Hyperperfusion syndrome after extracranial-intracranial bypass in a patient with moyamoya disease--case report

Early Detection of hyperemia with Magnetic Resonance Fluid Attenuation Inversion Recovery Imaging after Superficial Temporal Artery to Middle Cerebral Artery Anastomosis

OBJECTIVE

Cerebral hyperperfusion syndrome (CHS) manifests as a collection of symptoms brought on by heightened focal cerebral blood flow (CBF), afflicting nearly 30% of patients who have undergone superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The aim of this study was to investigate whether the amalgamation of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) and apparent diffusion coefficient (ADC) imaging via MRI can discern cerebral hyperemia after STA-MCA anastomosis surgery.

METHODS

A retrospective study was performed of patients who underwent STA-MCA anastomosis due to Moyamoya disease or atherosclerotic steno-occlusive disease. A protocol aimed at preventing CHS was instituted, leveraging the use of MRI FLAIR. Patients underwent MRI diffusion with FLAIR imaging 24 hours after STA-MCA anastomosis. A high signal on FLAIR images signified the presence of hyperemia at the bypass site, triggering a protocol of hyperemia care. All patients underwent hemodynamic evaluations, including perfusion MRI, single-photon emission computed tomography (SPECT), and digital subtraction angiography, both before and after the surgery. If a high signal intensity is observed on MRI FLAIR within 24 hours of the surgery, a repeat MRI is performed to confirm the presence of hyperemia. Patients with confirmed hyperemia are managed according to a protocol aimed at preventing further progression.

RESULTS

Out of a total of 162 patients, 24 individuals (comprising 16 women and 8 men) exhibited hyperemia on their MRI FLAIR scans following the procedure. SPECT was conducted on 23 patients, and 11 of them yielded positive results. All 24 patients underwent perfusion MRI, but nine of them showed no significant findings. Among the patients, 10 displayed elevations in both CBF and cerebral blood volume (CBV), three only showed elevation in CBF, and two only showed elevation in CBV. Follow-up MRI FLAIR scans conducted 6 months later on these patients revealed complete normalization of the previously observed high signal intensity, with no evidence of ischemic injury.

CONCLUSION

The study determined that the use of MRI FLAIR and ADC mapping is a competent means of early detection of hyperemia after STA-MCA anastomosis surgery. The protocol established can be adopted by other neurosurgical institutions to enhance patient outcomes and mitigate the hazard of permanent cerebral injury caused by cerebral hyperemia.

Combination of intraoperative indocyanine green video-angiography FLOW 800 and computed tomography perfusion to assess the risk of cerebral hyperperfusion syndrome in chronic internal carotid artery occlusion patients after revascularization surgery

Background and purpose

To study the changes of corticocerebral hemodynamics in surgical area and postoperative hyperperfusion syndrome in patients with chronic internal carotid artery occlusion (CICAO) by intraoperative indocyanine green videoangiography (ICGA)-FLOW 800 and CT perfusion after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery.

Methods

From October 2019 to January 2021, 77 patients diagnosed with CICAO underwent direct bypass surgery at Huadong hospital (affiliated with Fudan University) were enrolled. Regions of interest (ROIs) at STA, proximal MCA (PMCA), distal MCA (DMCA), cortical blood capillary (CBC), and cortical vein (CV) were identified after anastomosis by ICGV-FLOW 800 including peak fluorescence intensity (PFI), time to peak (TTP), and area under the time curve (AUC) of fluorescence intensity. All patients underwent perfusion-weighted CT before bypass surgery and those patients with HPS were verified by CTP after bypass.

Results

14 patients with HPS were verified by perfusion-weighted CT after bypass. In HPS group, the AUCTTP of DMCA was significantly larger (T = -3.301, p = 0.004) and TTP of CBC was shorter (T = -2.929, p = 0.005) than patients in non-HPS group. The larger AUCTTP of DMCA (OR = 3.024, 95%CI 1.390-6.578, p = 0.0050) was an independent risk factor by further multivariate logistic regression analysis.

Conclusion

The hemodynamic changes of cortical vessels during STA-MCA bypass surgery could be recorded accurately by ICGV-FLOW 800. Furthermore, the increased AUCTTP of DMCA and shorter TTP of CBC may be potential risk factors of HPS.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Individualized Perioperative Blood Pressure Management for Adult Moyamoya Disease: Experience from 186 Consecutive Procedures

BACKGROUND

In adult patients with moyamoya disease (MMD) underwent combined revascularization, cerebral infarction during the acute postoperative phase is common and can lead to neurological dysfunction after revascularization in MMD patients. The aim of this study was to share the experience of individualized perioperative blood pressure (BP) management for adult MMD patients in one single center.

METHODS

We retrospectively reviewed 144 adult patients with MMD who underwent 186 procedures of combined revascularization at our institution from March 2013 to July 2019. Clinical features and outcomes were analyzed, in particular regarding cerebral infarction and hyperperfusion syndrome (HPS). All of the patients received individualized management perioperatively, especially about the blood pressure management according to the characteristics of moyamoya disease.

