Six-month Outcomes after PulseRider- and Conventional Single Stent-assisted Embolization for Bifurcation Aneurysms: A Propensity-adjusted Comparison.

Endovascular treatment of wide-necked bifurcation aneurysms (WNBAs) remains challenging despite using a stent. PulseRider is a novel device specifically designed to treat WNBAs, protecting both daughter branches, but the outcomes have not been compared with conventional single stent-assisted embolization. This study aimed to compare the six-month outcomes of PulseRider and single stent-assisted embolization for intracranial unruptured WNBAs using propensity score adjustment. Between February 2012 and October 2021, 46 unruptured WNBAs (34 basilar and 12 middle cerebral arteries) smaller than 10 mm in diameter were treated with PulseRider-assisted embolization (n = 17) or single stent-assisted embolization (n = 29). The immediate and six-month outcomes were compared using inverse probability of treatment weighting analysis. The immediate adequate occlusion rates for the PulseRider- and single stent-assisted embolization were similar (47.1% vs. 62.1%). At six months, adequate occlusion rates for the two groups were also similar (94.1% vs. 86.2%). However, the complete obliteration rate was significantly high after PulseRider-assisted embolization (88.2% vs. 41.4%, adjusted OR 10.54, 95% CI 1.93-57.63). The angiographical improvement rate was also significantly high after PulseRider-assisted embolization (70.6% vs. 37.9%, adjusted OR 6.06, 95% CI 1.54-23.76). The neurologic thromboembolic complication rate was 0% after PulseRider-assisted embolization and 3.4% after single stent-assisted embolization. PulseRider-assisted embolization of WNBAs smaller than 10 mm in diameter was associated with complete obliteration and angiographical improvement at six months. The unique shape of the PulseRider might contribute to the improved midterm aneurysm occlusion.

Efficacy of arterial spin labeling for detection of the ruptured micro-arteriovenous malformation: illustrative cases.

BACKGROUND: Diagnosis of a microarteriovenous malformation (micro-AVM) is difficult, especially in the acute stage of rupture because of the small size of the nidus and the existence of hematoma. We report two cases of ruptured micro-AVMs detected by arterial spin labeling (ASL). OBSERVATIONS: In one case, a 45-year-old male was transported with a complaint of right hemiparesis. Computed tomography (CT) revealed a right parietal lobar hemorrhage. Standard magnetic resonance imaging (MRI) showed no abnormal findings as the cause of the hemorrhage. ASL 23 days after the onset demonstrated high signals on the medial wall of the hematoma. Digital subtraction angiography (DSA) showed a micro-AVM in accordance with the site of high signals on ASL. In another case, a 38-year-old female was transported with a complaint of left hemianopsia. CT on admission revealed a right parietal lobar hemorrhage. Standard MRI showed no abnormal findings as the cause of the hemorrhage. ASL 15 days after the onset demonstrated high signals on the internal wall of the hematoma. DSA showed micro-AVM in accordance with the site of high signaling on ASL. Both cases were successfully treated with open surgery. LESSONS: ASL can manifest micro-AVMs as high signals within the hematoma. ASL is a useful less-invasive screening tool for the detection of ruptured micro-AVMs.

Pathological changes of brain oscillations following ischemic stroke.

Brain oscillations recorded in the extracellular space are among the most important aspects of neurophysiology data reflecting the activity and function of neurons in a population or a network. The signal strength and patterns of brain oscillations can be powerful biomarkers used for disease detection and prediction of the recovery of function. Electrophysiological signals can also serve as an index for many cutting-edge technologies aiming to interface between the nervous system and neuroprosthetic devices and to monitor the efficacy of boosting neural activity. In this review, we provided an overview of the basic knowledge regarding local field potential, electro- or magneto- encephalography signals, and their biological relevance, followed by a summary of the findings reported in various clinical and experimental stroke studies. We reviewed evidence of stroke-induced changes in hippocampal oscillations and disruption of communication between brain networks as potential mechanisms underlying post-stroke cognitive dysfunction. We also discussed the promise of brain stimulation in promoting post stroke functional recovery via restoring neural activity and enhancing brain plasticity.

Wall enhancement in unruptured posterior communicating aneurysms with oculomotor nerve palsy on magnetic resonance vessel wall imaging.

