Hiroaki Shimizu

Kohnan Hospital, Sendai, Kagoshima, Japan

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Publications (118)159.49 Total impact

  • No shinkei geka. Neurological surgery 08/2014; 42(8):737-43. · 0.13 Impact Factor
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    ABSTRACT: Objective: Cerebral hyperperfusion syndrome (HPS) is a potential complication of extracranial-intracranial (EC-IC) bypass for moyamoya disease; however, the pathological threshold of the early cerebral blood flow (CBF) increases after EC-IC bypass has yet to be determined. The purpose of this study is to evaluate the predictive and diagnostic values of early quantitative CBF analysis for the detection of HPS after EC-IC bypass for moyamoya disease. Methods: We quantitatively evaluated regional CBF at the site of the anastomosis in 23 patients with moyamoya disease aged between 18 and 66 years (mean, 39·6) before and 1 day after superficial temporal artery-middle cerebral artery anastomosis by an auto-radiographic method using N-isopropyl-p-[(123)I]iodoamphetamine single-photon emission computed tomography. Results: Regional CBF 1 day after surgery was significantly higher in patients with HPS (n = 5; mean, 54·6 ml/100 g/minutes) than in patients without HPS (n = 18; mean, 40·5 ml/100 g/minutes) (P = 0·038). The postoperative/preoperative CBF ratio was significantly higher in patients with HPS (1·84) than in patients without HPS (1·34) (P = 0·044). Multivariate analyses showed that the regional CBF value 1 day after surgery (P = 0·036) and operating on the left hemisphere (P = 0·026) significantly correlated with HPS. All patients with HPS developed symptoms and/or intracerebral hemorrhage more than 2 days after EC-IC bypass. Receiver operating characteristic analysis indicated that the cutoff value of pathological postoperative CBF increase was 46·1 ml/100 g/minutes (sensitivity = 80%, specificity = 77·8%, AUC value = 0·81). Conclusion: Quantitative analysis of early postoperative CBF is useful for predicting and diagnosing HPS after revascularization surgery for moyamoya disease.
    Neurological Research 08/2014; · 1.18 Impact Factor
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    ABSTRACT: Reports of cervical perimedullary arteriovenous shunt (PMAVS) are limited, and treatment strategies have not been established.
    Neurosurgery 05/2014; · 2.53 Impact Factor
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    ABSTRACT: A 25-year-old man complained of disorientation and gait disturbance during the past 2 weeks. The patient had been treated for cerebellar astrocytoma by open surgery thrice, at ages 3, 5, and 11. Ventriculo-peritoneal shunt was performed for postoperative hydrocephalus at the age of 11. Magnetic resonance imaging(MRI)showed enlargement of both lateral ventricles, ballooning of the third ventricle, and obstruction of the aqueduct of Sylvius. The patient was diagnosed with recurrent hydrocephalus due to shunt malfunction, and treated by endoscopic third ventriculostomy(ETV)using a flexible endoscopic system. He was relieved of the symptoms immediately after surgery, and postoperative MRI showed reduced hydrocephalus. However, the symptoms reoccurred 6 days after surgery. Computed tomography did not show recurrence of hydrocephalus. Laboratory tests revealed hyponatremia(117mEq/L)and low serum osmolality(240mOsm/kg). The patient gained 2.4 kg over the preoperative body weight. The syndrome of inappropriate secretion of antidiuretic hormone(SIADH)was considered to be the cause of the hyponatremia, which was successfully treated with 3 days of fluid restriction. The patient was discharged 24 days after surgery. Hyponatremia is a relatively rare complication of ETV. When a patient shows recurrence of hydrocephalus-related symptoms during the early postoperative period after ETV, hyponatremia caused by SIADH should be considered.
