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F Mihara

Publications and source records attributed to F Mihara.

At least 19 recordsLinked to original sources
PubMed2006

Cerebral hemodynamics in Moyamoya disease: correlation between perfusion-weighted MR imaging and cerebral angiography.

BACKGROUND AND PURPOSE: In Moyamoya disease, the relationship between cerebral hemodynamics and angiographic findings has not been fully evaluated. The purpose of this study is to evaluate hemodynamics in Moyamoya disease with perfusion-weighted MR imaging (PWI) and cerebral angiography. METHODS: Twenty patients with Moyamoya disease were the subjects. Mean transit time (MTT) derived from PWI was calculated in the medial frontal lobes, the posterior frontal lobes, the occipital lobes, and the basal ganglia. From the angiographies, we classified the degrees of internal carotid artery (ICA) and posterior cerebral artery (PCA) stenoses as well as the degrees of Moyamoya vessels and leptomeningeal anastomosis (LMA). MTT in each region was compared with the angiographic findings. RESULTS: MTT positively correlated with the degree of ICA stenosis in the medial frontal (P < .01), posterior frontal (P < .001), and occipital (P < .001) lobes, as well as in the basal ganglia (P < .001). MTT correlated with the degree of PCA stenosis in the medial frontal (P < .001), posterior frontal (P < .001), and occipital (P < .001) lobes, as well as in the basal ganglia (P < .001). MTT correlated with the degree of Moyamoya vessels in the medial frontal (P < .05) and posterior frontal (P < .01) lobes. A multivariate analysis revealed that ICA and PCA stenoses and Moyamoya vessels were independent factors that prolonged MTT. CONCLUSION: Both ICA and PCA stenoses may influence overall cerebral perfusion in Moyamoya disease. The development of Moyamoya vessels may indicate hemodynamic impairment.

Adolescent↗
PubMed2003

Deterioration of pre-existing hemiparesis brought about by subsequent ipsilateral lacunar infarction.

Mechanisms of post-stroke recovery are still poorly understood. Recent evidence suggests that cortical reorganisation in the unaffected hemisphere plays an important role. A 59 year old man developed a small lacunar infarct in the left corona radiata, which then caused marked deterioration in a pre-existing left hemiparesis that had resulted from an earlier right putaminal haemorrhage. Functional magnetic resonance imaging showed that the paretic left hand grip activated the ipsilateral left motor areas, but not the right hemispheric motor areas. This suggests that partial recovery of the left hemiparesis had been brought about by cortical reorganisation of the left hemisphere and intensification of the uncrossed corticospinal tract. The subsequent small infarct may have damaged the uncrossed tract, thereby causing the pre-existing hemiparesis to deteriorate even further.

Brain Infarction↗
PubMed2001

Cerebral ganglioglioma with epilepsy: neuroimaging features and treatment.

Gangliogliomas are an increasingly recognized cause of epilepsy in children. In this study the clinical, neuroimaging, and neurophysiological data of five patients with cerebral ganglioglioma and epilepsy are reviewed retrospectively. The average age of these patients was 4.4 years at onset and the average duration of seizures before diagnosis was 11 months. Tumors were located in the frontal (3), parietal (1), and occipital (1) lobes. While one cystic and four solid tumors showed various densities on CT and MRI, one frontal lesion was not demonstrated by CT scan but clearly shown by MRI. Scalp electroencephalography (EEG) showed neither localized nor epileptiform abnormalities in three patients, while the remaining two had these abnormalities. In one patient, invasive chronic electrocorticography (ECoG) recordings with subdural electrodes revealed an ictal onset zone located in the hand motor area. In all patients, intraoperative ECoG failed to reveal any epileptiform activities, and tumor removal alone was performed. For a mean of 3.4 years after surgery, all patients are alive and seizure-free, with stable imaging findings. Tumor resection may be the most important factor for optimal seizure control and prevention of tumor recurrence despite the fact that EEG and ECoG findings may conflict on tumor location.

Adolescent↗
PubMed2001

Fetal germinal matrix and intraventricular haemorrhage diagnosed by MRI.

