Gamma Knife Radiosurgery for Patients with Petroclival Meningiomas: Cohort Study

Background: Standard management strategies for petroclival meningiomas (PCM) include observation, resection, stereotactic radiosurgery (SRS) or radiotherapy, with consideration for each depending on different factors. SRS has proven to be an attractive, safe, and effective strategy for appropriately selected patients. Given the relative rarity of these lesions, long-term clinical outcomes data after SRS are limited. This study aims to retrospectively review our experience in this field.

Methods: Cohort study of all PCM (meningiomas originating from the dura of the petroclival junction in the upper 2/3 of the clivus and medial to the trigeminal nerve) treated with up-front Gamma Knife radiosurgery (GKR) at our institution by the senior author during the study period, 2006–2022. Patients with any previous treatment or without 6 months of post-GKR imaging follow-up were excluded. Data abstraction included demographics, clinical presentation, treatment history, dosimetry and volumetric analysis (pre- and posttreatment). The primary outcome was treatment failure (defined as radiographic progression after SRS based on post-SRS MRI), the secondary outcome was radiation-induced complications (RIC).

Results: Thirty-six consecutive patients were included, 29 (80%) of whom were female with a mean radiological follow-up of 66 months (range, 6–174 months) and a mean clinical follow-up of 57 months (range, 4–170 months). Clinically, 14 patients were symptomatic at presentation; 8 patients (22%) presented with trigeminal neuropathy and 6 (17%) presented with diplopia. Twenty-two patients (61%) were asymptomatic and the tumor was discovered incidentally. The mean maximum dose to the tumor was 31 Gy (range, 26–37 Gy), the mean dose to the tumor margin was 15 Gy (range, 13–16 Gy), and the mean number of isocenters used was 12 (range, 2–20). The mean pre radiosurgical tumor volume was 3.4 cm³ (range, 0.2–12.2 cm³), and the mean postradiosurgical tumor volume was 2.3 cm³ (range, 0.2–8.7 cm³). At last radiological follow-up 10 patients (28%) displayed no change in tumor volume and 26 (72%) displayed a decrease in volume. No patients displayed an increase in tumor volume. There were no RIC. At last clinical follow-up, 20 (95%) of the 21 patients with incidental tumors remained asymptomatic. One patient (5%) developed atypical hemifacial pain syndrome. Four patients (29%) demonstrated improvement of symptoms and in 10 patients (71%) their symptoms remained unchanged.

Conclusion: The current cohort study is small but extensively followed, and demonstrates that up-front GKR for PCM can be effective and safe in selected patient, with high tumor control and a low incidence of post-SRS complications.

Publication History

Article published online:
05 February 2024