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Nobuyuki Yasui

Publications and source records attributed to Nobuyuki Yasui.

10 recordsLinked to original sources
PubMed2005

Carotid artery resection: preoperative temporary occlusion is not always an accurate predictor of collateral blood flow.

CONCLUSION: The morbidity predicted by means of preoperative PET studies does not always correlate with the morbidity experienced after permanent carotid artery occlusion. A pre-resection extracranial-intracranial bypass may be necessary to reduce the risk of neurologic morbidity, in particular when carotid artery resection is planned for tumors involving the skull base. OBJECTIVES: Carotid artery resection is generally considered the only curative treatment for patients with advanced head and neck carcinoma involving the carotid artery. PET can be used during temporary occlusion of the internal carotid artery to assess the safety of the procedure. The aims of this paper were to clarify the risk of carotid artery resection and the benefit of extracranial-intracranial bypass. MATERIAL AND METHODS: Twelve patients diagnosed with head and neck cancer adherent to the carotid artery and in proximity to the skull base who had shown good hemispheric collateral blood flow by means of PET underwent carotid artery resection without preoperative bypass. RESULTS: Of the 12 patients who underwent carotid artery resection without reconstruction, 10 suffered no serious neurologic complications; however, 2 suffered cerebral infarctions intraoperatively.

Adenocarcinoma↗
PubMed2005

Morbidity and mortality from surgical treatment of unruptured cerebral aneurysms at Research Institute for Brain and Blood Vessels-Akita.

OBJECTIVE: Although the necessity of craniotomy for an unruptured cerebral aneurysm (UCA) is controversial, surgery is warranted if surgical risks are less than the risks of natural history. In this study, we investigated the need for craniotomy for UCAs on the basis of surgical risk. METHODS: History of cerebrovascular disorders, aneurysm site and size, surgical complications, and clinical outcome were investigated in 368 patients (134 men, 234 women; ages 31-79 yr) who underwent craniotomy for treatment of UCA at our institute between 1993 and 2000. RESULTS: We investigated 549 aneurysms. The mean size was 6.0 mm. Sites affected were the anterior cerebral artery (101 aneurysms), internal carotid artery (224 aneurysms), middle cerebral artery (201 aneurysms), and vertebrobasilar artery (23 aneurysms). The most common previous cerebrovascular disorders were subarachnoid hemorrhage (58 patients, 15.8%) and cerebral infarction (41 patients, 11.1%). Eight patients experienced permanent neurological deficits, for a total morbidity of 2.2%. One patient died, for a total mortality of 0.3%. For UCAs less than 10 mm in size, the morbidity was 0.6% and the mortality was 0%. For UCAs greater than 10 mm in size, the morbidity was 6.1% and the mortality was 1.2%. For UCAs in the anterior cerebral artery or middle cerebral artery, the morbidity was 0.3%. Temporary deficits were more frequently observed in patients older than 70 years of age than in patients 70 years of age or less. CONCLUSION: Surgical treatment is a viable alternative for patients 70 years of age or less with UCAs less than 10 mm in size or UCAs located in the anterior cerebral artery or middle cerebral artery, because the surgical risk of treating such UCAs is sufficiently lower than the annual rupture rate of UCAs (2.3%) and the mental stress suffered by patients with untreated UCAs.

Adult↗
PubMed2004

Surgical treatment of unruptured intracranial aneurysms over the past 22 years.

The medical records of 312 patients who underwent surgical intervention for unruptured intracranial aneurysm by the same neurosurgeon between April 1979 and December 2000 were analyzed retrospectively to clarify the complexities of this treatment. Patients were divided into Groups I (earlier) to IV (later) according to the date of surgery. Outcome was evaluated as no change after surgery, transient postoperative deterioration (TD), or permanent deterioration (PD). Operative period, background disease, age, aneurysm location and size, postoperative results, and affecting factors were investigated. The overall rate of PD was 5%, including one death (0.3%), and the overall rate of TD was 11%. Cases of middle cerebral artery aneurysm and small aneurysm with diameters less than 10 mm in all locations showed favorable outcomes. There were no significant differences in operative results and period except the lower incidence of TD in Group IV. Surgical outcome was significantly correlated with aneurysm size. Vertebrobasilar artery aneurysm was associated with worse operative results. Most of the causes of PD were related to operative procedures, mainly perforator injury and general complications. Unruptured aneurysm can be treated safely, especially in cases of middle cerebral artery aneurysm and small aneurysm of less than 10 mm diameter in all locations. Larger aneurysms and vertebrobasilar artery aneurysm should be treated by experienced neurosurgeons.

