Toshihiro Yasui

Expansive Suboccipital Cranioplasty for the Treatment of Syringomyelia Associated with Chiari Malformation

Summary In order to treat syringomyelia associated with adult type Chiari malformation, the authors developed a method of expansive suboccipital cranioplasty (ESC) that involves enlarging the small posterior fossa to obtain a sufficient flow of cerebrospinal fluid (CSF). The relative effectiveness of ESC with the obex plugged and not plugged was also examined, as well as other factors influencing the operative results. Twenty patients without arachnoid adhesion at the major cistern underwent ESC without opening the arachnoid membrane at the major cistern. After surgery, all improved with no recurrence and CSF flow study using magnetic resonance (MR) imaging showed significant improvement of the flow at the major cistern. Another 20 patients without arachnoid adhesion also underwent ESC but with obex plugging. Sixteen improved and one displayed only temporary improvement with recurrent syringomyelia due to postoperative arachnoid adhesions. The remaining three showed no change in spite of shrinkage of the syrinx on postoperative MR imaging. These three patients had displayed pre-operative symptoms over an approximately 10-year period involving almost the entire axial plain of the spinal cord, and presented a large syrinx before surgery. In 4 patients with arachnoid adhesions, all required intra-arachnoid procedures in addition to ESC. Intra-arachnoid procedures are not necessary to facilitate restoration of CSF flow in patients without arachnoid adhesions, because ESC can release the CSF flow blockage in the major cistern even without plugging of the obex. An associated arachnoid adhesion at the major cistern or a long-standing syringomyelia with irreversible damage of the spinal cord results in a poor operative prognosis. When posterior fossa surgery fails, insufficient decompression or postoperative arachnoid adhesions at the major cistern as the cause of treatments failure should be evaluated by CSF flow studies using phase contrast MR imaging.

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.

Aneurysmal rupture during angiography.

The aim of the present study was to analyze the clinical data on rebleeding in cerebral aneurysms during angiography and to evaluate the importance of the time interval between the latest rupture and angiography. Fourteen personal cases and 202 patients reported in the literature are reviewed. Rebleeding during angiography occurred most often (78%) on Day O; 89% bled when angiography was performed within 6 hours of the latest rupture. The prognosis in such ruptures was poor, with a mortality of 79%. Intentional delay in angiography of at least 6 hours from the latest rupture is recommended if the associated hematoma is not large.

Moyamoya disease and pregnancy: case report and review of the literature.

OBJECTIVE AND IMPORTANCE Many female patients with moyamoya disease are of childbearing years, including those who were diagnosed before entering their childbearing years. However, there have been no extensive reviews of the management of pregnancy and delivery in association with moyamoya disease. The purpose of this report is to describe the case of a patient with moyamoya disease complicated by pregnancy and to review the literature on other such cases. CLINICAL PRESENTATION AND INTERVENTION We report a 23-year-old primipara with moyamoya disease who delivered uneventfully by cesarean section under spinal anesthesia at 38 weeks of gestation. In the literature, 30 cases were reported of patients who had been diagnosed with moyamoya disease before pregnancy and delivery, and 23 patients who were symptomatic and were diagnosed for the first time with moyamoya disease in association with pregnancy. CONCLUSION There is no evidence that pregnancy increases the risk of cerebrovascular accident or that bypass surgery decreases its risk. Poor prognosis of the patient or the newborn is mostly caused by cerebral hemorrhage and not by cerebral ischemia. It is important to control blood pressure and especially to avoid toxemia during pregnancy. Either cesarean section or vaginal delivery can be accomplished safely. Any anesthetic method can be used, provided special attention is given to avoiding hypocapnia, hypotension, and hypertension. Oral contraceptives should be avoided.

