Kuniaki Ogasawara

Aneurysms at nonbranching sites in the surpaclinoid portion of the internal carotid artery: internal carotid artery trunk aneurysms.

OBJECTIVEAneurysms at nonbranching sites in the supraclinoid internal carotid artery (ICA), known as blood blister-like aneurysms or ICA anterior or dorsal wall aneurysms, are not well understood. To clarify this clinical entity, 7408 patients with subarachnoid hemorrhage who were treated during a 5-year period were analyzed. METHODSForty-eight patients had aneurysms that were intraoperatively confirmed to be located at a nonbranching site in the supraclinoid portion of the ICA. Neuroradiological and clinicopathological features and outcomes were studied. RESULTSThe aneurysms were divided into the “blister type,” with a blood blister-like configuration and fragile walls, and the “saccular type,” with a saccular configuration and a relatively firm neck, like ordinary berry aneurysms. The most frequent origin was the anteromedial wall for both types. ICA dissection was associated only with the blister type, and hypertension was more frequent with the blister type (P = 0.0978). The preoperative conditions of the patients were the same, but the outcomes for patients with blister-type aneurysms were worse, because of frequent intra- and postoperative aneurysmal bleeding. Saccular-type aneurysms were safely clipped. Treatment of blister-type aneurysms by clipping on wrapping material achieved good results, but ICA trapping (P = 0.0952), clipping (P = 0.0146), and wrapping (P = 0.0110) were associated with much worse results. CONCLUSIONBlister-type and saccular-type aneurysms have different shapes and wall characteristics. The saccular type can be treated by clipping, whereas the blister type requires clipping on wrapping material. ICA trunk aneurysms may be a better designation to express the diversity of these aneurysms, rather than ICA blood blister-like or anterior or dorsal wall aneurysms.

Differences in CT Perfusion Maps Generated by Different Commercial Software: Quantitative Analysis by Using Identical Source Data of Acute Stroke Patients

PURPOSE To examine the variability in the qualitative and quantitative results of computed tomographic (CT) perfusion imaging generated from identical source data of stroke patients by using commercially available software programs provided by various CT manufacturers. MATERIALS AND METHODS Institutional review board approval and informed consent were obtained. CT perfusion imaging data of 10 stroke patients were postprocessed by using five commercial software packages, each of which had a different algorithm: singular-value decomposition (SVD), maximum slope (MS), inverse filter (IF), box modulation transfer function (bMTF), and by using custom-made original software with standard (sSVD) and block-circulant (bSVD) SVD methods. Areas showing abnormalities in cerebral blood flow (CBF), mean transit time (MTT), and cerebral blood volume (CBV) were compared with each other and with the final infarct areas. Differences among the ratios of quantitative values in the final infarct areas and those in the unaffected side were also examined. RESULTS The areas with CBF or MTT abnormalities and the ratios of these values significantly varied among software, while those of CBV were stable. The areas with CBF or MTT abnormalities analyzed by using SVD or bMTF corresponded to those obtained with delay-sensitive sSVD, but overestimated the final infarct area. The values obtained from software by using MS or IF corresponded well with those obtained from the delay-insensitive bSVD and the final infarct area. Given the similarities between CBF and MTT, all software were separated in two groups (ie, sSVD and bSVD). The ratios of CBF or MTTs correlated well within both groups, but not across them. CONCLUSION CT perfusion imaging maps were significantly different among commercial software even when using identical source data, presumably because of differences in tracer-delay sensitivity.

