Single center clinical experience with Cyberknife radiosurgery for skull base meningiomas
Objectives and Purposes
The aim of this retrospective study is to evaluate the efficacy in local control and tolerance of radiosurgery (single RS or hypofractionated HRS doses) for the treatment of skull base meningiomas
Material and methods
We analysed the treatment of 30 patients diagnosed with skull base meningiomas treated with CyberKnife Radiosurgery between March 2020 and February 2024.
Planning was performed using CT-plan with termoplastic inmobilization mask registered with brain nuclear magnetic resonance using T1-weighted MRI with contrast and fat saturation (useful in skull base tumors, orbital lesions, or surgical beds) and high-resolution T2-weighted MRI (useful in cisternal segments of cranial nerves, cavernous sinuses or Meckel’s cave). All contours are reviewed by a dedicated neuroradiologist.
In resected or unresected grade 1 meningiomas, the GTV = PTV. In grade 2 meningiomas, a margin of 1-5 mm was applied, according to international contouring guidelines.
Results
Out of 30 patients, 22 women and 8 men. Mean age 62 years old (39-87). Most common locations were: pontocerebellar angle (14p), cavernous sinus (6p), optic nerve (4p) and others (6p). 13 patients had undergone previous surgery.
83% (25p) received a total dose of 25-30Gy in 5 fractions, 17% (5p) single fraction (14-18Gy). Mean lesion volume 10cc .For the 5 fractions scheme: mean maximum dose (Dmax) in PTV was 46.04 Gy,, mean Dmax in visual pathway 30.67Gy, pituitary 36.69Gy and brainstem 30.50Gy. For 1 fraction scheme: mean Dmax in PTV was 20.96 Gy, mean Dmax in visual pathway 7.46Gy, pituitary 7.97 Gy and brainstem 9.84 Gy.Mean conformation index of 1.3.With a median follow-up of 24 months (3-59) for 26 p who underwent the first control RMI, 100% patients achieved radiological stability. Acute toxicity was reported in 46% of patients presenting minor grade 2 toxicity, most frequently mild transient headache and asthenia. Chronic toxicity was evaluated for 26p, 26% presented minor grade 2 headache (6), neurological deterioration (1) and tinnitus (1). No cases of stroke or cranial nerve palsy were reported. Radiologic radionecrosis occurred in 1 asymptomatic patient.
Conclusions
Our clinical experience using Cyberknife RS or HRS for skull-base meningiomas shows that these schemes are safe, effective, and helpfull for patients who are rarely candidates for complete resection.
