Low-Dose Intratympanic Gentamicin Injections for Intractable Meniere's Disease: How Many Are Optimal?

Background/Objectives: To compare the outcomes of low-dose intratympanic gentamicin injection (ITGM) in managing intractable Meniere's disease (MD) between patients receiving a single injection versus multiple injections, and to explore the optimal number of ITGM repetitions. Methods: This retrospective study was conducted at a single tertiary medical center. Clinical charts of patients diagnosed with definite MD between 2015 and 2020 and given low-dose ITGM for intractable vertigo attacks were reviewed. A total of 33 patients were divided into two groups based on the number of ITGM procedures: the single injection group (SG, n = 14) and the multiple injection group (MG, n = 19). In the MG, additional ITGM was performed up to four times. Audiograms, caloric responses, and video head impulse tests (vHIT) were reviewed at each repetition of ITGM. Results: After the first ITGM, both the SG and MG showed significant decreases in caloric responses and vHIT gains, without deterioration in hearing. In the MG group, a second ITGM was needed on average 8.1 ± 6.4 months after the initial ITGM due to persistent vertigo attacks. After the second ITGM, 8 out of 19 MG patients showed additional benefits in terms of reduced vertigo and further decreases in caloric responses. However, after the third and fourth ITGM, no further significant decline in vestibular function was observed, and there was no improvement in subjective dizziness. In the MG, gradual deterioration of hearing was observed. Conclusions: This finding suggests that performing additional low-dose ITGM in poorly responding or recurrent cases appears reasonable up to the second injection. For those who continue to experience vertigo episodes after two ITGM procedures, alternative therapeutic approaches should be considered to preserve hearing.