Study designs of evaluations included in the review
Randomised controlled trials, case-control studies, and prospective cohorts or retrospective cohorts reporting on 10 or more patients were eligible for inclusion. Comments, letters, editorials and reviews were excluded.
Specific interventions included in the review
Studies administrating gentamicin into the middle ear by transtympanic injection or by using a specially designed catheter were eligible for inclusion. Interventions with concomitant administration of other drugs, such as dexamethasone, by local, oral or parenteral route were excluded.
The majority of the studies applied a titrated protocol, according to the patient's symptoms, rather than a fixed-dose protocol. The number of injections and dose varied in the included studies (e.g. 1 to 24 injections).
Participants included in the review
Studies with patients diagnosed according to the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology Head and Neck Surgery (1985 or 1995) as having definitive Meniere's disease were eligible for inclusion. Patients with related conditions (i.e. post-traumatic, post infectious, syphilis, Cogan syndrome) were not eligible.
Outcomes assessed in the review
Vertigo control, hearing and word recognition, functionality and disability were considered. Most of the included studies reported the frequency of vertigo and hearing reduction (measured in dB). Some studies reported also on word recognition (expressed as a percentage), functional level and the results of caloric tests.
How were decisions on the relevance of primary studies made?
Two independent otolaryngologists reviewed the retrieved articles. Any disagreements were resolved through discussion or by consulting a third reviewer.