Subependymal germinal matrix haemorrhage and intraventricular haemorrhage (GMIVH) is a common complication of delivery in preterm neonates but has rarely been observed in the fetus. We report two cases of GMIVH in fetuses of 36 weeks gestation, clearly demonstrated by antenatal MRI. In both cases progressive ventriculomegaly was observed, and ventriculoperitoneal shunts were placed at 19 and 6 months of age, respectively. Prenatal GMIVH may be a cause of congenital hydrocephalus, for which no aetiology has yet been found.

Adult↗
PubMed2001

Cerebral abnormalities in lumbosacral neural tube closure defect: MR imaging evaluation.

OBJECTS: It was decided that patients with caudal neural tube closure defect should be evaluated by means of cranial MR scans, with special attention devoted to cerebral malformations other than craniospinal abnormalities. METHODS: Twenty-four patients with lumbosacral neural tube closure defects, classified into myeloschisis (MS, 9 cases), meningo(myelo)cele (MMC, 10 cases) and spina bifida occulta with lumbosacral lipoma (LL, 5 cases), were evaluated in this way, and cerebral anomalies were found to be present in all MS patients, 8 with MMC and 2 with LL. The cerebral hemispheres were mildly to moderately hypoplastic in 6 patients, and hydrocephalus was present in 6 patients with MS and in 5 with MMC; LL was not associated with ventriculomegaly in any patient. Polymicrogyria was present in 6 patients with MS, in 3 with MMC, and in none of those with LL. Heterotopic gray matter was observed in only 2 patients with MS. Partial agenesis of the corpus callosum was found in 6 MS patients and in 6 patients with MMC, but was not seen in patients with LL. Cervicomedullary anomalies, such as herniation of the cerebellar tonsils through the foramen magnum, were found in 7 patients with MS, in 4 with MMC and in 2 with LL. While patients with LL were accompanied by only mild forebrain anomalies, cerebral abnormalities in MS and MMC were generally more severe in degree than those in LL. Among 21 patients in whom intellectual and performance status was evaluated, 9 of the 17 patients with cerebral anomalies had some degree of retardation, and the 4 without cerebral anomalies were normal. CONCLUSIONS: Caudal neural tube closure defect is not a single developmental abnormality, and can be regarded as one part of the spectrum of malformations causing primary insults that are as yet unidentified to the developing central nervous system.

Adolescent↗
PubMed2001

Subependymal giant cell astrocytoma: clinical and neuroimaging features of four cases.

The clinical history, neuroimaging features, treatments, and outcome of 4 patients with histologically verified subependymal giant cell astrocytomas (SEGA) were retrospectively reviewed. The average age at the time of surgery was 13.3 years. Headache related to raised intracranial pressure was the first and only sign in 2 patients, with the remaining 2 being admitted because of sequential neuroimaging studies over several years revealing the growth of 'subependymal nodules' into intraventricular tumours. In each case the tumour was in the region of Monro's foramen and was associated with ventricular dilatation. On computed tomography (CT), multiple subependymal nodules were found in 3 patients, and these well circumscribed isodense SEGAs were markedly enhanced by contrast medium. On magnetic resonance imaging (MRI), which was obtained in 3 patients, 2 SEGAs were isointense with the cerebral cortex and one with the white matter on T1-weighted images, and on T2-weighted images, 2 were isointense with the cortex and one with the white matter. At surgery the tumours appeared to originate from the inferolateral wall of the lateral ventricle in the region of the head of the caudate nuclei. Total macroscopic removal was achieved in 3 patients, and subtotal removal in one patient. Follow up ranged from 4.6 to 13.2 years, and all patients have exhibited similar physical and mental conditions to preoperative. So far there has been no evidence of any recurrences. The diagnosis and the surgical indications for SEGA are discussed, with periodic monitoring with neuroimaging studies being recommended even for asymptomatic patients with 'subependymal nodules'.

Adolescent↗
PubMed2001

[Clinical trial of bradykinin-enhancing chemotherapy for a recurrent malignant glioma: a case report].

