Cystic vestibular schwannoma: surgical outcome

We investigated the proportion of the cystic form of vestibular schwannoma and assessed the results of surgery in this subtype of the condition. The d efinition of cystic vestibular schwannomas was based on the following crite ria: per-operative identification of cystic components; occurrence of the h ypodense/hypointense areas on computed tomography (CT) and/or magnetic reso nance (MR); and histological verification of S-100 protein membrane-like st ructures. In a study of 773 Danish patients with vestibular schwannomas, 44 (5.7 per cent) displayed cystic components. The outcome of surgery on 44 c ystic vestibular schwannoma (mean tumour size 39 mm) was evaluated and comp ared with that for 151 solid grant vestibular schwannoma (mean tumour size 49.8 mm). Per-operatively, we found a substantially higher adherence to dif ferent intracranial structures in the solid giant vestibular schwannoma com pared with the cystic vestibular (95 per cent vs 70 per cent for brainstem, 91 per cent vs 59 per cent for trigeminal nerve, 85 per cent vs 45 per cen t for cranial nerves X and XI, 67 per cent vs 32 per cent for dura). Nevert heless, the preservation of the facial nerve function was much better in pa tients with solid giant vestibular schwannoma compared with those with cyst ic vestibular schwannoma (House-Brackmann facial nerve dysfunction grade 6 (one year post-operative): 27 per cent vs 41 per cent, respectively p<0.04) . We conclude that the cystic components in vestibular schwannoma are assoc iated with a less favourable surgical outcome, probably due to the rapid tu mour growth acid symptoms caused by compression of the posterior fossa stru ctures.