Search PubMed⌕ Search

Biomedical subjects

K Mizoi

Publications and source records attributed to K Mizoi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Symptomatic vessel narrowing caused by spontaneous rupture of craniopharyngioma cyst--case report.

A 36-year-old female presented with cerebral infarction due to severe vessel stenosis after spontaneous rupture of a craniopharyngioma, manifesting as aphasia and drowsiness. Neuroimaging showed the suprasellar cystic tumor with wall enhancement and cerebral infarction in the left temporoparietal region, and also enhancement of the left sylvian fissure and prepontine cistern. Angiography showed severe narrowing at the C1 portion of the left internal carotid artery (ICA) and the M1 portion of the left middle cerebral artery (MCA). The tumor was subtotally removed via a bifrontal craniotomy. There was accumulated milky-white debris around the left ICA and MCA. She became alert within a few days postoperatively. Repeat angiography 1 month after surgery demonstrated slight improvement of vessel narrowing. The neuroimaging and intraoperative findings suggested that the stenosis was due to vasospasm induced by chemical meningitis resulting from cyst rupture.

Adult↗
PubMed1998

Multimodality treatment for large and critically located arteriovenous malformations.

To define the current status of the multimodality treatment for large and critically located arteriovenous malformations (AVMs), we have made a retrospective review of 54 consecutive patients with Spetzler-Martin grade IV and V AVMs. The size of nidus is larger than 3 cm in diameter in all cases. Initially, all but one were treated by nidus embolization with the aim of size reduction. Only one patient had complete nidus occlusion by embolization alone. In 52 patients, the obliteration rate of nidus volume averaged 60% after embolization. Ten patients underwent complete surgical resection of AVMs following embolization with no postoperative neurological deterioration. Thirty-one patients underwent stereotactic radiosurgery following embolization. At the time of this analysis, 30 patients underwent follow-up angiography 2-3 years after radiosurgery. The results of radiosurgery correlated well with the preradiosurgical AVM volume. Of 16 patients with small residual AVMs (< 10 cm3, a mean volume of 4.7 cm3), nine (56%) had complete obliteration, and six (38%) had near-total or subtotal obliteration by 3 years after radiosurgery. In contrast, of 14 patients with large residual AVMs (> or = 10 cm3, a mean volume of 17.9 cm3), only two (14%) had complete obliteration, and eight (57%) had near-total or subtotal obliteration. Repeat radiosurgery was performed for the patients with remaining AVMs at 3-year follow-up review. This study indicates that a certain number of large and critically located AVMs can be safely treated by either microsurgery or radiosurgery following a significant volume reduction by nidus embolization. The present data also suggest the need and possible role of repeat radiosurgery in improving complete obliteration rate of large difficult AVMs, since many of those AVMs have significantly responded to initial radiosurgery.

Adolescent↗
PubMed1998

Dural arteriovenous shunts at the craniocervical junction.

OBJECT: A retrospective analysis was conducted of 10 patients (three women and seven men) who were treated for spinal dural arteriovenous shunts (AVSs) located at the craniocervical junction. This analysis was performed to evaluate the characteristics of this unusual location in contrast with those of the more common thoracic and lumbar AVSs. METHODS: Seven patients presented with subarachnoid hemorrhage (SAH) and one with slowly progressive quadriparesis and dyspnea due to myelopathy. The other two cases were detected incidentally and included a transverse-sigmoid dural AVS and a cerebellar arteriovenous malformation. Angiographic studies revealed that the spinal dural AVSs at the C-1 and/or C-2 levels were fed by the dural branches of the radicular arteries that coursed from the vertebral artery and drained into the medullary veins. Venous drainage was caudally directed in the patient with myelopathy. In contrast, the shunt flow drained mainly into the intracranial venous system in patients with SAH. Furthermore, in four of these patients a varix was found on the draining vein. In all patients, the draining vein was interrupted surgically at the point at which this vessel entered the intradural space, using intraoperative digital subtraction angiography to monitor flow. The postoperative course was uneventful in all patients and no recurrence was confirmed on follow-up angiographic studies obtained in seven patients at 6 months after discharge. CONCLUSIONS: If computerized tomography scanning shows SAH predominantly in the posterior fossa and no abnormalities are found on intracranial four-vessel angiographic study, proximal vertebral angiography should be performed to detect dural AVS at the craniocervical junction. The results of surgical intervention for this disease are quite satisfactory.