RESULTS

Postoperative cerebral infarction and HPS within 14 days after revascularization were recorded. Cerebral infarction occurred in four (2.1%) procedures among four patients. No patients suffered from a malignant cerebral infarction and only one patient had permanent neurological deficits. The incidence of HPS was 10.8% and no one presented with intracranial hemorrhage. All of the symptoms were reversible without any brain parenchymal injury.

CONCLUSIONS

Our findings suggest that we can decrease the incidence and extent of cerebral infarction in adult MMD patients following combined revascularization by individualized perioperative BP management.

Limits and pitfalls of indirect revascularization in moyamoya disease and syndrome

Moyamoya vasculopathy is a rare chronic cerebrovascular disorder characterized by the stenosis of the terminal branches of the internal carotid arteries and the proximal tracts of anterior and middle cerebral arteries. Although surgical revascularization does not significantly change the underlying pathogenic mechanisms, it plays a pivotal role in the management of affected individuals, allowing to decrease the risk of ischemic and hemorrhagic complications. Surgical approaches may be direct (extracranial-intracranial bypass), indirect, or a combination of the two. Several indirect techniques classifiable according to the tissue (muscle, periosteum, galea, dura mater, and extracranial tissues) or vessel (artery) used as a source of blood supply are currently available. In this study, we reviewed the pertinent literature and analyzed the advantages, disadvantages, and pitfalls of the most relevant indirect revascularization techniques. We discussed the technical aspects and the therapeutical implications of each procedure, providing a current state-of-the-art overview on the limits and pitfalls of indirect revascularization in the treatment of moyamoya vasculopathy.

Crossed cerebellar diaschisis as an indicator of severe cerebral hyperperfusion after direct bypass for moyamoya disease

Cerebral hyperperfusion (HP) complicates the postoperative course of patients with moyamoya disease (MMD) after direct revascularization surgery. Crossed cerebellar diaschisis (CCD) has been considered to be rarely associated with HP after revascularization surgery. This study aimed to describe the clinical features and factors associated with CCD secondary to cerebral HP after revascularization surgery for MMD. We analyzed 150 consecutive hemispheres including 101 in adults and 49 in pediatric patients who underwent combined direct and indirect bypass for MMD. Using single-photon emission computed tomography (SPECT), serial cerebral blood flow (CBF) was measured immediately after the surgery and on postoperative days 2 and 7. Pre- and postoperative voxel-based analysis of SPECT findings was performed to compare the changes in regional CBF. Multivariate logistic regression analysis was performed to test the effect of multiple variables on CCD. Asymptomatic and symptomatic HP was observed in 41.3% (62/150) and 16.7% (25/150) of the operated hemispheres, respectively. CCD was observed in 18.4% (16/87) of these hemispheres with radiological HP. Multivariate analysis revealed that the occurrence of CCD was significantly associated with symptomatic HP (p = 0.0015). Voxel-based analysis showed that the CBF increase in the operated frontal cortex, and the CBF reduction in the contralateral cerebellar hemisphere on day 7 were significantly larger in symptomatic HP than in asymptomatic HP (median 11.3% vs 7.5%; - 6.0% vs - 1.7%, respectively). CCD secondary to postoperative HP is more common than anticipated in MMD. CCD could potentially be used as an indicator of severe postoperative HP in patients with MMD.

Cerebral Hyperperfusion Syndrome After Revascularization Surgery in Patients with Moyamoya Disease: Systematic Review and Meta-Analysis

BACKGROUND

Cerebral hyperperfusion syndrome (CHS) after bypass surgery is known as a complication of moyamoya disease (MMD). However, the incidence of CHS has not been accurately reported, and there is no consensus on related risk factors.

OBJECTIVE

To evaluate the incidence and characteristics of CHS in patients with MMD after revascularization surgery via meta-analysis.

METHODS

Relevant cohort studies were retrieved through a literature search of PubMed, Embase, and Ovid until December 1, 2018. Eligible studies were identified per search criteria. A systematic review and meta-analysis were used to assess the CHS total incidence, incidence in pediatric patients with MMD and adult patients with MMD, incidence for direct and combined bypass surgery, progress rate, and proportion of each symptom (including transient neurologic deficits [TNDs], hemorrhage, and seizure).

RESULTS

A total of 27 cohort studies with 2225 patients were included in this meta-analysis. The weighted proportions per random-effects model were 16.5% (range, 11.3%-22.3%) for CHS total incidence, 3.8% (range, 0.3%-9.6%) for pediatric patients with MMD, 19.9% (range, 11.7%-29.4%) for adult patients with MMD, 15.4% (range, 5.4%-28.8%) for direct bypass surgery, and 15.2% (range, 8.4%-23.2%) for combined bypass surgery. Progress rate was 39.5% (range, 28.7%-50.8%). The most common CHS-related symptom was TNDs (70.2%; range, 56.3%-82.7%), followed by hemorrhage (15.0%; range, 5.5%-26.9%) and seizure (5.3%; range, 0.6%-12.9%).

