Biomedical subjects

Kentaro Hayashi

Publications and source records attributed to Kentaro Hayashi.

27 records · Page 2Linked to original sources

PubMed2004

[Two cases of spinal arteriovenous malformation presenting with subarachnoid hemorrhage].

Two cases of spinal arteriovenous malformation (AVM) with subarachnoid hemorrhage (SAH) are reported. The first case is that of a 14-year-old boy who was transferred to our hospital with a sudden onset of headache. Neurological examination revealed no motosensory deficit, but a brain CT showed a slight diffuse SAH. A left vertebral angiogram demonstrated intramedullary AVM in the cervical region of the spinal cord. This AVM was therefore occluded using a solid embolization material. The patient was then discharged without neurological deficit. The second case is that of a 67-year-old man who visited our hospital with a sudden onset of headache. Neurological examination revealed no motor or sensory deficit, but a brain CT showed SAH, which was dominant in the posterior fossa. Initial cerebral angiography demonstrated no abnormality such as cerebral aneurysm or AVM except for laterality of the C1 radiculo-meningeal artery. A second angiogram on day 11 demonstrated spinal arteriovenous fistula (AVF), which was fed by the left radiculo-meningeal artery and drained to the posterior spinal vein. Embolization for the AVF was performed using liquid material. He was then discharged without neurological deficit. These two cases revealed non-specific SAH symptoms and were indistinguishable from other ruptured aneurysms. Although the brain CT can show a slight SAH or posterior fossa dominant SAH, repeated angiography may be necessary to verify and conclude the diagnosis of spinal AVM.

Adolescent↗

PubMed2003

A case of intimal hyperplasia induced by stenting for vertebral artery origin stenosis: assessed on intravascular ultrasound.

We report a case of proximal vertebral artery restenosis following stent placement. Intravascular ultrasound study helped delineate its characteristics. A 69-year-old man was admitted because of dysarthria and dysphagia. Angiography revealed hypoplasia of left vertebral artery (VA) and remarkable stenosis of the proximal right VA with inadequate collateral flow from the anterior circulation. Balloon angioplasty and stent placement at the VA was performed to an excellent angiographic result with recovery of neurological symptoms. His condition deteriorated six months later due to intimal hyperplasia, which we evaluated by intravascular ultrasound (IVUS). Balloon angioplasty was then performed. Stent placement may induce intimal hyperplasia and IVUS is useful to assess the lesion.

Aged↗

PubMed2003

Bootstrap approach to inference and power analysis based on three test statistics for covariance structure models.

We study several aspects of bootstrap inference for covariance structure models based on three test statistics, including Type I error, power and sample-size determination. Specifically, we discuss conditions for a test statistic to achieve a more accurate level of Type I error, both in theory and in practice. Details on power analysis and sample-size determination are given. For data sets with heavy tails, we propose applying a bootstrap methodology to a transformed sample by a downweighting procedure. One of the key conditions for safe bootstrap inference is generally satisfied by the transformed sample but may not be satisfied by the original sample with heavy tails. Several data sets illustrate that, by combining downweighting and bootstrapping, a researcher may find a nearly optimal procedure for evaluating various aspects of covariance structure models. A rule for handling non-convergence problems in bootstrap replications is proposed.

Humans↗

PubMed2003

[Coma caused by hypermagnesemia in a pregnant woman complicated with HELLP syndrome].

This case report describes a pregnant woman with acute renal failure, caused by aggravation of HELLP syndrome, who developed coma induced by overdose of continuous magnesium sulfate administration for eclampsia. Before examination of serum concentration of magnesium, coma was suspected to be the result of brain vascular problem or brain infarction. Patient was treated in ICU and hemodialysis was started, and she recovered fully from abnormal neurological symptoms. This case illustrate that hypermagnesemia should be considered in the pregnant woman with coma at ER and ICU. Furthermore, the accurate information about the continuous administration of magnesium by previous clinician helped us to make correct diagnosis and to treat the patient successfully.

Adult↗

PubMed2003

[A case of atypical meningioma associated with acute deterioration and cerebral herniation].

Brain tumors not uncommonly display a chronic course, with symptoms occurring insidiously. This case report describes a meningioma patient who presented sudden onset and rapidly progressing symptoms. She was 49 years old, a referred case from a nearby hospital, with severe headache and fever. This was also accompanied by unconsciousness and left hermiparesis which necessitated emergency brain CT and MRI scanning. A right temporal 5 cm ring enhancing lesion with massive surrounding edema was revealed. Despite osmotic diuretics to relieve brain edema, symptoms worsened, so decompressive right temporal craniotomy and total excision of the tumor was performed. This mass lesion was found to be extra axial, with histology revealing on atypical meningioma with massive necrosis. This rare case which is thought to be due to massive peritumoral edema, possibly from an ischemic occluded major feeder, conforms to glioma radiologically; while the clinical picture has a similarity to brain abscess. This case is presented as a reminder to neurosurgery practice that meningioma can also be a possibility when a ring enhancing cerebral mass in encountered and is accompanied by such a bizarre sudden and rapidly progressing neurologic condition.

Acute Disease↗

PubMed2002

Endovascular treatment for cervical carotid artery stenosis presenting with progressing stroke: three case reports.

