Misao Nishikawa

Methionine positron emission tomography for differentiation of recurrent brain tumor and radiation necrosis after stereotactic radiosurgery--in malignant glioma.

ObjectFollowing stereotactic radiosurgery (SRS), we examined how to differentiate radiation necrosis from recurrent malignant glioma using positron emission tomography (PET) with11C-methionine (Met).MethodsMet-PET scans were obtained from 11 adult cases of recurrent malignant glioma or radiation injury, suspected on the basis of magnetic resonance images (MRI). Patients had previously been treated with SRS after primary treatment. PET images were obtained as a static scan of 10 minutes performed 20 minutes after injection of Met. We defined two visual grades (e.g., positive or negative Met accumulation). On Met-PET scans, the portion of the tumor with the highest accumulation was selected as the region of interest (ROI), tumor-versus-normal ratio (TN) was defined as the ratio of average radioisotope counts per pixel in the tumor (T), divided by average counts per pixel in normal gray matter (N). The standardized uptake value (SUV) was calculated over the same tumor ROI. Met-PET scan accuracy was evaluated by correlating findings with subsequent histological analysis (8 cases) or, in cases without surgery or biopsy, by the subsequent clinical course and MR findings (3 cases).ResultsHistological examinations in 8 cases showed viable glioma cells with necrosis in 6 cases, and necrosis without viable tumor cells in 2 cases. Three other cases were considered to have radiation necrosis because they exhibited stable neurological symptoms with no sign of massive enlargement of the lesion on follow-up MR after 5 months. Mean TN was 1.31 in the radiation necrosis group (5 cases) and 1.87 in the tumor recurrence group (6 cases). Mean SUV was 1.81 in the necrosis group and 2.44 in the recurrence group. There were no statistically significant differences between the recurrence and necrosis groups in TN or SUV. Furthermore, we made a 2 x 2 factorial cross table (accumulation or no accumulation, recurrence or necrosis). From this result, the Met-PET sensitivity, specificity, and accuracy in detecting tumor recurrence were determined to be 100%, 60%, and 82% respectively. In a false positive-case, glial fibrillary acidic protein (GFAP) immunostaining showed a positive finding.ConclusionThere were no significant differences between recurrent malignant glioma and radiation necrosis following SRS in Met-PET. However, this study shows Met-PET has a sensitivity and accuracy for differentiating between recurrent glioma and necrosis, and presents important information for developing treatment strategies against post radiation reactions.

The role of postoperative patient posture in the recurrence of chronic subdural hematoma: a prospective randomized trial

BACKGROUND Chronic subdural hematoma is known to have a significant recurrence rate. In this report, we evaluate the relationship between the recurrence rate of chronic subdural hematoma and postoperative patient posture. METHODS We conducted a prospective randomized study of 46 patients with chronic subdural hematoma treated surgically at the Osaka City General Hospital from January 1997 to December 1999. In Group A, the patients were kept in a supine position for 3 days after the operation. In Group B, the patients assumed a sitting position on the day after the operation. RESULTS The recurrence rates in Group A and Group B were not significantly different. CONCLUSIONS Assuming an upright posture soon after operation in cases of chronic subdural hematoma is not thought to be a risk factor for recurrence.

Gamma knife surgery for skull base meningiomas: The effectiveness of low-dose treatment

BACKGROUND The surgical removal of skull base meningiomas has a high morbidity rate, even by modern microsurgical standards. We evaluated the results of gamma knife surgery for skull base meningiomas using a relatively low radiation dose for the tumor margins. METHODS We reviewed 24 cases of skull base meningiomas during a 30-month period. The locations of the tumors were the petroclival region in 11 cases, the cavernous sinus region in 9 cases, and the cerebellopontine angle region in 4 cases. Eight patients (33%) had been operated on previously and fourteen patients (67%) had been treated by neuroimaging. The marginal doses for the tumors were 8 Gy to 15 Gy (median, 10.6 Gy). A large petroclival tumor 58 mm in diameter was treated with a staged treatment protocol with a 6-month interval between treatments. RESULTS Tumor regression was observed in 46% of the patients imaged during the follow-up period (median, 17.1 months). No patients revealed tumor growth in the follow-up period (100% tumor control rate). Eleven patients (46%) had improved clinically by the time of the follow-up examinations. Preexisting cranial nerve deficit in one patient worsened because of radiation injury. CONCLUSION Although a longer follow-up period is required, the relatively low minimum tumor radiation dose treatment for skull base meningiomas using a gamma knife seems to be an effective treatment with low morbidity.

