Biomedical subjects

S Ohue

Publications and source records attributed to S Ohue.

At least 19 recordsLinked to original sources

PubMed2004

The dural tail of intracranial meningiomas on fluid-attenuated inversion-recovery images.

We evaluated the "dural tail" associated with 48 intracranial meningiomas on fluid-attenuated inversion-recovery (FLAIR) and contrast-enhanced T1-weighted images. In 30 (62.5%), a dural tail was observed on contrast-enhanced T1-weighted images, and thickening of the dura mater and abnormal signal were identified in the corresponding region on FLAIR images. Thus, FLAIR imaging was useful for showing dural abnormality associated with meningiomas without the needed for contrast medium.

Adult↗

PubMed2001

Discrimination of brain abscess and cystic tumor by in vivo proton magnetic resonance spectroscopy.

Proton magnetic resonance (MR) spectroscopy was evaluated for the differentiation of brain abscesses and cystic brain tumors. Proton MR spectroscopy was performed in vivo in two patients with brain abscess and eight patients with various cystic brain tumors (anaplastic astrocytoma, glioblastoma, and metastatic brain tumor). MR imaging with contrast medium demonstrated ring-like enhanced mass lesions in all patients. The various resonance peaks in proton MR spectra were assigned to metabolites according to chemical shifts. Treatment of the cystic brain lesions was based on the information from proton MR spectroscopy. Aspirated pus from one patient with brain abscess was examined using ex vivo proton MR spectroscopy. The in vivo spectra of brain abscess contained resonance peaks attributed to acetate, lactate, alanine, amino acids, and lipids in both cases, and an additional peak of succinate in one case. In vivo spectra of the neoplasms contained resonance peaks corresponding to lactate, lipids, choline, creatine, and N-acetyl aspartate. Proton MR spectroscopy is useful for discriminating brain abscess from cystic tumors with similar neuroimaging appearance, which is very important for determining the treatment strategy.

Acetates↗

PubMed2001

Measurement of cerebral hemodynamics with perfusion-weighted MR imaging: comparison with pre- and post-acetazolamide 133Xe-SPECT in occlusive carotid disease.

BACKGROUND AND PURPOSE: We generated regional cerebral blood volume (rCBV) and regional cerebral blood flow (rCBF) studies from dynamic susceptibility contrast-enhanced MR images after an intravenous bolus injection of contrast agent (perfusion-weighted imaging [PWI]) by applying indicator dilution theory. We used a multishot echo-planar imaging (EPI) sequence to obtain adequate arterial input function (AIF). Our purpose was to compare the cerebral hemodynamics measured by PWI with the rCBF values and cerebral perfusion reserve obtained by xenon-133 single-photon emission CT (133Xe-SPECT). METHODS: Eight patients with chronic internal carotid artery occlusion or stenosis were examined. PWI data were acquired using a multishot EPI sequence, and the AIF was determined automatically. Our procedure was based on indicator dilution theory and deconvolution analysis. To eliminate the effect of superficial vessels, the automatic threshold selection method was used. RESULTS: AIF was adequate to generate rCBF and rCBV images. The rCBF and rCBV images by PWI were superior to 133Xe-SPECT scans in spatial resolution, and the rCBF values obtained by PWI correlated well with those obtained by 133Xe-SPECT. The regions with severely decreased perfusion reserve, which were determined by pre- and post-acetazolamide 133Xe-SPECT, showed significantly lower rCBF and higher rCBV by PWI than did regions with normal and moderately decreased perfusion reserve. CONCLUSION: The rCBF and rCBV images generated by our procedure using PWI data appear to provide important clinical information for evaluating the degree of cerebral perfusion reserve impairment in patients with chronic ischemia.

Acetazolamide↗

PubMed2000

Selection of surgical approaches for small acoustic neurinomas.