OBJECTIVE: Recent MR vessel wall imaging studies of unruptured intracranial aneurysms (UIAs) have revealed that aneurysm wall enhancement (AWE) can be an indicator for aneurysm evolution; however, the degree of AWE among different types of evolving UIAs has yet to be clarified. The authors assessed the degree of AWE in unruptured posterior communicating artery (PcomA) aneurysms with oculomotor nerve palsy (ONP), which may be a subgroup of evolving UIAs with rapid enlargement and high rupture risk. METHODS: The degree of AWE was analyzed in 35 consecutive evolving PcomA aneurysms (19 with and 16 without ONP). UIAs were considered to be evolving when showing growth or ONP. A 3D T1-weighted fast spin echo sequence was obtained after contrast media injection, and the contrast ratio of the aneurysm wall against the pituitary stalk (CRstalk) was calculated as the indicator of AWE. The CRstalk in evolving UIAs with ONP was compared with that in UIAs without ONP. RESULTS: The CRstalk was significantly higher in evolving UIAs with ONP than in those without ONP (0.85 vs 0.57; p = 0.006). In multivariable analysis, the CRstalk remained a significant indicator for ONP presentation in evolving UIAs (OR 6.13, 95% CI 1.21-31.06). CONCLUSIONS: AWE was stronger in evolving PcomA aneurysms with ONP than in those without ONP, suggesting the potential utility of AWE for risk stratification in evolving UIAs. The degree of AWE can be a promising indicator of a rupture-prone UIA, which can be useful information for the decision-making process in the treatment of UIAs.

Quantitative assessment of microstructural evolution of intracranial aneurysm wall by vessel wall imaging.

PURPOSE: This study aimed to evaluate new quantitative parameters of aneurysm wall enhancement (AWE) on magnetic resonance vessel wall imaging (VWI) in differentiating between the stable and evolving unruptured intracranial aneurysms (UIAs). METHODS: Thirty-eight consecutive patients with UIAs (27 stable and 11 evolving) underwent VWI with contrast-enhanced 3D T1 volume isotropic turbo spin echo acquisition. The voxel-based enhancement maps were created using pre- and post-contrast images. The aneurysmal lumen with signal suppression by black-blood method was segmented. Then, one voxel outer and inner layers of the lumen contour were automatically segmented. The shape features of the aneurysms and AWE of the two layers were compared between stable and evolving groups. RESULTS: The shape features, including aneurysm volume, surface, and compacity were significantly different between the stable and evolving groups (P = 0.024, 0.028, and 0.033, respectively). Stable and evolving groups also differed significantly in the AWE at the union of outer and inner layers of the aneurysm wall (P = 0.0082) but not in that of the outer or inner layer alone. Multivariate logistic regression analysis revealed significant differences in aneurysm volume, surface, and AWE at the union of outer and inner layers between the two groups (P = 0.0029, 0.0092, and 0.0033, respectively). Receiver operating characteristics curve analysis revealed that the area under the curve of the logistic regression model was 0.89. CONCLUSION: Quantitative combined analysis of aneurysm shape features and AWE of the union of outer and inner layers were effective for differentiating between stable and evolving UIAs.

[How to Avoid Intraoperative Rupture and What to Do When It Ruptures].

Intracranial aneurysm rupture is the main fatal complication of coil embolization for an intracranial aneurysm performed in conjunction with systemic heparinization. We answered five clinical questions about anesthesia, systemic heparinization, intraoperative aneurysmal rupture, the balloon-assisted technique, and the next step of initial response in case of aneurysmal rupture. It is crucial to understand when and why intraoperative aneurysmal rupture occurs to reduce its mortality rate. In cases of intraoperative problems, never pull the microcatheter or coil when perforating an aneurysm; lowering blood pressure, administering protamine for the reversal of heparin, and occluding blood flow into an aneurysm by inflating balloon(s) will help in the treatment. It is our pleasure that this chapter will help in your daily care.

Arteriovenous malformation of the trigeminal nerve root presented with venous congestive edema of the medulla oblongata and upper cervical cord: illustrative case.

