Efficacy and Safety of Intratympanic Botulinum Toxin Injection on Middle Ear Myoclonic Tinnitus

Abstract

Objectives: Investigating the efficacy and safety of intratympanic Botulinum toxin (IT-BTX) injection as a novel treatment for middle ear myoclonic tinnitus (MEMT).

Methods: Medical records and tinnitus questionnaires of the patients with MEMT who underwent IT-BTX were retrospectively reviewed. The efficacy of IT-BTX on MEMT as well as its safety were evaluated by audiology tests and tinnitus questionnaires.

Results: A total of 57 patients who completed the questionnaires at pre- and post-IT-BTX were enrolled. Tinnitus handicap inventory (THI) scores decreased significantly from pre-IT-BTX (44.31 ± 26.8) to 31.42 ± 23.6 (p < 0.001), 32.92 ± 24.9 (p = 0.004), and 25.71 ± 22.9 (p < 0.001) at 1-, 3-, and 6-months post-IT-BTX, respectively. Additionally, visual analog scales (VAS) of loudness (LD), awareness (AW), annoyance (AN), and effect on life (EF) significantly decreased post-IT-BTX (p < 0.05): LD from 4.19 ± 2.4 to 2.47 ± 2.0, 2.89 ± 2.2, and 2.38 ± 1.9 at 1-, 3-, and 6-months; AW from 41.75 ± 29.5 to 24.38 ± 23.3, 26.94 ± 23.3, and 22.10 ± 21.7; AN from 5.00 ± 2.8 to 2.82 ± 2.1, 3.47 ± 2.4, and 2.78 ± 2.2; EF from 4.82 ± 2.8 to 2.89 ± 2.2, 3.28 ± 2.4, and 2.73 ± 2.2 at 1-, 3-, and 6-months post-IT-BTX. Notably, 40.3% of the IT-BTX patients experienced a complete cure of their MEMT symptoms, while 50.8% demonstrated partial resolution after IT-BTX. There were no side effects or complications after IT-BTX during their follow-up period. Comparing delta values between the single injection group and multiple injection group revealed significant differences in VAS LD at the post-1-month time point and between the 1-month and 6-month intervals.

Conclusion: IT-BTX is an effective, safe treatment for MEMT, significantly improving symptoms without complications, and offers a promising alternative before middle ear tendon resection.

Keywords: botulinum toxin; intratympanic injection; middle ear myoclonic tinnitus.

FIGURE 1

Method of procedure and mechanism of botulinum toxin effect. (A) Position of injection. (B) Injection site. (C) Illustration of intratympanic botulinum toxin injection and the mechanism of botulinum toxin at the neuromuscular junction.

FIGURE 2

Outcomes of IT‐BTX injection. (A) Comprehensive outcome of all patients. (B) Significant decreased results after injection of all patients. (C) Outcomes of the single injection group. (D) Outcomes of the multiple injection. AN, annoyance; AW, awareness; EF, effect on life; IT‐BTX, intratympanic botulinum toxin; LD, loudness; THI, tinnitus handicap inventory; VAS, visual analog scale. Error bars represent 95% confidence intervals.

FIGURE 3

Audiologic tests between pre‐ and at any point of post‐IT‐BTX injection. (A) Result of all patients. (B) Result of the single injection group. (C) Result of the multiple injection group. ABG, air‐bone gap; AC, air conduction; BC, bone conduction; IT‐BTX, intratympanic botulinum toxin; PTA, pure tone audiometry; SDS, speech discrimination score. Error bars represent 95% confidence intervals.