Cerebellopontine Angle Schwannomas: Surgery, Hypofractionated Stereotactic Radiotherapy, Combined Therapy. Strategy for Harmless Therapy

Objective: The pontocerebellar angle schwannomas represent a neurosurgical challenge because after radical removal important neurological deficits can result.

Design: To evaluate the best therapy concerning control of tumoral evolution and functional outcome.

Methods: A series of 13 vestibular schwannomas and 3 Gasserian ganglion schwannomas is presented. According to the size, three were defined as small (maximum extrameatal diameter 2 cm), eight tumors were classified as large (diameter 2.5 to 4 cm), and the last five tumors were defined as giant (diameter 4.5 to 6 cm). Thirteen patients underwent the retrosigmoid microsurgical approach, followed by hypofractionated stereotactic radiotherapy (HSRT) in 11 of the patients. Intraoperative brainstem-evoked potentials and monitoring of facial nerve were done. Two other tumors were submitted to HSRT alone. The last one was submitted to seriated controls.

Results: Gross total removal (postoperative tumor remnant less than 1 cm of maximum diameter) was achieved in 10 patients; subtotal removal (postoperative remnant 1 to 2 cm) was performed in the other three patients. After surgery, worsening of a preoperative facial nerve paresis occurred in one patient operated on (gross total removal) for a giant tumor. After HSRT alone, temporary paucisymptomatic hydrocephalus occurred in one patient, treated by low-dose betamethasone and diuretics. Hearing function was preserved in all patients.

Conclusions: Our results showed that for symptomatic schwannomas, gross total removal followed by HSRT is a valid therapeutic strategy, allowing improved symptoms and avoiding tumor recurrence with very a low rate of neurological deficit.