    No shinkei geka. Neurological surgery 04/2014; 42(4):335-9. · 0.13 Impact Factor
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    ABSTRACT: Moyamoya disease (MMD) is a chronic occlusive cerebrovascular disease with unknown etiology. Recent genome-wide and locus-specific association studies identified RNF213 as an important MMD susceptibility gene. However, the exact mechanism by which an abnormality in RNF213 leads to MMD is unknown. To evaluate the role of RNF213 in the etiology of MMD, we generated RNF213-deficient mice (RNF213-/-) by deleting exon 32 of RNF213 by the Cre-lox system, and investigated whether they developed MMD. The temporal profile of cervical/intracranial arteries was evaluated by 9.4-Tesla magnetic resonance angiography (MRA). The anatomy of the circle of Willis was analyzed by a trans-cardiac injection of carbon black dye. The common carotid arteries (CCA) were sectioned and the arterial wall thickness/thinness was evaluated by Elastica-Masson staining before and after CCA ligation, which selectively induced vascular hyperplasia. As a result, RNF213-/- grew normally, and no significant difference was observed in MRA findings, the anatomy of the circle of Willis, or vascular wall thickness/thinness between RNF-/- and wild-type littermates (Wt.) under normal conditions until 64 weeks of age. However, Elastica-Masson staining demonstrated that both the intimal layer and medial layer were significantly thinner after CCA ligation in RNF213-/- than in Wt. at 14 days (P<0.01). In conclusion, mice lacking the RNF213 gene did not spontaneously develop MMD, indicating that a functional loss of RNF213 did not sufficiently induce MMD. Suppression of vascular remodeling in RNF213-/- requires further examination to clarify the role of RNF213.
    Brain research 01/2014; · 2.46 Impact Factor
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    ABSTRACT: Stachybotrys microspora triprenyl phenol-7 (SMTP-7) is a new thrombolytic agent that exhibits anti-inflammatory effects. We previously demonstrated that the hemorrhagic transformation was fewer with SMTP-7 than with recombinant tissue plasminogen activator (rt-PA) following ischemia-reperfusion in animal models. We hypothesized that SMTP-7 may decrease hemorrhagic transformation after ischemia-reperfusion under the warfarin-treated condition. Transient middle cerebral artery occlusion (MCAO) was induced for three hours using an intraluminal suture in warfarin-treated mice to produce hemorrhagic transformation. Warfarin was administered orally for a 24-hour feeding period before MCAO through bottled drinking water (5 mg in 375 ml tap water), resulting in a mean INR of 5.6±0.2. Mice were treated with vehicle, rt-PA, or SMTP-7 five minutes before reperfusion. Twenty percent of vehicle-treated and 50.0% of rt-PA-treated mice died 24 hours after reperfusion, while all SMTP-7-treated mice survived. Hemorrhagic severity in SMTP-7-treated mice was significantly lower than that in rt-PA-treated mice. Neurological deficit was significantly lower in SMTP-7-treated mice than vehicle- and rt-PA-treated mice. These results indicate that SMTP-7 decreases mortality, hemorrhagic transformation, and neurological deficits, and can be a safe thrombolytic agent following MCAO under the warfarin-treated condition.
    Brain Research. 01/2014;
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    ABSTRACT: Sjögren syndrome affecting the major cerebral arteries is rare, and an optimal therapeutic strategy to counteract such a lesion has not yet been established. We herein report a case of a 39-year-old woman with a history of primary Sjögren syndrome, which had previously been treated with immunosuppressive therapy, manifesting with a crescendo transient ischemic attack because of left middle cerebral artery stenosis. Despite the administration of high doses of prednisolone and azathioprine for active Sjögren syndrome, the frequency of crescendo transient ischemic attacks increased with the progression of stenosis and magnetic resonance imaging showed the development of subacute cerebral infarction. Single-photon emission computed tomography with N-isopropyl[123I]-p-iodoamphetamine revealed apparent hemodynamic compromise in the affected cerebral hemisphere. In light of the increased risk of further progression of cerebral infarction, we decided to perform surgical revascularization in spite of her active inflammatory condition. The patient underwent extracranial–intracranial bypass without complications and was treated with intensive immunosuppressive therapy during the perioperative period. Based on our findings, we recommend surgical revascularization for occlusive cerebrovascular disease with hemodynamic compromise in combination with intensive immunosuppressive therapy, even in the active inflammatory state of autoimmune diseases, if ischemic symptoms are medically uncontrollable.