BACKGROUND: Progressing stroke is said to occur when symptoms and signs worsen in cases of ischemic stroke. Although conservative methods using volume expansion with antithrombotic or anticoagulative agents are widely used for progressing stroke, in some hospitals, emergency carotid endarterectomy (CEA) has been performed for carotid stenosis, with mixed results. Here we report three cases with progressing ischemic stroke that were managed by endovascular surgical intervention. CASE DESCRIPTION: We performed endovascular surgery in three patients with cervical carotid artery stenosis presenting with progressing stroke or crescendo transient ischemic attacks. Endovascular treatment was less invasive and feasible for acute phase treatment. While local thrombolysis alone was found to be less effective, stent placement induced complete resolution of stenosis, but may result in hyperperfusion syndrome or hemorrhagic infarction. CONCLUSIONS: In an emergency, percutaneous transluminal angioplasty with proper dilatation is preferred, and then CEA or stenting should be considered after the patient's condition stabilizes.

Aged↗

PubMed2002

Biogenesis of 2-phenylethanol in rose flowers: incorporation of [2H8]L-phenylalanine into 2-phenylethanol and its beta-D-glucopyranoside during the flower opening of Rosa 'Hoh-Jun' and Rosa damascena Mill.

To clarify the biosynthetic pathway to 2-phenylethanol (2), the deuterium-labeled putative precursor, [2H8]L-phenylalanine ([2H8-1]), was fed to the flowers of Rosa 'Hoh-Jun' and R. damascena Mill. throughout maturation, ceasing feeding at the commencement of petal unfurling and at full bloom. Based on GC-MS analyses, [2H8]-1 was incorporated into both 2 and 2-phenylethyl beta-D-glucopyranoside (3) when the flowers were fed until full bloom, whereas no such incorporation into 2 was apparent when feeding was ceased earlier. In both species of rose, the labeling pattern for 2 was almost identical to that for 3, and indicated the presence of [2H6]-, [2H7]- and [2H8]-2, and [2H6]-, [2H7]- and [2H8]-3. This may be ascribed to the equilibrium between 2 and 3. The labeling pattern for 2 and 3 also indicated that these compounds were produced from 1 via several routes, the route involving phenylpyruvic acid being the major one.

Gas Chromatography-Mass Spectrometry↗

PubMed2002

Depicting cerebral veins by three-dimensional CT angiography before surgical clipping of aneurysms.

BACKGROUND AND PURPOSE: Cerebral veins show wide variation, and unexpected veins occasionally limit surgical procedures for clipping of cerebral aneurysms. This study was undertaken to assess the utility of three-dimensional CT angiography (3D-CTA) in the evaluation of venous anatomy before surgical clipping of cerebral aneurysms. METHODS: 3D-CTA was performed in 19 patients before pterional craniotomy. The venous anatomy visualized by use of 3D-CTA was compared retrospectively with intraoperative findings. RESULTS: 3D-CTA clearly depicted the superficial sylvian veins (SSVs) in 17 of 19 cases. In three of these 17 cases, 3D-CTA failed to reveal the additional connecting veins from SSVs to the midportion of the sphenoid wing. 3D-CTA also depicted bridging veins from: 1) the basal vein of Rosenthal to the sphenoparietal sinus (SPS) (three cases); 2) a junction of the anterior cerebral vein and the deep middle cerebral vein to the SPS (two cases); 3) the anterior cerebral vein into the cavernous sinus (one case); and 4) the deep middle cerebral vein to the cavernous sinus in one case. Surgical findings corresponded well with the angiographic findings. 3D-CTA depicted bridging veins from the frontal base into the SPS in two cases; retraction of the frontal lobe was severely limited in these cases. 3D-CTA also exhibited anatomic variation of deep cerebral veins, which suggests the utility of 3D-CTA in evaluating the risks carried by sacrifice of some bridging veins. In two patients, aneurysmal dissection was restricted because of adhering veins. 3D-CTA depicted these cerebral veins to be lying in contact with the aneurysm. In one case, the contiguous vein was hidden behind a large middle cerebral artery aneurysm; 3D-CTA was helpful for visualization of this vein. CONCLUSION: 3D-CTA can clearly depict the venous anatomy of the brain and is useful for surgical planning of a pterional or temporopolar approach for cerebral aneurysms.

Adult↗

PubMed2002

[A case of basilar artery stenosis treated by stent placement].

Symptomatic basilar artery stenosis invariably has poor prognosis owing to limited treatment options. Modernized stent system delivery technology has paved the way for treating tortuous vascular segments of intracranial system. The authors hereby report on the use of intracranial stent to treat basilar artery stenosis. A-61-year old man presented with one month history of recurrent dizziness and dysarthria. He remained symptomatic despite having oral antiplatelets. Magnetic resonance image showed pontine ischemic lesion. Stenosis of proximal portion of basilar artery was detected by magnetic resonance angiography (MRA). Although balloon angioplasty was performed, restenosis was demonstrated by MRA four months later. Stenting was then performed with excellent angiographic results, and there were no procedural complications. The availability of new flexible intravascular stents, allowing access to tortuous proximal intracranial vessels, provides a new therapeutic approach to basilar artery stenosis cases. However long term follow-up is advised to assess the durability of this approach.

Angioplasty, Balloon↗