Adult↗
PubMed1998

Therapeutic results of intra-arterial chemotherapy in patients with malignant glioma.

Thirty-three adult patients with anaplastic astrocytoma or glioblastoma multiforme, verified between 1990 and 1997, received postoperative intra-arterial ACNU chemotherapy and irradiation. Since our previous strategies to malignant gliomas had included intra-venous ACNU, the purpose of the present study is to evaluate the advantage of intra-arterial ACNU over its intra-venous counterpart as the historical control (37 patients). The median survival was 74.7 weeks for the former and 81.7 weeks for the latter. Although both groups were equivalent in survival, toxicity was less frequent in the intra-arterial group. Histopathological diagnosis, patient age and the Karnofsky's performance status related well with the survival.

Adult↗
PubMed1998

[Superficial siderosis appeared in a case of suprasellar embryonal carcinoma].

A case of superficial siderosis that appeared in a case of suprasellar embryonal carcinoma is reported. A 24-year-old man presented polydipsia and vertigo. MRI revealed a suprasellar tumor. The tumor contained high intense spots on T1-weighted images, suggesting intratumoral hemorrhage. He underwent a surgery, which proved it as embryonal carcinoma pathologically. Cerebrospinal fluid was xanthochromic at surgery, suggesting terminal hemorrhage. After surgery, he received a total dose of 56 Gy of irradiation. Tumor decreased in size and symptoms improved. However, he presented occipital headache 7 months after surgery. MRI showed disseminated tumors in the subarachnoid spaces. He received irradiation for the whole spine and adjuvant chemotherapy. During treatment, MRI demonstrated low signals on the surface of the brain stem, suggesting the superficial siderosis. The lesions spread to the surface of the cerebellum and tentorium cerebelli. Superficial siderosis is characterized by the deposition of hemosiderin in the leptomeninges, cranial nerves and spinal cord. The etiology of the hemosiderin deposition is thought to be chronic or recurrent bleeding into subarachnoid space. Experimentally, similar lesions have been produced in the animals following intrathecal injection of blood or hemolysed red cells. In the literature, MRI demonstrated a rim of marked hypo-intensity on T2-weighted images, consistent with hemosiderin deposits, on the surface of cerebellum and brain stem. Gradient-echo sequences have been more sensitive than T2-weighted images of spin echo sequences. In the present case, the superficial siderosis seems to be due to chronic tumoral hemorrhage. This phenomenon could be related to chemotherapy using CDDP and etoposide.

Adult↗
PubMed1997

Importance of management of unruptured cerebral aneurysms.

BACKGROUND: Since excellent recovery is hardly expected in patients with severe subarachnoid hemorrhage, management of unruptured aneurysms is essential in reducing the overall mortality and morbidity rates. The widespread use of less invasive imaging tools such as magnetic resonance angiography (MRA) has made "Brain Check-up Systems" very popular in Japan. Therefore, unruptured aneurysms have been found much more often than before. METHODS: During the 1-year period of 1994, 80 patients underwent radical surgery for aneurysms in our institute. Thirty-two patients (40%) underwent surgery for unruptured aneurysms, while 48 patients (60%) underwent surgery for ruptured aneurysms. In patients with unruptured aneurysms, we have operated when the aneurysm is larger than approximately 5 mm in diameter, arising from the common sites in the circle of Willis, and when the patient's age is under 70 years. To prevent surgical complications in unruptured aneurysms, we often use a wrapping technique with Bemsheets (cotton) and adhesives. RESULTS: The outcomes were good in all 32 cases of unruptured aneurysms. CONCLUSIONS: We believe that early detection and prophylactic surgery for unruptured aneurysms will improve the overall outcome of aneurysm treatment in the future.

Aged↗
PubMed1997

Localizing the central sulcus by functional magnetic resonance imaging and magnetoencephalography.

To further validate the potential of functional magnetic resonance imaging (fMRI) for localization of the sensorimotor cortex, fMRI was compared with somatosensory evoked fields (SEFs) in eight normal volunteers. A conventional 1.5 T MRI scanner and an MRI-linked 66-channel whole head magnetoencephalography system were used. fMRI activated by unilateral hand squeeze movement indicated the highest activation on the central sulci that were localized by SEFs in all 16 contralateral hemispheres. This indicates that although the fMRI signal activation may originate from a vein running along the central sulcus, fMRI is reliable to detect the central sulcus. The pre-central gyrus also indicated some signal activation on fMRI implying better visualization of spatial distribution of activation. fMRI and SEFs are complementary methods for localizing the central sulcus.