    Journal of Stroke and Cerebrovascular Diseases. 01/2014;
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    ABSTRACT: Bilateral giant internal carotid artery (ICA) aneurysms at the cavernous portion with bilateral cranial nerve symptoms are extremely rare. Extracranial–intracranial (EC-IC) bypass with parent artery occlusion (PAO) is one of the preferred procedures for giant ICA aneurysm at the cavernous portion with cranial nerve palsy; however, optimal bypass selection and the timing of surgery are controversial, particularly in bilateral cases. A 28-year-old woman developed left third nerve palsy with giant ICA aneurysms at the bilateral cavernous portion. Because only the left aneurysm was symptomatic, she initially underwent left EC-IC bypass using a saphenous vein graft with PAO without complications, which relieved her symptoms. However, she developed right third/fifth nerve palsy 10 months later, at which time magnetic resonance (MR) imaging and MR angiography revealed an enlarged right ICA aneurysm and shrunken left ICA aneurysm. Balloon test occlusion of the right ICA identified sufficient ischemic tolerance; therefore, she underwent right superficial temporal artery–middle cerebral artery bypass with PAO. Both bypasses were confirmed by MR angiography to be patent after surgery. Cranial nerve palsy gradually improved postoperatively, and single-photon emission computed tomography confirmed static cerebral hemodynamics. In conclusion, high-flow EC-IC bypass with PAO is recommended in the first stage of surgery on a unilaterally symptomatic side to minimize postoperative hemodynamic stress to the contralateral aneurysm. Once the contralateral side becomes symptomatic, second stage EC-IC bypass with PAO, either low-flow or high-flow bypass, is recommended based on the results of balloon test occlusion.
    Journal of Stroke and Cerebrovascular Diseases. 01/2014;
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    ABSTRACT: We report two cases with internal carotid artery(ICA)aneurysms, in which fusion image effectively indicated the anatomical variations of the anterior choroidal artery(AchoA). Fusion image was obtained using fusion application software(Integrated Registration, Advantage Workstation VS4, GE Healthcare). When the artery passed through the choroidal fissure, it was diagnosed as AchoA. Case 1 had an aneurysm at the left ICA. Left internal carotid angiography(ICAG)showed that an artery arising from the aneurysmal neck supplied the medial occipital lobe. Fusion image showed that this artery had a branch passing through the choroidal fissure, which was diagnosed as hyperplastic AchoA. Case 2 had an aneurysm at the supraclinoid segment of the right ICA. AchoA or posterior communicating artery(PcomA)were not detected by the right ICAG. Fusion image obtained from 3D vertebral angiography(VAG)and MRI showed that the right AchoA arose from the right PcomA. Fusion image obtained from the right ICAG and the left VAG suggested that the aneurysm was located on the ICA where the PcomA regressed. Fusion image is an effective tool for assessing anatomical variations of AchoA. The present method is simple and quick for obtaining a fusion image that can be used in a real-time clinical setting.
    No shinkei geka. Neurological surgery 12/2013; 41(12):1075-1080. · 0.13 Impact Factor
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    ABSTRACT: Background: Timing of the onset of subarachnoid hemorrhage (SAH) is important for treatment decision-making, especially as some patients visit hospital several weeks after the onset of SAH. T2*-weighted (T2*W) magnetic resonance (MR) imaging is regarded as a sensitive method for the detection of deoxyhemoglobin or hemosiderin deposits. This study investigated the characteristics of the abnormal low intensity changes on T2*W imaging in patients with SAH, how long the abnormal low intensity persisted, and whether the day of onset could be predicted based on the T2*W imaging changes. Methods: The study included patients treated for SAH associated with ruptured cerebral aneurysms, or who had previously suffered such SAH and were followed up at our hospital, between 2006 and 2007. MR imaging was performed using a whole-body 3.0-tesla MR scanner. All patients underwent gradient recalled echo (GRE) and echo planar (EP) T2*W imaging. The strength of the low intensity areas was evaluated as the following 5 grades: grade 0, no abnormal low intensity on both GRE and EP T2*W images; grade 1, no abnormal intensity on GRE T2*W images and low intensity on EP T2*W images; grade 2, spotty abnormal low intensity on both GRE and EP T2*W images; grade 3, medium abnormal low intensity (<5 mm) on both GRE and EP T2*W images, and grade 4, large abnormal low intensity (≥5 mm) on both GRE and EP T2*W images. Results: A total of 50 patients with 74 MR images were included during the study period. Abnormal low intensity on T2*W imaging was observed in all patients. The T2* score gradually decreased from the onset of SAH until day 90, showing a significant negative linear correlation (R(2) = 0.25, p = 0.0002). On the other hand, the T2* score did not change after 1 year. The square correlation coefficient between the recorded and calculated days from the onset of SAH was 0.29 (p = 0.0107). The pure error was ±10 days. Conclusion: The T2* score gradually decreased until 90 days from the onset of SAH, but persisted for 16 years after the onset. We could predict the day of onset with pure error ±10 days in patients with SAH within 90 days of onset using our grading system for T2*W images. © 2013 S. Karger AG, Basel.