Bilateral Dissecting Aneurysms of the Vertebral Arteries Resulting in Subarachnoid Hemorrhage: Case Report

OBJECTIVE AND IMPORTANCE We present the case of a patient with bilateral dissecting aneurysms of the vertebral arteries resulting in subarachnoid hemorrhage. CLINICAL PRESENTATION A 44-year-old man suffered a sudden onset of severe occipital headache and nausea and then dysphasia caused by subarachnoid hemorrhage. A computed tomographic scan demonstrated right side dominant subarachnoid hemorrhage mainly in the posterior fossa. Angiography revealed bilateral, vertebral dissecting aneurysms. The right aneurysm was larger and had a bleb-like protrusion, which strongly suggested a causative lesion of the subarachnoid hemorrhage. Six months later, the patient was referred to our hospital for further evaluation and treatment. INTERVENTION The ruptured right aneurysm was trapped surgically through a lateral suboccipital approach. The patients postoperative course was unremarkable, and he was discharged on the 14th day after surgery. However, postoperative angiography demonstrated slight enlargement of the left nonruptured aneurysm. Four months after surgery, the patient developed brain stem ischemic symptoms. The angiography conducted at that time showed further enlargement of the left aneurysm. Five months after surgery, fatal rupture of the left aneurysm occurred. CONCLUSION These results indicate that sacrifice of the unilateral vertebral artery may result in an enlargement of the contralateral nonruptured aneurysm and may thus be dangerous in the case of a patient with bilateral dissecting aneurysms.

Endovascular Treatment of Intractable Oronasal Bleeding Associated with Severe Craniofacial Injury

BACKGROUND Severe craniofacial injury may cause intractable oronasal bleeding, which is refractory to conventional treatments. This study will evaluate the efficacy of endovascular treatment for such oronasal bleeding. METHODS Nine males between the ages of 19 and 62 years who had intractable oronasal bleeding resulting from severe craniofacial injuries received treatments of transarterial embolization using Gelfoam pledgets, polyvinyl alcohol particles, or platinum coils. We then reviewed their clinical and neuroradiologic characteristics retrospectively. RESULTS In all but one case, angiography demonstrated bleeding points as extravasation. These bleeding points were multiple in seven cases. Except for bleeding from ethmoidal arteries, selective embolization was successful. In all cases, intractable oronasal bleeding was controlled. Patient survival was not directly related to oronasal bleeding, but rather was strongly correlated with associated brain injuries. CONCLUSION Endovascular treatment is an acceptable treatment for intractable oronasal bleeding associated with severe craniofacial injuries when conventional treatments have failed.

Multiple appearing and vanishing aneurysms: primary angiitis of the central nervous system. Case report.

The authors present the case of a patient with ischemic episodes and recurrent intracerebral hemorrhages probably caused by primary angiitis of the central nervous system (CNS). An initial angiogram revealed multiple cerebral artery aneurysms as well as vascular wall irregularity; a second angiogram obtained 2 years later, however, did not demonstrate the previous aneurysms but instead showed new ones together with stenosis. Based on the histopathological findings and clinical course in this case, the multiple aneurysms appear to have been induced by vascular wall fragility and subsequent self-repair resulting from primary angiitis of the CNS. The authors present the histological and clinical characteristics of this unusual case of granulomatous, necrotizing CNS vasculitis.

Chiari I malformation associated with ventral compression and instability: one-stage posterior decompression and fusion with a new instrumentation technique.