Patients with malignant glioma undergo a combined treatment with surgical resection, radiotherapy, and chemotherapy. Although those treatments usually show some restraining effects on the tumor, a relapse occurs in most of the patients within a few years. We have investigated the feasibility and safety of intra-arterial chemotherapy for malignant brain tumors by enhancing vascular permeability using intra-arterial bradykinin infusion. In 2001, The Committee of Ethics in Kyushu University approved our clinical trial of the bradykinin-enhancing chemotherapy for recurrent malignant gliomas. We here report the first case of our clinical trial. A 31-year-old man, who had undergone surgical resection followed by chemotherapy and irradiation for malignant progression of the left frontal astrocytoma over a period of 2 years, had a relapse of the tumor in the bilateral frontal lobes. After obtaining informed consent, bradykinin and carboplatin were infused through a microcatheter at the left A1 portion under general anesthesia. By dose escalation of bradykinin, the enhanced lesion in the bilateral frontal lobes diminished on magnetic resonance imaging after 3 trials with 3-week intervals, regardless of new lesions outside of the treated area. No neurological or physiological complication including myelosuppression was noted. Bradykinin-enhancing chemotherapy appeared to be effective and safe for malignant glioma. Because it was able to increase drug delivery to the tumor, it was possible to reduce the size of the dose of chemotherapeutic agent, which resulted in minimum complication.

Adult↗
PubMed2000

Subependymoma of the lateral ventricles.

Four subependymomas of the lateral ventricle were reviewed with regard to clinical presentation, neuroimaging features, treatment, histopathological features, and long-term follow-up. There were two male and two female patients ranging in age from 27 to 60 years (mean 48.3 years). While two patients presented with symptoms and signs of raised intracranial pressure, two others were found incidentally during neuroimaging investigations to have intraventricular tumors. Neuroimaging characteristics of these tumors included no paraventricular extension, iso- or hypodensity with minimal enhancement on computerized tomography (CT), or iso- or hypointensity on T1-weighted and hyperintensity on T2-weighted magnetic resonance images (MRI). The usual finding on MRI was of no or scarce contrast enhancement, but one case showed heterogeneous enhancement. Three patients underwent total resection of the tumor and one underwent partial resection. No patients received postoperative radiation therapy. All patients have been doing well 4.8 to 15.4 years (mean 8.8 years), after surgery. Although there are no absolutely specific features to distinguish these tumors from other intraventricular tumors preoperatively, subependymoma should be kept in mind for differential diagnosis, as this tumor may safely be removed without sacrificing contiguous normal tissue and with good long-term results.

Adult↗
PubMed2000

Diagnostic usefulness of diffusion-weighted magnetic resonance imaging in influenza-associated acute encephalopathy or encephalitis.

A magnetic resonance imaging (MRI) study was performed for a 20-month-old girl with an influenza type A infection who presented acute encephalopathy. Conventional MRI performed 8 days after the onset of encephalopathy, including T1-weighted, T2-weighted, and fluid-attenuated inversion recovery imaging, revealed only vague lesions in the right frontal, temporal, and parietal lobes. In contrast, diffusion-weighted imaging (DWI) then demonstrated the lesions much more intensively. On the 26th day, the lesions previously observed on DWI had become less discernible. The hyperintensity observed on DWI might reflect cytotoxic edema. Thus, DWI may be useful for evaluation of acute influenzal encephalopathy/encephalitis.

Acute Disease↗
PubMed2000

Correlation between proton magnetic resonance spectroscopic lactate measurements and vascular reactivity in chronic occlusive cerebrovascular disease: a comparison with positron emission tomography.

The purpose of this study is to investigate the correlation between lactate levels and cerebral vascular reactivity (VR) in regions outside an area of chronic cerebral infarction. Multivoxel proton magnetic resonance spectroscopy ((1)H-MRS) and positron emission tomography (PET) were performed in 11 patients who suffered chronic cerebral infarction. Of these 11 patients, 4 were examined before and after bypass surgery. Two regions-of-interests (ROIs) were placed outside the area of chronic infarction. One ROI was placed within a control region on the contralateral side. A lactate peak area was obtained in all ROIs. An N-acetyl aspartate (NAA) peak area was obtained in the ROI within the control region. The ratio of the lactate peak area and NAA peak area (Lct/NAA) was calculated for normalization of the lactate level, and was found to be 0.13 +/- 0. 10 (range, 0 to 0.43). The VR was recorded at 13.3 +/- 20.7% (range, - 44.3 to 68.9%), utilizing PET and administering acetazolamide. A significant negative correlation was observed between the Lct/NAA ratio and VR (r = - 0.709, p < 0.0001). These results suggest that lactate levels and VR are closely related in regions outside areas of chronic cerebral infarction.

