Tetsuro Kawaguchi

Cerebral Vasoreactivity and Internal Carotid Artery Flow Help to Identify Patients at Risk for Hyperperfusion After Carotid Endarterectomy

Background and Purpose— Hyperperfusion syndrome is a rare but potentially devastating complication after carotid endarterectomy (CEA). The aim of this study was to investigate whether preoperative measurement of cerebral vasoreactivity (CVR) and intraoperative measurement of internal carotid artery (ICA) flow could identify patients at risk for hyperperfusion after CEA. Methods— For 26 patients with unilateral ICA stenosis ≥70%, cerebral blood flow (CBF) and CVR were investigated before and 1 month after CEA, with resting and acetazolamide-challenge single-photon emission CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter during surgery. Results— Ipsilateral CBF on the first postoperative day significantly increased relatively (56.6±53.2%) as well as absolutely (37.9±8.8 to 57.7±18.0 mL/100 g per minute) in the reduced CVR group (CVR <12%) but not in the normal CVR group (CVR ≥12%) (10.3±15.5% and 40.6±7.9 to 43.9±5.7 mL/100 g per minute, respectively). One month later, this difference almost disappeared. Two patients showed ipsilateral CBF increase of ≥100%. A significant association of intracerebral steal with hyperperfusion (CBF increase ≥100%) on the first postoperative day was also observed. ICA flow increase after reconstruction significantly correlated with CBF increase on the first postoperative day in the reduced CVR group but not in the normal CVR group. The threshold of ICA flow increase for hyperperfusion was estimated to be 330 mL/min in the reduced CVR group. Conclusions— Single-photon emission CT with acetazolamide challenge and ICA flow measurement during surgery could identify patients at risk for hyperperfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively.

Prediction of Hyperperfusion After Carotid Endarterectomy by Brain SPECT Analysis With Semiquantitative Statistical Mapping Method

Background and Purpose— Hyperperfusion syndrome is a rare but disastrous complication after carotid endarterectomy (CEA). The aim of this study was to investigate the relationship between preoperative cerebral blood flow (CBF) abnormalities and postoperative hyperperfusion through the use of statistical brain mapping analysis. Methods— For 41 patients with unilateral carotid stenosis ≥70%, CBF and cerebral vasoreactivity (CVR) were investigated with resting and acetazolamide-challenge single photon emission CT before CEA. CBF 1 day after CEA was also measured. Three-dimensional stereotactic surface projection (3D-SSP) analysis of CBF changes was performed by use of a control database of 20 subjects. Results— Patients with reduced CVR (CVR <10%, n=15) were categorized into 2 groups based on the severity of CBF reduction relative to the control database by 3D-SSP analysis without normalization: type I (ipsilateral CBF decrease <20%, n=8) and type II (ipsilateral CBF decrease ≥20%, n=7). With thalamic normalization, the patients were also categorized into 2 groups: type A (ipsilateral Z score ≤2, n=10) and type B (ipsilateral Z score >2, n=5). Severe CBF reduction (≥20% or Z score >2) was significantly associated with postoperative hyperperfusion (CBF increase ≥100%). However, 3D-SSP with thalamic normalization (Z score) demonstrated a higher predictive value (80%) and specificity (91%) for hyperperfusion than 3D-SSP without normalization (percent reduction) (57% and 73%, respectively). No patients with normal CVR (CVR ≥10%, n=26) demonstrated postoperative hyperperfusion. Conclusions— Objective evaluation of abnormalities of CBF and CVR with 3D-SSP could identify patients at risk for postoperative hyperperfusion.