Cerebrovascular Reactivity to Acetazolamide and Outcome in Patients With Symptomatic Internal Carotid or Middle Cerebral Artery Occlusion A Xenon-133 Single-Photon Emission Computed Tomography Study

Background and Purpose— The present study prospectively evaluated relationships among baseline characteristics, cerebral hemodynamics, and outcome of patients with symptomatic major cerebral artery occlusion, by quantitative measurement of cerebral blood flow using xenon-133 (133Xe) inhalation and single-photon emission computed tomography (SPECT). Methods— Regional cerebrovascular reactivity (rCVR) to acetazolamide was calculated at entry to the study using 133Xe SPECT. Seventy consecutive patients aged less than 70 years with unilateral internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion were divided into 2 groups: normal or reduced rCVR, and prospectively followed up for a period of 24 months. Results— During the follow-up period, recurrent strokes occurred in 8 of the 23 patients with reduced rCVR at entry and in 3 of 47 patients with normal rCVR. Cumulative recurrence-free survival rates in all patients, and in each subgroup of patients with ICA or MCA occlusion and reduced rCVR on entry, were significantly lower than in those with normal rCVR (P =0.0030, P =0.0404, and P =0.0310, respectively; Kaplan-Meier analysis). Among the factors considered, only lower rCVR and resting regional cerebral blood flow values were significantly associated with the risk of stroke recurrence (P =0.0019 and P =0.0080, respectively; Cox regression multivariate analysis). Conclusions— The present study demonstrated that reduced rCVR to acetazolamide as determined by 133Xe SPECT is significantly associated with an increased risk of stroke recurrence in patients with symptomatic MCA or ICA occlusion.

Intracranial hemorrhage associated with cerebral hyperperfusion syndrome following carotid endarterectomy and carotid artery stenting: retrospective review of 4494 patients.

OBJECT Intracranial hemorrhage associated with cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) or carotid artery stenting (CAS) is a rare but potentially devastating complication. In the present study the authors evaluated 4494 patients with carotid artery stenosis who had undergone CEA or CAS to clarify the clinicopathological features and outcomes of those with CHS and associated intracranial hemorrhage. METHODS Patients with postoperative CHS were retrospectively selected, and clinicopathological features and outcomes were studied. RESULTS Sixty-one patients with CHS (1.4%) were identified, and intracranial hemorrhage developed in 27 of them (0.6%). The onset of CHS peaked on the 6th postoperative day in those who had undergone CEA and within 12 hours in those who had undergone CAS. Results of logistic regression analysis demonstrated that poor postoperative control of blood pressure was significantly associated with the development of intracranial hemorrhage in patients with CHS after CEA (p = 0.0164). Note, however, that none of the tested variables were significantly associated with the development of intracranial hemorrhage in patients with CHS after CAS. Mortality (p = 0.0010) and morbidity (p = 0.0172) rates were significantly higher in patients with intracranial hemorrhage than in those without. CONCLUSIONS Cerebral hyperperfusion syndrome after CEA and CAS occurs with delayed classic and acute presentations, respectively. Although strict control of postoperative blood pressure prevents intracranial hemorrhage in patients with CHS after CEA, there appears to be no relationship between blood pressure control and intracranial hemorrhage in those with CHS after CAS. Finally, the prognosis of CHS in patients with associated intracerebral hemorrhage is poor.

Diffusion tensor imaging for preoperative evaluation of tumor grade in gliomas

The relationship between water diffusion parameters measured using diffusion tensor imaging (DTI) and histological malignancy of gliomas was investigated. DTI was performed using a 3.0T MR scanner in 41 consecutive patients with histologically proven gliomas. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated and compared with the WHO classification of the gliomas. The FA values of grade 1 gliomas (0.150 +/- 0.017) were significantly lower than those of grade 3 (0.23 +/- 0.033) or grade 4 gliomas (0.229 +/- 0.033) (P < 0.0001, respectively). The FA values of grade 2 gliomas (0.159 +/- 0.018) were significantly lower than those of grade 3 or grade 4 gliomas (P = 0.0002, P < 0.0001, respectively). The FA threshold between low grade and high grade gliomas was 0.188. The MD values of grade 1 gliomas (1619.1 +/- 157.4 x 10(-6) mm2/s) were significantly higher than those of grade 3 (1084.5 +/- 218.9 x 10(-6) mm2/s) (P = 0.0036) or grade 4 gliomas (1098.0 +/- 291.6 x 10(-6) mm2/s) (P = 0.0002). The MD values were not correlated with the other grades of glioma. FA values can distinguish between high grade and low grade gliomas. This is useful in deciding the surgical strategy or selecting the site of stereotactic biopsy.

