Zonisamide is a new type antiepileptics developed by Dainippon Pharmaceutical Company, and has unique pharmacological action such as brain protector, free radical scavenging action and inhibitor of epileptogenesis in experimental model. November, 1990, to September, 1992, 41 Japanese neurosurgical centers in Cooperative Study Group participated in a prospective randomized double-blind controlled trial of zonisamide(ZNS)vs.phenobarbital(PB)to test whether treatment with this agent prevents epilepsy. High risk patients for epilepsy who were craniotomized for their brain tumors, cerebrovascular diseases and head injuries entered into this study. Medication was started with 2 tab./day of either ZNS(100mg/tab.)or PB(40mg/tab.), until 1 month after craniotomy. The controller committee allocated ZNS or PB to each patient randomly. The dose was adjusted to therapeutic serum concentration from 10 to 30 μg/ml trough blood concentration monitoring. The data of serum concentration was informed blindly to doctor-in-charge from the controller committee. Medication was continued up to 1 year, thereafter the patients was followed-up till 3 years after surgery, including 6 months tapering period. Among registered 278 cases, 255 cases were analyzed excluding 23 unsuitable cases. The 129 assigned to the ZNS-treated group and the 126 patients to the PB-treated group were balanced with regard to demographic data such as age, sex, surgical interventions and so on. The frequency of epilepsy during medication period was similar between two groups(5.4% of ZNS-treated group vs.6.3% of PB-treated group, not statistically significant). The frequency of epilepsy during follow-up period in ZNS-treated group was lower than that of PB-treated group(7.1% of ZNS-treated group vs.12.1% of PB-treated group, not statistically significant). Six cases(5.6%)out of 107 PB-treated patients developed partial seizure, whereas no patients among 112 ZNS-treated patients experienced partial seizure(Fisher's test:p=0.013). Regarding brain tumor, the seizure of the patients with meningioma in ZNS-treated group was less than that of in PB-treated group(2.5% of 40 ZNS-treated patients vs.16.2% of 37 PB-treated cases, not statistically significant). Concerning side effects, statistical significant difference between both groups was not observed. Both PB and ZNS suppressed postoperative seizure, therefore significant difference in the frequency of epilepsy during medication period was not observed. ZNS inhibits formation of postoperative epileptogenesis as shown in experimental models whereas PB does not, consequently a reduction in frequency of epilepsy on ZNS-treated group was observed during follow-up period. These data suggests that ZNS has true prophylactic effect for postoperative epilepsy, therefore routine prophylaxis with ZNS would seem to be indicated, particularly in high-risk patients.

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We used three-dimensional(3D)images for preoperative surgical simulation and intraoperative navigation in 23 patients with intracranial tumors. Preoperative 3D images provided useful information concerning the relationship among the tumors, critical cortices and vessels, and allowed a choice of the optimal surgical approach and the extent of tumor resection in order to minimize surgical destruction of vital structures. Intraoperative navigation using 3D images was useful to keep the intraoperative orientation by real-time anatomical interaction. Functional mapping and intraoperative monitoring were also useful for preservation of postoperative motor function. Therefore, presurgical simulation and intraoperative navigation using 3D images are essential to perform less invasive surgery.

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Hypertrophic pachymeningitis is an inflammatory fibrous process which involves the dura mater, especially the cerebellar tentorium. Idiopathic hypertrophic cranial pachymeningitis is essentially a diagnosis of exclusion. The authors describe three patients with idiopathic hypertrophic cranial pachymeningitis who presented a variety of clinical features. Imaging studies revealed diffuse thickening of the dura mater. The first patient presented with headache and cranial nerve palsies. MRI revealed enhancing hypertrophic dura mater over the subdural effusion. The second patient complained of headache and nausea. CT demonstrated hydrocephalus and thickening of the falx and cerebellar tentorium. Imaging studies of the third patient showed a mass lesion mimicking meningioma en plaque. Etiology of the pachymeningitis is not clarified in any of these three cases, which are therefore diagnosed as idiopathic hypertrophic cranial pachymeningitis.

