PubMed Health⌕ Search

Biomedical subjects

Yuhei Yoshimoto

Publications and source records attributed to Yuhei Yoshimoto.

7 recordsLinked to original sources
PubMed2006

A mathematical model of the natural history of intracranial aneurysms: quantification of the benefit of prophylactic treatment.

OBJECT: The International Study of Unruptured Intracranial Aneurysms (ISUIA) data raised new controversy regarding the threshold size that requires treatment. In particular, this study has been criticized for disagreeing with previous epidemiological data. METHODS: The author first used a Markov model to simulate the natural history of intracranial aneurysms, making three key assumptions based on prospective ISUIA data and other recent reports: that the rate of de novo aneurysm formation is constant after the age of 20 years; that unruptured aneurysms gain volume at a constant rate; and that unruptured aneurysms rupture at a volume-dependent rate. Next, he expressed outcomes for patients with unruptured aneurysms in terms of expected number of quality-adjusted life years (QALY) and compared two hypothetical cohorts, one receiving treatment and the other not being treated. These assumptions enabled the construction of a mathematical model with epidemiologically compatible findings. The benefits of treatment for unruptured aneurysms were highly influenced by aneurysm size and were calculated as -0.28, 0.25, and 1.07 QALY for patients having unruptured aneurysms with diameters of 7, 10, and 13 mm, respectively. CONCLUSIONS: Under the author's assumptions, the prospective ISUIA data may be consistent with epidemiological findings. Prophylactic treatment for unruptured aneurysms may produce some benefits in large aneurysms if acceptable treatment risks can be assured, but it is not likely to offer improvement over the natural history for patients with small aneurysms.

Age Factors↗
PubMed2005

Basilar artery dissection.

OBJECT: Little is understood about the clinical manifestations of basilar artery (BA) dissections, which can present with subarachnoid hemorrhage (SAH), brainstem compression, or ischemia. In any instance, the prognosis seems poorer than that for vertebral artery (VA) dissection. The authors analyzed clinical presentations and radiological features of BA dissection with and without rupture. METHODS: Between 1998 and 2003, the authors treated 10 patients (eight men and two women, ranging in age from 32-78 years; mean age 54 years) with BA dissection. Diagnosis was based on clinical and radiological findings, including those from magnetic resonance imaging and cerebral angiography studies. Of the 10 patients, five had impaired consciousness at disease onset. Among four patients presenting with SAH, two were treated conservatively and had fair outcomes without recurrent hemorrhage. The other two patients with SAH were treated using unilateral endovascular VA occlusion, but one of them subsequently suffered fatal rebleeding. A fifth patient presented with progressive signs of a mass involving the brainstem, whereas the remaining five patients showed brainstem ischemia; all were treated conservatively. Four patients could not return to their previous daily activities. CONCLUSIONS: Basilar artery dissections are rare lesions associated with significant morbidity and death. The natural course of and the treatment options for BA dissection differ considerably from those for VA dissections. Management of these lesions is controversial and difficult, and requires particular care.

Adult↗
PubMed2005

Systematic review of the natural history of vestibular schwannoma.

OBJECT: Magnetic resonance (MR) imaging now permits diagnosis of increasing numbers of small, minimally symptomatic vestibular schwannomas (VSs). Because VS growth patterns over time are very important in refining treatment strategies, these matters were systematically reviewed. METHODS: An extensive MEDLINE search was performed to cull studies on VS growth according to sequential imaging. The percentages of growing and regressing tumors and lesions requiring treatment during follow-up periods were calculated. Factors associated with differences among studies were identified. Twenty-six studies including 1340 patients met all inclusion criteria. The overall frequency of VS growth during a mean follow-up period of 38 months was 46% (95% confidence interval [CI] 43-48%) and that of regression was 8% (95% CI 6-10%). The mean annual tumor growth rate was 1.2 mm/year. Furthermore, the percentage of cases requiring treatment during follow up was 18% (95% CI 16-21%). According to results of a sensitivity analysis, evaluation by serial MR imaging (39%, 95% CI 35-43%) and a prospective study design (29%, 95% CI 21-37%) were associated with less frequent reported tumor growth. CONCLUSIONS: Although their applicability may be limited to relatively elderly patients with small tumors, data revealing a limited frequency of VS enlargement and an infrequent necessity for eventual therapy should assist decision-making in the treatment of small VSs causing minimal symptoms.

Aged↗
PubMed2004

Angiographic assessment of cerebral circulation time for outcome prediction in patients with subarachnoid hemorrhage.

BACKGROUND: In the acute stage following subarachnoid hemorrhage (SAH), prolonged cerebral circulation time reflects increased intracranial pressure (ICP), which can lead to irreversible brain damage. We evaluated the ability of cerebral circulation time to predict outcome in SAH patients. METHODS: We prospectively studied 40 consecutive patients treated for SAH according to standard intensive care guidelines. Lateral views in preoperative carotid digital subtraction arteriograms (DSA) were used to determine arteriovenous transit time (AVTT), defined as interval from initial opacification of the intracranial internal carotid artery to that of the Rolandic vein. We then analyzed relationship of AVTT to other prognostic parameters and outcome. RESULTS: AVTT depended on initial Glasgow Coma Scale score (GCS), ranging from 3.4 to 8.0 seconds (mean: 5.4) when initial GCS was 13 to 15; from 4.5 to 8.7 seconds (mean: 6.4) when initial GCS was 7 to 12; and from 5.8 to 15.0 seconds (mean: 9.1 seconds, excluding angiograms with nonfilling) when initial GCS was 3 to 6. AVTT correlated significantly with prognosis, longer AVTT predicting poorer outcome. No patient with an AVTT above 12 seconds recovered to a functioning state. CONCLUSIONS: AVTT obtained from routinely performed acute-phase DSA in SAH patients reflects ICP and functional prognosis, representing a cost-effective, practical, and reliable outcome predictor.

Adult↗