BACKGROUND: The purpose of this study was to evaluate the results of surgery for small acoustic neurinomas at our institute via the middle cranial fossa and retrosigmoid approaches, and to determine the indications for each approach. METHODS: Fifty-three patients with unilateral tumors less than 2 cm in diameter were studied. Surgery was performed via the middle cranial fossa approach in 36 tumors and via the retrosigmoid approach in 17 tumors. RESULTS: The hearing preservation rate was 68% (36/53) in all patients, 93% (14/15) in patients with intracanalicular tumors, 79% (15/19) in patients with tumors less than 1 cm in diameter, and 43% (7/19) in patients with tumors between 1 and 2 cm in diameter. The facial nerve function was excellent or good in 80% (42/53), 74% (11/15), 84% (16/19), and 78% (15/19), respectively. Among the 19 patients with tumors between 1 and 2 cm in diameter, the frequencies of hearing preservation and of excellent or good facial nerve function (47% and 87%, respectively) in the 15 patients approached via the retrosigmoid approach were higher than those (0% and 50%, respectively) in the four patients approached via the middle cranial fossa approach. CONCLUSIONS: We conclude that tumors smaller than 2 cm should be removed because preservation of hearing as well as facial nerve function may be possible in almost all of these patients. Tumors larger than 1 cm should be surgically treated through the retrosigmoid approach.

Adult↗

PubMed2000

Massive deep vein thrombosis after cesarean section treated with a temporary inferior vena cava filter: a case report.

A 25-year-old woman suffered a massive deep vein thrombus in her left common iliac vein extending to the inferior vena cava after an abdominal cesarean section. The massive and floating inferior vena cava thrombus was considered to pose a high risk of pulmonary thromboembolism. After placement of a temporary inferior vena cava filter via the left brachial vein, thrombolytic therapy and anticoagulation therapy were instituted. The filter successfully prevented pulmonary thromboembolism during thrombolytic therapy. This patient was confined to bed because the filter moved vertically with left shoulder joint abduction. Although a temporary inferior vena cava filter is very useful for the prevention of pulmonary thromboembolism in a patient with deep vein thrombus, the appropriate range of activity for such a patient needs careful consideration.

Adult↗

PubMed1999

Diagnostic use of isotropic diffusion-weighted MRI in patients with ischaemic stroke: detection of the lesion responsible for the clinical deficit.

We examined the diagnostic use of isotropic diffusion-weighted (DW) MRI in 140 consecutive patients suspected of or diagnosed as having an ischaemic stroke. Isotropic DW imaging could demonstrate the lesion responsible for the clinical deficit in patients with multiple cerebral infarcts at an early stage, even small lesions without a perifocal oedema or mass effect. Accurate diagnosis by DW images may, however, be difficult about 2 weeks after the onset of stroke.

Adult↗

PubMed1999

Greater superficial petrosal nerve neurinoma. Case report.

The authors report a case of middle cranial fossa neurinoma arising from the left greater superficial petrosal nerve in a 21-year-old woman who presented with a left-sided otitis media that chronically recurred over a period of 5 years. On examination, the patient had a left-sided mild conductive hearing impairment and a slight disturbance in tear secretion on the left side, with sensory disturbance in the left palate. Three-dimensional computerized tomography scans clearly demonstrated the enlargement of the foramen lacerum and foramen ovale, and heavily T2-weighted magnetic resonance images revealed the tumor's location along with the course of the greater superficial petrosal nerve and its extension into the tympanic cavity. Following complete surgical excision of the tumor and tympanoplasty via a middle cranial fossa approach, the patient retained useful hearing without facial palsy.

Adult↗

PubMed1998

Magnetic resonance angiography in patients with acute stroke treated by local thrombolysis.

Although magnetic resonance angiography (MRA) is accepted for showing chronic intracranial stenotic or occlusive lesions, the method has not been practically examined in patients with acute cerebral ischaemia. We carried out three-dimensional time-of-flight MRA in six patients with acute ischaemia treated by local thrombolysis, and compared the findings with those of digital subtraction angiography (DSA). In all patients, MRA before thrombolysis clearly demonstrated the occluded arteries, which corresponded precisely to those shown by DSA. In four patients with complete recanalisation of the occluded vessels after thrombolysis, the recanalisation could be demonstrated by postoperative MRA. In one patient with reocclusion of the recanalised artery, repeat MRA also demonstrated the reocclusion, confirmed by DSA. These results suggest that MRA may be helpful for noninvasive investigation before and after thrombolysis.

Adult↗

PubMed1998

Impairment in biochemical level of arterial dilative capability of a cyclic nucleotides-dependent pathway by induced vasospasm in the canine basilar artery.