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Meningiomas rarely metastasize through the cerebrospinal pathway. The authors reported a case of cerebrospinal fluid(CSF)dissemination of malignant meningioma. A 49-year-old female was admitted to our hospital with progressive nausea and headache. MRI demonstrated a space occupying lesion in the right-mid frontal area which was homogeneously enhanced with Gd-DTPA. The tumor which was attached to the falx was resected subtotally. Because of the rapid tumor progression, a reoperation was done in 3 months after the initial operation. Pathohistological examinations revealed meningotheliomatous meningioma mixed with a sarcomatous component. Postoperative irradiation could not be performed because of patient's refusal. In 9 months after the initial operation, the patient developed tetraparesis, dysarthria, dysphagia, and disturbance of consciousness. MRI disclosed the metastatic tumor at the lower half of the fourth ventricle protruding into the medulla oblongata. This tumor in the fourth ventricle was totally removed and found to be consisted of only sarcomatous component pathohistologically. Although her neurological status improved postoperatively, she expired 3 weeks after operation. Seventeen reported cases and our case are summarized and reviewed. Malignant meningioma may have the high tendency for the CSF dissemination.

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The authors report 3 cases of traumatic acute subdural hematoma. Two of the three hematomas, showing mixed density on computed tomography, were rapidly resolved, but one of the three hematomas was not resolved. Two mechanisms of rapid resolution of acute subdural hematoma were thought to be : 1)obliteration by the pressure produced by acute brain swelling, and ; 2)participation of the cerebrospinal fluid leakage secondary to tearing of the arachnoid membrane, which may have played an important role in washing out the hematoma.

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The pathogenesis of spasmodic torticollis can be classified into three categories : extrapyramidal, peripheral and psychogenic. Recently, as a method of treating spasmodic torticollis of the peripheral type, microvascular decompression of the accessory nerve has been reported to be effective. In this report, we described a case of spasmodic torticollis who markedly improved after microvascular decompression. This twenty-year-old man had painful spasmodic torticollis of the left horizontal type. Following failure of conservative therapies including sedatives, muscle relaxants, stretching, EMG biofeedback and peripheral nerve block, the patient underwent suboccipital craniectomy and C1 laminectomy. In the operation, the right accessory nerve was found to be fixed on the right vertebral artery at the C1 level due to the aberrant nerve and was also compressed by a branch of the posterior inferior cerebellar artery and veins in the right cerebellomedullary fissure. Microvascular decompression was performed at these two parts. Immediately after surgery, the patient showed remarkable improvement of his spasmodic torticollis. Although it is rare that the spasmodic torticollis is caused by multiple vascular compression of the accessory nerve, careful observation in the whole course of accessory nerve will be important when the spasmodic torticollis is surgically treated with microvascular decompression.

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A case of the late postpartum convulsion due to highly similar mechanisms on "late postpartum eclampsia" without toxemia of pregnancy is reported. A 30-year-old female in 5 days after delivery was admitted due to a suddenly developed generalized clonic convulsion after headache with scintillating scotoma. On admission, she had hypertension without any neurological deficits. On day 0 CT scans showed a low-density lesion in the left occipital subcortical area. On day 10 MR-images(MRI)revealed hyperintensity on T2-weighted images in the same area. MR-angiograms(MRA)on day 10 and cerebral angiograms on day 13 demonstrated multi-local vasospasm in the bilateral main arterial trunks of the anterior and posterior circulations. On a satisfactory course the patient was discharged without sequelae 3 weeks after the attack. All the abnormal findings disappered on MRI and MRA 7 weeks after the attack. Convulsions with initial presentation more than 48 hours but less than 4 weeks after delivery with toxemia of pregnancy are referred to as "late postpartum eclampsia". In our case, the late postpartum convulsion without toxemia suggested occurring in the highly similar mechanisms on "eclampsia", because of the convulsion with hypertension after the prodromal symptoms, the reversible multiple cerebral vasospasms, and no other systemic diseases. We emphasize that closer attention to these prodromal symptoms can prevent postpartum women, even in the absence of antecedent preeclampsia, from this entity.

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Ventriculoperitoneal shunt(VPS)or lumboperitoneal shunt(LPS)has an important role to relieve hydrocephalus. Kinking of the peritoneal tube is a serious problem caused by surgical procedure, which may produce shunt malfunction and requires reoperation. Kinking mostly occurs at the site of stitches on the sheath of rectus abdominis muscle. Until now neurosurgeon loosely sutured the sheath drawing on his experience. In the present study, authors introduce a newly developed silicon outer guard device that prevents kinking of the peritoneal tube in VPS and LPS systems.

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