BACKGROUND: Arteriovenous malformation (AVM) of the trigeminal nerve root (TNR) is a rare subtype of the lateral pontine AVM. Most of them are diagnosed when they bleed or exert trigeminal neuralgia. Venous congestive edema is a rare phenomenon caused by TNR AVMs. OBSERVATIONS: An 82-year-old man was admitted with progressive limb weakness and dysphasia. Magnetic resonance imaging (MRI) revealed extensive edema of the medulla oblongata and the upper cervical cord with signal flow void at the C3 anterior spinal cord. Vertebral angiography revealed a small nidus fed mainly by the pontine perforating arteries (PPAs). The anterior pontomesencephalic vein (AMPV) was dilated, functioning as the main drainage route. This suggests that venous hypertension triggered the brainstem and upper cervical cord edema. MRI with gadolinium enhancement showed that the nidus was located around the right TNR. Because the nidus sat extrinsically on the pial surface of the right TNR's base, microsurgical obliteration with minimum parenchymal injury was achieved. Postoperative MRI showed disappearance of the brainstem and cervical cord edema with improved clinical symptoms. LESSONS: TNR AVM is rarely associated with brainstem and upper cervical cord edema caused by venous hypertension of the congestive drainage system.

The effect of type 2 diabetes on CD36 expression and the uptake of oxLDL: Diabetes affects CD36 and oxLDL uptake.

We investigated whether type 2 diabetes mellitus (T2DM), a risk factor of stroke, affects the level of scavenger receptor CD36 and the uptake of its ligand, oxidized LDL (oxLDL); and whether pioglitazone, a drug that enhances CD36, promotes oxLDL uptake. Compared to normoglycemic db/+ mice, adult db/db mice showed a pronounced reduction in surface CD36 expression on myeloid cells from the blood, brain, and bone marrow as detected by flow cytometry, which correlated with elevated plasma soluble-CD36 as determined by ELISA. Increased CD36 expression was found in brain macrophages and microglia of both genotypes 7 days after ischemic stroke. In juvenile db/db mice, prior to obesity and hyperglycemia, only a mild reduction of surface CD36 was found in blood neutrophils, while all other myeloid cells showed no difference relative to the db/+ strain. In vivo, oral pioglitazone treatment for four weeks increased CD36 levels on myeloid cells in db/db mice. In vitro, uptake of oxLDL by bone marrow derived macrophages (BMDMs) of db/db mice was reduced relative to db/+ mice in normal glucose medium. OxLDL uptake inversely correlated with glucose levels in the medium in db/+ BMDMs. Furthermore, pioglitazone restored oxLDL uptake by BMDMs from db/db mice cultured in high glucose. Our data suggest that T2DM is associated with reduced CD36 on adult myeloid cells, and pioglitazone enhances CD36 expression in db/db cells. T2DM or high glucose reduces oxLDL uptake while pioglitazone enhances oxLDL uptake. Our findings provide new insight into the mechanism by which pioglitazone may be beneficial in the treatment of insulin resistance.

Optimal Timing of Extracranial-Intracranial Bypass with Microsurgical Trapping for Ruptured Blister Aneurysms of the Internal Carotid Artery.

OBJECTIVE: Ruptured blister aneurysms of the internal carotid artery are challenging to treat because of their difficult diagnosis and the fragility of the wall structure. Here, we sought to clarify the efficacy of extracranial-intracranial bypass followed by trapping (bypass/trapping) for ruptured blister aneurysms. METHODS: A retrospective study identified 45 patients with ruptured blister aneurysms between 1998 and 2017. Our principle was to attempt bypass/trapping as early as possible after diagnosis (early surgery). If early diagnosis was difficult, patients underwent elective surgery in the later stage when aneurysms were detected (elective surgery). Patient characteristics, radiologic findings, clinical course, and outcomes were analyzed. RESULTS: Forty-three patients were treated by bypass/trapping. Twenty-eight patients were classified as early surgery and 15 as elective surgery. Two patients experienced fatal rebleeding and did not undergo surgery. All 15 patients in the elective surgery group showed rebleeding and/or aneurysmal growth while awaiting surgery. In the elective surgery group, 10 aneurysms were missed initially by catheter angiography. In the early surgery group, 9 patients were assessed by vessel wall magnetic resonance imaging, which showed circumferential enhancement along the aneurysm wall, most of which was shown as only a small bulge in the angiography. Postoperative rebleeding did not occur in any of the patients. CONCLUSIONS: Bypass/trapping is effective to prevent rebleeding. Early surgery may be beneficial, because most patients in the elective surgery group showed rebleeding or aneurysmal growth. Vessel wall magnetic resonance imaging is a useful adjunct for early diagnosis and may contribute to prompt early surgery.

