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Biomedical subjects

K Yanaka

Publications and source records attributed to K Yanaka.

At least 37 records · Page 2Linked to original sources
PubMed2000

Superficially-located oligodendroglioma associated with intratumoral and peritumoral cysts--case report.

A 72-year-old male presented with a superficially-located oligodendroglioma associated with intratumoral and peritumoral cysts. Neuroimaging showed the outer cyst wall as enhanced but not the inner cyst wall. The outer cyst was removed and a biopsy taken of the solid component. The inner cyst wall appeared to consist of non-neoplastic tissue. Histological examination showed the tumor was an oligodendroglioma with tumor cells in the outer wall. The outer cyst was probably the result of blood-brain barrier disruption and intratumoral hemorrhage. The inner cyst probably resulted from reactive gliosis or peritumoral edema. Cyst formation in intraaxial tumors occurs through similar mechanisms to those of extraaxial tumors.

Aged↗
PubMed2000

Intracerebellar penetrating injury and abscess due to a wooden foreign body--case report.

A 4-year-old boy presented with chopstick penetration into the cerebellum via the temporal squamosa and tentorium cerebelli, which resulted in a cerebellar abscess 1.5 years after the injury. The neuroimaging appearance of the wooden chopstick were unusual, hyperdense on computed tomography, and isointense on T2-weighted and hypointense on T2-weighted magnetic resonance imaging. Abscess aspiration and continuous drainage was performed with real-time intraoperative ultrasound guidance. The chopstick fragment was surgically removed and the patient discharged with minor neurological deficits. Wooden foreign body may show changes in properties after a long period of intraparenchymal retention. Extra care is required to remove wooden foreign bodies because of the high risk of infection.

Brain↗
PubMed2000

Ruptured aneurysm at the origin of the median artery of the corpus callosum associated with accessory middle cerebral artery--case report.

A 62-year-old male presented with ruptured anterior communicating artery (ACoA) aneurysm manifesting as severe headache associated with the rare combination of median artery of the corpus callosum (MACC) and accessory middle cerebral artery (MCA). Computed tomography demonstrated diffuse subarachnoid hemorrhage. Left carotid angiography demonstrated an anomalous vessel originating from the ACoA complex and passing forward in the interhemispheric fissure between the two companion A2 segments. This vessel was identified as the MACC. Another anomalous vessel originated from the left A1-A2 segment and passed into the sylvian fissure. This vessel was identified as the accessory MCA. Left frontotemporal craniotomy was performed to clip the neck of the aneurysm. After identifying both A1 and A2 segments, accessory MCA, and the MACC, the aneurysm neck was occluded successfully. The ACoA complex is one of the most frequent sites of vascular anomalies. Preoperative and intraoperative care is required to identify the presence of anomalies of the ACoA complex prior to clip placement, to avoid accidental damage or clipping, which may result in severe neurological deficits.

Anterior Cerebral Artery↗
PubMed2000

Infratentorial arteriovenous malformation associated with persistent primitive trigeminal artery--case report.

A 58-year-old male presented with a rare association of an infratentorial arteriovenous malformation (AVM) and ipsilateral persistent primitive trigeminal artery (PPTA) manifesting as sudden onset of headache and vomiting. Computed tomography revealed subarachnoid hemorrhage, and digital subtraction angiography demonstrated an infratentorial AVM mainly fed by the left superior cerebellar artery via the left PPTA. The patient refused radical treatment for the AVM, and was conservatively treated. The adjacent AVM may have been important in the preservation of the PPTA, as blood flow into the infratentorial AVM via the PPTA and the hemodynamic stress to the PPTA could have disturbed the spontaneous closure of the PPTA.

Cerebral Angiography↗
PubMed2000

[Usefulness of Doppler echocardiography in patients with ischemic cerebrovascular disease].

We carried out transthoracic Doppler echocardiography on 213 patients with ischemic cerebrovascular disease to examine cardiac functions. The prevalence of valvular regurgitation, left ventricular diastolic function (E/A ratio), and ejection fraction (EF) of each patient were studied by transthoracic Doppler echocardiography. In patients with embolic strokes, the prevalence of valvular regurgitation of the left ventricular system such as mitral regurgitation was significantly higher than that of normal controls. In contrast, there was no significant difference in the prevalence of valvular regurgitation in the right ventricular system. Although there was no significant difference in the ejection fraction between groups, the E/A ratio in patients with ischemic cerebrovascular disease showed a significantly lower value than that in normal controls. Patients with ischemic cerebrovascular disease showed a tendency to have an atherosclerotic change in the systemic arteries including cerebral and coronary arteries, reflecting an aggravation of cardiac wall compliance and diastolic dysfunction resulting in lowering of the E/A ratio. Thus, transthoracic Doppler echocardiography was useful to evaluate cardiac diastolic dysfunction and valvular regurgitation in patients with ischemic cerebrovascular disease.