Effect of clot removal and surgical manipulation on regional cerebral blood flow and delayed vasospasm in early aneurysm surgery for subarachnoid hemorrhage

BACKGROUND Effect of clot removal and surgical manipulation on cerebral blood flow (CBF) and delayed vasospasm was studied in early aneurysm surgery for subarachnoid hemorrhage (SAH). METHODS Thirty-two patients in this study fulfilled the following criteria: ruptured anterior communicating aneurysms, computed tomography (CT) within 2 days and unilateral pterional approach within 3 days after the ictus, bilaterally symmetrical clots without intracerebral hematoma, no postoperative complication, and CBF studies with single photon emission computed tomography (SPECT) with 123I-IMP. RESULTS Postoperative regional hypoperfusion due to brain retraction was frequently recognized on 123I-IMP-SPECT without infarction. The regional CBF (rCBF) showed a continuous fall during the first 4 weeks after the ictus, followed by improvement. The rCBF in the vicinity of the surgical route was significantly lower, especially in the acute stage (Day 3-7). A significant association between decrease of cisternal blood after surgery and the degree of local vasospasm and local CBF values during spasm stage was observed in the interhemispheric cisterns, A2 and medial frontal cortex, but not in the sylvian fissure or insular cisterns, M1 or M2, and frontal watershed and temporal cortex. CONCLUSIONS The present study provides evidence for the effectiveness of direct clot removal by early surgery for SAH on local vasospasm and CBF reduction. However, a potential improvement in local CBF with clot removal could be masked by brain retraction, which was demonstrated to affect rCBF adversely. Therefore, it is critical to perform brain retraction as gently as possible.

Saccular Aneurysms of the Proximal (M1) Segment of the Middle Cerebral Artery

We report A series of 20 consecutive patients with 21 saccular aneurysms of the proximal (M1) segment of the middle cerebral artery. The incidence of M1 aneurysms was 3.0% among 660 patients with intracranial aneurysms and 12.9% among 155 patients with middle cerebral artery aneurysms in our center. Of the 20 patients, 2 were men and 18 were women. The aneurysms were classified into two types: the superior wall type (9 cases), arising at the origin of the lenticulostriate or fronto-orbital artery, and the inferior wall type (12 cases), arising at the origin of the early temporal branches. Twelve (60%) patients had ruptured M1 aneurysms. The incidence of multiple aneurysms was high (nine patients, 45%), and M1 aneurysms were responsible for subarachnoid hemorrhage in four patients. Of 14 M1 aneurysms greater than 5 mm in diameter, 11 (78.6%) ruptured. In contrast, only one (14.3%) of seven small (< or = 5 mm) aneurysms ruptured. In 12 patients with ruptured M1 aneurysms, intracerebral hematomas were recognized in 6 (50%). Intracerebral hematomas by the superior wall M1 aneurysms were located in the frontal lobe, and those by the inferior wall M1 aneurysms were in the temporal lobe. Fifteen patients (75%) made a useful recovery 6 months after surgery. Four patients (20%), who were in poor grade condition preoperatively, remained severely disabled. One patient died of sepsis 2 months after she recovered well from the operation. Special attention to the lenticulostriate arteries to avoid injury is critical for successful surgical treatment.

Cerebral perfusion pattern of idiopathic normal pressure hydrocephalus studied by SPECT and statistical brain mapping.

Objectives: To investigate the specific pattern of cerebral blood flow (CBF) in subjects with idiopathic normal pressure hydrocephalus (iNPH) using voxel-based analysis.Methods:N-isopropyl-p-[123I]iodoamphetamine (IMP) single photon emission computed tomography (SPECT) images were performed in 30 iNPH patients, who met probable iNPH criteria, 30 Alzheimer disease (AD) patients and 15 normal control (NC) subjects. Inter-group comparisons between iNPH patients and NC subjects and between AD patients and NC subjects were performed using three-dimensional stereotactic surface projection (3D-SSP) analysis. Individual 3D-SSP images of the iNPH patients were assessed by visual inspection.Results: On the Z-score maps, areas of relative hypoperfusion were recognized around the corpus callosum in all 30 iNPH patients, as well as in the Sylvian fissure regions in 19 of 30 iNPH patients which included artifacts by dilated ventricles and the Sylvian fissures. Ten frontal dominant, eight parietotemporal dominant, and 12 diffuse hypoperfusion types were demonstrated. Inter-group comparison between iNPH and NC subjects showed relative hypoperfusion in the frontal and parietotemporal areas and severe hypoperfusion around the corpus callosum and Sylvian fissure regions, while parietotemporal and posterior cingulate CBF reduction was demonstrated between the AD and NC groups.Conclusion: Voxelbased analysis showed a characteristic pattern of regional CBF reduction with frontal dominant or diffuse cerebral hypoperfusion accompanying severe hypoperfusion around the corpus callosum and Sylvian fissures with artifacts.