CONCLUSIONS

CHS is a common complication after revascularization surgery in MMD. It is more frequently seen in adult patients. The most common CHS-related symptom was TNDs, followed by hemorrhage and seizure.

Phase-Contrast Magnetic Resonance Imaging Analysis of Cerebral Hyperperfusion Syndrome After Surgery in Adult Patients with Moyamoya Disease

OBJECTIVE

To investigate potential risk factors for cerebral hyperperfusion syndrome (CHS) after surgery in patients with moyamoya disease (MMD) using phase-contrast magnetic resonance imaging (MRI).

METHODS

The study included 84 adult patients (89 brain hemispheres) with MMD who underwent surgery. Preoperative phase-contrast MRI scans were performed for all patients. Peak velocity, average velocity, average flow, forward volume, and region of interest area of the bilateral internal and external carotid arteries, superficial temporal artery, and vertebral artery were calculated and analyzed. Patients were divided into CHS and non-CHS groups. Patients' age, sex, clinical symptoms, Suzuki stage, and MRI flow examination results were compared between the 2 groups.

RESULTS

Nineteen of 84 patients (89 hemispheres) with MMD were in the CHS group. Patients with ischemic onset symptoms were more likely to develop CHS after surgery (P < 0.05). There were no significant differences in age, sex, and Suzuki stage between the 2 groups. For surgery ipsilateral vessels, peak velocity, average flow and forward volume of superficial temporal artery and average flow of external carotid artery and region of interest area of internal carotid artery in the CHS group were significantly lower compared with the non-CHS group (P < 0.05). For surgery contralateral vessels, forward volume of superficial temporal artery and external carotid artery in the CHS group was significantly lower compared with the non-CHS group (P < 0.05).

CONCLUSIONS

Patients with MMD and ischemic onset symptoms are more likely to develop CHS after surgery. Preoperative phase-contrast MRI analysis may be helpful to predict CHS in patients with MMD after surgery.

Risk factors for and outcomes of postoperative complications in adult patients with moyamoya disease

OBJECTIVE

The risk factors and clinical significance of postoperative complications in moyamoya disease are still unclear. The aim of this study was to investigate the predictors of postoperative complications in moyamoya disease and examine the impact of complications on outcomes.

METHODS

The authors reviewed consecutive cases involving adult moyamoya disease patients who underwent indirect, direct, or combined bypass surgery in their hospital between 2009 and 2015. Preoperative clinical characteristics and radiographic features were recorded. Postoperative complications within 14 days after surgery were examined. Multivariate logistic regression analyses were performed to identify the risk factors for either postoperative ischemia or postoperative cerebral hyperperfusion. Outcome data, including recurrent strokes and neurological status (modified Rankin Scale [mRS]) during follow-up, were collected. Outcomes were compared between patients who had complications with those without complications, using propensity-score analysis to account for between-group differences in baseline characteristics.

RESULTS

A total of 500 patients (610 hemispheres) were included in this study. Postoperative complications were observed in 74 operations (12.1%), including new postoperative ischemia in 30 cases (4.9%), hyperperfusion in 27 (4.4%), impaired wound healing in 12 (2.0%), and subdural effusion in 6 (1.0%). The complication rates for different surgery types were as follows: 12.6% (n = 25) for indirect bypass, 12.7% (n = 37) for direct bypass, and 10.0% (n = 12) for combined bypass (p = 0.726). Postoperative ischemic complications occurred in 30 hemispheres (4.9%) in 30 different patients, and postoperative symptomatic hyperperfusion occurred after 27 procedures (4.4%). Advanced Suzuki stage (OR 1.669, 95% CI 1.059-2.632, p = 0.027) and preoperative ischemic presentation (OR 5.845, 95% CI 1.654-20.653, p = 0.006) were significantly associated with postoperative ischemia. Preoperative ischemic presentation (OR 5.73, 95% CI 1.27-25.88, p = 0.023) and admission modified Rankin Scale (mRS) score (OR 1.81, 95% CI 1.06-3.10, p = 0.031) were significantly associated with symptomatic postoperative cerebral hyperperfusion syndrome (CHS). Compared with patients without postoperative complications, patients who experienced any postoperative complications had longer hospital stays and worse mRS scores at discharge (both p < 0.0001). At the final follow-up, no significant differences in functional disability (mRS score 3-6, 11.9% vs 4.5%, p = 0.116) and future stroke events (p = 0.513) between the 2 groups were detected.

CONCLUSIONS

Advanced Suzuki stage and preoperative ischemic presentation were independent risk factors for postoperative ischemia; the mRS score on admission and preoperative ischemic presentation were independently associated with postoperative CHS. Although patients with postoperative complications had worse neurological status at discharge, postoperative complications had no associations with future stroke events or functional disability during follow-up.

Safety of Extracranial-Intracranial Arterial Bypass in the Treatment of Moyamoya Disease

OBJECTIVE

The purpose of this study is to uncover the controversial problems and review the safety of extracranial-intracranial arterial bypass (EC-IC arterial bypass) in the treatment of moyamoya disease.