    Cerebrovascular Diseases 11/2013; 36(5-6):421-429. · 2.81 Impact Factor
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    ABSTRACT: Cerebral hyperperfusion (CHP) is a potential complication of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD), and optimal postoperative management has not yet been established. Minocycline, a neuroprotective antibiotic agent, plays a role in blocking matrix metalloproteinase-9 (MMP-9), which contributes to edema formation and hemorrhagic conversion following cerebral ischemia-reperfusion. Patients with MMD have been shown to have increased serum MMP-9 levels. To examine the effect of minocycline on the prevention of postoperative CHP following STA-MCA anastomosis for MMD. N-isopropyl-p-[I]iodoamphetamine single-photon emission computed tomography was performed 1 and 7 days after STA-MCA anastomosis on 109 hemispheres from 86 consecutive patients with MMD (9-69, mean 37 years old). Postoperative systolic blood pressure was strictly controlled under 130 mmHg in all 109 surgeries. The most recent 60 hemispheres were managed by the intra-operative and postoperative intravenous administration of minocycline hydrochloride (200 mg/day). The incidence of focal neurologic deterioration (FND) due to CHP was then compared with 36 patients undergoing 49 surgeries managed without minocycline. FND due to CHP was observed on 4 operated hemispheres in patients treated without minocycline (4/49, 8.16%), and on none in the minocycline-treated group (0/60) (p=0.00241). Multivariate analysis revealed that minocycline administration (p<0.0001), surgery on the left hemisphere (p=0.0314), and a smaller recipient artery diameter (p=0.0005) significantly correlated with FND due to CHP. The administration of minocycline with strict blood pressure control may represent secure and effective postoperative management to prevent symptomatic CHP after STA-MCA anastomosis for MMD.
    Neurosurgery 10/2013; · 2.53 Impact Factor
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    ABSTRACT: Angiography-based balloon test occlusion (BTO) has been empirically used to predict tolerance to permanent carotid artery occlusion. We tested the hypothesis that the laterality of the hemispheric circulation time (HCT) of the contrast medium at cerebral angiography would reflect bilateral asymmetry of the cerebral blood flow (CBF) during BTO. Thirty-one consecutive patients who underwent BTO of the internal carotid artery were retrospectively analyzed. HCT was defined as the interval between the time-to-peak in the middle cerebral artery and the cortical veins calculated using time-density curve. The difference in HCT between the occluded and nonoccluded side was calculated at the carotid or dominant vertebral angiograms obtained during BTO. We estimated the correlation between the difference in HCT and bilateral asymmetry of the CBF, which was quantitatively determined by single-photon emission computed tomography. The HCT was 5.3±1.5 seconds and regional CBF was 41.3±11.3 mL/100 g per minute in the occluded side, compared with 3.6±0.9 seconds and 48.4±14.9 mL/100 g per minute in the nonoccluded side, respectively. The difference in HCT was strongly correlated with the asymmetry ratio of the CBF (r(2)=0.89, P<0.0001). Angiographically based measurement of the cerebral circulation time can provide valuable information concerning cerebral hemodynamics.Journal of Cerebral Blood Flow & Metabolism advance online publication, 9 October 2013; doi:10.1038/jcbfm.2013.176.
    Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 10/2013; · 5.46 Impact Factor
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    ABSTRACT: Intracranial aneurysms can have atherosclerotic wall properties that may be important in predicting aneurysm history or estimating the potential risks of surgical treatments. To investigate hemodynamic characteristics of atherosclerotic lesions in intracranial aneurysms using computational fluid dynamics (CFD). Intra-operative video recordings of thirty consecutive patients with an unruptured middle cerebral artery aneurysm were examined to identify atherosclerotic lesions on aneurysm wall. For CFD analyses, geometries of aneurysms and adjacent arteries were reconstructed from three-dimensional rotational angiography. Transient simulations were conducted under patient-specific pulsatile inlet conditions measured by phase-contrast magnetic resonance velocimetry. Three hemodynamic wall parameters were calculated: time-averaged wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT). Statistical analyses were performed to discriminate the risk factors of atherosclerotic lesion formation. Among 30 aneurysms, seven atherosclerotic lesions with remarkable yellow lipid deposition were identified in five aneurysms. All seven atherosclerotic lesions were spatially agreed with the area with prolonged RRT. Univariate analysis revealed that male (P = 0.031), cigarette smoking (P = 0.047) and maximum RRT (P = 0.024) are significantly related to atherosclerotic lesion on the intracranial aneurysmal wall. Of those variables that influenced atherosclerotic lesion of the intracranial aneurysmal wall, the variable male (P = 0.0046) and maximum RRT (P = 0.0037) remained significant in the multivariate regression model. The area with prolonged RRT co-localized with atherosclerotic change on the aneurysm wall. Male and maximum RRT were independent risk factors for atherogenesis in intracranial aneurysms.
    Neurosurgery 07/2013; · 2.53 Impact Factor
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    ABSTRACT: BACKGROUND: Progressing stroke is one of the major determinants of outcome after acute ischemic stroke. A pilot randomized controlled trial was conducted to investigate the effect of cilostazol on progressing stroke. METHODS: Adult patients with noncardioembolic ischemic stroke within 24 hours after onset were randomized to receive cilostazol 200 mg/day (cilostazol group) or no medication (control group) in addition to the optimum medical treatments (a free radical scavenger plus an antiplatelet agent or an antithrombin agent). The primary endpoints were the rate of progressing stroke, defined as aggravation of the National Institutes of Health Stroke Scale (NIHSS) score by ≥4 points on days 3 and/or 5 and a modified Rankin Scale score of 0 to 1 at 3 months after enrollment. Aggravation caused by systemic complications, edema, hemorrhagic infarction, or recurrent stroke was not considered as progressing stroke. This trial was registered as UMIN000001630. RESULTS: A total of 510 patients were enrolled from 55 institutions in Japan between February 2009 and July 2010. The rate of progressing stroke was 3.2% and 6.3% in the cilostazol and control groups, respectively (P = .143). The modified Rankin Scale score of 0 to 1 at 3 months did not differ between the groups. CONCLUSIONS: Cilostazol failed to show a preventive effect against acute progressing stroke. However, the tendency to reduce progressing stroke and the results of stratified analyses may encourage additional studies to clarify the effect of cilostazol in the treatment of acute ischemic stroke.
    Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 03/2013;
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    ABSTRACT: Background: Cilostazol, an inhibitor of phosphodiesterase 3, has various pleiotropic effects besides its antiplatelet activity. This study examined the efficacy of cilostazol for the treatment of acute perforating artery infarction. Methods: In this prospective, randomized, open-label, blinded-end point trial, 100 patients with cerebral infarction in the territory of the lenticulostriate arteries were enrolled within 48 h of onset. Patients were randomly treated with both cilostazol and ozagrel for 14 days (n = 50, cilostazol group) or ozagrel alone for 14 days (n = 50, control group). The primary end point was the proportion of favorable outcomes 30 days after randomization as defined by a modified Rankin Scale (mRS) score of 0-2. Secondary end points included the incidence of neurological deterioration (an increase of ≥2 on the National Institutes of Health Stroke Scale within 7 days). Results: Favorable outcomes (mRS scores 0-2) were similar in both groups (81.3 and 82.0% in the cilostazol and control groups, respectively). The incidence of neurological deterioration was lower in the cilostazol group than the control group (12.5 and 16.0%, respectively) with a 21.9% relative risk reduction, although the difference was not statistically significant. Conclusions: Cilostazol did not prevent the neurological deterioration of perforating artery infarction.
