Early and late facial neuropathy after radiosurgery of vestibulocochlear schwannomas

Abstract

Stereotactic radiosurgery (SRS) is the method of choice for the treatment of vestibular schwannomas, due to its high frequency of tumor growth control and low complication rate. According to the world scientific literature, one of the rare late radiation induced complications is facial nerve paralysis. It is extremely rare to find reports of cases of prosoparesis that occurred during the first week after performing SRS. The potential etiology, pathogenesis, and management of this type of complication still remain a subject for discussion. As potential risk factors for the development of radiation-induced complications for cranial nerves, such indicators as the patient's age, the maximum diameter of the tumor, the presence of a fundal fluid cap, the amount of prescribed, average and maximum radiation dose per cochlea, the extent of the tumor's contact with the nerve trunk, or the radiation dose beyond the boundaries of the tumor are currently being studied. However, further study of predictors of the post-radiation neuropathy requires cohort studies. The article presents two cases of early and late radiation-induced neuropathy of the facial nerve after radiosurgery of vestibular schwannomas. Predictors and risk factors for the development of this type of complications after SRS are discussed. The important role of steroid therapy in the complex treatment of this group of patients was noted. In the presented patients, no reliable pathogenetic mechanisms leading to early radiation damage to the facial nerve were revealed. Despite the restoration or improvement of the strength of facial muscles, complications of facial neuropathy (hypertension, synkinesia) developed, which required timely detection and correction with the mandatory supervision of a neurologist.