Gamma Knife Radiosurgery for residual and recurrent vestibular schwannomas after previous surgery: clinical results in a series of 90 patients and review of the literature

Abstract Object Complete vestibular schwannomas (VS) removal is not always achievable without any risk of disabling postoperative complications, especially in terms of facial nerve function. Moreover, even after gross total removal a relevant rate of recurrence has been reported. The aim of this study is to validate Gamma Knife radiosurgery (GKRS) as an effective strategy to treat tumor’s regrowth after previous surgery. Methods Ninety patients treated with GKRS for VS after previous microsurgery were included in the present study. GKRS was performed at a median of 31 months (range 4-174 months) postoperatively. Mean tumor volume was 3.35 cm3 (median 2.5 cm3 , range 0.027-13 cm3 ) and median marginal dose was 13 Gy. Results At a mean follow-up of 77.2 months, tumor control was achieved in 90% of patients: 2 patients underwent repeated GKRS, while 7 patients underwent further microsurgery. Tumor shrinkage at last FU was recorded in 80.3% of cases. Complications rate was very low; many of them consisted in a transient worsening of pre-existing symptoms. The overall incidence of persisting facial nerve deficit and trigeminal nerve impairment was, in both cases, 3.3%. Two out of 5 patients (40%) preserved functional hearing at last follow-up. One patient (1.1%) underwent ventriculoperitoneal shunting 12 months after GKRS. Conclusions GKRS is a safe and effective treatment for growing residual and recurrent VSs, with a tumor control obtained in 90% of cases and a very low morbidity rate. Moreover, the possibility of treating patients with major medical comorbidities constitute a significant advantage over repeated surgery.