The authors investigated the changes and the potential of cyclic nucleotide-dependent signal transduction, which induces smooth muscle relaxation, in the basilar artery with severe vasospasm in dogs with double experimental subarachnoid hemorrhage (SAH) to explore at which biochemical level the arterial dilative capability was impaired. The amount of cyclic adenosine and guanosine monophosphates (cAMP and cGMP) decreased significantly in the basilar artery after SAH. The activities of adenylate and guanylate cyclases also were decreased significantly in the smooth muscle cells of the basilar artery 4 days after SAH. In addition to the failure of the pathways to produce cyclic nucleotides, the activities of cAMP- and cGMP-dependent protein kinases, which are representative actual enzymes that amplify the signal for vascular dilation, also significantly decreased together with the almost total loss of activation by cyclic nucleotides in the same basilar artery after SAH. It was revealed that the system for smooth muscle relaxation was impaired severely in the cerebral arteries with severe vasospasm after SAH, on the biochemical basis of significantly less vasodilative capability and in several of the steps to produce the cyclic nucleotides of intracellular signal transduction.

Adenylyl Cyclases↗

PubMed1998

Usefulness of heavily T2-weighted magnetic resonance imaging in patients with cerebellopontine angle tumors.

OBJECTIVE: Heavily T2-weighted magnetic resonance imaging (MRI) has been reported to be useful for the diagnosis of lesions of the inner ear or its central connections. We evaluated the usefulness of heavily T2-weighted MRI in 18 patients with cerebellopontine angle tumors. METHODS: The lesions were acoustic neuromas in 14 patients and meningiomas in 4 patients. The findings of heavily T2-weighted MRI were compared with those of three-dimensional T1-weighted gradient field echo MRI. RESULTS: An accurate description of the situation of the tumor in the internal auditory canal (IAC) was possible, because the inner ear was clearly shown on the heavily T2-weighted magnetic resonance images. We could therefore detect the acoustic neuromas located at the fundus of the IAC and the meningiomas growing into the IAC. The residual tumor in the IAC can be shown postoperatively. It was difficult to demonstrate these findings using three-dimensional T1-weighted gradient field echo MRI because of the poor presentation of the petrous bone structures. The lower cranial nerves and the VIIth and VIIIth cranial nerves were more clearly demonstrated by heavily T2-weighted MRI than by three-dimensional T1-weighted gradient field echo MRI. Using heavily T2-weighted MRI, the VIIth and VIIIth cranial nerves of the lesion side were demonstrated in half of the patients with acoustic neuromas smaller than 2.5 cm. CONCLUSION: We conclude that heavily T2-weighted MRI is useful to detect the relationship among the tumor, the IAC, the inner ear, and the surrounding cranial nerves.

Adult↗

PubMed1998

Four cases of vertebrobasilar insufficiency.

Four cases of vertebrobasilar insufficiency are reported. Case 1 was a 38-year-old man who felt a sudden onset of dizziness when he turned his head to the back. An abnormal positional nystagmus was observed when he rotated his head to the left. A magnetic resonance angiogram (MRA) demonstrated total occlusion of the left vertebral artery (VA). Case 2 was a 31-year-old woman who had a total occlusion of her left VA as observed in the MRA. Case 3 was a 68-year-old man who noted dizziness. The systolic blood pressure change on his Schellong test was 28 mmHg. On his MRA, severe displacement of the basilar and the vertebral arteries was visible. Case 4 was a 76-year-old woman who noted a blackout-like sensation. Optokinetic nystagmus was noted with a hyponystagmus pattern, and an eye tracking test showed a saccadic pattern. On her MRA, the vertebrobasilar system was narrowed. The arterial architecture and any stenosis of the blood vessels could be detected non-invasively by MRA.

Adult↗

PubMed1998

MR-angiographic findings of patients with central vestibular disorders.

