Cystic versus solid vestibular schwannomas: a series of 80 grade III-IV patients

Cystic acoustic neuromas are less frequent than solid ones and present different clinical and radiological features. Cystic schwannomas are larger, show a shorter clinical history and a different risk of postoperative complications. This study was designed to compare surgical results and complications of solid and cystic vestibular schwannomas of matching size operated upon via either a retrosygmoid or a translabyrinthine approach. The study included 80 patients presenting with grade III and IV acoustic vestibular schwannomas referred to the Neurosurgical and ENT team in the Department of Neuroscience of Torino, Italy. Twenty-six were cystic and 54 were solid tumours. Clinical history, surgical results and complications were compared between the two groups. In cystic tumors, rapid clinical worsening is common, due to sudden expansion of cystic elements. Tighter adherences are found between cystic tumours and nervous elements (particularly brainstem and possibly facial nerve), once compared to solid ones. Operative morbidity appears to be higher in cystic tumours. A wait and see policy should not to be applied to patients with cystic tumours. Careful technique, possibly sharp dissection, to divide the tumour adherences from the nervous tissue must be employed, in order to avoid lesions on brainstem veins and traction on a thin facial nerve. Severe complications may be caused by the excessive efforts to dissect brainstem adherences.