Adolescent↗
PubMed2000

[Neuroimaging features of intraventricular neurocytoma].

We presented the clinicopathological features of 8 cases of intraventricular neurocytoma, which was a rare, benign tumor of neuronal origin and affected young patients. In each case the intraventricular tumor existed near the foramen of Monro and/or body of the lateral ventricle, and was associated with ventricular dilatation. A CT scan demonstrated a well-circumscribed iso- or hyperdense mass with some calcification, intratumoral cysts of various sizes and a heterogeneous enhancement. MRI, which was performed in 4 cases, confirmed a mass of isointense or slightly hyperintense on T 1-weighted images, and with multiple sites of attachment (mainly to the septum pellucidum and the head of the caudate nucleus). While these neuroimaging features are helpful in eliminating alternative diagnosis such as ependymomas, choroid plexus papillomas, subependymal giant cell astrocytomas and meningiomas, age of the patient and the tumor location within the lateral ventricle are important features for differential diagnosis.

Adult↗
PubMed2000

[Occipital encephalocele and epilepsy].

We report the incidence of epilepsy in 7 patients with occipital encephalocele (meningocele: 6 cases, meningoencephalocystocele: 1 case). Two cases had epilepsy and a case without the history of epileptic seizure had an epileptic pattern on the EEG. All these 3 cases had cortical dysplasia(CD) such as schizencephaly and subcortical gray matter, and two of them were associated with mental retardation. The location of the prominent CD was correlated with the EEG abnormalities and clinical epileptic pattern in each case. Associated hydrocephalus and placement of VP shunt had no significant influence on the occurrence of the epilepsy. Thus, complicated CD is thought to be epileptogenic in patients with occipital encephalocele.

Adolescent↗
PubMed2000

Ketoacidosis accompanied by epileptic seizures in a patient with diabetes mellitus and mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS).

We herein report a rare case of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and diabetes mellitus with ketoacidosis. An 18-year-old female patient was diagnosed to have diabetes mellitus and insulin therapy was thereafter initiated. At 26 years of age, she was hospitalized for diabetic ketoacidosis, soon followed by a loss of consciousness, left-sided dysmetria, and ataxic speech. MELAS was diagnosed because of the presence of ragged red fibers in a muscle biopsy. At 33 years of age, she was admitted to our hospital because of ketoacidosis and partial status epilepticus. A blood gas examination revealed as follows; arterial pH, 6.88; bicarbonate, 2.1 mmol/l; base excess - 29.8 mmol/l. The serum level of glucose had also increased to 30 mmol/l. The serum levels of lactate and B-hydroxybutyrate were elevated to 11.4 mmol/l and 1,990 micromol/l, respectively. Ketoacidosis improved by fluid replacement and continuous intravenous insulin infusion. A brain MRI demonstrated hyperintensity areas on FLAIR images in the bilateral temporal lobes and the cerebellum. A proton MRS demonstrated the abnormal lactate accumulation in the bilateral temporal and occipital lobes. Since epileptic seizures are rare in patients with diabetic ketoacidosis, such seizures may indicate the existence of MELAS syndrome.

Adult↗
PubMed1999

Possible role of an endovascular provocative test in the diagnosis of glossopharyngeal neuralgia as a vascular compression syndrome.