Adult↗
PubMed1997

Clinico-pathological study of Cushing's disease with large pituitary adenoma.

OBJECTIVE: To explore the biological and morphological differences between large Cushing's adenomas and small adenomas, we investigated the clinical, endocrinological, neuroradiological, and histological features of patients with large Cushing's adenomas and compared them with patients with small Cushing's adenomas. PATIENTS: Five of 250 patients with Cushing's disease undergoing trans-sphenoidal operations from 1989 to 1995 had large adenomas with maximum diameters greater than 30 mm. The clinical characteristics of these five patients were compared with the 14 patients with Cushing's disease with small adenomas in our series. RESULTS: Oedema, myopathy, and mental disturbance were more frequent and hypertension was less frequent among patients with large adenomas. The high-dose (8 mg) dexamethasone test did not suppress cortisol production in any of the five patients. Invasion into surrounding tissue was demonstrated by magnetic resonance imaging in all five cases. All five large adenomas had scarce or no periodic acid-Schiff-positive granules and were sparsely granulated ultrastructurally. Three tumours contained cells with honeycomb Golgi apparatus which rarely contained immature secretory granules. One Crooke's cell adenoma contained trapped or displaced secretory granules. The other tumour had dilated trans-Golgi network-derived vacuoles that contained reticular or circular electron-dense material. These findings were in striking contrast to those of small Cushing's adenomas, which showed strong PAS positivity, densely-packed granulation, and had prominent Golgi complex harbouring developing secretory granules. CONCLUSIONS: We found that the tumour cells in large adenomas produced only small amounts of ACTH, and showed indications of disturbances in the regulated exocytotic pathways. These factors may account for the different clinical characteristics of Cushing's disease with large pituitary adenomas.

Adenoma↗
PubMed1997

Striate cortical generators of the N75, P100 and N145 components localized by pattern reversal visual evoked magnetic fields.

Magnetic fields evoked by checkerboard pattern reversal visual stimulation to the monocular left or right half-field were recorded over the whole head using a helmet-shaped 64 channel magnetoencephalography system in fourteen normal subjects. The sources of the triphasic N75m-P100m-N145m responses were located using a single current dipole model. Relative locations and orientations of the N75m and N145m dipoles to the P100m dipole were calculated for each subject to reduce errors due to 'anatomical variability and then averaged for all subjects under the same stimulus conditions. These averaged parameters showed that N75m and N145m originated from the same location in the striate cortex as P100m and reversed their orientations successively by 180 degrees during the time course.

Adult↗
PubMed1997

Neuromagnetic evaluation of cortical auditory function in patients with temporal lobe tumors.

The N100m wave response of the auditory evoked magnetic field originates in the posterior part of the bilateral superior temporal planes for either contra- or ipsilateral ear stimulus. Cortical auditory function was evaluated in 14 patients with temporal lobe tumors using a magnetic resonance (MR) imaging-linked whole-head magnetoencephalography (MEG) system. Before surgery, seven patients had normal N100m latency (within the range of the mean +/- 2 standard deviations of 37 normal volunteers) in both normal hemispheres and in those with lesions, and MR imaging indicated no tumor invasion or edema in the posterior one-third of the superior temporal planes, even when the sylvian fissure was shifted upward due to the mass effect. Seven patients had prolonged N100m latency or absence of N100m in the hemisphere containing the lesion, and the posterior portion of the superior temporal plane was involved by the tumor or perifocal edema. Prolonged N100m latency recovered to the normal range after removal of tumors in two of four patients investigated postoperatively. The MEG system can be used to evaluate cortical auditory function noninvasively before and after surgical treatment of temporal lobe tumors.

Adult↗
PubMed1997

[Evaluation of various somatosensory stimulations for functional MRI].