Diagnostic Value of Contrast-Enhanced Magnetic Resonance Vessel Wall Imaging on the Onset Type of Vertebral Artery Dissection.

BACKGROUND: Circumferential enhancement along the aneurysm wall (CEAW) by magnetic resonance (MR) vessel wall imaging has been reported to be a useful indicator for the biological activity of intracranial aneurysms such as growth and rupture. However, the significance of CEAW in vertebral artery dissection (VAD) has not been examined in detail. We quantitatively analyzed CEAW on VAD focusing on the differences in the clinical onset type. METHODS: The subjects were 37 patients diagnosed with VAD who were evaluated by MR imaging in the acute phase of onset between January 2014 and May 2019. The clinical onset of VAD was categorized into 3 subtypes: (1) incidentally detected (incidental group), (2) sudden headache without cerebral ischemia and/or intracranial hemorrhage (headache group), and (3) hemorrhagic onset (hemorrhage group). Three-dimensional T1-weighted fast spin echo sequences were obtained before and after contrast material injection, and the contrast ratio (CR) of the aneurysm wall against the pituitary stalk was calculated as the indicator of CEAW. RESULTS: The CR values of VAD in the hemorrhage group were significantly higher than those in the headache group (0.95 vs. 0.65, p < 0.05), and the headache group had significantly higher CR values than the incidental group (0.65 vs. 0.56, p < 0.05). On receiver operating characteristic curve analysis, the optimal cutoff value of CR to distinguish the hemorrhage group from the headache group was 0.83 and that to distinguish the headache group from the incidental group was 0.61. CONCLUSION: The extent of CEAW precisely reflected the deleterious impact of VAD in the acute stage, including hemorrhagic presentation. The predictive value of CEAW for the prognosis of unruptured VAD should be evaluated in future studies.

Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Levels as a Biomarker of Acute Intracerebral Hemorrhage.

BACKGROUND: Correct diagnosis of cerebral stroke type, hemorrhagic or ischemic, is essential in the early stage to establish the optimum treatment. The diagnosis is mainly determined based on imaging studies. Other more available diagnostic methods are desirable, such as blood sample examination. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is very important in vascular dysfunction induced by oxidized low-density lipoprotein, including cell apoptosis. The present study evaluated LOX-1 as a biomarker for cerebral stroke. SUBJECTS AND METHODS: Patients with newly diagnosed stroke were prospectively enrolled between February and July 2014. LOX-1 serum values were measured twice, within 24 hours and 2 months after the onset. RESULTS: A total of 16 patients were enrolled; 7 patients with intracerebral hemorrhage (ICH) and 9 patients with cerebral infarction. Median LOX-1 values of patients with ICH and infarction in the acute phase were 1825.8 and 593.9 pg/mL, respectively, significantly higher in patients with ICH than in patients with infarction (P < .0001). CONCLUSION: LOX-1 serum level has potential as a biomarker of ICH.

Circumferential wall enhancement in evolving intracranial aneurysms on magnetic resonance vessel wall imaging.

OBJECTIVE: Recent MR vessel wall imaging studies have indicated intracranial aneurysms in the active state could show circumferential enhancement along the aneurysm wall (CEAW). While ruptured aneurysms frequently show CEAW, CEAW in unruptured aneurysms at the evolving state (i.e., growing or symptomatic) has not been studied in detail. The authors quantitatively assessed the degree of CEAW in evolving unruptured aneurysms by comparing it separately to that in stable unruptured and ruptured aneurysms. METHODS: A quantitative analysis of CEAW was performed in 26 consecutive evolving aneurysms using MR vessel wall imaging. Three-dimensional T1-weighted fast spin echo sequences were obtained before and after contrast media injection, and the contrast ratio of the aneurysm wall against the pituitary stalk (CRstalk) was calculated as the indicator of CEAW. Aneurysm characteristics of evolving aneurysms were compared with those of 69 stable unruptured and 67 ruptured aneurysms. RESULTS: The CRstalk values in evolving aneurysms were significantly higher than those in stable aneurysms (0.54 vs 0.34, p < 0.0001), and lower than those in ruptured aneurysms (0.54 vs 0.83, p < 0.0002). In multivariable analysis, CRstalk remained significant when comparing evolving with stable aneurysms (odds ratio [OR] 12.23, 95% confidence interval [CI] 3.53-42.41), and with ruptured aneurysms (OR 0.083, 95% CI 0.022-0.310). CONCLUSIONS: The CEAW in evolving aneurysms was higher than those in stable aneurysms, and lower than those in ruptured aneurysms. The degree of CEAW may indicate the process leading to rupture of intracranial aneurysms, which can be useful additional information to determine an indication for surgical treatment of unruptured aneurysms.