Voxel-Based Analysis of Gray Matter and CSF Space in Idiopathic Normal Pressure Hydrocephalus

Aims: To investigate regional morphologic changes in idiopathic normal pressure hydrocephalus (INPH) based on diagnosis with INPH Guidelines using voxel-based morphometry. Method: Three-dimensional magnetic resonance imaging was performed in 34 INPH patients, who met probable INPH criteria, probable 34 Alzheimer disease patients, and 34 normal control subjects. Results: Statistical parametric mapping was used to conduct voxel-based morphometry analysis of the morphologic data and revealed enlarged ventricles and sylvian fissures and stenotic sulci of high convexity, especially in the precuneus in the INPH group, with decreased gray matter density in the insula, caudate and thalamus. Conclusion: In INPH, morphologic change occurs in the frontoparietal high convexity with ventricular dilatations, dilated sylvian fissures and tight sulci in the medial parietal lobes.

Influence of degree of carotid artery stenosis and collateral pathways and effect of carotid endarterectomy on cerebral vasoreactivity.

OBJECTIVE The goal was to determine the influence of the degree of internal carotid artery (ICA) stenosis and collateral pathways on cerebral vasoreactivity (CVR). The effect of carotid endarterectomy on CVR is also presented. METHODS For 36 patients with unilateral ICA stenosis of at least 70%, regional cerebral blood flow (rCBF) and regional CVR (rCVR) were investigated before and after carotid endarterectomy, with resting and acetazolamide-challenge single photon emission computed tomographic scans. The degree of ICA stenosis and the status of the collateral pathways (sizes of the A1 segment and the posterior communicating artery) were evaluated by angiography. RESULTS Thirteen patients were classified as Type N/N (normal rCBF and normal rCVR), 5 as Type R/N (reduced rCBF and normal rCVR), 6 as Type N/R (normal rCBF and reduced rCVR), and 12 as Type R/R (reduced rCBF and reduced rCVR). The degree of ICA stenosis correlated with rCVR status. The size of the A1 segment was a second-rank factor and was less effective in affecting rCVR. The size of the posterior communicating artery was not associated with rCVR. The predictive value of reduced rCVR for postoperative improvement (100%) was significantly higher than that of reduced rCBF (50%). CONCLUSION The present results indicate that the degree of ICA stenosis is a more significant determinant of CVR than are the collateral pathways in patients with carotid artery stenosis. The high predictive rate of reduced rCVR for postoperative improvement implies that acetazolamide-challenge single photon emission computed tomographic scanning might be useful in selecting patients with asymptomatic ICA stenosis who might benefit from carotid endarterectomy.

Predictors of the disappearance of triad symptoms in patients with idiopathic normal pressure hydrocephalus after shunt surgery.