The aim of this functional magnetic resonance imaging (fMRI) study was to test detectability of activated area using various somatosensory stimulations. The following stimulations were performed in normal volunteers: regular or irregular electrical median nerve stimulation (n = 5, each), tactile stimulation to the palm and fingers (n = 8), pain stimulation to the index finger (n = 5) or to the palm and fingers (n = 5). fMRI was acquired with a spoiled gradient echo sequence at 1.5 T. Detectability of activated area was the highest when the pain stimulation was applied to the palm and fingers (80%). A successful rate for the tactile stimulation was 25%, and the other stimulations failed to demonstrate any activation. When successful, the highest signal activation on fMRI was seen on a sulcus, which presumably arose from a vein. The sulcus was defined as the central sulcus by somatosensory evoked field using a median nerve stimulation. Our study indicates that the pain stimulation to the palm and fingers may be a choice for the sensory fMRI.

Adult↗
PubMed1997

[Postoperative normalization of prolonged P100m latency in the visual evoked magnetic field in a patient with occipital meningioma].

A 49-year-old female with a left occipital parasagittal meningioma was found to have prolonged P100m latency of the pattern reversal visual evoked magnetic field only in the hemisphere containing the lesion. After total removal of the tumor, the P100m latency was normalized in the affected hemisphere. Based on current dipole models, all the P100m dipoles were localized at the lateral bottom of the calcarine fissures bilaterally, as indicated by our previous study with normal subjects. Since the tumor was located near the parietoocipital sulcus and distant from the primary visual cortex, disturbance of the higher visual cortex probably affected the P100m latency.

Brain Mapping↗
PubMed1997

[Fatal brain stem infarction due to rupture of a brain abscess: a case report].

We report a case of a brain abscess which initially presented with subcortical hematoma and ultimately resulted in fatal brain stem infarction due to its rupture into the subarachnoid space. A 50-year-old male was admitted to a nearby hospital with complaints of headache, fever, and sensory aphasia. He had ventricular septal defect found 15 years previously, sinusitis, and liver cirrhosis. Computerized tomographic (CT) scan revealed a left temporal subcortical hematoma. Gadolinium-DTPA enhanced magnetic resonance imaging (MRI) showed faint ring-like enhancement at the margin of the lesion. The left internal carotid angiogram demonstrated the vascular blush and early venous filling of the vein of Labbé. Administration of antibiotics and predonine resulted in resolution of fever within five days. MRI obtained 17 days after the onset showed typical ring-like enhancement. The mass was just adjacent to the lateral ventricle. The patient was transferred to our hospital for further examination and treatment 21 days after the onset. Fever had recurred 2 days before admission to our hospital. One day after admission, the patient began to vomit. About 15 hours following this symptom, he suddenly became comatose and tetraplegic. CT scan demonstrated a rupture of the abscess. Emergent drainage from the lateral ventricle and the abscess cavity was undertaken. Follow-up CT scan revealed multiple infarctions involving the upper brain stem and the bilateral thalamus. He died on the 29th day after the onset. The mechanisms of hemorrhage with a brain abscess and cerebral infarction after rupture of brain abscess are discussed. Hemorrhage with brain abscess is extremely rare. However, brain abscess should be considered as a possible etiology of an atypical hematoma. To avoid fatal rupture of the brain abscess, immediate treatment is essential. Once the rupture of the brain abscess occurs, its contents might cause vasospasm severe enough to cause cerebral infarction.

Brain Abscess↗
PubMed1996

Types of unruptured cerebral aneurysms reviewed from operation video-recordings.

To estimate the proportion of unruptured cerebral aneurysms with thin-walled sac, we have analyzed the operative findings of 78 incidental cerebral aneurysms found in 51 consecutive surgical cases by reviewing of intra-operative videotape recordings. Among 78 unruptured aneurysms, 23 (30%) were evaluated as thick-walled aneurysms (Type A), 39 (50%) with partially thin-walled sac (Type B) and 16 (20%) with entirely thin wall sacs (Type C). The mean size of Type A aneurysms was 10.4 mm (ranging from 3 to 22 mm), in Type B it was 9.8 mm (ranging 4 to 25 mm) and in Type C it was 4.4 mm (between 2-12 mm). Approximately two-thirds of Type C aneurysms were 4 mm in size or smaller, and Type C aneurysms were significantly smaller than Type A aneurysms. In summary, this preliminary study has provided two original data. 1) About 70% of incidental unruptured aneurysms have a partially or entirely thin-walled sac. 2) Many of the small aneurysms have an entirely thin sac. Assuming that thin-walled aneurysms are at a high risk of subsequent rupture, the surgical intervention for incidental unruptured aneurysms may be recommended irrespective of their size if the surgical risk is considered low.

