Frameless, Real-Time, Surface Image-Guided Radiosurgery (SIG-RS): Short-Term Safety Profile in the Management of Benign Skull Base Lesions

Background: Stereotactic radiosurgery (SRS) is a therapeutic option for the treatment of surgically challenging benign skull base lesions. The development of the technology for SRS delivery has progressed from rigid fixation with head frames to frameless stereotaxy using custom-fitted masks and bite blocks. We have developed a technology that obviates the need for bite blocks by using infrared cameras to monitor the movement of facial features in SRS. Here we report the safety of this technology in the treatment of benign skull base lesions.

Objective: To provide a safety profile for real-time, frameless, surface image-guided radiosurgery (SIG-RS) in the immediate post-treatment period in benign skull base lesions.

Methods: Twenty-two patients underwent SIG-RS for skull base lesions at our institution; 13 meningiomas, 7 schwannomas, and 2 pituitary adenomas. Charts were retrospectively reviewed. SIG-RS was administered with a median fraction of 3 (1-5) and a mean dose of 19.86 Gy (range, 12-25 Gy). Mean follow-up was 5.2 months (range, 0-24 months). Initial post-radiosurgery MRI was available in 11 patients at a mean time of 5.3 months (range, 2-8 months). We evaluated for immediate side effects, neurologic complications, and acute changes on MR FLAIR sequences.

Results: None of the patients available for follow-up suffered permanent neurologic deficits or MR FLAIR sequence changes post-treatment. One patient (vestibular schwannoma) experienced severe headache within a week of SIG-RS and resolved spontaneously. Another patient (pituitary adenoma) suffered diplopia that resolved with a 1-week course of steroid therapy. No recurrence was noted within the follow-up period.

Conclusions: SIG-RS is a safe alternative in the treatment of benign skull base lesions. However, longer follow-up is needed to evaluate its efficacy as a treatment for benign skull lesions.