Measurement of fractional anisotropy using diffusion tensor MRI in supratentorial astrocytic tumors.

In vivo, water diffusion displays directionality due to presence of complex microstructural barriers in tissue. The extent of directionality of water diffusion can be expressed as a fractional anisotropy (FA) value, using diffusion tensor MR imaging (DTI). The aim of this study was to determine whether FA values indicate microstructures in astrocytic tumors. We performed DTI in 31 patients with astrocytic tumor, and measured the FA values of tumor and normal brain regions prior to CT-guided stereotactic biopsy. After biopsy, FA values were compared to assess the cellularity and vascularity of tumor tissue. Although mean FA values trended to differ among histological types, all mean tumor FA values were lower than those of normal brain regions. Positive correlation was observed between FA values and both cellularity (r = 0.65, p < 0.05) and vascularity (r = 0.45, p < 0.05). We had hypothesized that the FA value of an astrocytic tumor would be determined by a balance between factors increasing the directionality of water diffusion, such as high cellularity and/or vascularity, and factors decreasing the directionality of water diffusion, such as fiber destruction. However, our results suggest that the FA values of glioblastoma, anaplastic astrocytoma, diffuse astrocytoma and pilocytic astrocytoma are largely affected by cellularity and/or vascularity, whereas that of gliomatosis cerebri are largely affected by the preservation of nerve fibers. Measurement of FA value using DTI will allow prediction of histological characteristics such as cellularity, vascularity and/or fiber structure in astrocytic tumors.

Pretreatment with the free radical scavenger edaravone prevents cerebral hyperperfusion after carotid endarterectomy.

OBJECTIVE: Cerebral hyperperfusion syndrome after carotid endarterectomy (CEA) is a rare but potentially devastating complication. The purpose of the present study, which was not a randomized controlled trial but a case cohort study with historical control, was to determine whether pretreatment with a novel free radical scavenger, edaravone, could prevent occurrence of cerebral hyperperfusion after CEA. METHODS: Fifty patients with ipsilateral internal carotid artery stenosis (≥70%) underwent CEA with administration of edaravone before internal carotid artery clamping. Preoperative cerebral blood flow and cerebrovascular reactivity (CVR) to acetazolamide were assessed with single-photon emission computed tomography (SPECT). Cerebral blood flow also was measured immediately after CEA and on the 3rd postoperative day. RESULTS: Cerebral hyperperfusion (cerebral blood flow increase ≥100% compared with preoperative values) was revealed by SPECT performed immediately after CEA in only one patient (2%), who also exhibited reduced preoperative CVR. The incidence of post-CEA hyperperfusion as revealed by SPECT in the control group (51 CEA patients without administration of edaravone) was significantly higher (16%) (P = 0.0310, control versus treatment group). In addition, in a subgroup of patients with reduced preoperative CVR, the incidence of post-CEA hyperperfusion as revealed by SPECT in the edaravone group (7%) was significantly lower than that in the control group (67%) (P = 0.0029). Logistic regression analysis demonstrated that reduced preoperative CVR and absence of pretreatment with edaravone were significant independent predictors of post-CEA hyperperfusion as revealed by SPECT. CONCLUSION: Pretreatment with edaravone can prevent occurrence of cerebral hyperperfusion after CEA.

Effects of EC-IC bypass surgery on cognitive impairment in patients with hemodynamic cerebral ischemia

