tests (Mann-Whitney U) and considered significant if p < 0.05.

2

Methods

This is a retrospective case series of patients surgically treated with endolymphatic sac decompression and shunt placement at University Hospitals Cleveland Medical Center between 2002 and 2013. All patients met criteria for definite or probable MD according to the 1995 American Academy of Otolaryngology — Head and Neck Surgery (AAO-HNS) guideline on MD . Patients with possible MD or cochlear hydrops were excluded from the study. Additional inclusion criteria were adult age (18 years old or greater) and failure of medical management consisting of low-sodium diet, hydration, avoidance of triggers, and a diuretic. Patients were also offered IT steroids for disease exacerbations. Endolymphatic sac procedures were offered only after failure of medical management and with persistent severe vertigo, progressive hearing loss, or widely fluctuant hearing. Endolymphatic decompression and shunt placement is not utilized as first-line therapy. Intratympanic gentamicin is offered to patients that decline an endolymphatic sac procedure or are poor surgical candidates. Revision procedures were excluded. There were no bilateral cases. Patients also had to have clinical follow-up of at least 18-months.

Chart review, data collection, and questionnaire mailings were done in compliance with the University Hospitals Cleveland Medical Center Institutional Review Board (IRB #08-12-40). The data inquiry sought to stratify patients’ preoperative and postoperative functional level, hearing stage, and vertigo control class as defined by the 1995 AAO-HNS guideline . Hearing stage is defined by the four-tone average with stage 1 being < 25 dB (dB), stage 2 between 25 and 40 dB, stage 3 between 41 and 70 dB, and stage 4 > 70 dB. Vertigo control class A is complete vertigo control, class B represents a 60% or greater reduction in vertigo attacks, and class C represents a 20 to 59% reduction in attacks. Classes D and E are limited vertigo control and class F indicates additional treatment was required to help with vertigo symptoms. Both classes A and B are considered successful vertigo control. The functional level scale also conformed to the 1995 AAO-HNS guideline ( Appendix 1 ) .

Preoperative data included patient demographics, medical comorbidities, medical management, vertigo frequency, hearing status, and functional level. The worst preoperative audiogram in the 6-months before surgery was used as the audiometric baseline. Pure tone average (PTA) was based on thresholds at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. Speech discrimination score (SDS) were also collected, although these are not factored into the 1995 AAO-HNS hearing stages. Postoperative data included vertigo frequency, functional level, and hearing status based on the most recent audiogram and clinical documentation.

The patient questionnaire assisted clinical documentation for the functional level calculation. The questionnaire responses were also analyzed independently. Patients were asked about their preoperative, postoperative (18–24 months), and long-term (> 24 months) symptoms, specifically tinnitus, aural fullness, subjective hearing, and quality of life ( Appendix 1 ). The symptoms were graded as better, worse, or the same since the surgery. This study and questionnaire design were meant to parallel the methods used by Brinson et al. . Questionnaire data is reported separately. Length of follow-up refers to the last clinical examination.

The senior authors, C.A.M. and M.T.S., performed all surgeries. Operative data was reviewed including technique, confirmation of shunt placement and method of steroid delivery. All procedures involved a mastoidectomy with wide decompression of the posterior fossa plate, incision of the endolymphatic sac, and placement of a T-shaped silastic stent. Patients were stratified into three cohorts based on the method of steroid delivery. This variation reflects the evolution of the senior authors operative technique. The cohorts include: Group A did not receive any local steroid administration; Group B received IT dexamethasone prior to the postauricular incision; Group C received dexamethasone via both IT injection and direct instillation into the endolymphatic sac during silastic shunt placement. The concentration of dexamethasone varied between 4 mg/ml and 10 mg/ml. The amount of steroid administration was difficult to quantify because the mastoid cavity was often filled with the steroid solution and steroid soaked gel-foam were placed around the open endolymphatic sac. Intravenous steroids were not accounted for, but per anesthesia protocol patients received a 10 mg intraoperative dose of intravenous dexamethasone.

Vertigo class control was analyzed using a Chi-square test of independence. Functional level was analyzed with a one-way analysis of variance (ANOVA). A value of p < 0.05 was considered statistically significant. In accordance with 1995 AAO-HNS guideline, hearing results were considered significant if the PTA changed by 10 dB or the SDS changed by 15-percentage points . Confidence intervals (CI), standard deviation (SD), or ranges were reported when relevant. Changes in PTA and SDS were also analyzed using non-parametric tests (Mann-Whitney U) and considered significant if p < 0.05.