Impact of bifurcation angle and inflow coefficient on the rupture risk of bifurcation type basilar artery tip aneurysms.

OBJECTIVE Risk factors for aneurysm rupture have been extensively studied, with several factors showing significant correlations with rupture status. Several studies have shown that aneurysm shape and hemodynamics change after rupture. In the present study the authors investigated a static factor, the bifurcation angle, which does not change after rupture, to understand its effect on aneurysm rupture risk and hemodynamics. METHODS A hospital database was retrospectively reviewed to identify patients with cerebral aneurysms treated surgically or endovascularly in the period between 2008 and 2015. After acquiring 3D rotational angiographic data, 3D stereolithography models were created and computational fluid dynamic analysis was performed using commercially available software. Patient data (age and sex), morphometric factors (aneurysm volume and maximum height, aspect ratio, bifurcation angle, bottleneck ratio, and neck/parent artery ratio), and hemodynamic factors (inflow coefficient and wall shear stress) were statistically compared between ruptured and unruptured groups. RESULTS Seventy-one basilar tip aneurysms were included in this study, 22 ruptured and 49 unruptured. Univariate analysis showed aspect ratio, bifurcation angle, bottleneck ratio, and inflow coefficient were significantly correlated with a ruptured status. Logistic regression analysis showed that aspect ratio and bifurcation angle were significant predictors of a ruptured status. Bifurcation angle was inversely correlated with inflow coefficient (p < 0.0005), which in turn correlated directly with mean (p = 0.028) and maximum (p = 0.014) wall shear stress (WSS) using Pearson's correlation coefficient, whereas aspect ratio was inversely correlated with mean (0.012) and minimum (p = 0.018) WSS. CONCLUSIONS Bifurcation angle and aspect ratio are independent predictors for aneurysm rupture. Bifurcation angle, which does not change after rupture, is correlated with hemodynamic factors including inflow coefficient and WSS, as well as rupture status. Aneurysms with the hands-up bifurcation configuration are more prone to rupture than aneurysms with other bifurcation configurations.

Circumferential Wall Enhancement on Magnetic Resonance Imaging is Useful to Identify Rupture Site in Patients with Multiple Cerebral Aneurysms.

BACKGROUND: Identification of rupture sites in patients with multiple intracranial aneurysms is largely based on aneurysm size, location, and shape. Finding circumferential enhancement along the aneurysm wall (CEAW) on magnetic resonance (MR) vessel wall imaging was recently shown to be indicative of ruptured aneurysm. OBJECTIVE: To investigate the hypothesis that a higher degree of CEAW would identify the site of rupture in patients with multiple aneurysms. METHODS: We prospectively performed quantitative analysis of CEAW in consecutive patients with both aneurysmal subarachnoid hemorrhage and multiple aneurysms (26 patients with a total of 62 aneurysms), using MR vessel wall imaging. Three-dimensional T1-weighted fast spin-echo sequences were obtained before and after injection of contrast media, and the wall enhancement index (WEI) was calculated. Aneurysm characteristics (size, location, irregular shape, aspect ratio [neck-to-dome length/neck width], and WEI) were compared between ruptured and unruptured aneurysms. Odds ratios with 95% confidence intervals for ruptures were calculated with conditional univariable logistic regression analysis. Analyses were repeated after adjustment for aneurysm size. RESULTS: Large aneurysm size, high aspect ratio, WEI (above the median values), and irregular shape were significantly associated with aneurysm rupture. After adjustment for aneurysm size, WEI (adjusted odds ratio: 8.8; 95% confidence interval, 1.1-72.6) as well as irregular shape and aspect ratio showed a strong association with rupture. CONCLUSION: CEAW is associated with rupture of intracranial aneurysm independent of aneurysm size and patient characteristics. Contrast-enhanced MR vessel wall imaging helps to identify the site of rupture in patients with multiple aneurysms.

Preoperative embolization and immediate removal of a giant pituitary adenoma: a case report.

