Non-occlusive hydrocephalus after radiosurgery for vestibular schwannomas

Stereotactic radiosurgery has firmly entered the arsenal of methods for treating vestibular schwannomas along with traditional surgical removal, providing high control of tumor growth and a low level of functional complications. Meanwhile, there is evidence of a possible relationship between the irradiation performed and the subsequent development of non-occlusive hydrocephalus. Purpose: to retrospectively assess the current level of development of hydrocephalus after stereotactic radiosurgery for vestibular schwannomas. Materials and methods: of 541 patients who received treatment with the Gamma Knife for unilateral vestibular schwannoma, 456 (84.3%) patients initially had no signs of non-occlusive hydrocephalus (group 1), while in 85 (15.7%) patients, MRI signs of internal non-occlusive hydrocephalus were revealed at the time of radiosurgery (group 2), of whom in 1 case VP shunting had previously been performed. In all cases, non-occlusive hydrocephalus at the time of SRS had a compensated course without clinical manifestations. Results: after radiosurgery, the development of de novo non-occlusive hydrocephalus in 7 (1.5%) patients from group 1 and its progression in 11 (12.9%) patients from group 2 were noted. The overall incidence of non-occlusive hydrocephalus after radiosurgery was 3.3%. Ventriculoperitoneal shunting was required in 3 cases in group 1 and 7 cases in group 2 due to the occurrence of neurological symptoms (1.8%). Conclusion: In some cases, radiosurgery can lead to decompensation of existing non-occlusive hydrocephalus, but it rarely occurs de novo. The asymptomatic course of non-occlusive hydrocephalus allows for SRS, as the risk of decompensation with subsequent need for VP shunting is low. Patients with non-occlusive hydrocephalus before SRS require more careful monitoring with assessment of neurological status and control MRI.