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tone thresholds. We compared changes in hearing threshold and frequency of vertigo after ITG.

American Academy of Otolaryngology–Head and Neck Surgery (AAO–HNS). Eighty-nine patients of definite MD group and seventeen patients of secondary EH group received additional interven- tions such as ITG, endolymphatic sac decompression (ELSD), and application of the Meniett device after the failure of medi- cal treatment. They were followed up for at least 2 years (range: 2.1–7.5 years), and their treatment flow and outcomes were analyzed. A total of 21 patients were excluded from analysis due to the inadequate follow up or data collection. This study was approved by the Seoul National University Bundang Hospi- tal Institutional Review Board (B-1310/222-102). Selection of the Treatment Options For intractable patients, next treatment options were dis- cussed with patients and considered mainly depending on the patient’s hearing status. ELSD was suggested if the patient’s pure tone average was better than 40 dB by averaging the 0.5, 1, 2, and 3 kHz; and ITG was recommended if it was not. In some patients, ITG was not feasible due to chronic otitis media, and gentamicin was applied around the round window and oval window after removing of thickened mucosa during a tympano- mastoidectomy. ITG was basically considered for the patients whose vertigo was not controlled by medical treatment for more than 3 to 6 months and had worse than 40 dB hearing thresh- olds. However, ITG was also performed for some patients under serious risk of head trauma due to recurrent Tumarkin crises, although they had better than 40 dB hearing level. Gentamicin was administered as described below. Patients were lying down in supine position with the head elevated up to 30 degrees and turned to the other side at 45 degrees. The ear canal and tympanic membrane were anesthetized, and two holes were made with a 26-G needle at anterosuperior area of tympanic membrane. About 0.3 to 0.5 mL of gentamicin solu- tion (gentamicin sulfate, 40 mg/mL) was administered into the middle ear cavity. Patients were advised to remain in the same position at least 20 minutes and to avoid swallowing or yawning. Characteristics of dizziness were asked, and an office exam was conducted to evaluate vestibular status at 2 weeks and 4 weeks after injection to determine the efficacy of the pre- vious administration. If typical paralytic nystagmus to the con- tralateral side (spontaneous nystagmus, post-head shaking nystagmus, vibration-induced nystagmus) or laboratory evi- dence of attenuation (or ablation) of remaining vestibular func- tion on a caloric test was evident, the injection was thought to be successful and no additional administration was considered. However, if the patients experienced episodic vertigo spells instead of crescendo–decrescendo type persistent dizziness or there was no evidence of attenuation of vestibular function, injections were repeated until signs of ipsilateral vestibular hypofunction were more evident. Analysis of Changes in Hearing and Vertigo All hearing and vertigo data were analyzed according to the 1995 AAO–HNS guideline. 15 Vertigo was assessed as the average number of definite spells per month for the 6 month periods prior to ITG and compared with that assessed between 18 to 24 months after ITG. Hearing level was assessed at the same time periods by averaging the 0.5, 1, 2, and 3 kHz pure Protocols for the Intratympanic Injection of Gentamicin

Analysis of Problems After ITG For the patients who were refractory even after ITG, exploratory tympanotomy and gentamicin application (ETG), labyrinthectomy, and vestibular neurectomy were then consid- ered. Among them, ETG was primarily considered the next step to rule out any anatomical problem that might obscure the pas- sage of gentamicin into the inner ear for those whose vestibular function was not ablated sufficiently by ITG. We applied ETG when the patients showed no improvement after three or four attempts of ITG. That was determined on the basis of our find- ings that most cases with successful improvement of vertigo improved after only two (75%) or three (86%) rounds of ITG and that the chance of failed control of vertigo increased with multi- ple injections (odds ratio 5 11.8; P 5 0.005, Fischer’s exact test). Failure due to insufficient attenuation of vestibular function or recurrent dangerous event, such as Tumarkin crises even after ITG, was also considered. Labyrinthectomy and vestibular neu- rectomy were considered if symptoms had not improved even after ETG. We analyzed the outcomes of the treatment options used and their problems. Long-term time course of hearing loss were analyzed to clarify the cause of hearing aggravation after ITG. Bilateral progression of MD after ITG and its problems were analyzed. The average age of the total 95 patients was 58 years old (range: 28–75 years old; definite MD group: 57.5 years old, secondary EH group: 60.1 years old); there were 38 male patients (48.7%) in the definite MD group and eight male patients (47.0%) in the secondary EH group. The patients experienced 7.1 vertigo attacks in a month for the definite MD group and 5.4 vertigo attacks in a month for the secondary EH group when averaged for 6 months prior to ITG. Vestibular function on bithermal caloric test before injection was decreased in 14 patients (82.4%) of the secondary EH group and in 53 patients (67.9%) of the definite MD group ( P 5 0.38, Fischer’s exact test). Tumarkin attacks were present in five cases (29.4%) of the secondary EH group and in 15 patients (19.2%) of the definite MD group ( P 5 0.34, Fischer’s exact test). Overall Treatment Flow Of the 667 patients with definite MD, 578 (86.7%) patients showed improvements with lifestyle modifica- tion or medical treatment. Additional interventions such as ITG, ELSD, and application of the Meniett device were performed in 89 (13.3%) patients due to intractable vertigo, and ITG (78 patients, 87.6%) occupied the majority among them (Fig. 1). The patients group who received ITG included four patients whose vertigo attack was not controlled, even after ELSD treatment. ELSD achieved 45.5% (5 of 11 patients) of class A and B vertigo control and showed 9.1% (1 of 11 patients) of more than 10 dB hearing loss after surgery. Although treatments RESULTS Patients’ Characteristics and Applied Treatment Options

Laryngoscope 125: April 2015

Rah et al.: Intractable Menie` re’s Disease

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