Acute Disease↗
PubMed2000

[Clinical usefulness of diffusion-weighted magnetic resonance imaging in patients with ischemic cerebrovascular disease].

Diffusion-weighted magnetic resonance imaging was performed to determine the detectability of ischemic changes in patients with ischemic cerebrovascular disease. We retrospectively reviewed 103 patients with symptoms suggestive of ischemic cerebrovascular disease. All patients underwent computed tomography, routine magnetic resonance imaging, and diffusion-weighted imaging. Of 103 patients, 18 were imaged within 3 hours after onset, 57 were imaged between 3 and 24 hours, and 29 were imaged between 24 and 144 hours. Eighty-eight patients were diagnosed as ischemic cerebrovascular disease. Magnetic resonance imaging was performed at a 1.0 Tesla clinical machine using single-shot spin-echo/echo-planar imaging sequence. In each case, three sets of DWI with motion-probing gradient pulses in the x, y, and z directions were taken. The detectability of ischemic changes of each imaging modality was compared. DWI detected ischemic changes in 83 of 88 cases with clinical diagnoses of cerebral ischemia(sensitivity; 94.3%). In contrast, DWI showed negative findings in 15 of the 15 patients with diagnoses other than cerebral ischemia(selectivity; 100.0%). DWI detected ischemic changes in 16 out of 18 patients(88.6%) within 3 hours after the onset. In contrast, T 2-weighted image did not detect any ischemic changes in the same period. These results suggest that DWI is considered to be highly useful for the early diagnosis of cerebral ischemia.

Adolescent↗
PubMed2000

[Treatment of peripheral aneurysms of the posterior circulation].

Peripherally located aneurysms of the posterior circulation are extremely rare. The outcome of patients with peripherally located aneurysms has been poor, and the treatment of such aneurysms has been surgically challenging. We report a consecutive series of peripherally located ruptured aneurysms in the posterior circulation, and discuss in this article the optimal treatment strategy for such lesions. Clinical presentation, neuroradiological findings, treatment method, and the outcome were reviewed retrospectively. Two cases with distal posterior cerebral artery aneurysm, two with distal posterior inferior cerebellar artery aneurysm, two with anterior inferior cerebellar aneurysm, and one with superior cerebellar artery aneurysm were included in this study (mean age, 59.3 +/- 16.0, M:F = 1:6). Three patients with good neurological status on admission who underwent clipping of the aneurysmal neck via craniotomy showed a favorable outcome. In contrast, four patients with poor neurological status on admission who underwent endovascular proximal occlusion of the parent artery showed an unfavorable outcome. Although the outcome of patients who underwent endovascular surgery was poor, endovascular proximal occlusion was effective in preventing re-rupture of the aneurysms. Proximal occlusion of the parent artery has several shortcomings such as cerebral infarction, but proximal occlusion at the very distal area of the parent arteries would not be critical because of good collateral circulation. Thus, endovascular proximal occlusion may provide us another option in the treatment of peripherally located aneurysms especially in patients with poor neurological status. Further data is needed to discover the optimal treatment for patients with peripherally located cerebral aneurysms.

Adult↗
PubMed2000

[Cardiac function estimated by Doppler echocardiography in patients with hypertensive intracerebral hemorrhage].

We carried out transthoracic Doppler echocardiography on 38 patients with hypertensive intracerebral hemorrhage(ICH) to examine cardiac functions. The ratio of myocardial hypertrophy and the prevalence of valvular regurgitation were investigated. The E/A ratio which reflects left ventricular diastolic function and the ejection fraction(EF) of each patient were also studied to demonstrate cardiac functions in patients with hypertensive ICH. Myocardial hypertrophy was found in 39.5% of patients with hypertensive ICH. The aortic regurgitation showed a trend to have a higher prevalence in patients with hypertensive ICH when compared to normal volunteer group. Although there was no significant differences in the ejection fraction between groups, the E/A ratio in patients with hypertensive ICH showed a significantly lower value than in normal volunteer group. Therefore, transthoracic Doppler echocardiography demonstrated that patients with intracerebral ICH showed a trend to have a myocardial hypertrophy, aortic valvular regurgitation, and the lower ventricular diastolic function. Thus, transthoracic Doppler echocardiography is useful to evaluate cardiac functions in patients with hypertensive ICH.

