Conservative management of vestibular schwannomas of 15 to 31 mm intracranial diameter.

Objective: To study the natural course of vestibular schwannomas 15 to 31 mm in diameter.

Methods: A retrospective study of 45 patients conservatively managed with interval scanning was performed. Outcome measures were: changes in tumour size, clinical features and hearing. A tumour was considered to be growing if it increased in size by more than 2 mm.

Results: Initial tumour sizes ranged from 15 to 31 mm, with a mean (± standard deviation) diameter of 20.1 ± 4.3 mm. The duration of follow up ranged from 6 months to 14 years (median, 3 years). Tumours grew in 11 cases (24.4 per cent), remained stable in 30 cases (66.7 per cent) and regressed in 4 cases (8.9 per cent). The overall mean tumour growth rate was 0.9 ± 2.2 mm per year; in growing tumours, it was 3.6 ± 2.9 mm per year.

Conclusion: Outcomes were similar to those reported for smaller tumours. These findings suggest that patients with medium or moderately large tumours can be safely offered an initial period of conservative management before intervention is considered.