BACKGROUND: Giant pituitary adenomas, with maximum diameter of at least 40 mm, continue to involve high surgical risks despite recent advances in microsurgical and/or endoscopic surgery. We treated a case of giant pituitary adenoma with preoperative endovascular embolization in an attempt to reduce blood loss. CASE PRESENTATION: A 48-year-old Japanese Woman presented with severe right visual disturbance. Magnetic resonance imaging revealed a giant pituitary adenoma with maximum diameter of 82 mm. Angiography revealed significant tumor stain, with blood supply mainly from the branches of the right meningohypophyseal trunk. These feeding arteries were endovascularly embolized with n-butyl cyanoacrylate. Subsequently, the tumor was safely removed by transsphenoidal surgery in two stages. The patient showed significant improvement of visual disturbance postoperatively, and was discharged without other neurological deficit. The surgical policy was explained preoperatively to the patients and written informed consents were obtained. CONCLUSIONS: Preoperative embolization of a giant pituitary adenoma is a useful procedure that can potentially decrease the morbidity and mortality of this devastating tumor.

Daughter Sac Formation Related to Blood Inflow Jet in an Intracranial Aneurysm.

OBJECTIVE: We performed a hemodynamic study of an intracranial aneurysm with a newly developed daughter sac during observation to investigate the role of hemodynamics on the formation of a daughter sac. METHODS: A 75-year-old man underwent magnetic resonance angiography that revealed a large internal carotid artery aneurysm with inflow jet inside the aneurysm. The aneurysm was stable for 18 months, but a new daughter sac developed at the tip of the aneurysm during the next 6 months. The daughter sac seemed to be related to the inflow jet on magnetic resonance angiography. Aneurysm geometries before and after daughter sac formation were reconstructed using the longitudinal data of magnetic resonance angiography. Computational fluid dynamic simulations were conducted under the patient-specific pulsatile inlet conditions measured by magnetic resonance velocimetry. RESULTS: The hemodynamic simulation revealed that the inflow jet impinged on 2 sites of the aneurysm: the right side of the aneurysmal dome and the tip of the aneurysm. The flow impingement caused elevation of pressure at both sites. However, the daughter sac formed at the latter site surrounded by the basal cistern but did not form at the former site that was in contact with the right temporal lobe. CONCLUSIONS: Blood inflow jet caused local elevation of pressure, and the formation of the daughter sac occurred at the site with high pressure but without the surrounding structure, which may cancel the perpendicular wall tension.

High-grade Cerebral Arteriovenous Malformation Treated with Targeted Embolization of a Ruptured Site: Wall Enhancement of an Intranidal Aneurysm as a Sign of Ruptured Site.

Partial targeted embolization of the ruptured site of cerebral arteriovenous malformations (AVMs) is considered effective to prevent rebleeding. The site of rupture is usually determined by morphological features, such as an intranidal aneurysm or a venous varix; however, the site can be difficult to identify in high-grade AVM with complicated angioarchitecture. The authors present a case of a 36-year-old woman with high-grade AVM presented with repeated hemorrhage. Cerebral angiography showed intranidal aneurysm, which was considered the ruptured site. The T1-weighted imaging with gadolinium enhancement demonstrated linear enhancement along the outer surface of the thickened wall of the intranidal aneurysm, which could be supplementary information to identify the ruptured site. Obliteration of the intranidal aneurysm was successfully achieved by emergent targeted embolization using N-butyl cyanoacrylate. The patient recovered and regained an independent status. The patient underwent volume-staged radiosurgery and experienced no further hemorrhage during the 26 months follow-up. Targeted embolization of the ruptured site is considered effective to prevent rebleeding in high-grade cerebral AVMs. Wall enhancement of the intranidal aneurysm, in addition to the structural characteristics, could be helpful in identifying the site of rupture embedded in the complicated angioarchitecture.

Usefulness of laser speckle flowgraphy for the assessment of ocular blood flow in extracranial-intracranial bypass.