METHODS

Published randomized controlled clinical trials were searched from PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Web of science without date or language limitations until September 2016. Meta-analysis was performed as recommended by the Cochrane Collaboration of trials.

RESULTS

In total 2 studies were included by strict inclusion and exclusion criteria. The result of meta-analysis showed that surgical group had a greater reduction of the primary end points (OR [0.35], 95% CI [0.15, 0.84], I = 0%) than that of the nonsurgical group.

CONCLUSION

Surgical therapy significantly lowers incidence of the primary end points (including rebleeding attack; completed stroke resulting in significant morbidity; mortality from any medical cause and requirement for bypass surgery fora nonsurgical patient as determined by a registered neurologist) compared with nonsurgical therapy. High-quality randomized controlled trials are required to confirm this conclusion.

Postoperative Dilatation of Superficial Temporal Artery Associated with Transient Neurologic Symptoms After Direct Bypass Surgery for Moyamoya Angiopathy

OBJECTIVE

In moyamoya angiopathy, transient neurologic symptoms (TNS) are occasionally observed after superficial temporal artery (STA)-middle cerebral artery direct bypass surgery. The purpose of this study was to investigate the correlation between TNS and postoperative magnetic resonance imaging as well as perform a perfusion study.

METHODS

We reviewed 52 hemispheres in 33 consecutive patients with moyamoya angiopathy. TNS were defined as reversible neurologic dysfunction without any apparent intracranial infarction or hemorrhage. All patients underwent magnetic resonance imaging and single-photon emission computed tomography before and within 5 days after surgery. Maximum diameter of STA on time-of-flight magnetic resonance angiography and the dilatation ratio of STA were calculated. The presence of signal changes on fluid-attenuated inversion recovery images and regional cerebral blood flow were also evaluated.

RESULTS

TNS were observed in 13 of 52 (25%) cases 1-16 days after surgery. The mean preoperative STA dilatation, postoperative STA dilatation, and dilatation ratio of STA were 1.33 mm ± 0.27, 1.67 mm ± 0.30, and 29.31% ± 28.13%. Postoperative intraparenchymal cortical hyperintensity lesions and high-intensity signals in the cortex sulci (ivy sign) were detected in 24 (46.2%) cases and 29 (55.8%) cases, respectively. Univariate analyses demonstrated no association between TNS and postoperative signal change on fluid-attenuated inversion recovery images as well as cerebral blood flow. Only >1.5-fold dilatation of STA was significantly correlated with TNS (P < 0.0001).

CONCLUSIONS

STA dilatation was correlated with TNS after direct bypass surgery for moyamoya angiopathy.

Intracerebral Hemorrhage Caused by Cerebral Hyperperfusion after Superficial Temporal Artery to Middle Cerebral Artery Bypass for Atherosclerotic Occlusive Cerebrovascular Disease

Few papers have reported detailed accounts of intracerebral hemorrhage caused by cerebral hyperperfusion after superficial temporal artery to middle cerebral artery bypass (STA-MCA) bypass for atherosclerotic occlusive cerebrovascular disease. We report a case of vasogenic edema and subsequent intracerebral hemorrhage caused by the cerebral hyperperfusion syndrome (CHS) after STA-MCA bypass for atherosclerotic occlusive cerebrovascular disease disease without intense postoperative blood pressure control. A 63-year-old man with repeating left hemiparesis underwent magnetic resonance angiography (MRA), which revealed right internal carotid artery (ICA) occlusion. We performed a double bypass superficial temporal artery (STA)–middle cerebral artery (MCA) bypass surgery for the M2 and M3 branches. While the patient’s postoperative course was relatively uneventful, he suffered generalized convulsions, and computed tomography revealed a low area in the right frontal lobe on Day 4 after surgery. We considered this lesion to be pure vasogenic edema caused by cerebral hyperperfusion after revascularization. Intravenous drip infusion of a free radical scavenger (edaravone) and efforts to reduce systolic blood pressure to <120 mmHg were continued. The patient experienced severe left hemiparesis and disturbance of consciousness on Day 8 after surgery, due to intracerebral hemorrhage in the right frontal lobe at the site of the earlier vasogenic edema. Brain edema associated with cerebral hyperperfusion after STA-MCA bypass for atherosclerotic occlusive cerebrovascular disease should be recognized as a risk factor for intracerebral hemorrhage. The development of brain edema associated with CHS after STA-MCA bypass for atherosclerotic occlusive cerebrovascular disease requires not only intensive control of blood pressure, but also consideration of sedation therapy with propofol.