    European Neurology 11/2012; 69(2):122-128. · 1.50 Impact Factor
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    ABSTRACT: Object Dural arteriovenous fistulas (DAVFs) and perimedullary arteriovenous fistulas (PAVFs) are uncommonly associated in the craniocervical junction. The purpose of this study was to describe the clinical and angiographic characteristics of such concurrent lesions. Methods Authors reviewed 9 cases with a coexistent DAVF and PAVF at the craniocervical junction. Clinical presentation, angiographic characteristics, intraoperative findings, and treatment outcomes were assessed. Results All patients (male/female ratio 5:4; mean age 66.3 years) presented with subarachnoid hemorrhage. Angiography revealed that 8 patients had both a DAVF and PAVF on the same side, whereas 1 patient had 3 arteriovenous fistulas, 1 DAVF, and 1 PAVF on the right side and 1 DAVF on the left side. All of the fistulas shared dilated perimedullary veins (anterior spinal vein, 7 cases; anterolateral spinal vein, 2 cases) as a main drainage route. The shared drainage route was rostrally directed in 8 of 9 cases. Eight patients exhibited an arterial aneurysm on the distal side of the feeding arteries to the PAVF, and the aneurysm in each case was intraoperatively confirmed as a bleeding point. One patient had ruptured venous ectasia at the perimedullary fistulous point. All patients underwent direct surgery via a posterolateral approach. No recurrence was observed in the 4 patients who underwent postoperative angiography, and no rebleeding event was recorded among any of the 9 patients during the follow-up period (mean 38.4 months). Conclusions The similarity of the angioarchitecture and the close anatomical relationship between DAVF and PAVF at the craniocervical junction suggested that these lesions are pathogenetically linked. The pathophysiological mechanism and anatomical features of these lesions represent a unique vascular anomaly that should be recognized angiographically to plan a therapeutic strategy.
    Journal of Neurosurgery 11/2012; · 3.15 Impact Factor
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    ABSTRACT: Object Internal coil trapping is a treatment method used to prevent rebleeding from a ruptured intracranial vertebral artery dissection (VAD). Postoperative medullary infarctions have been reported as a complication of this treatment strategy. The aim of this study was to determine the relationship between a postoperative medullary infarction and the clinical outcomes for patients with ruptured VADs treated with internal coil trapping during the acute stage of a subarachnoid hemorrhage (SAH). Methods A retrospective study identified 38 patients who presented between 2006 and 2011 with ruptured VADs and underwent internal coil trapping during the acute stage of SAH. The SAH was identified on CT scanning, and the diagnosis for VAD was rendered by cerebral angiography. Under general anesthesia, the dissection was packed with coils, beginning at the distal end and proceeding proximally. When VAD involved the origin of the posterior inferior cerebellar artery (PICA) with a large cerebellar territory, an occipital artery (OA)-PICA anastomosis was created prior to internal coil trapping. The pre- and postoperative radiological findings, clinical course, and outcomes were analyzed. Results The internal coil trapping was completed within 24 hours after admission. An OA-PICA anastomosis followed by internal coil trapping was performed in 5 patients. Postoperative rebleeding did not occur in any patient during a mean follow-up period of 16 months. The postoperative MRI studies showed medullary infarctions in 18 patients (47%). The mean length of the trapped VAD for the infarction group (15.7 ± 6.0 mm) was significantly longer than that of the noninfarction group (11.5 ± 4.3 mm) (p = 0.019). Three of the 5 patients treated with OA-PICA anastomosis had postoperative medullary infarction. The clinical outcomes at 6 months were favorable (modified Rankin Scale Scores 0-2) for 23 patients (60.5%) and unfavorable (modified Rankin Scale Scores 3-6) for 15 patients (39.5%). Of the 18 patients with postoperative medullary infarctions, the outcomes were favorable for 6 patients (33.3%) and unfavorable for 12 patients (66.7%). A logistic regression analysis predicted the following independent risk factors for unfavorable outcomes: postoperative medullary infarctions (OR 21.287 [95% CI 2.622-498.242], p = 0.003); preoperative rebleeding episodes (OR 7.450 [95% CI 1.140-71.138], p = 0.036); and a history of diabetes mellitus (OR 45.456 [95% CI 1.993-5287.595], p = 0.013). Conclusions A postoperative medullary infarction was associated with unfavorable outcomes after internal coil trapping for ruptured VADs. Coil occlusion of the long segment of the VA led to medullary infarction, and an OA-PICA bypass did not prevent medullary infarction. A VA-sparing procedure, such as flow diversion by stenting, is an alternative treatment in the future, if this approach is demonstrated to effectively prevent rebleeding.