OBJECTIVE AND IMPORTANCE:We describe an alternative surgical technique for treatment of Chiari I malformation associated with ventral compression and instability of the region. An expansive suboccipital cranioplasty and a rigid occipitocervical fixation are performed in one stage. METHODS:The occipitocervical fixation is performed by use of metal rods fixed on the cranial side by screws inserted into the diploic layer of occipital bone and on the caudal side by screws inserted into the pedicle of the axis or in a transarticular fashion into the lateral masses of axis and atlas vertebra. A large piece of autologous bone is placed in the region between the rostral edge of cranial decompression and the axis, with the aim of achieving both expansive suboccipital cranioplasty and occipitocervical fusion. RESULTS:We performed this procedure in two patients with Chiari I malformation associated with basilar invagination and occipitalization of the atlas. Postoperatively, decompression of the brainstem and restoration of normal cerebrospinal fluid flow at the craniovertebral junction were confirmed radiologically, and the patients were relieved of their symptoms. At 1 and 3 years of follow-up, respectively, solid bone fusion was observed between the occipital bone and axis in both patients. CONCLUSION:Simultaneous posterior decompression and occipitocervical fixation with an alternative instrumentation technique is discussed. The procedure can be performed regardless of the size of suboccipital craniectomy. Screw insertion into the diploic layer of the occipital bone has not been described previously.

Very poor prognosis in cases with extravasation of the contrast medium during angiography

BACKGROUND The rebleeding of a ruptured intracranial aneurysm in the acute stage has been thought to indicate a very poor prognosis. In our experience, the outcome of patients with extravasation of the contrast medium is worse than that of patients with rerupture under circumstances other than angiography. We demonstrated the poorer outcome of the patients with extravasation, compared to that of the patients developing rerupture under circumstances other than angiography, and examined the factors that contributed to the poorer outcome of the patients with extravasation. METHODS Among the 641 cases of ruptured intracranial aneurysm, we have handled over the past 10 years, 36 (5.6%) patients have rebled before surgery was performed. Thirteen patients rebled during angiography (Group I), and the remaining 23 patients rebled in other circumstances (Group II). We compared the outcome of both groups. RESULTS The rebleeding occurred within 6 hours of the initial rupture in 29 (80%) patients. The outcome of Group I was significantly poorer than that of Group II (p < 0.05). In Group I, SD was achieved in only 1 patient and the remaining 12 patients died, while in Group II, 8 patients were in GR or MD, 2 were in SD, and the remaining 13 patients died. CONCLUSION Because rebleeding during angiography most often occurs in the acute stage and because the outcome of patients with extravasation is very poor, we recommend that the performance of angiography be delayed at least between 3 and 6 hours after the initial rupture.

Lateral situated sinus pericranii. case report

We hereby report a case of a laterally situated sinus pericranii, which is rare. According to the articles regarding this kind of lesion, carotid angiograms revealed no pathological findings, and venograms taken with direct injection of contrast medium into the mass were useful. It should be stressed that the lesion could be demonstrated in the late phase of carotid angiograms, and digital subtraction angiography was especially useful for diagnosis. The literature is also reviewed.

Microsurgical interruption of dural arteriovenous fistula at the foramen magnum

We report two rare cases of progressive congestive myelopathy caused by dural arteriovenous fistulae (DAVF) at the foramen magnum. The first, a 69-year-old male with a 2-year history of progressive myelopathy, had symptoms unrecognized due to a past history that included spinal caries and congenital dislocation of the hip. The second, a 60-year-old male, had a recurrence of the myelopathy three months after endovascular occlusion of the DAVF feeding artery. Both patients were successfully treated by direct microsurgical interruption of the arterialized medullary vein with functional and radiological improvement. The clinical manifestations of DAVF at the foramen magnum are nonspecific, mimicking those of cervical spondylotic myelopathy or cervical neoplasm. Accurate and early diagnosis followed by complete obliteration of the fistula is mandatory to avoid permanent neurological deficit.