We identified factors that predict the disappearance of the triad of symptoms (gait disturbance, cognitive impairment and urinary incontinence) of idiopathic normal pressure hydrocephalus (iNPH) following shunt surgery in this study. We classified 71 patients with iNPH into those whose objective symptoms disappeared (disappearance group) or remained (residual group), for each of the triad symptoms 12 months after shunt surgery. Logistic regression analyses were used to identify the predictors of the disappearance of symptoms among 10 variables before shunt surgery (e.g., age, sex, severity of symptoms, Evans index, cerebrospinal fluid (CSF) pressure, CSF stasis on computerized tomographic cisternography, regional cerebral blood flow on single photon emission computed tomography, three kinds of prior diseases). For each of the triad symptoms, mild symptoms before shunt surgery were predictors of the disappearance of the symptom. Young age was also a predictor of the disappearance of gait disturbance. When the analysis was conducted using subscores of the Mini Mental State Examination, a successful visuoconstruction subtest and an absence of hypertension were predictors of the disappearance of cognitive impairment. None of the neuroimaging examinations predicted the disappearance of symptoms after shunt surgery in this study.

Treatment of subdural effusion with hydrocephalus after ruptured intracranial aneurysm clipping.

OBJECTIVE This study was conducted to determine whether a ventriculoperitoneal shunt alone was effective in treating subdural effusion with hydrocephalus. METHODS Using only a ventriculoperitoneal shunt, we successfully treated eight patients who had subdural effusion with hydrocephalus after ruptured intracranial aneurysmal clipping, despite ventricular deformity and midline shift. RESULTS For all of the patients, both the subdural effusion and ventriculomegaly subsided and clinical symptoms lessened after surgery. CONCLUSION Ventriculoperitoneal shunting alone is an effective and satisfactory procedure; no subdural peritoneal shunt is needed for patients with subdural effusion accompanied by hydrocephalus. To-and-fro communication between the subdural effusion and ventricles is considered to be present in these patients. When selecting the treatment for subdural effusion, it is important to consider whether hydrocephalus (disturbance of cerebrospinal fluid circulation) is present.

Comparison of Conventional Region of Interest and Statistical Mapping Method in Brain Single-photon Emission Computed Tomography for Prediction of Hyperperfusion after Carotid Endarterectomy

OBJECTIVE:Hyperperfusion after carotid endarterectomy (CEA) has been proposed as the main mechanism of intracerebral hemorrhage, which is a disastrous complication. The aim of this study was to compare the predictive value of cerebral blood flow (CBF) abnormalities for hyperperfusion after CEA with the conventional region of interest (ROI) analysis and statistical brain mapping analysis. METHODS:For 46 patients with unilateral carotid stenosis of 70% or more, CBF and cerebral vasoreactivity were investigated with resting and acetazolamide-challenge single-photon emission computed tomography before CEA and 1 day after CEA. Three-dimensional stereotactic surface projection (3-D-SSP) analysis of CBF changes was performed by automatic quantification with a predefined template. RESULTS:Logistic regression analysis demonstrated CBF reduction (z-score) to be the only significant variable for postoperative hyperperfusion on 3-D-SSP with thalamic normalization but no significant variable with the ROI method. Receiver operating characteristic (ROC) analysis demonstrated significant improvement in the predictive value of CBF reduction (z-score) on 3-D-SSP (area under the ROC curve = 0.93) in comparison with the ROI method (area under the ROC curve = 0.78) (P = 0.049). According to the optimal cutoff values provided by ROC analysis, patients were categorized into two groups: Type I (CBF decrease <20%, n = 23) and Type II (CBF decrease ≥20%, n = 23) on ROI analysis and Type A (z-score ≤2, n = 40) and Type B (z-score >2, n = 6) on 3-D-SSP. There was a significant difference in incidence of hyperperfusion between Type A (1 of 40) and Type B (5 of 6) on 3-D-SSP (P = 0.00003) but not between Type I (1 of 23) and Type II (5 of 23) on ROI analysis. Cerebral vasoreactivity did not show significant value in the prediction of hyperperfusion with either the ROI or the 3-D-SSP method. CONCLUSION:Objective assessment of CBF status, especially baseline CBF reduction (z-score), with automatic quantification by 3-D-SSP with normalization had a higher diagnostic value than conventional ROI analysis to identify patients at risk for hyperperfusion after CEA.