Adult↗
PubMed2004

Incidence and risk factors for the growth of unruptured cerebral aneurysms: observation using serial computerized tomography angiography.

OBJECT: The goal of this study was to examine the growth of unruptured intracranial aneurysms with the focus on the risk factors and incidence of these lesions. METHODS: One hundred sixty-six untreated cerebral saccular aneurysms were analyzed in 140 patients. The age of the patients ranged from 29 to 82 years (mean 62.8 years), the female/male ratio was 94:46, and the mean follow-up period was 17.7 months. Aneurysms were located at the internal carotid artery (ICA) in 68 patients, the middle cerebral artery (MCA) in 43, the anterior cerebral artery in 38, the basilar artery (BA) in 13, and the vertebral artery in four patients. The maximum diameter of the lesions ranged from 2 to 20 mm (mean 4.1 mm). All patients were examined using serial computerized tomography angiography to evaluate signs of aneurysm growth. Although growth was identified in 10 aneurysms (nine patients 16.4%]), no bleeding occurred. Growth-related changes were significantly associated with the size of the aneurysm and occurred in three (2.4%) of 125 aneurysms measuring 2 to 4 mm, three (9.1%) of 33 lesions measuring 5 to 9 mm, and four (50%) of eight lesions measuring 10 to 20 mm. These changes were more frequently found in aneurysms located at the BA bifurcation (two [40%] of five lesions) and the ICA (six [8.8%] of 68 lesions) than in those located at the MCA (zero of 43 lesions, p < 0.05). The 1-, 2-, and 3-year cumulative growth rates calculated using the Kaplan-Meier method were 2.5, 8, and 17.6%, respectively. CONCLUSIONS: A diameter of at least 10 mm and a location at the BA bifurcation or the ICA were significant risk factors for aneurysm growth. The incidence of growth was 2.5% in the 1st year and this risk increased yearly. Computerized tomography angiography is useful for follow up of patients with aneurysms because it allows the detection of even subtle morphological changes.

Adult↗
PubMed2003

Extracranial-intracranial bypass for reconstruction of internal carotid artery in the management of head and neck cancer.

Extracranial-intracranial bypass surgery was performed prior to carotid resection in eight patients with head and neck carcinoma that involved the carotid artery near the skull base. Four patients underwent the standard one-stage extracranial-intracranial bypass procedure. A two-stage procedure was performed in the remaining four patients. The procedure first involved an anastomosis between the M3 segment of the middle cerebral artery and the superficial temporal artery, followed by a bypass between the M2 segment of the middle cerebral artery and the internal carotid artery. One of the patients who underwent the standard one-stage extracranial-intracranial bypass procedure suffered an intraoperative infarction. Despite even longer occlusion times of the M2 segment, none of the patients who underwent the two-stage bypass suffered from any serious neurologic consequences. Three of seven patients who underwent the curative operations, survived more than 4 years, however, the remaining patients died within 1 year from recurrence. Our results show that carotid artery resection yields an opportunity for cure. In extracranial-intracranial bypass surgery, the temporary occlusion of the middle cerebral artery may also induce serious ischemia; however, the two-stage extracranial-intracranial bypass procedure appears to minimize the risk.

Adenocarcinoma↗
PubMed2003

Anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette.

OBJECTIVE: During cranial base surgery, use of a high-speed drill for osteotomy has become common. We performed anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette, and we report the advantages and clinical applications of this method. DESCRIPTION OF INSTRUMENTATION: The ultrasonic surgical equipment comprises a power supply unit, footswitch, and handpiece (weight, 110 g; diameter, 20 mm; length, 140 mm from tip to angled section). The handpiece tip is 2 mm wide, and the amplitude of longitudinal vibration can be varied from 120 to 365 microm at an ultrasonic frequency of 25 kHz. Cool-controlled irrigation fluid emerges near the tip, through the sheath. EXPERIENCE AND RESULTS: We performed anterior clinoidectomy in eight cases of paraclinoid aneurysm and opening of the internal auditory canal in six cases of acoustic neuroma without damage to the dura mater or nearby structures such as brain tissue, blood vessels, and cranial nerves. In addition, no damage to the facial nerve or labyrinthine organ resulted from heat or vibration caused by the ultrasonic bone curette. CONCLUSION: Ultrasonic bone curettage represents safe instrumentation for performance of anterior clinoidectomy and opening of the internal auditory canal without damage to surrounding structures. This technique allows surgeons to perform procedures on deep areas without incurring psychomotor stress.

