Gamma knife radiosurgery for arteriovenous malformations: the Furukawa experience.

The Furukawa experience treating 534 patients with cerebral arteriovenous malformations using gamma knife radiosurgery (GKRS) is summarized. By repeating radiosurgery for any residual nidus after the first GKRS, the rates of cumulative complete obliteration 7 years after this initial GKRS, according to four volume categories (< or =1, 4 > or = >1, 10 > or = > 4, > 10cm3), were 92, 89, 68 and 43%, respectively. Bleeding after GKRS was observed in 8.1% of the patients and was more frequently seen in patients with a large nidus and history of bleeding two or more times before GKRS. Cyst formation was recognized in 4.7% of patients, two thirds of which required some form of surgical intervention. Refinement of the total GKRS system contributed to earlier and more effective nidus obliteration.

[A case of primary meningeal melanocytoma of the left middle fossa].

A 29-year-old woman presented with a primary meningeal melanocytoma of the left middle fossa manifesting as headache and nausea. Computed tomography (CT) with contrast medium demonstrated a clearly demarcated, homogeneously enhanced high density area surrounded by a cyst in the left temporal lobe. Magnetic resonance (MR) imaging showed the mass as a slightly high signal intensity area on the T1-weighted image and as a low signal intensity area on the T2-weighted image. Cerebral angiography revealed shift of the middle cerebral artery but no tumor stain. The solid part of the tumor had rapidly increased in size with reduction of the cyst 3 months later. Left frontotemporal craniotomy disclosed a clearly demarcated jet-black tumor attached to the dura. The black-colored lesion in the dura and the bone extended to the skull base, so malignant melanoma was a possibility. The solid part of the tumor was gross totally removed, and the dura and the skull bone were preserved. Histological examination of the tumor specimen revealed meningeal melanocytoma. Melanophages were present in the specimen of the black-colored lesion in the dura and the bone, but no neoplastic infiltration was present. The postoperative course was uneventful, and the patient's headache and nausea disappeared. CT and MR imaging taken 1 month later confirmed total removal of the tumor. No recurrence has been observed for 2.5 years after surgery. Preoperative differentiation of meningeal melanocytoma from malignant melanoma is difficult, but the primary goal of therapy is gross total resection of the solid part of the tumor irrespective of tumor type.