Study designs of evaluations included in the review
Studies of any design appeared to be eligible for inclusion. Other criteria were applied according to the therapeutic option: for conservative management with radiologic follow-up, studies had to have included a minimum of 20 patients and followed up participants for a mean period of at least 2 years; trials of GK radiosurgery and trials of microsurgery had to have included at least 100 patients. The mean follow-up periods were 3.1 years and 3.8 years for conservative management and GK radiosurgery, respectively; it ranged from 0.25 to 17 years for microsurgery.
Specific interventions included in the review
Studies of GK radiosurgery, microsurgery, and conservative management with radiologic follow-up were eligible for the review. The included studies of conservative management employed magnetic resonance imaging and/or computed tomography for radiologic follow-up. The included studies of GK radiosurgery used maximum doses of 15 to 53 Gy and marginal doses of 9 to 20 Gy.
Participants included in the review
Studies of patients with sporadic unilateral acoustic neurinomas were eligible for the review. Studies that contained none or only a limited number of neurofibromatosis 2(NF2) diagnoses were not excluded. Studies of conservative management in participants with recurrent or previously treated tumours were excluded. Specifically for the review of microsurgery, trials had to have a definition of the patient population.
The mean age of the patients in the included studies ranged from 46 to 75 years (overall range: 10 to 94). The size of tumour at presentation was expressed differently for the three therapeutic options: in studies of conservative management with radiologic follow-up the mean size ranged from 4.9 to 16 mm; in studies of GK radiosurgery the mean tumour volume, where measured, was 2.7 mL; and in studies of microsurgery the proportion of patients with large tumours ranged from 0 to 42%. Other therapy-specific demographic details were tabulated in the review. Trials of microsurgery were excluded if their populations were exclusively of patients with tumours larger than 3 cm.
Outcomes assessed in the review
Outcomes were not specified as inclusion criteria for the review. The outcomes reported from the included studies were: change in tumour size; the proportion of patients who required intervention (after study intervention); tumour growth rate; patients who underwent microsurgery after GK radiosurgery; hearing preservation rate (Gardner-Robertson or equivalent scale); tumour recurrence; facial function (House-Black scale); and complications (facial palsy, trigeminal neuropathy, hydrocephalus, mortality, major disability, cerebrospinal fluid leak).
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.