Fluid-fluid levels in intracranial schwannomas.

Intracranial cystic neurogenic tumours constitute an uncommon subset of tumours with a distinct clinico-biological behaviour. The presence of fluid-fluid levels within the tumours, although rare, confirms the cystic nature of the neoplasms. Barring the acoustic schwannomas, cystic cranial nerve schwannomas are exceptionally uncommon. Imaging findings of fluid-fluid levels in two non-acoustic cranial nerve schwannomas are described; one was a cystic trigeminal schwannoma and the other was a glossopharyngeal nerve schwannoma. The causes of the fluid-fluid level and its implications are analysed.