We utilized endovascular provocative techniques to identify the indications for microvascular decompression surgery in a serious case of glossopharyngeal neuralgia. This is the first reported case in which an endovascular provocative test was applied for diagnosis of glossopharyngeal neuralgia as a vascular compression syndrome. A 68-year-old woman presented with severe paroxysmal facial pain which could not be controlled by medical therapy. Partial effectiveness to carbamazepine led us to wonder whether or not the selection of microvascular decompression surgery would be appropriate. Pre-operative angiography was performed. During the examination a microcatheter was inserted into the right posterior inferior cerebellar artery (PICA), and an attack of typical glossopharyngeal neuralgia occurred. The patient thus underwent microvascular decompression surgery. The PICA was verified to compress the glossopharyngeal nerve and therefore was moved to induce decompression. The patient has since experienced no further pain for one year postoperatively. The diagnosis of glossopharyngeal neuralgia is sometimes complex and it is difficult to select the most appropriate surgical modality. In such cases this endovascular provocative technique may thus be useful for making a definitive decision or microvascular decompression surgery.

Aged↗
PubMed1999

Combining steady-state constructive interference and diffusion-weighted magnetic resonance imaging in the surgical treatment of epidermoid tumors.

We describe the usefulness of three-dimensional Fourier transformation-constructive interference in steady-state (CISS) imaging and diffusion-weighted imaging (DWI) in the pre- and postoperative magnetic resonance imaging evaluation of intracranial epidermoid tumors. Two surgically proven epidermoid tumors in the cerebellopontine (CP) angle were not identified in conventional T1- and T2-weighted images because of a signal intensity similar to that of cerebrospinal fluid (CSF). CISS images clearly demonstrated displacement of the cranial nerves and a shift caused by a lesion in the cistern, but the signal intensity of the tumor by CISS was not sufficiently different from that of CSF to demonstrate the tumor directly. Using DWI, the tumor in the cistern was shown clearly by its increased signal intensity. Together, CISS and DWI compensated for each other's disadvantages, and this combination was useful in guiding surgical treatment of epidermoid tumors in the CP cistern.

Adult↗
PubMed1999

Diffusion-weighted images and vasogenic edema in eclampsia.

BACKGROUND: In eclampsia, it is mandatory to recognize specific cerebrovascular complications before initiation of treatment. Diffusion-weighted magnetic resonance imaging (MRI) is a new technique that differentiates between cerebral infarction and hypertensive encephalopathy with vasogenic edema. CASE: A 23-year-old primigravida developed eclampsia at 29 weeks' gestation. Focal neurologic signs and neuroimaging findings by computed tomography and MRI were consistent with acute infarction or vasogenic edema. Diffusion-weighted MRI did not show an abnormal signal, indicating vasogenic edema. Control of the severe hypertension without anticoagulation therapy was begun. After delivery, the woman's neurologic abnormalities disappeared. CONCLUSION: Diffusion-weighted MRI differentiated between cerebral infarction and vasogenic edema, helping in the management of eclampsia.

Adult↗
PubMed1999

HLA-DPB1*0501-associated opticospinal multiple sclerosis: clinical, neuroimaging and immunogenetic studies.

In order to clarify the relationship between the clinical phenotype and the human leucocyte antigen (HLA) in multiple sclerosis in Asians, 93 Japanese patients with clinically definite multiple sclerosis underwent clinical MRI and HLA-DPB1 gene typing studies. According to a neurological examination, 29 patients were classified as opticospinal multiple sclerosis, 17 as spinal multiple sclerosis and 47 as Western type multiple sclerosis showing the involvement of multiple sites in the CNS including either the cerebrum, cerebellum or brainstem. The opticospinal multiple sclerosis showed a significantly higher age of onset, higher expanded disability status scale scores and higher CSF cell counts and protein content than the Western type multiple sclerosis. On brain and spinal cord MRI, the opticospinal multiple sclerosis showed a significantly lower number of brain lesions, but a higher frequency of gadolinium-enhancement of the optic nerve and a higher frequency of spinal cord atrophy than in Western type multiple sclerosis. The frequency of the HLA-DPB1*0501 allele was found to be significantly greater in opticospinal multiple sclerosis (93%) than in healthy controls (63%, corrected P value = 0.0091 and relative risk = 7.9), but not in Western type multiple sclerosis (66%) or spinal multiple sclerosis (82%). The marked differences in the clinical and MRI findings as well as in the immunogenetic backgrounds between the opticospinal multiple sclerosis and Western-type multiple sclerosis together suggest that HLA-DPB1*0501-associated opticospinal multiple sclerosis is a distinct subtype of multiple sclerosis.

Adult↗