Cystic vestibular schwannoma--clinical and experimental studies.

The cystic variant of vestibular schwannoma (VS) presents a therapeutic dilemma. Several studies have previously demonstrated that the surgical outcome in this tumour entity is less favourable than that of solid tumours of comparable size. The "wait and scan" policy has not been recommended for these tumours, as the cystic elements expand, causing displacement of the brainstem and compression of the 4th ventricle, resulting in hydrocephalus. The large tumour size at diagnosis and the cystic contents do not support the role of radiosurgery as a therapeutic option. We have previously published the surgical outcome of 23 cystic VS. The present study includes 44 patients (44 cystic tumours) in a series of 773 tumours (5.7%) who underwent surgery in the period 1976 to 1996. This paper presents the neuroradiological and histological features of the tumours, as well as the results of tumour specimen implantation and surgery in athymic nude mice. Therapeutic options are also discussed.