Magnetic resonance angiography (MRA) is a new, noninvasive, and useful method to estimate the posterior circulation in patients with vertigo. From June 1995 to May 1997, 180 patients were examined by magnetic resonance imaging (MRI) and MRA in our department. One hundred and forty-seven patients were vertiginous patients. We measured the displacement angle of the basilar artery with MRA, and examined the relationship between the findings from some neurological examinations and MRA findings in patients with vertigo and dizziness. One hundred and forty-seven patients with vertigo or dizziness were examined by MRI and MRA. They were diagnosed with MRI images in addition to several neurological examinations. MRA was not used for the diagnosis but rather for measuring the displacement angle of the basilar artery. Eighty-six cases with central vestibular disorders, 11 cases with vertebrobasilar insufficiency, and 26 cases with autonomic nerve disorders were recognized. In the cases of central vestibular disorders, the incidences of hyperlipidemia and hypotension were higher than the incidence of anemia. The average displacement angle of the basilar artery (n = 180) was 153.4 degrees +/- 39.4 degrees (mean +/- S.D.). MRA findings were classified into five categories. Ten patients were classified as category III, which represented unilateral partial vertebral artery stenosis. The detection rate for category III and IV abnormalities by neurological examination was higher than that for the other categories. MRI and MRA are important methods to examine patients with central nervous disorders. Distal vertebral artery stenosis may carry a higher risk of a stroke than brainstem infarction.

Autonomic Nervous System Diseases↗

PubMed1998

[Surgical management for preserving motor function in patients with gliomas near the primary motor cortex: usefulness of preoperative identification of motor cortex and intraoperative monitoring of motor evoked potentials].

Preoperative identification of precentral gyrus and intraoperative monitoring of motor evoked potentials (MEPs) were performed to preserve postoperative motor function in seven patients with gliomas near the primary motor cortex. Tumors were astrocytomas in 3 patients, glioblastomas in 2 patients, anaplastic astrocytoma and mixed glioma in one patient each. Preoperative identification of the primary motor cortex was performed by three-dimensional (3D) display of magnetic resonance (MR) images and by functional images using MR imaging and single-photon emission tomography. The primary motor cortex identified by 3D display of MR images coincided well with that identified by functional images. 3D display of MR images was also useful for detecting the relationship between the tumor and the primary motor cortex. Intraoperatively, the central sulcus was confirmed by the finding of phase reversal of cortical somatosensory evoked potential, and this corresponded with the preoperative identifications by 3D display and by functional mapping. The primary motor cortex was stimulated electrically, and MEP (corticospinal evoked potential) was continuously monitored during surgery using electrodes inserted in the cervical epidural space. The amplitude of direct waves of MEPs during surgery was maintained above half of that recorded at the beginning of tumor removal, and all patients showed preservation of preoperative motor function. These results suggest that preoperative identification of precentral gyrus and intraoperative MEP monitoring provide useful information for preserving motor function in patients with gliomas near the primary motor cortex.

Adult↗

PubMed1997

Three-dimensional imaging for presentation of the causative vessels in patients with hemifacial spasm and trigeminal neuralgia.

BACKGROUND: In patients with hemifacial spasm and trigeminal neuralgia, preoperative detection of the relationship between the blood vessels and the cranial nerves involved is essential. METHODS: We studied the causative vessels in 20 patients with hemifacial spasm and six patients with trigeminal neuralgia by means of magnetic resonance (MR) imaging with spoiled gradient recalled acquisition in the steady state (SPGR), MR angiography, and three-dimensional (3-D) imaging reconstructed from the data of SPGR MR imaging by the surface rendering method at a workstation. RESULTS: In all patients, the preoperative SPGR MR images demonstrated that the causative vessels compressed or were in contact with the root exit or root entry zone (REZ) of the facial or trigeminal nerve. These causative vessels were identified by inspection of the MR angiographic and 3-D images. The 3-D images provided clear information as to the anatomic relationship between the causative vessels and the REZ of these nerves. These findings were corroborated by the intraoperative findings. The symptoms were completely relieved after surgery in 18 of the patients with hemifacial spasm and in all six patients with trigeminal neuralgia. In all patients, sufficient decompression was depicted on the postoperative SPGR MR images at the causative vessels and the REZ of the nerve. CONCLUSION: SPGR MR images, MR angiography, and 3-D images are useful for the identification of the causative vessels in patients with hemifacial spasm or trigeminal neuralgia. The 3-D images are particularly useful for the simulation planning of the operative procedure.

Adult↗

PubMed1997

Evaluation of prognostic factors following expansive laminoplasty for cervical spinal stenotic myelopathy.