Craniotomy↗
PubMed2003

Cooperative study of ruptured vertebrobasilar artery aneurysms in the Tohoku district in Japan.

A multicenter study investigated the clinical characteristics and overall outcome of 342 cases of ruptured vertebrobasilar artery aneurysms among 6783 ruptured intracranial berry aneurysms in 73 hospitals across the Tohoku district in Japan between 1992 and 1996. The incidence of ruptured vertebrobasilar artery aneurysms was less frequent than previously reported. The incidence was 5% among all intracranial berry aneurysms. One hundred eleven patients had aneurysms of the basilar artery bifurcation, 98 had vertebral-posterior inferior cerebellar artery aneurysms, 44 had basilar-superior cerebellar artery aneurysms, and 28 had distal posterior inferior cerebellar artery aneurysms. Aneurysm clipping was performed in 238 cases (70%), intravascular treatment in 22 (6%), drainage in 22 (6%), and conservative treatment in 60 (18%). Approximately 50% of patients were in good condition at admission. At 3-month follow up, 46% had good recovery, 14% had moderate disability, 10% had severe disability, 4% were vegetative state, and 27% died. Vertebral artery aneurysms showed favorable outcomes compared to basilar artery bifurcation aneurysms. Surgical results in the 238 operated cases were good recovery in 60%, moderate disability in 18%, severe disability in 10%, vegetative state in 2%, and death in 11% of cases. Worse postoperative outcomes were observed in patients with high preoperative Hunt and Kosnik grades or aneurysms larger than 10 mm, and in patients over 70 years of age.

Aged↗
PubMed2002

Diffusion-weighted magnetic resonance imaging in patients with subarachnoid hemorrhage.

OBJECTIVE: To evaluate the occurrence and distribution of direct brain injury caused by acute subarachnoid hemorrhage (SAH) by the use of magnetic resonance imaging. METHODS: Computed tomography and magnetic resonance imaging, including diffusion-weighted imaging (DWI), were performed in 32 patients with SAH by use of a 1.5-T whole-body superconductive scanner equipped with an echo planar imaging system. In all cases, computed tomographic and magnetic resonance imaging scans were obtained at the time of admission, before angiography and surgical intervention. RESULTS: No abnormalities were revealed by DWI in any of the low-grade SAH patients. However, five (71%) of seven patients diagnosed as having poor-grade SAH (World Federation of Neurosurgical Societies Grades 4 and 5) displayed multiple, patchy focal abnormalities on DWI. Computed tomographic scans obtained at admission failed to clearly demonstrate all of the damaged areas of the brain that were visualized by DWI. These lesions were located in supratentorial cerebral parenchyma, but not in the thalamus, basal ganglia, or cerebellar hemisphere. These multiple widespread lesions exhibiting laminar involvement of the cerebral cortex were not associated with the site of the ruptured aneurysm. CONCLUSION: DWI revealed widespread multifocal lesions in the cerebral cortex of acute poor-grade SAH patients. DWI provides accurate images of all areas of brain damage directly attributable to SAH.

Adult↗
PubMed2002

[Analysis using positron emission topography (PET) in hemiparetic patients with chronic subdural hematoma].

Chronic subdural hematoma (CSH) is a disease caused by minor head trauma and can be cured by surgical treatment. It remains unclear why CSH can cause neurologic dysfunction such as hemiparesis, although some reports describe the contribution of impaired cerebral blood flow (CBF) and oxygen metabolism of patients with CSH. We studied five hemiparetic patients with unilateral CSH using positron emission tomography (PET). Before the operation, both the regional CBF (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO2) were observed to have decreased slightly in the motor cortex and the lentiform nucleus on the bilateral side. However, regional oxygen extraction fraction (rOEF), regional cerebral blood volume (rCBV) and cerebral vascular response (CVR) in the same regions were normal. In the thalamus, no significant findings were observed. Although rCBF and rCMRO2 recovered to within normal range in the motor cortex and lentiform nucleus on the bilateral side by four weeks after the the operation, hemiparesis improved in all the patients within 3 days after the operation. In conclusion, this study suggests that a circulatory disturbance in the motor cortex under the hematoma was not indicated as a definite cause that induced hemiparesis with CSH.

Aged↗