Shunsuke Kawamoto

Results of radiosurgery for brain stem arteriovenous malformations.

OBJECTIVE To assess the treatment results of radiosurgery for brain stem arteriovenous malformations (AVMs) and to seek optimal dose and treatment volume prescription for these lesions. METHODS The clinical and radiological data of 30 consecutive patients with brain stem AVM treated with gamma knife radiosurgery were retrospectively reviewed with a mean follow up period of 52.2 months. There were 26 patients with previous haemorrhages and 21 with neurological deficit. Seventeen AVMs were located in the midbrain, 11 in the pons, and two in the medulla oblongata. All of the lesions were small with the intra-axial component occupying less than one third of the area of brain stem parenchyma on axial section of multiplaner MRI or CT. The mean diameter of the nidus was 1.26 cm, and the nidus volume within the brain stem parenchyma ranged from 0.1 to 2.0 cm3. The mean radiation dose to the AVM margin was 18.4 Gy. RESULTS The actuarial 3 year obliteration rate was 52.2%; 69.4% in cases treated with standard doses (minimum target dose, 18–20Gy), and 14.3% in cases treated with low doses (<18 Gy) (p<0.05). Two patients sustained symptomatic radiation injury, but there was no permanent neurological deficit caused by radiosurgery. Five patients had haemorrhage from the AVM after irradiation, including four fatal cases, resulting in a 4.0% annual rate of post-treatment bleeding. CONCLUSIONS Radiosurgery is a viable treatment modality for patients with small deep parenchymal brain stem AVMs. A standard radiosurgical dose is safe and effective when directed to a small treatment volume. However, latent interval haemorrhage remains a significant problem until the nidus is obliterated completely.

Control of epilepsy associated with cerebral arteriovenous malformations after radiosurgery

OBJECTIVE To investigate the effect of radiosurgery for symptomatic epilepsy associated with cerebral arteriovenous malformations (AVMs). METHODS Thirty five patients with unruptured epileptogenic AVMs were studied with a mean follow up of 43.0 months. The duration of epilepsy before radiosurgery ranged from 2 months to 21 years (mean 2.8 years). Fifteen patients showed partial seizures; eight of these had associated secondary generalisation. The remaining 20 patients showed only generalised seizures without preceding focal seizures. RESULTS At the final follow up examination, 28 patients remained seizure free, whereas seizures continued in seven. Variables significantly associated with continuity of seizures after radiosurgery were the number of seizures before therapy (p<0.01) and duration of epilepsy (p<0.05). According to Engel’s classification, the 10 patients with intractable seizures before treatment included five with grade I, four with grade III, and one with grade IV. The frequency of seizures began to decrease several months after radiosurgery; much shorter than the time required for morphological change in the AVMs. CONCLUSIONS Radiosurgery seems to be beneficial for seizure control in patients with unruptured epileptogenic AVM.

Role of radiosurgery in the management of cavernous sinus meningiomas.

Objective ‐ To provide our early experience and philosophy in the utility of radiosurgery in the management of cavernous sinus meningiomas. Methods ‐ Twenty‐five consecutive cases with cavernous sinus meningiomas treated between 1990 and 1995 were reviewed. Three cases were treated with gamma‐knife radiosurgery, 15 with preceding surgery and gamma knife, 7 with surgery. Mean follow‐up following radiosurgery and surgery were 34.8 and 25.4 months, respectively. Results ‐ The 5‐year actuarial tumor control rate following radiosurgery was 85.7% and tumor remission rate was 61.4%. Permanent neurological deterioration after radiosurgery was seen in 1 case (5.9%), whereas newly developed or worsened neurological deficits permanently persisted in 59.1% of patients after surgery. There was a clear correlation between surgical radicality and postoperative morbidity rate. Conclusions ‐ Gamma‐knife radiosurgery is a valuable addition to surgical removal in the treatment of cavernous sinus meningiomas. Combination of non‐radical resection and subsequent radiosurgery is recommended to improve treatment‐associated morbidity.

Primary cavernous sinus malignant lymphoma treated by gamma knife radiosurgery: case report and review of the literature.