Clinical implications of the cortical hyperintensity belt sign in fluid-attenuated inversion recovery images after bypass surgery for moyamoya disease

OBJECTIVE Transient neurological symptoms are frequently observed during the early postoperative period after direct bypass surgery for moyamoya disease. Abnormal signal changes in the cerebral cortex can be seen in postoperative MR images. The purpose of this study was to reveal the radiological features of the "cortical hyperintensity belt (CHB) sign" in postoperative FLAIR images and to verify its relationship to transient neurological events (TNEs) and regional cerebral blood flow (rCBF). METHODS A total of 141 hemispheres in 107 consecutive patients with moyamoya disease who had undergone direct bypass surgery were analyzed. In all cases, FLAIR images were obtained during postoperative days (PODs) 1-3 and during the chronic period (3.2 ± 1.13 months after surgery). The CHB sign was defined as an intraparenchymal high-intensity signal within the cortex of the surgically treated hemisphere with no infarction or hemorrhage present. The territory of the middle cerebral artery was divided into anterior and posterior parts, with the extent of the CHB sign in each part scored as 0 for none; 1 for presence in less than half of the part; and 2 for presence in more than half of the part. The sum of these scores provided the CHB score (0-4). TNEs were defined as reversible neurological deficits detected both objectively and subjectively. The rCBF was measured with SPECT using N-isopropyl-p-[¹²³I]iodoamphetamine before surgery and during PODs 1-3. The rCBF increase ratio was calculated by comparing the pre- and postoperative count activity. RESULTS Cortical hyperintensity belt signs were detected in 112 cases (79.4%) and all disappeared during the chronic period. Although all bypass grafts were anastomosed to the anterior part of the middle cerebral artery territory, CHB signs were much more pronounced in the posterior part (p < 0.0001). TNEs were observed in 86 cases (61.0%). Patients with TNEs showed significantly higher CHB scores than those without (2.31 ± 0.13 vs 1.24 ± 0.16, p < 0.0001). The CHB score, on the other hand, showed no relationship with the rCBF increase ratio (p = 0.775). In addition, the rCBF increase ratio did not differ between those patients with TNEs and those without (1.15 ± 0.033 vs 1.16 ± 0.037, p = 0.978). CONCLUSIONS The findings strongly suggest that the presence of the CHB sign during PODs 1-3 can be a predictor of TNEs after bypass surgery for moyamoya disease. On the other hand, presence of this sign appears to have no direct relationship with the postoperative local hyperperfusion phenomenon. Vasogenic edema can be hypothesized as the pathophysiology of the CHB sign, because the sign was transient and never accompanied by infarction in the present series.

Progress on Complications of Direct Bypass for Moyamoya Disease

Moyamoya disease (MMD) involves progressive occlusion of the intracranial internal carotid artery resulting in formation of moyamoya-like vessels at the base of the brain. It can be characterized by hemorrhage or ischemia. Direct vascular bypass is the main and most effective treatment of MMD. However, patients with MMD differ from those with normal cerebral vessels. MMD patients have unstable intracranial artery hemodynamics and a poor blood flow reserve; therefore, during the direct bypass of superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis, perioperative risk factors and anesthesia can affect the hemodynamics of these patients. When brain tissue cannot tolerate a high blood flow rate, it becomes prone to hyperperfusion syndrome, which leads to neurological function defects and can even cause intracranial hemorrhage in severe cases. The brain tissue is prone to infarction when hemodynamic equilibrium is affected. In addition, bypass vessels become susceptible to occlusion or atrophy when blood resistance increases. Even compression of the temporalis affects bypass vessels. Because the STA is used in MMD surgery, the scalp becomes ischemic and is likely to develop necrosis and infection. These complications of MMD surgery are difficult to manage and are not well understood. To date, no systematic studies of the complications that occur after direct bypass in MMD have been performed, and reported complications are hidden among various case studies; therefore, this paper presents a review and summary of the literature in PubMed on the complications of direct bypass in MMD.

Intraoperative assessment of cortical perfusion by indocyanine green videoangiography in surgical revascularization for moyamoya disease

BACKGROUND

Postoperative hyperperfusion is a potential complication of the direct bypass procedure for moyamoya disease (MMD). However, no reliable modality is available yet for the prediction of postoperative hyperperfusion during surgery for MMD. This study aimed to investigate whether semiquantitative analysis of indocyanine green (ICG) videoangiography could contribute to the prediction of postoperative hyperperfusion in MMD.

METHODS

This study included 12 hemispheres from 10 patients who underwent surgical revascularization for MMD. Intraoperative ICG videoangiography was performed before and after a direct bypass procedure. The ICG intensity-time curves were semiquantitatively analyzed to evaluate cortical perfusion by calculating the blood flow index (BFI). Using single-photon emission computed tomography (SPECT), postoperative cerebral blood flow measurements were performed thrice: immediately, and 2 and 7 days after surgery.

RESULTS

BFI significantly increased from 21.3 ± 10.5 to 38.4 ± 20.0 after bypass procedures in all the hemispheres (p < 0.01). The ratio of BFI before and after the bypass procedure was 2.4 ± 2.0, ranging from 0.5 to 8.0. Postoperative hyperperfusion was observed in nine of the 12 operated hemispheres within 7 days after surgery. Of these, three hemispheres developed hyperperfusion immediately after surgery. In the adult cases, the increase in the ratio of BFI after bypass was significantly greater in those who developed hyperperfusion immediately after surgery than in those who did not (6.5 ± 0.5 vs. 1.8 ± 2.1, p < 0.01). In contrast, no significant increase in BFI was observed in the pediatric MMD patients who experienced immediate hyperperfusion. No correlation between the changes in BFI and the occurrence of delayed hyperperfusion was observed.

