# Tinnitus: an underreported condition following microvascular decompression for hemifacial spasm

## TL;DR

Tinnitus is a common but underreported side effect after surgery for hemifacial spasm, with moderate severity and possible links to preoperative tinnitus.

## Contribution

This study is the first to systematically assess tinnitus prevalence and predictors after microvascular decompression for hemifacial spasm.

## Key findings

- Tinnitus occurred in 36% of patients post-surgery, often on the surgical side.
- Preoperative tinnitus was the strongest predictor of postoperative tinnitus.
- New tinnitus typically appeared within days to a year after surgery.

## Abstract

While hearing loss is a well-known condition following microvascular decompression (MVD) for hemifacial spasm (HFS), tinnitus is an underreported one. This study aims to identify prevalence, characteristics, severity, and predictors of tinnitus following MVD for HFS.

A single-center cohort of 55 HFS patients completed a questionnaire approximately 5 years following MVD. Data encompassed tinnitus presence, side, type, onset, and severity measured by a 10-point Visual Analogue Scale (VAS). Descriptive, correlation, and logistic regression analyses were conducted.

At surgery, participants’ median age was 58 years (IQR 52–65). The median duration of HFS symptoms before surgery was 5 years (IQR 3–8), slightly predominant on the left (60%). Postoperative tinnitus was reported by 20 patients (36%), versus nine (16%) that reported preoperative tinnitus. Postoperative tinnitus was ipsilateral on the surgical side in 13 patients (65%), bilateral in six (30%), and contralateral in one (5%). Among patients with bilateral postoperative tinnitus, 33% did not have this preoperatively. Tinnitus was continuous in 70% of cases and pulsatile in 30%. Onset of new tinnitus was in 58% immediately or within days, in 25% within three months, and in 17% between three months and one year after surgery. The mean severity of postoperative tinnitus was 5.1 points on the VAS. Preoperative tinnitus and presence of arachnoid adhesions had suggestive associations with postoperative tinnitus in initial analyses (p = 0.005 and p = 0.065). However, preoperative tinnitus was the only significant predictor of postoperative tinnitus (p = 0.011).

Tinnitus is a common condition following MVD for HFS, with a moderate overall severity. Causes behind postoperative tinnitus remain obscure but could be related to those of postoperative hearing loss in this patient population. Clinicians should be aware of tinnitus following MVD and vigilantly monitor its occurrence, to facilitate prevention efforts and optimize outcome for HFS patients undergoing MVD.