BACKGROUND Malignant lymphomas originating primarily in the cavernous sinus have not been histologically verified by any authors. The first reported case to our knowledge of primary cavernous sinus malignant lymphoma, initially diagnosed as benign meningioma and treated by gamma knife radiosurgery, is presented. CASE DESCRIPTION The patient was a 77-year-old man whose initial symptoms were left facial hypesthesia and diplopia on left gaze. During the 21-month follow-up period after gamma knife radiosurgery, no evidence of tumor regrowth was seen in the irradiated area, but an unirradiated mass expanded with invasion of the brain stem. Subsequent surgery provided histologic verification of the diagnosis. Despite successful local tumor control, the patient died due to sepsis 31 months after the onset of symptoms. Autopsy failed to disclose any remaining lymphoma cells either in the primary lesion or anywhere throughout the entire body. CONCLUSION Primary cavernous sinus malignant lymphoma is an extremely rare brain tumor, but it must be considered in the differential diagnosis of an enhanced mass in the cavernous sinus. Stereotactic radiosurgery using the gamma knife technique for intracranial brain tumors, especially in the cavernous sinus, is associated with risk, as was seen in our patient. Our experience points out the pitfalls of gamma knife radiosurgery; it should be performed only after histologic confirmation has been obtained.

Gamma knife surgery for arteriovenous malformations involving the corpus callosum

OBJECT The purpose of this study was to evaluate the safety and efficacy of gamma knife surgery (GKS) for the treatment of arteriovenous malformations (AVMs) involving the corpus callosum. METHODS Thirty-two patients aged from 7 to 65 years (median 25 years) with AVMs of the corpus callosum underwent GKS between 1990 and 2002. The maximum AVM diameter was more than 3 cm in 11 patients (34%). The AVM volume ranged from 0.1 to 19.1 cm3 (median 1.6 cm3). The median dose to the AVM margin was 20 Gy (range 17-28 Gy). Patients were followed for 1 to 12 years (median 9 years). The angiographically confirmed actuarial obliteration rate was 64% and 74% at 4 and 6 years, respectively. Younger patient age (p < 0.05) and lower radiosurgery-based grading score (calculated from the patient age and AVM volume; p < 0.01) were the significant factors affecting successful AVM obliteration. No patient suffered a hemorrhage after GKS, although 28 patients (88%) had a history of hemorrhage from their AVMs. Radiation-induced neurological deficit was observed only in one patient (3%) who had undergone previous radiotherapy (50 Gy). No patient experienced complications of occlusion or stenosis of the normal vascular structures adjacent to the AVM. CONCLUSIONS Gamma knife surgery is a safe and effective treatment for selected patients with AVMs involving the corpus callosum, and it carries a low risk of damaging adjacent critical vascular structures. Even ruptured AVMs with relatively large diameter can be successfully treated, especially in younger patients, with minimal morbidity and a low risk of repeated hemorrhage.

Basilar artery occlusion due to spontaneous basilar artery dissection in a child.

Summary Basilar artery occlusion (BAO) causing brainstem infarction occurred in a 7-year-old boy without any basic disorders. A diagnosis of BAO due to basilar artery dissection (BAD) was suspected at angiography, and this was confirmed by gadolinium-enhanced magnetic resonance imaging (MRI). These investigations clearly showed all the typical diagnostic signs such as a pseudolumen, double lumen and intimal flap, and a pseudolumen in resolution. The spontaneous healing of the dissection was clearly demonstrated during 10 months of follow-up. We stress that BAD can occur in young children and that combined diagnosis with gadolinium-enhanced MRI and angiography is conclusive for diagnosis of dissecting aneurysms. Wider use of these combined diagnostic methods will allow the detection of less severe basilar artery dissection, thus extending the spectrum of presentation and prognosis.

