Introduction: Recently, CyberKnife (CK) Radiosurgery (CKRS) has been used in the treatment of skull base meningiomas as both adjuvant and primary therapy. Even though tumor control in this region has been quite successful; as with any kind of procedure in this critical area, there are still possibilities of procedure related cranial nerve (CN) deficits. Therefore, we reviewed our experience with CK in the treatment of skull base meningiomas and the development of new onset CN deficits following CKRS.
Methods: 40 patients who underwent CKRS for diagnosed skull base meningiomas were retrospectively reviewed. Data was collected on patient’s clinical, radiological and CKRS outcome. New onset CN deficit was determined by thorough neurological exam and patient history. CN irradiation secondary to treatment was assessed through review of treatment planning data and images. Mean length of follow-up was 29 months.
Results: 39 patients were symptomatic with numerous neurological deficits prior to CK. The presenting symptoms improved in 14, remained stable in 21, and worsened in 4 cases after CK. 9 (22.5%) patients developed new CN deficits post-CKRS: trigeminal neuropathy (n=4), optic neuropathy (n=4), and vestibulocochlear neuropathy (n=1)). The CN involved with new onset symptoms had been irradiated with a median maximal dose of 25Gy (range, 15.26-33.20Gy), delivered over a median of 5 fractions (range, 3-5) and an Isodose line ranging from 44-86%. The new CN deficits were not attributable to tumor recurrence or progression, as tumor size in each case was the same or had decreased compared to pre-CKRS imaging.
Conclusions: CK is an effective treatment for complex skull base meningiomas. However, there still seems to be quite a considerable amount of treatment related morbidity, where new onset CN deficits are concerned.
Patient Care: It will increase physician and patient’s awareness of the potential development of new onset neurological deficits after CK treatment for complex skull base meningiomas.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance and benefits of CK radiosurgery treatment for complex skull base meningiomas. Understand the treatment related morbidities, specifically new onset CN deficits that may present following CK radiosurgery. 2) Identify effective CK treatment planning options to minimize CN injury and promote safer outcomes.