Comparative study of microsurgery and Gamma-knife surgery in patients with vestibular schwannoma

Vestibular schwannomas (VSs) are benign neoplasms of Schwann cell origin. Although benign in nature, the treatment of vestibular schwannoma remains a challenge for modern neurosurgery. Patients with vestibular schwannomas have several management options including observation, surgical resection, stereotactic radiosurgery, fractionated radiation therapy, or combinations of these. We study two patient groups that have been treated using either Gamma-Knife radiosurery or microneurosurgery. We analyze the criteria for primary referral to one of the therapeutic procedures and look at their results in terms of tumor control and facial nerve function preservation. The surgical group consisted mostly of patients with tumors equal or bigger than 3 cm (70%) out of which 75% showed imagistic or clinical signs of brainstem compression. The radiosurgery group consisted exclusively of tumors smaller than 3 cm. Facial nerve function preservation results were unsatisfactory in the surgical group but were good for the patients referred to radiosurgery. Our results show that tumor size is a major factor in facial nerve function preservation. However for large tumors surgery is the only therapeutic method possible. For those patients with smaller tumors and very good preoperative neurological function radiosurgery should be the therapy of choice, keeping in mind that in 12% of the cases in our series there has been an enlargement in tumor volume that could raise the indication for microneurosurgery.