CONCLUSIONS

Our results suggest that semiquantitative analysis of BFI by intraoperative ICG videoangiography is useful in evaluating changes in cortical perfusion after bypass procedures for MMD and can predict the occurrence of early-onset hyperperfusion in MMD patients after direct bypass.

Arachnoid Membrane Suturing for Prevention of Subdural Fluid Collection in Extracranial-intracranial Bypass Surgery

Objective

Water-tight closure of the dura in extracranial-intracranial (EC-IC) bypass is impossible because the superficial temporal artery (STA) must run through the dural defect. Consequently, subdural hygroma and subcutaneous cerebrospinal fluid (CSF) collection frequently occur postoperatively. To reduce these complications, we prospectively performed suturing of the arachnoid membrane after STA-middle cerebral artery (STA-MCA) and evaluated the clinical usefulness.

Materials and Methods

Between Mar. 2005 and Oct. 2010, extracranial-intracranial arterial bypass (EIAB) with/without encephalo-myo-synangiosis was performed in 88 cases (male : female = 53 : 35). As a control group, 51 patients (57 sides) underwent conventional bypass surgery without closure of the arachnoid membrane. Postoperative computed tomography (CT) scan was performed twice in three days and seven days later, respectively, for evaluation of the presence of subdural fluid collection and other mass lesions.

Results

The surgical result was excellent, with no newly developing ischemic event until recent follow-up. The additional time needed for arachnoid suture was five to ten minutes, when three to eight sutures were required. Post-operative subdural fluid collection was not seen on follow-up computed tomography scans in all patients.

Conclusion

Arachnoid suturing is simple, safe, and effective for prevention of subdural fluid collection in EC-IC bypass surgery, especially the vulnerable ischemic hemisphere.

Cerebral hyperperfusion syndrome after revascularization surgery in patients with moyamoya disease

Moyamoya disease (MMD) is a progressive occlusive disease of the distal internal carotid artery that is primarily treated by superficial temporal artery-middle cerebral artery (STA-MCA) bypass. Despite its effectiveness, several postoperative complications have been reported with STA-MCA bypass. Cerebral hyperperfusion syndrome (CHS) after STA-MCA has attracted considerable attention as a hemodynamics-related complication because more cases of CHS after STA-MCA bypass are reported in MMD than in non-MMD patients. The mechanisms underlying CHS after revascularization in MMD patients are poorly understood. This report presents a comprehensive review of the literature on CHS after revascularization in MMD patients, focusing on the pathogenesis, clinical features, imaging techniques, treatment, and prognosis of CHS. Impaired cerebrovascular autoregulation has been implicated in the pathogenesis of CHS, which is characterized by unilateral headache, face and eye pain, seizures, and focal neurological deficits secondary to cerebral edema, and intracranial hemorrhage. Imaging techniques, such as single photon emission computed tomography (SPECT), 3-T magnetic resonance imaging/angiography, and selective arterial spin-labeling magnetic resonance imaging, are valuable for identifying patients at risk for CHS. Treatment strategies include strict blood pressure control, intracranial hemorrhage prevention, and free oxygen radical scavenger administration. Most patients can achieve a satisfying prognosis after effective treatment.

Predictors and clinical features of postoperative hyperperfusion after surgical revascularization for moyamoya disease: a serial single photon emission CT/positron emission tomography study

BACKGROUND AND PURPOSE

Clinical features and pathophysiology of postoperative hyperperfusion in moyamoya disease are still unclear. This study was aimed to clarify the incidence and time course of postoperative hyperperfusion and to determine the independent predictors of postoperative hyperperfusion in moyamoya disease.

METHODS

This prospective study included 41 patients who underwent surgical revascularization for moyamoya disease. Using (15)O-gas positron emission tomography, hemodynamic and metabolic parameters were quantified before surgery. Using single photon emission computed tomography, cerebral blood flow was serially measured just after surgery and on 2 and 7 days postsurgery. A multivariate logistic regression analysis was conducted to test the effect of multiple variables on postoperative hyperperfusion.

RESULTS

Postoperative hyperperfusion was observed in 29 (50.0%) of 58 operated hemispheres. The incidence of both radiological and symptomatic hyperperfusion was significantly higher in adult patients than in pediatric ones (P=0.026 and P=0.0037, respectively). Hyperperfusion just after surgery more often led to subsequent neurological deficits (P=0.033). A multivariate analysis revealed that preoperative cerebral blood volume increase was an independent predictor of both radiological and symptomatic hyperperfusion after surgery in adult moyamoya disease (OR, 6.6 and 12.3, respectively).