BACKGROUND: Expansive laminoplasty of several types has been proposed for patients with cervical multisegmental stenotic myelopathy to reduce postlaminectomy complications. Its effectiveness has not been fully explored by evaluating long-term results and magnetic resonance imaging (MRI) findings before and after surgery. METHODS: We conducted a 5-year follow-up study of 22 patients with cervical spondylotic myelopathy and/or ossification of the posterior longitudinal ligament surgically treated with expansive laminoplasty. The operative results were examined using the Japanese Orthopedic Association (JOA) disability scale, with reference to the findings of MRI, computed tomography, and radiography. RESULTS: Postoperative improvement was observed in 18 (81.8%) of the 22 patients. In 11 patients the percentage recovery of the JOA score was higher than 50% (average: 83.1%), while in the remaining 11 patients it was lower than 50% (average: 20.1%). Factors contributing to incomplete recovery appear to be related mainly to cord degeneration with atrophy (depicted as a T2-high intensity area) and to specific factors such as long symptom duration, age higher than 70 years, deterioration due to trauma, severe cord compression, radiculopathy, and kyphotic cervical curvature. CONCLUSIONS: In cervical myelopathy, patients with multisegmental stenosis, expansive laminoplasty can be expected to provide a favorable outcome by providing sufficient cord decompression and stabilization of the cervical spine, when the stenotic cervical canal is enlarged to the normal range (over 12 mm residual anteroposterior diameter and 200 mm2 residual canal area). The efficacy can be restricted by various factors, especially irreparable cord degeneration.

Aged↗

PubMed1997

Asymptomatic, unruptured carotid-ophthalmic artery aneurysms: angiographical differentiation of each type, operative results, and indications.

BACKGROUND: Some types of carotid-ophthalmic artery aneurysms are still difficult to clip successfully because their exposure requires opening the cavernous sinus and/or retracting the optic nerve. It is useful to know the complications and to determine the type of aneurysm preoperatively for the management of carotid-ophthalmic artery aneurysms. METHODS: The operative results in 15 patients with asymptomatic unruptured carotid-ophthalmic artery aneurysms were surveyed. The aneurysms were small in all the patients, and they underwent direct operation. Four patients presented with other ruptured aneurysms, four with other diseases (infarction, trauma, or pituitary adenoma), and seven were evaluated with magnetic resonance angiography for symptoms such as vertigo or headache. Among them, five had carotid cave aneurysms and one had paraclinoid aneurysm. RESULTS: Neck clipping was performed in 13 patients. Postoperatively, ipsilateral visual loss was encountered in one patient, and ipsilateral visual field defect was encountered in three patients. The visual field defect was lower nasal quadrant hemianopsia in two patients and lower hemianopsia in one patient. The cause of this complication was suspected to be retraction and/or the heat of the drill near the optic nerve. It seemed to be possible to distinguish the carotid cave or the paraclinoid aneurysm from the other carotid-ophthalmic aneurysms using carotid angiography preoperatively. CONCLUSION: When direct operation is performed for a carotid-ophthalmic artery aneurysm, care must be taken to avoid optic nerve injury caused by the retraction and/or the heat of the drill.

Adult↗

PubMed1995

Primary spinal chondrosarcoma localized in the cervical spinal canal and intervertebral foramen--case report.

A 48-year-old male presented with a very rare case of spinal chondrosarcoma localized in the cervical spinal canal and intervertebral foramen, but without marked destruction of the vertebral column. Spinal chondrosarcoma is characterized by radiological evidence of destruction of the surrounding bone structure and mottled calcification. Magnetic resonance imaging was useful in the diagnosis and determination of the extent of this spinal chondrosarcoma. However, preoperative differential diagnosis of the tumor was not possible based on neuroimaging evidence.

Cervical Vertebrae↗

PubMed1994

Chronic subdural hematoma associated with middle fossa arachnoid cysts--three case reports.

Three patients with chronic subdural hematoma associated with middle fossa arachnoid cyst were treated by irrigating the hematoma through burr holes, because the symptoms were considered mainly due to increased intracranial pressure caused by the subdural hematoma. The symptoms disappeared immediately afterwards, so no surgery for the middle fossa arachnoid cyst was done. The patients were followed by magnetic resonance imaging. No subdural hematoma recurred during a postoperative period of 11 months to 2.5 years, and the arachnoid cyst reduced in size in two patients. We recommend irrigation of the subdural hematoma as the initial procedure of choice for such cases.

Adolescent↗