J H Sim

Gamma knife surgery for intracranial cavernous hemangioma

OBJECT The purpose of this study was to assess the benefits of radiosurgery for cavernous hemangioma. METHODS Sixty-five cavernous hemangiomas were treated with gamma knife surgery (GKS) between October 1994 and December 2002. Forty-two patients attended follow up. The mean patient age was 37.6 years (range 7-60 years). The lesions were located in the frontal lobe in 12 cases, deep in the parietal lobe in five, in the basal ganglia in five, in the temporal in three, in the cerebellum in three, in the pons/midbrain in six, and in multiple locations in eight cases. The presenting symptoms were seizure in 12, hemorrhage in 11, and other in 19. The maximum dose was 26.78 Gy, and the mean margin dose was 14.55 Gy. The mean follow-up period after radiosurgery was 29.6 months (range 5-93 months). The tumor decreased in size in 29 cases, was unchanged in 12, and increased in size in one. In the seizure group, seizures were controlled without anticonvulsant medication in nine cases (81.8%) after 31.3 months (range 12-80 months). After 93 months, one patient developed a cyst, which was resected. Rebleeding occurred in one case (2.3%). On T2-weighted imaging changes were seen in 11 cases (26.2%), in three (7.1%) of which neurological deterioration was correlated with imaging changes. In other cases these deficits were temporary. CONCLUSIONS The authors found that GKS was an effective treatment modality for cavernous hemangiomas, especially for those located within the brainstem, basal ganglia, or deep portions of the brain. It can reduce seizure frequency significantly although this takes time. In the group receiving a marginal dose below 15 Gy the patients fared better than when the dose exceeded 15 Gy.

A Case of Very Large Cyst Formation with Gamma Knife Radiosurgery for an Arteriovenous Malformation

A 17-year-old male patient underwent Gamma Knife radiosurgery (GKRS) for a left parietal arteriovenous malformation (AVM), which presented with hemorrhage. The 15.0 cm3 nidus was covered with the 50% isodose. The maximum dose was 50 Gy and the margin dose was 25 Gy. Eleven months later he developed a right hemiparesis and MRI showed a large cyst. Cerebral angiography showed partial obliteration of the AVM nidus. Stereotactic removal of cyst fluid (about 70 cm3) was performed, and an Ommaya reservoir was inserted. Cyst formation after GKRS for cerebral arteriovenous malformation is a is side effect of radiosurgery about which we need to learn more.

Microelectrode recording: lead point in STN-DBS surgery

BACKGROUND Microelectrode recording is an integral part of many surgical procedures for movement disorders. We evaluate the Lead point compared to the NeuroTrek system. We used NeuroTrek in 18 Parkinsonian patients, Lead point-4 in 12 patients, during STN-DBS surgery. We compared MR-Stir image with Microelectrode recording. METHOD The MicroGuide system with its integrated screen display provides the user with all the information needed during the surgery on its screen. Microelectrode recordings showed characteristic neuronal discharges on a long trajectory (5-6 mm), intraoperative stimulation induces dramatic improvement of Parkinsonian motor symptoms. FINDINGS Microrecording data of the Leadpoint showed high background activity, and firing rate of 14-50 Hz. The discharge pattern is typically chaotic, with frequent irregular bursts and pauses. DISCUSSION The microelectrode recording of the neuroTrek and Lead point-4 showed unique results of the typical STN spike. The DBS effect is maximized associated by MER mapping.