Effectiveness of a 1-day aspiration plus Gamma Knife surgery procedure for metastatic brain tumor with a cystic component

OBJECT Gamma Knife surgery (GKS) has gained increasing relevance in the treatment of metastatic brain tumors, but many metastatic tumors contain a large cystic component and often exceed the size limit for GKS. For such lesions, the authors adopted a procedure in which stereotactic aspiration is first performed and followed immediately by GKS on the same day. In this paper, the authors describe this 1-day combined procedure and evaluate its efficacy. METHODS Between 2005 and 2010, 25 cystic metastases in 25 patients were treated at Dokkyo Medical University. The patients first underwent MRI and stereotactic aspiration of the cyst while stationary in a Leksell stereotactic frame; immediately afterward, the patients underwent a second MR imaging session and Gamma Knife treatment. Tumor volume reduction, tumor control rate, and overall survival were examined. RESULTS Tumor volume, including the cystic component, decreased from 8.0-64.2 cm(3) (mean 20.3 cm(3)) to 3.0-36.2 cm(3) (mean 10.3 cm(3)) following aspiration, and the volume of 24 of 25 lesions decreased to less than 16.6 cm(3), which is equivalent to the volume of a 3.16-cm sphere. At least 20 Gy was delivered to the entire lesion in 24 of 25 cases. Good tumor control was obtained in 16 of 21 cases that could be evaluated during a median follow-up period of 11 months (range 1-27 months); however, reaccumulation of cyst contents was observed in 2 patients who required Ommaya reservoir placement. CONCLUSIONS The 1-day aspiration plus GKS procedure is an effective and time-efficient treatment for large cystic brain metastases.

Neuromuscular choristoma of the oculomotor nerve: case report.

OBJECTIVENeuromuscular choristomas (NMC) are rare benign tumors of the peripheral nerves. We report an NMC affecting the oculomotor nerve. CLINICAL PRESENTATIONAn 18-year-old girl presented with long-standing intermittent retro-orbital pain and oculomotor paresis. Magnetic resonance imaging scans demonstrated a small nodular lesion on the left oculomotor nerve, similar to the findings for a schwannoma. INTERVENTIONThe tumor was resected with the parental oculomotor nerve, which was reconstructed using a peroneal nerve graft. Postoperatively, the patient became pain-free, and her oculomotor function partially recovered. Histologically, the lesion consisted of well-differentiated smooth muscle fibers intermingled with mature nerve elements consistent with the diagnosis of an NMC, although the possibility of leiomyoma in this rare location was not excluded completely. CONCLUSIONNMC may need histological confirmation for diagnosis if they occur in the intracranial space. The resection is feasible, and the function of the affected nerve can be at least partially restored with the nerve reconstruction.

Relief of hemiballism from a basal ganglia arteriovenous malformation after radiosurgery

Article abstract A patient with a 3-year history of progressive hemiballism presented with an unruptured arteriovenous malformation (AVM) in the contralateral caudate nucleus and putamen. PET demonstrated a matched reduction of cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in the basal ganglia and adjacent frontal lobe. The patient underwent radiosurgery for the AVM. After a period of no clinical change for 6 months, the movement disorder resolved by month 7 post-treatment. The AVM was successfully obliterated 2 years after irradiation without any significant change in the regional CBF or CMRO2.

Comparison of numerical change of epidermal growth factor receptor gene among pre- and postradiation glioma, and gliosis, and its clinical use

Surgery with following chemoradiotherapy is the mainstream glioma treatment. In the course of postradiation events, however, it is sometimes difficult for neurosurgeons, radiologists, and pathologists to discriminate tumor recurrence from radiation necrosis. The epidermal growth factor receptor (EGFR) gene, on chromosome 7, is known to gain in copy number frequently in high-grade gliomas. The authors applied the fluorescence in situ hybridization (FISH) method to observe the genes numerical status in pre- and postradiation glioma samples to elucidate whether this technique is useful in the discrimination of glioma recurrence from radiation necrosis. When 15 postradiation glioma samples and 4 postradiation nonglioma samples were tested, all the recurrent glioma tissue harbored numerical aberrations of the gene, whereas no abnormality could be observed in necrosis or in nonglioma gliosis. FISH could even prove a residual glioma cell in a gliotic tissue taken by needle biopsy after gamma-knife radiosurgery, which had been executed on a supposed metastatic brain tumor. FISH is considered to be of help in accurate diagnosis, especially when the usual histopathological diagnosis is difficult because of radiation effects or small sample size.