Adult↗
PubMed1996

Indirect revascularization for moyamoya disease: is there a beneficial effect for adult patients?

BACKGROUND: It is generally accepted that excellent development of collateral circulation can be achieved through indirect nonanastomotic bypass procedures for pediatric patients with moyamoya disease. However, there are no definitive conclusions about the effect of indirect revascularization for adult patients. To clarify the value of indirect bypass surgery for adult moyamoya disease, we have analyzed their follow-up angiographic results in comparison with those of the pediatric patients. METHODS: Between 1989 and 1993, 23 patients underwent combined direct and indirect bypass surgery. They consisted of 16 adults (mean age, 35; range, 20-59) and seven children (mean age, 10; range, 3-16). The main symptoms were those due to cerebral ischemia in all but 1 of 23 patients. Preoperative cerebral blood flow studies showed all patients to have decreased vascular reserve (misery perfusion). Postoperative follow-up angiography was done in all patients at a median of 6 months after the surgery. RESULTS: All pediatric patients showed good or moderate development of collaterals through the indirect bypass. Among the adult group, seven patients aged 20 to 29 had angiographic results similar to those of the pediatric group . On the other hand, nine patients older than 30 had results contrary to those of pediatric patients: (1) the degree of indirect revascularization declined to moderate or poor grades (especially in patients older than 40) and (2) the degree of direct bypass filling improved to high or medium grades. CONCLUSIONS: The results suggest that advancing age apparently affects the development of collateral formation through the indirect bypass. Consequently, direct bypass is thought to be the main treatment option for patients older than 40.

Adolescent↗
PubMed1996

A pitfall in the surgery of a recurrent aneurysm after coil embolization and its histological observation: technical case report.

OBJECTIVE AND IMPORTANCE: This case report details the unexpected surgical difficulty encountered in treating a recurrent aneurysm after coil embolization and presents the histological findings of the resected aneurysm. This is only the second reported case of histological description of an aneurysm after coil embolization in a human. CLINICAL PRESENTATION: A 60-year-old woman experienced a 3-month history of chronic headache. Neuroimaging studies demonstrated a 2-cm anterior communicating artery aneurysm. The aneurysm was treated with a two-stage endovascular coil embolization, resulting in almost complete occlusion of the aneurysm. A cerebral angiogram at 6-month follow-up demonstrated slight refilling of the aneurysm, and angiography at 18 months showed a marked increase in the size of the small remnant. Therefore, the patient was referred for direct surgical repair of the aneurysm. INTERVENTION: The distal aneurysm dome, which had been packed with the coils and thrombus, was resected under temporary arterial trapping. An intra-aneurysmal endarterectomy was required, because the aneurysm wall developed intimal dissection that extended to the orifices of afferent and efferent arteries. The aneurysm was then obliterated with multiple clips, reconstructing the patent vessel lumen. However, the patient awoke from surgery with left hemiparesis. A postoperative angiogram disclosed occlusion of the right anterior cerebral artery. An histological study of the thrombosed aneurysm showed that the luminal surface of thrombus was not lined by endothelium. CONCLUSION: This case demonstrated not only the limited efficacy of coil embolization treatment for wide-necked aneurysms but also the potential difficulty in the direct surgical repair for such recurrent aneurysms.

Aortic Dissection↗
PubMed1996

[Auditory evoked magnetic fields in cases with temporal lobe glioma].

Auditory evoked magnetic field (AEF) is known to be suitable to separate left and right hemispheric activities while auditory evoked potential is not. To evaluate cortical auditory function in ten patients with temporal lobe gliomas, we measured AEF for monaural tone stimuli using a helmet-shaped 66-channel MEG system. Latency of the N 100 m, the most prominent peak with a latency around 90 ms, was measured in the hemisphere contralateral to the stimulus onset. In five patients, the N 100 m latency was within our normal range (mean +/- 2 s.d.). In these five cases, tumor was located in the anterior or the inferior part of the temporal lobe. We observed significant delay of the N 100 m latency in four patients and disappearance of the N 100 m in another patient. In the later five patients, tumor extended to the superior and posterior part of the temporal lobe. AEF can be used to evaluate cortical auditory function noninvasively in cases with temporal lobe gliomas.

Adult↗