Adult↗
PubMed2000

Current and future therapies for ischemic cerebrovascular disease.

Stroke is the third leading cause of death in the adult population. It makes great demands on patients, who must not only survive the complications of the acute stages but also must cope with the great physical and economic costs of long-term disabilities. Therefore, there is an urgent need to establish generally useful treatments for ischemic stroke. Currently, there are three treatment approaches based on pathophysiologic concepts derived from basic research: (i) pharmacologic strategies for arterial recanalization, (ii) neuronal protection and (iii) the inhibition of undesirable damaging host responses. The key to current treatment is the emergent administration of tissue plasminogen activator (t-PA). Thrombolytic treatment improves outcome when given to carefully selected patients within 3 h of stroke onset. Numerous neuroprotective agents have been developed in the last decade, and a new wave of therapies is now on the horizon that could potentially minimize ischemic brain damage. This article highlights recent advances in pharmacological interventions for ischemic stroke.

Journal Article↗
PubMed1999

Postoperative brainstem high intensity is correlated with poor outcomes for patients with spontaneous cerebellar hemorrhage.

OBJECTIVE: The outcomes for patients with cerebellar hemorrhage are thought to be influenced by anatomic damage to the brainstem. In this study, we investigated the magnetic resonance imaging findings in the brainstem, to examine the relationship between the degree of brainstem damage and the outcomes for patients with spontaneous cerebellar hemorrhage who are in poor-grade condition. METHODS: The results for 31 patients with spontaneous cerebellar hemorrhage, with Glasgow Coma Scale scores of 8 or less at admission, who underwent magnetic resonance imaging examinations were reviewed. All patients underwent surgical intervention. The patients were divided into two groups according to their Glasgow Outcome Scale scores at the time of discharge, i.e., patients who experienced good recoveries or exhibited moderate disabilities (Group I, n = 8) and patients who exhibited severe disabilities, were in a persistent vegetative state, or had died (Group II, n = 23). We investigated obliteration of the fourth ventricle and the perimesencephalic cistern and the presence of hydrocephalus in initial computed tomographic scans and the presence of areas of high signal intensity in the brainstem in T2-weighted images. RESULTS: Eight patients experienced good outcomes, and 23 patients experienced poor outcomes. The overall mortality rate was 32.3%. There were no significant differences between groups with respect to computed tomographic findings such as hematoma size, but the incidence of high signal intensities in the pons and midbrain in T2-weighted images for Group II was significantly higher than that for Group I (P < 0.01). CONCLUSION: Magnetic resonance imaging clearly demonstrated brainstem damage, and high signal intensity in the brainstem was a significant prognostic factor for determining outcomes for patients with spontaneous cerebellar hemorrhage who were in poor-grade condition.

Aged↗
PubMed1999

Image-guided procedures in brain biopsy.

Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound-guided methods, can assist neurosurgeons in localizing the relevant pathology. The characteristics of image-guided procedures are important for their appropriate use, especially in brain biopsy. This study reviewed the results of various image-guided brain biopsies to ascertain the advantages and disadvantages. Brain biopsies assisted by CT-guided stereotactic, ultrasound-guided, Neuronavigator-guided, and the combination of ultrasound and Neuronavigator-guided procedures were carried out in seven, eight, one, and three patients, respectively. Four patients underwent open biopsy without a guiding system. Twenty of 23 patients had a satisfactory diagnosis after the initial biopsy. Three patients failed to have a definitive diagnosis after the initial procedure, one due to insufficient volume sampling after CT-guided procedure, and two due to localization failure by ultrasound because the lesions were nonechogenic. All patients who underwent biopsy using the combination of ultrasound and Neuronavigator-guided methods had a satisfactory result. The CT-guided procedure provided an efficient method of approaching any intracranial target and was appropriate for the diagnosis of hypodense lesions, but tissue sampling was sometimes not sufficient to achieve a satisfactory diagnosis. The ultrasound-guided procedure was suitable for the investigation of hyperdense lesions, but was difficult to localize nonechogenic lesions. The combination of ultrasound and Neuronavigator methods improved the diagnostic accuracy even in nonechogenic lesions such as malignant lymphoma. Therefore, it is essential to choose the most appropriate guiding method for brain biopsy according to the radiological nature of the lesions.

Aged↗
PubMed1999

External carotid endarterectomy with patch angioplasty using internal jugular vein--two case reports.