Boost radiosurgery for treatment of brain metastases after surgical resections

BACKGROUND We evaluated results of resection surgery followed by boost radiosurgery for the treatment of brain metastases. METHODS We treated 21 patients (13 male, 8 female) with surgical resection (subtotal or total) followed by boost radiosurgery. The mean patient age was 61 years (range, 41-80 years); supratentorial lesions were treated in 12 patients, and posterior fossa lesions were treated in 9 patients. The most common primary cancers were lung (24%) and colon (24%). Fifty-three percent of patients had brain metastases only, whereas 47% had extracranial metastases. The radiosurgery dose plan was designed to radiate the operative cavity; the mean treatment volume (50% isodose) was 10.7 mL (range, 3.4-23.3 mL), and the mean marginal dose was 17 Gy (range, 13-20 Gy). RESULTS Local control was achieved in 16 (76%) patients. However, new intracranial lesions developed in 10 patients, and meningeal carcinomatosis occurred in 5 patients. Local tumor recurrence occurred more often for patients treated with lower radiotherapy doses (<18 vs > or =18 Gy, P = .03), and meningeal carcinomatosis occurred more often in patients with posterior fossa lesions (P = 0.05). Gamma knife radiosurgery was performed in 13 patients, and whole-brain radiation was performed in 2 patients. No patients experienced symptomatic radiation injury, and the median survival time was 20 months. CONCLUSIONS Although boost radiosurgery is less invasive and reduces morbidity, the radiosurgical dose must be higher than 18 Gy for the treatment to be most effective. Treatment of lesions of the posterior fossa must be considered carefully because of the higher frequency of meningeal carcinomatosis. Also, we recommend that the surgeons who operate on the metastatic tumors must try to decrease the resected cavity volume and to prevent cerebrospinal fluid dissemination at the operation for posterior fossa lesions.

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.

Basal Meningoencephalocele, Anomaly of Optic Disc and Panhypopituitarism in Association with Moyamoya Disease

Basal meningoencephalocele is frequently associated with midfacial anomaly, optic disc anomaly, brain anomaly, cerebrospinal fluid rhinorrhea, chiasma syndrome, and endocrinologic disturbance. The combination of basal meningoencephalocele and moyamoya disease is extremely rare. A 29-year-old man had basal meningoencephalocele (transsphenoidal type), anomaly of the optic disc (morning glory syndrome), panhypopituitarism and moyamoya disease. The patient was treated by hormone replacement, but surgical intervention was not required. Basal meningoencephalocele and moyamoya disease are a possible combination of the diseases.

Primary intracranial germinoma in the medulla oblongata.

BACKGROUND Primary intracranial germ cell tumor in the medulla oblongata is very rare; only five cases, including our case, have been reported. CASE REPORT Our patient, an 18-year-old woman, was diagnosed with a primary intracranial germinoma in the medulla oblongata by an open biopsy. She was treated successfully with chemotherapy and radiosurgery. CONCLUSION All five tumors in this site were histologically diagnosed as germinomas. The finding of female predominance in germ cell tumors in this region is shown.

Venous angiomas with arteriovenous shunts: report of three cases and review of the literature

OBJECTIVE AND IMPORTANCE: In spite of recent recognition of the benign nature of venous angioma (VA), only limited information is available on the clinical features of VA with arteriovenous shunt (AVS). The purpose of this study was to elucidate the clinical profile of VA with AVS. CLINICAL PRESENTATION AND INTERVENTION: We describe three patients having a VA with AVS and review the clinical features of 31 patients reported in the literature, including our three patients. The patients included 12 women and 19 men, ranging in age from 18 to 54 years. Seven patients (22.6%) presented with intracranial hemorrhage, and none of 16 patients developed a new or recurrent hemorrhage (mean follow-up period, 11 months). Treatment was conservative in 14 patients, lobectomy or partial resection of the VA in 6, removal of hematoma in 4, operation only for coexisting aneurysm or arteriovenous malformation in 4, and not known in 3. The outcome was reported as good recovery in 19 patients, persistent neurological deficits in 2, death or deterioration not related to the VA in 3, and not known in 7. CONCLUSION: Although there remains some uncertainty as to the clinical features of VA with AVS, its prognosis seems to be essentially as benign as that of VA without AVS. Thus, conservative treatment is recommend except for patients with a large hematoma or with a coexisting arteriovenous malformation or a symptomatic, accessible cavernous angioma, which may be treated by surgical intervention. Further collection of data is required to establish definite treatment guidelines.