Object: Surgery is the first choice treatment for large (Koos IV) vestibular schwannomas. Postoperative facial and acoustic deficits are essentially due to the removal of the medial tumor capsule. Subtotal tumor removal may decrease these risks and tumor remnants may remain stable or shrink over time, or may be later treated by radiation. In this study, we describe the natural history of residual vestibular schwannoma and the clinical results after intended subtotal resection.
Methods: In the first step, we retrospectively evaluated all patients operated at our former institution for a vestibular schwannoma Koos grade IV between June 2009 and December September. Tumor volume was followed. Tumor recurrence was defined as a volume increase by >25% compared to baseline. Tumor regression was defined as a volume decrease by >0% and the others were considered as progression. Facial Function was defined as follows: “Good” (House- Brackmann 1-2), “Fair” (HB 3) and “Poor” (HB 4-6)
Results: thirthy –eight cases with ages between 20 and 86 years old (mean 58 yoa) were included in the study. The mean preoperative tumor volume was 12,79 cm3. The mean
volume of postoperative tumor remnant was 1,430 cm3. At last follow-up (mean 753,9 days after surgery) the mean tumor volume was 1,09 cm3. At the last follow-up (n=38), 3 cases (8%) showed tumor progression, twenty-two (58%) were stable and three (8%) with recurrence. Progression and recurrence were correlated with higher preoperative tumor volume, but not with postoperative residual volume (p=0,0004) and rate (p=0,0001)
For what concerns Facial Nerve: on preoperative thirty-seven patients had Good function and only one “Fair”. On the 1st follow up we found thirty cases of “Good” function, two of “Fair” and 6 with “Poor”. At last follow-up, only two patients had “Poor” function and three “Fair”. No statistical correlation was founded between residual volume and facial function (p=0,04) and residual rate and facial function neither (p<0,0001)
Conclusion: No statistical association was found between residual volume/rate and recurrence rate and with facial outcome neither. Intended subtotal removal leading to less postoperative deficits and recurrence rate, may therefore be a good treatment strategy as compared to radical resection