CONCLUSIONS

Postoperative hyperperfusion after surgical revascularization is not rare in moyamoya disease. Adult patients with a cerebral blood volume increase may be at high risk for radiological and symptomatic hyperperfusion after surgery. Careful perioperative management would reduce surgical complications and improve long-term outcome in moyamoya disease.

Ischemic complications occurring in the contralateral hemisphere after surgical treatment of adults with moyamoya disease

OBJECTIVE

Direct revascularization surgery is regarded as the most effective method of treatment of adults with moyamoya disease. These patients, however, have a higher risk of perioperative ischemic complications than do patients with atherosclerotic stroke, and are at risk for ischemic complications in the hemisphere contralateral to the one operated on. We investigated the incidence and risk factors for ischemic stroke in the contralateral hemisphere after surgical treatment of adults with moyamoya disease.

METHODS

We retrospectively reviewed the medical records and results of neuroimaging studies on 79 hemispheres of 73 consecutive patients with adult moyamoya disease (mean±SD age, 37.96±11.27 years; range, 18-62 years) who underwent direct bypass surgery over 6 years.

RESULTS

Ischemic complications occurred in 4 of 79 (5.1%) contralateral hemispheres, one with Suzuki stage 3 and three with Suzuki stage 4. Three patients showed posterior cerebral artery (PCA) involvement by moyamoya vessels. Advanced stage of moyamoya disease (Suzuki stages 4/5/6; p=0.001), PCA involvement (p=0.001) and postoperative hypotension (mean arterial blood pressure <80% of preoperative mean arterial blood pressure) on the first (p<0.0001) and second (p=0.003) days after surgery were significantly correlated with postoperative contralateral ischemic complications.

CONCLUSION

In patients with advanced moyamoya disease and involvement of the PCA, intentional hypotension can result in ischemic stroke in the hemisphere contralateral to the one operated on. Careful control of perioperative blood pressure is crucial for good surgical results.

Intraoperative blood flow analysis of direct revascularization procedures in patients with moyamoya disease

Moyamoya disease is characterized by the progressive stenosis and often occlusion of the terminal internal carotid arteries, which leads to ischemic and hemorrhagic injuries. The etiology is unknown and surgical revascularization remains the mainstay treatment. We analyzed various hemodynamic factors in 292 patients with moyamoya disease, representing 496 revascularization procedures, including vessel dimension and intraoperative blood flow, using a perivascular ultrasonic flowprobe. Mean middle cerebral artery (MCA) flow rate was 4.4 ± 0.26 mL/min. After superficial temporal artery (STA)-MCA bypass surgery, flows at the microanastomosis were increased fivefold to a mean of 22.2 ± 0.8 mL/min. The MCA flows were significantly lower in the pediatric (16.2 ± 1.3 mL/min) compared with the adult (23.9 ± 1.0 mL/min; P<0.0001) population. Increased local flow rates were associated with clinical improvement. Permanent postoperative complications were low (<5%), but very high postanastomosis MCA flow was associated with postoperative stroke (31.2 ± 6.8 mL/min; P=0.045), hemorrhage (32.1 ± 10.2 mL/min; P=0.045), and transient neurologic deficits (28.6 ± 5.6 mL/min; P=0.047) compared with controls. Other flow and vessel dimension data are presented to elucidate the hemodynamic changes related to the vasculopathy and subsequent to surgical intervention.

Incidence and Predictive Factors of Cerebral Hyperperfusion After Extracranial-Intracranial Bypass for Occlusive Cerebrovascular Diseases

BACKGROUND:

Although many studies of postoperative cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy have been reported, there are few reports related to extracranial-intracranial (EC-IC) bypass for atherosclerotic occlusive cerebrovascular diseases.

OBJECTIVE:

To examine the incidence of cerebral hyperperfusion and CHS after EC-IC bypass and to investigate predictive factors.

METHODS:

Fifty consecutive patients undergoing EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases were studied. Immediately after bypass surgery, resting regional cerebral blood flow was determined under continuous sedation, and postoperative hyperperfusion was evaluated according to the definitions as follows: &gt; 50% increase in regional cerebral blood flow compared with the contralateral side (method 1) and &gt; 100% increase in corrected regional cerebral blood flow compared with preoperative values (method 2). Logistic regression analysis was conducted to determine the effect of multiple variables on postoperative hyperperfusion.

RESULTS:

Transient symptoms of CHS were observed in 3 patients. Cerebral hyperperfusion was detected in 12 patients (24%) as defined by method 1 and in 9 patients (18%) by method 2. Postoperative hyperperfusion occurred significantly more frequently in patients with the steal phenomenon (regional cerebral vasoreactivity ≤ 0%; P = .001 by method 1 and P = .001 by method 2) and correlated with impaired preoperative regional cerebral vasoreactivity (P &lt; .001). Logistic regression analysis revealed that the steal phenomenon was a significant risk factor for hyperperfusion as defined by both methods 1 (P = .009) and 2 (P = .03).