A 59-year-old male and a 74-year-old male presented with occlusion of the right internal carotid artery and stenosis at the origin of the ipsilateral external carotid artery manifesting as cerebral ischemia. External carotid endarterectomy with patch angioplasty using the internal jugular vein was performed. Special care was taken to obliterate the stump of the carotid artery using a Weck clip in one case and plication with non-absorbable sutures in the other. Cerebral blood flow in the affected hemisphere was increased after surgery and the patients remained asymptomatic. External carotid endarterectomy has several special aspects such as patch angioplasty and elimination of the stump which must be understood.

Aged↗
PubMed1999

Anomaly of the axis causing cervical myelopathy. Case report.

Although the craniovertebral junction is one of the most common sites at which anomalies develop, spina bifida occulta of the axis (C-2) associated with cervical myelopathy is extremely rare. The authors present the case of a 46-year-old man who developed progressive tetraparesis caused by a cervical canal stenosis at the level of the axis. The spinal cord was compressed by an invaginated bifid lamina of the axis. The patient made a remarkable recovery after undergoing decompressive laminectomy of C-3 and removal of the bifid posterior arch of the axis.

Axis, Cervical Vertebra↗
PubMed1999

[A case of multiple myeloma presenting with a subcutaneous mass: significance of "dural tail sign" in the differential diagnosis of the meningeal tumors].

A 65-year-old female was admitted to our hospital with a 6-month history of a gradually enlarging subcutaneous mass in the frontal region. Neurological examination on admission showed no significant abnormality. Skull X-P showed an osteolytic lesion of the frontal bone. External carotid angiogram demonstrated a tumor stain fed by the middle meningeal artery. Computed tomography (CT) showed a slightly high density mass with a marked homogeneous enhancement. MRI revealed an iso-intensity mass on both T1- and T2-weighted images. Gd-DTPA-enhanced T1-weighted images showed a mass with a marked homogeneous enhancement with the "dural tail sign" in the dura adjacent to the tumor. The tumor was totally removed; this mass was diagnosed as a multiple myeloma. No tumor cells were seen in the dura adjacent to the tumor and the mechanism of dural enhancement around the tumor was not clear. However, it is possible that the "dural tail" is due to increased vascular permeability of the dural vessels. Although the "dural tail" sign has been considered as a highly specific feature of meningioma, multiple myeloma can show the same findings on MRI. Therefore, it is important to consider the possibility of multiple myeloma in the differential diagnosis of meningeal tumors.

Aged↗
PubMed1999

[A case of primary brain-stem injury recovered from persistent vegetative state after L-dopa administration].

A 51-year-old male was transferred to our hospital just after traffic accident. On admission, the patient was comatose (Glasgow Coma Scale of 6) and showed a left hemiparesis with a left oculomotor nerve palsy. Computed tomography demonstrated a traumatic subarachnoid hemorrhage without mass lesion. Magnetic resonance imaging showed high intensity lesions on the left dorsolateral midbrain and the right cerebral peduncle. The distribution of lesions implied diffuse axonal injury involving dopaminergic systems such as the substantia nigra and the ventral tegmental area. After several months of conservative management, the patient showed no recovery and was diagnosed as persistent vegetable state. The administration of L-dopa was then started and the patient showed remarkable neurological improvement. Therefore the patient's neurological status was thought to be modified with primary brain stem injury and accompanying traumatic Parkinson's syndrome. It is important to understand "pseudo" persistent vegetative state in the management of patients showing prolonged consciousness disturbance. L-dopa should be considered as the drugs of pharmacological intervention for the patients of masked parkinsonism behind "pseudo" persistent vegetative state whose dopaminergic systems might have been damaged.

Accidents, Traffic↗
PubMed1998

Combined carotid endarterectomy and coronary artery bypass graft.

Atherosclerosis is a generalized disease which afflicts a considerable number of patients in both the carotid and coronary arteries. Although the risk of stroke or death use to combined carotid endarterectomy (CEA) and coronary artery bypass graft (CABG) is thought to be higher than that of each individual operation, the combined procedure is generally preferred over staged operations to treat such patients. We performed the combined procedure safely with the aid of intraoperative portable digital subtraction angiography (DSA). This report describes our experience with the operative strategy of simultaneous CEA and CABG. Ninety CEA and 404 CABG were carried out between January 1989 and December 1997. A total of six patients received the combined procedure with the aid of intraoperative DSA; they were studied retrospectively. Postoperative mortality and morbidity after the combined procedure was 0%. In the combined procedure, neurological complications are difficult to detect after CEA because the patient must be maintained under general anesthesia and extracorporeal circulation during the subsequent CABG. However, intraoperative DSA can confirm patency of the internal carotid artery and absence of flap formation after CEA, and the CABG can be performed safely. Intraoperative portable DSA between CEA and CABG is helpful in preventing perioperative stroke in the combined procedure.

Aged↗