    Journal of Neurosurgery 10/2012; · 3.15 Impact Factor
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    ABSTRACT: OBJECTIVE: Quantitative cerebral blood flow (CBF) measured by single photon emission computed tomography (SPECT) with arterial blood sampling is one of the most reliable methods to assess the hemodynamics in individual patients. SPECT with venous blood sampling is less invasive. The present study compared the measurement of CBF using N-isopropyl-p-(iodine-123)-iodoamphetamine SPECT with venous blood sampling and with arterial blood sampling in patients with major cerebral artery occlusive disease. METHODS: Two normal subjects and 14 patients with major cerebral artery occlusive disease underwent SPECT with arterial and venous blood sampling. The microsphere method was used for quantitative SPECT imaging. Whole brain radioactivity was corrected when the detectors rotated in the forward direction (F(1)-F(7)). Venous sampling was performed 30min after radiotracer injection. Arterial blood radioactivity was estimated by multiple regression analysis from these parameters. The cerebrovascular reactivity to acetazolamide was also measured. RESULTS: Multiple regression analysis established the following formula:(where Ca(10) is the arterial blood radioactivity at 10min, F(1)-F(7) are the whole brain radioactivity in the forward direction, Cv(30) is the venous blood radioactivity at 30min). Mean CBF values were 32.2±6.6ml/100g/min for measured arterial radioactivity and 42.2±7.8ml/100g/min for calculated arterial radioactivity based on venous radioactivity. CONCLUSIONS: The present modified method of calculating quantitative CBF from whole brain and venous blood radioactivities correlated well with values determined with arterial blood radioactivity.
    Clinical neurology and neurosurgery 08/2012; · 1.30 Impact Factor
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    ABSTRACT: Threshold image intensity for reconstructing patient-specific vascular models is generally determined subjectively. We assessed the effects of threshold image intensity differences on computational fluid dynamics (CFD) using a simple method of threshold determination. This study included 11 consecutive patients with internal carotid artery aneurysms collected retrospectively between April 2009 and March 2010. In 3-dimensional rotational angiography image data, we set a line probe across the coronal cross-section of the parent internal carotid artery, and calculated a profile curve of the image intensity along this line. We employed the threshold coefficient (C(thre)) value in this profile curve, in order to determine the threshold image intensity objectively. We assessed the effects of C(thre) value differences on vascular model configuration and the wall shear stress (WSS) distribution of the aneurysm. The threshold image intensity increased as the C(thre) value increased. The frequency of manual editing increased as the C(thre) value decreased, while disconnection of the posterior communicating artery occurred more frequently as the C(thre) value increased. The volume of the vascular model decreased and WSS increased according to the C(thre) value increase. The pattern of WSS distribution changed remarkably in one case. Threshold image intensity differences can produce profound effects on CFD. Our results suggest the uniform setting of C(thre) value is important for objective CFD.
    Journal of biomechanics 07/2012; 45(14):2355-61. · 2.66 Impact Factor
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    ABSTRACT: OBJECT: The brain temperature at rest is determined by the balance between heat produced by cerebral energy turnover, which is identical to cerebral metabolism, and heat that is removed, primarily by cerebral blood flow. The present study investigated whether brain temperature measured by proton magnetic resonance (MR) spectroscopy can detect cerebral hemodynamic impairment in patients with arteriovenous malformations (AVMs) as shown by single photon emission computed tomography (SPECT). METHODS: Brain temperature, cerebral blood flow, and cerebrovascular reactivity were measured using proton MR spectroscopy and SPECT in five healthy volunteers and six patients with AVMs. Regions of interest were selected adjacent to the AVMs and in the corresponding contralateral region. RESULTS: Brain temperature around AVMs was calculated in all subjects using MR spectroscopy. The mean brain temperature in volunteers was 37.1±0.41°C. A significant correlation was observed between brain temperature ratio (affected side/contralateral side) and cerebrovascular reactivity ratio (affected side/contralateral side) (r=-0.82, p=0.0480). CONCLUSION: Brain temperature measured by proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with AVMs. Further investigations regarding the relationships between brain temperature and clinical feature in patients with AVMs are needed.
    Clinical neurology and neurosurgery 07/2012; · 1.30 Impact Factor

Publication Stats

567 Citations
159.49 Total Impact Points

Institutions

  • 2002–2013
    • Kohnan Hospital
      Sendai, Kagoshima, Japan
    • Tohoku University
      • • Department of Neurosurgery
      • • Graduate School of Medicine
      Sendai, Kagoshima, Japan
    • Iwate Medical University
      • Department of Neurosurgery
      Morioka-shi, Iwate-ken, Japan
  • 2004
    • Akita University Hospital
      Akita, Akita, Japan