gms | German Medical Science

Objective: Vestibular schwannomas (VS) are classified according to their extension in the cerebello-pontine angle as well as to their intra-and extrameatal expansion. A subgroup of these tumours appears with a cystic component. Our objective is to provide a classification incorporating the cystic nature of the vestibular schwannoma and to evaluate the significance of the postoperative functional integrity thereof.

Methods: Two-hundred patients who underwent vestibular schwannoma resection in the period of 2008 to 2010 were included in this study. The tumours were graded according to their cystic content: 0-type tumours that are solid; type-1 tumours with microcysts, type-2 tumours having a cystic portion up to 50% of the total volume; type-3 tumours having a cystic portion more than 50% of the total volume. The morphologic evaluation was based on the preoperative diagnostic MRI. The functional analysis was based on the preoperative and postoperative audiograms as well as on the collected clinical evaluation of facial nerve using the House-Brackmann Score pre-, postoperatively and during the follow-up.

Results: 118 VS (59%) had cystic components, whereas 65 of them corresponded to type 1, 45 to type 2, and 9 to the type 3. According to the Hannover classification seven cases of VS were assigned as T1, 13 as T2, while T3- and T4- were 34 and 64 patients, respectively. Hearing preservation rates were significantly lower in cystic VS regardless of size (20% vs. 52%). Applying the new cystic classification to the facial nerve function the HB-scale was initially worse in cystic VS compared to solid VS, after 3–6 month regeneration the facial nerve function of the two groups (solid vs. cystic) were comparable.

Conclusions: The study demonstrates that not only the tumour size but also the cystic component is an important predictor of post-operative functional integrity of cochlear and facial nerve.