BACKGROUND Chronic ischemia because of internal carotid artery (ICA) occlusive disease may result in dementia. The goal of this study was to assess cognitive impairment in symptomatic patients with hemodynamic cerebral ischemia and determine the efficacy of extracranial-intracranial (EC-IC) bypass in restoring neuropsychologic integrity. METHODS Twenty-five patients were defined by clinical and neuroradiological criteria as suffering from hemodynamic cerebral ischemia because of unilateral ICA or middle cerebral artery occlusion. Subjects underwent assessment of cerebral blood flow and metabolism using positron emission tomography (PET) before and after bypass surgery. To provide data regarding cognition, changes in the Japanese Wechsler Adult Intelligence Scale Revised (WAIS-R) were recorded. RESULTS Preoperative study of patients revealed significant impairment in cerebral blood flow and metabolism as well as reduced WAIS-R score. Among the factors considered, only elevated regional oxygen extraction fraction and reduced regional cerebral metabolic rates of oxygen were significantly associated with preoperative cognitive impairment (p = 0.0032 and p = 0.0255, respectively; logistic regression analysis). After bypass surgery, cerebral blood flow and metabolism improved significantly, and the WAIS-R score increased. CONCLUSIONS Symptomatic patients with hemodynamic cerebral ischemia displayed impaired cognition that was partially alleviated with EC-IC bypass surgery.

Cerebral Hyperperfusion after Carotid Endarterectomy is Associated with Preoperative Hemodynamic Impairment and Intraoperative Cerebral Ischemia

The aim of this study was to investigate whether postoperative hyperperfusion is associated with preoperative cerebral hemodynamic impairment due to chronic ischemia and with acute cerebral ischemia during clamping of the internal carotid artery (ICA) during carotid endarterectomy (CEA). Transcranial cerebral oxygen saturation (SO2) was monitored intraoperatively using near-infrared spectroscopy in 89 patients undergoing CEA for ipsilateral ICA stenosis (> 70%). Cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide were also measured using single photon emission computed tomography (SPECT) before CEA. In addition, CBF was measured immediately after CEA and on the third postoperative day. Hyperperfusion (CBF increase > 100% compared with preoperative values) was observed immediately after CEA in 10 of 18 patients (56%) with reduced preoperative CVR. Also, post-CEA hyperperfusion was observed in nine of 16 patients (56%) whose SO2 during clamping of the ICA decreased to less than 90% of the preclamping value. Logistic regression analysis showed that reduced preoperative CVR and reduced SO2 during ICA clamping were significant independent predictors of the development of hyperperfusion immediately after CEA. In fact, all patients with reduced preoperative CVR and reduced SO2 during ICA clamping developed post-CEA hyperperfusion, and two of these patients developed cerebral hyperperfusion syndrome. These data suggest that development of cerebral hyperperfusion after CEA is associated with preoperative hemodynamic impairment and intraoperative cerebral ischemia.

Transcranial Regional Cerebral Oxygen Saturation Monitoring during Carotid Endarterectomy as a Predictor of Postoperative Hyperperfusion

OBJECTIVEHyperperfusion syndrome is a rare but potentially devastating complication that can occur after carotid endarterectomy (CEA). The purpose of this study was to determine whether intraoperative transcranial regional cerebral oxygen saturation (rSO2) monitoring via near-infrared spectroscopy could be reliably used to identify patients at risk for post-CEA hyperperfusion. METHODSrSO2 was intraoperatively monitored for 50 patients undergoing CEA for treatment of ipsilateral internal carotid artery stenosis (≥70%). Cerebral blood flow (CBF) was also assessed, with single-photon emission computed tomography, before and immediately after CEA. RESULTSPost-CEA hyperperfusion (CBF increase of ≥100%, compared with preoperative values) was observed for six patients. A significant linear correlation was observed between the rSO2 increases immediately after declamping of the internal carotid artery and the CBF increases immediately after CEA (r2 = 0.247, P = 0.0002). The sensitivity and specificity of the rSO2 increases for detection of post-CEA hyperperfusion were 100 and 86.4%, respectively, with a cutoff point of 5%. A strong linear correlation was observed between the rSO2 increases at the end of the procedure and the CBF increases immediately after CEA (r2 = 0.822, P < 0.0001). Both the sensitivity and the specificity of the rSO2 increases for detection of post-CEA hyperperfusion were 100% with a cutoff point of 10%. Hyperperfusion syndrome developed for one patient with post-CEA hyperperfusion, but intracerebral hemorrhage did not occur. CONCLUSIONIntraoperative rSO2 monitoring can reliably identify patients at risk for hyperperfusion after CEA.