Tinnitus after treatment of vestibular schwannoma: a systematic review and comparative analysis of microsurgery and stereotactic radiosurgery.

[PURPOSE] The purpose of this systematic review and meta-analysis was to compare tinnitus outcomes following microsurgery and stereotactic radiosurgery for vestibular schwannoma.

[METHODS] The databases MEDLINE (via Ovid), EMBASE (via Ovid), Cochrane Central Register of Controlled Trials (via Ovid), SCOPUS, CINAHL (EBSCO), and Web of Science were searched for studies comparing microsurgery and radiosurgery treatment, and reporting tinnitus outcomes. Longitudinal tinnitus assessment with pre-treatment evaluation was required for inclusion. Fractionated radiotherapy treatment was excluded. Newcastle-Ottawa scale was used to assess the quality of the included studies. A separate random-effects meta-analysis was performed for the continuous, binary and ordinal tinnitus outcomes, with pooled effects described as a standardised mean difference or a log odds ratio as appropriate.

[RESULTS] Thirteen studies involving 5814 patients were included in the review; 4 were prospective studies, and the rest were retrospective cohort studies. The median follow-up duration in the microsurgery and radiosurgery groups was 39.5 months and 41.1 months, respectively. Studies were diverse with respect to inclusion criteria and method of tinnitus outcome assessment. Only 4 studies reported tinnitus scores using tinnitus questionnaires, while others used Likert scale, visual analogue scale, binary (present or absent) scale or ordinal (improved, same or worse) scale. Four studies reported better tinnitus outcomes after microsurgery than radiosurgery. However, the overall quality of the studies was low, and most did not control for important confounders, such as age, tumour characteristics, and hearing impairment. Meta-analysis of continuous and binary tinnitus outcomes showed no difference between the interventions (standardised mean difference = -0.04, 95% CI -0.37 to 0.28, p = 0.80; log odds ratio = 0.32, 95% CI -1.11 to 1.74, p = 0.66). Meta-analysis of tinnitus outcomes on an ordinal scale showed microsurgery increased the odds of reporting improved tinnitus compared to radiosurgery (log odds ratio = 0.83, 95% CI 0.01 to 1.64, p = 0.045). Heterogeneity between the studies was high for all outcome measures (I > 56%).

[CONCLUSION] Meta-analyses of tinnitus outcomes were largely inconclusive, except when tinnitus was reported as an ordinal outcome, which favoured microsurgery. However, due to the low quality of studies and high heterogeneity, no definitive conclusions could be drawn favouring either treatment.