Treatment Outcome of Gamma Knife Radiosurgery for Petroclival Meningiomas: Retrospective Analysis of a Single Institution Experience.

BACKGROUND: Although Gamma Knife radiosurgery (GKRS) has been widely used for intracranial meningiomas as an alternative or adjuvant treatment, guidelines have not been established for the selection of patients with petroclival meningioma (PCM) for GKRS. In this study, we reported the factors related to tumor progression and postoperative complications in PCM patients treated by GKRS, with a review of the literatures. METHODS: Between 2004 and 2019, 64 patients (52 patients for alternative and 12 patients for adjuvant treatment) with PCM underwent GKRS in our institution. The clinical and radiological factors were retrospectively analyzed. The mean radiologic follow-up duration was 58.4 months (range, 6-164 months). The mean tumor volume and diameter before GKRS were 13.4 cm³ and 2.9 cm, respectively. The median marginal dose was 12 Gy (range, 10-14 Gy) with a 50% median isodose line. Fractionation was used in 19 cases (29%, two fractionations in 5 cases & three fractionations in 14 cases). RESULTS: Progression was noted in 7 cases (10.9%) and the progression-free survival rates were 91.1% at 5 years and 69.6% at 10 years. Although large in volume, moderate to severe peritumoral edema and male gender were somewhat related to progression, they did not reach statistical significance. Ten patients (15.6%) developed complications after GKRS. The most common complication was cranial nerve deficit (n=8), followed by hemiparesis, cognitive dysfunction, and hydrocephalus. Large size (maximal diameter ≥5 cm) [hazard ratio (HR) 0.091, 95% confidence interval (CI) 0.014-0.608; p=0.013] and multiplicity (HR 0.102, 95% CI 0.018-0.573; p=0.009) were independent factors for developing complications after GKRS. CONCLUSION: GKRS can be considered an effective and safe treatment for large-volume PCM. However, for patients with large size or multiple masses, the treatment method should be determined with caution because the probability of complications after GKRS may increase.

Wedge Resection of the Falx to Clip a Distal Anterior Cerebral Artery Aneurysm.

BACKGROUND: The unilateral anterior interhemispheric approach has been widely used for distal anterior cerebral artery (DACA) aneurysms. However, there are some drawbacks of this approach because of the narrow operative field, including possible brain traction injury, bridging vein injury, and inadequate exposure of the aneurysm. Here, we report a case of a DACA aneurysm covered by the falx that could not be totally exposed with the unilateral interhemispheric approach. We successfully obtained a wide view with wedge resection of the falx, avoiding excessive brain traction and division of the superior sagittal sinus. CASE DESCRIPTION: A 76-year-old woman with a 6-mm unruptured DACA aneurysm underwent a unilateral craniotomy with the anterior interhemispheric approach. In the operative field, the aneurysm was found at the midline, just below the falx. The aneurysm was covered by the falx and could not be completely exposed with the usual brain retraction. Therefore, we performed wedge resection of the falx, thus obtaining sufficient surgical field and totally exposing the aneurysm. We were then able to apply the clip successfully. Postoperative brain computed tomography angiography showed no remnant aneurysm sac or complications of falx resection or brain retraction, such as bleeding or vessel injury. CONCLUSIONS: When an aneurysm is located just below the falx and is exposed inadequately, performing wedge resection of the falx can expose the aneurysms adequately for application of the clip.

Acute Parent Artery Occlusion in Thrombosed Middle Cerebral Artery Aneurysm Presenting with Ischemic Stroke.

BACKGROUND: Thrombosed intracranial aneurysms are complex and unstable lesions that are especially associated with ischemic stroke. Although acute parent artery occlusion manifesting with ischemic stroke is very rare, it can lead to catastrophic consequences. CASE DESCRIPTION: This study presents 2 cases of acute parent artery occlusion in thrombosed large and giant middle cerebral artery bifurcation aneurysms manifesting with ischemic stroke. Both patients were successfully treated with emergent double-barrel superficial temporal artery-to-middle cerebral artery bypass followed by aneurysm trapping. CONCLUSIONS: Emergent superficial temporal artery-to-middle cerebral artery bypass could be a salvageable treatment option in patients with progressive neurologic deficits and significant mismatch between diffusion- and perfusion-weighted imaging in acute parent artery occlusions associated with large or giant thrombosed aneurysms. Besides diffusion- and perfusion-weighted imaging, preoperative assessment of the collaterals will help in predicting postoperative prognosis.

Primary Intraparenchymal Central Nervous System Solitary Fibrous Tumor/Hemangiopericytoma Presenting with Intracerebral Hemorrhage: A Case Report.

A 53-year old man who had a left hemiparesis from head injury of traffic accident 20 years ago visited an emergency room with suddenly developed semi-comatose mental status. Brain CT showed 8.6-cm sized solid and cystic mass on right temporal lobe that was associated with hemorrhage. Solid lesion showed a strong enhancement after an administration of contrast media. Because of severe mass effect, emergency operation was performed. The mass was an intraparenchymal lesion with yellowish cystic fluid and the firm reddish-brown solid lesion was hemorrhagic. The lesion was totally resected. Pathologically, anaplastic solitary fibrous tumor/hemangiopericytoma was diagnosed with 70/10 high power fields. Postoperative radiotherapy of 50 Gy was done. Postoperative 2 months later, the patient was recovered to alert mental state. We report this unusual case of non-dural based intraparenchymal solitary fibrous tumor/hemangiopericytoma with high mitotic index and acute massive hemorrhage. Rapid tumor growth of hypervascular tumor might have a chance of bleeding.