Laser speckle flowgraphy (LSFG) is a noninvasive technique that can measure relative blood flow velocity in the optic fundus. The authors present a case of symptomatic internal carotid artery occlusion treated with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in which an improvement of ocular circulation was confirmed by LSFG. A 47-year-old man presented with a 1-month history of repeated left blurred vision and motor weakness of the right leg. Diffusion-weighted magnetic resonance imaging revealed a small infarction in the left frontal lobe. Carotid angiography revealed that the left internal carotid artery was occluded at the C4 portion. Single-photon emission computed tomography indicated that the cerebral blood flow in the left MCA territory was markedly impaired. Ophthalmologic examination revealed ischemic change of the left optic fundi, and LSFG revealed decreased blood flow around the left optic disc. Left STA-MCA bypass was successfully performed. Both ischemic ocular symptoms and the ischemic symptoms of the right leg were completely recovered after surgery. Postoperative ophthalmologic examination revealed improvement of both ischemic changes of the left optic fundi. Moreover, LSFG revealed improvement of the blood flow around the left optic disc. LSFG can be a promising clinical tool for the assessment of ocular circulation before and after bypass surgery for occlusive cerebrovascular disease.

Local hemodynamics at the rupture point of cerebral aneurysms determined by computational fluid dynamics analysis.

BACKGROUND: Cerebral aneurysms carry a high risk of rupture and so present a major threat to the patient's life. Accurate criteria for predicting aneurysm rupture are important for therapeutic decision-making, and some clinical and morphological factors may help to predict the risk for rupture of unruptured aneurysms, such as sex, size and location. Hemodynamic forces are considered to be key in the natural history of cerebral aneurysms, but the effect on aneurysm rupture is uncertain, and whether low or high wall shear stress (WSS) is the most critical in promoting rupture remains extremely controversial. This study investigated the local hemodynamic features at the aneurysm rupture point. METHODS: Computational models of 6 ruptured middle cerebral artery aneurysms with intraoperative confirmation of rupture point were constructed from 3-dimensional rotational angiography images. Computational fluid dynamics (CFD) simulations were performed under pulsatile flows using patient-specific inlet flow conditions. Time-averaged WSS (TAWSS) and oscillatory shear index (OSI) were calculated, and compared at the rupture point and at the aneurysm wall without the rupture point. We performed an additional CFD simulation of a bleb-removed model for a peculiar case in which bleb formation could be confirmed by magnetic resonance angiography. RESULTS: All rupture points were located at the body or dome of the aneurysm. The TAWSS at the rupture point was significantly lower than that at the aneurysm wall without the rupture point (1.10 vs. 4.96 Pa, p = 0.031). The OSI at the rupture point tended to be higher than at the aneurysm wall without the rupture point, although the difference was not significant (0.0148 vs. 0.0059, p = 0.156). In a bleb-removed simulation, the TAWSS at the bleb-removed area was 6.31 Pa, which was relatively higher than at the aneurysm wall (1.94 Pa). CONCLUSION: The hemodynamics of 6 ruptured cerebral aneurysms of the middle cerebral artery were examined using retrospective CFD analysis. We could confirm the rupture points in all cases. With those findings, local hemodynamics of ruptured aneurysms were quanti-tatively investigated. The rupture point is located in a low WSS region of the aneurysm wall. Bleb-removed simulation showed increased WSS of the bleb-removed area, associated with the flow impaction area. Although the number of subjects in this study was relatively small, our findings suggest that the location of the rupture point is related to a low WSS at the aneurysm wall. Further investigations will elucidate the detailed hemodynamic effects on aneurysm rupture.

Distinctive flow pattern of wall shear stress and oscillatory shear index: similarity and dissimilarity in ruptured and unruptured cerebral aneurysm blebs.

OBJECT: The difference in the hemodynamics of wall shear stress (WSS) and oscillatory shear index (OSI) between ruptured and unruptured aneurysms is not well understood. The authors investigated the hemodynamic similarities and dissimilarities in ruptured and thin-walled unruptured aneurysm blebs. METHODS: Magnetic resonance imaging-based fluid dynamics analysis was used to calculate WSS and OSI, and hemodynamic and intraoperative findings were compared. The authors also compared ruptured and unruptured thin-walled blebs for the magnitude of WSS and OSI. RESULTS: Intraoperatively, 13 ruptured and 139 thin-walled unruptured aneurysm blebs were identified. Twelve of the ruptured (92.3%) and 124 of the unruptured blebs (89.2%) manifested low WSS and high OSI. The degree of WSS was significantly lower in ruptured (0.49 ± 0.12 Pa) than in unruptured (0.64 ± 0.15 Pa; p < 0.01) blebs. CONCLUSIONS: Ruptured and unruptured blebs shared a distinctive pattern of low WSS and high OSI. The degree of WSS at the rupture site was significantly lower than in the unruptured thin-walled blebs.