CONCLUSION:

The incidence of cerebral blood flow-assessed postoperative hyperperfusion after EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases was not rare. Post EC-IC bypass CHS could be reduced by continuous, strict blood pressure control under sedation.

Intraoperative EC-IC bypass blood flow assessment with indocyanine green angiography in moyamoya and non-moyamoya ischemic stroke

OBJECTIVE

Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis has been used in moyamoya disease (MD) and non-moyamoya ischemic stroke (non-MD). It is important to monitor hemodynamic changes caused by bypass surgery for postoperative management. We evaluated the bypass blood flow during STA-MCA anastomosis by using indocyanine green (ICG) fluorescence angiography.

METHODS

We evaluated the bypass blood flow in 13 MD and 21 non-MD patients during STA-MCA anastomosis by means of ICG angiography with injection of ICG into the anastomosed STA. The ICG perfusion area was calculated when the ICG fluorescence intensity reached maximum. We measured cortical oxygen saturation before anastomosis by means of visual light spectroscopy.

RESULTS

ICG angiography demonstrated bypass blood flow from the anastomosed STA to the cortical vessels in all patients. The ICG perfusion area in MD (20.7 ± 6.6 cm(2)) was significantly larger than that in non-MD (8.4 ± 9.1 cm(2), P < 0.05). The cortical oxygen saturation (58.9% ± 8.3%) in MD was significantly lower than that in non-MD (73.4% ± 9.5%, P < 0.05).

CONCLUSIONS

ICG angiography with injection of ICG into the bypass artery allowed quantitative assessment of bypass blood flow. The bypass supplies blood flow to a greater extent in MD than in non-MD during surgery. This might be caused by a larger pressure gradient between the anastomosed STA and recipient vessels in MD. These observations indicate that MD requires careful control of systemic blood pressure after surgery to avoid cerebral hyperperfusion syndrome. ICG angiography is considered useful for facilitating safe and accurate bypass surgery and providing information for postoperative management.

Prognostic factors associated with perioperative ischemic complications in adult-onset moyamoya disease

BACKGROUND

To clarify the risk factors associated with perioperative ischemic complications in adult-onset moyamoya disease.

MATERIAL AND METHODS

The incidence and causes of perioperative ischemic complications in adult-onset moyamoya disease were retrospectively examined by reviewing 165 surgically treated adult patients. Two hundred forty-six revascularization procedures were performed in these patients.

RESULTS

There were 19 (7.7%) perioperative ischemic complications (four infarctions with neurological sequelae and 15 reversible ischemic neurological deficits with a new lesion). The complications occurred in the initially affected hemispheres in 17 (89.4%) of the 19 ischemic complications, regardless of the side of the operation. Multiple ischemic episodes (defined as over four-symptom episodes before treatment), the presence of a preoperative low density area (LDA) on computed tomographic (CT) scanning, and a high signal intensity on diffusion-weighted magnetic resonance (MR) imaging were significantly correlated with perioperative ischemic complications (p < 0.05, p < 0.05, and p < 0.01, respectively). Non-surgical hemodynamic risk factors, i.e., hypercapnia, hypocapnia, or hypotension/hypovolemia, were noted in all of the 19 cases. None of the surgical factors evaluated were associated with the complications identified.

CONCLUSIONS

Avoidance of non-surgical hemodynamic risk factors as well as maintaining vital collateral vessels is essential for the prevention of perioperative hemodynamic brain damage in patients with adult-onset moyamoya disease. In addition, very close monitoring of the perioperative care of patients with preoperative multiple ischemic episodes and an LDA or high signal intensity on preoperative CT or diffusion-weighted MR imaging is extremely important.

Long-term outcome of superficial temporal artery-middle cerebral artery bypass for patients with moyamoya disease in the US

OBJECT

The authors report the long-term results of a series of direct superficial temporal artery-middle cerebral artery (STA-MCA) bypass procedures in patients with moyamoya disease from the western US.

METHODS

All patients with moyamoya disease treated at the University of Washington from 1990 through 2004 (39 patients) were included in this study. Patients underwent pre- and postoperative evaluation of cerebral perfusion dynamics. Surgical revascularization procedures were performed in all patients with impaired cerebral blood flow (CBF) findings.

RESULTS

The mean age of patients at diagnosis was 34 years (range 10-55 years). All 39 patients had impaired CBF and/or vasomotor reserve and underwent revascularization procedures: 26 patients underwent bilateral operations, 13 unilateral (65 total procedures). An STA-MCA bypass was technically possible in 56 procedures (86.2%); saphenous vein interposition grafts were required in 3 procedures (4.6%); encephaloduroarteriosynangiosis was performed in 6 procedures (9.2%). Three patients died due to postoperative complications, yielding a procedure-related mortality rate of 4.61%, and 8 experienced non-life threatening complications (for a procedure-related rate of 12.3%). Long-term follow-up appeared to indicate a reduction in further ischemic events in surviving patients compared with the natural history. Cerebral perfusion dynamics improved postoperatively in all 36 surviving patients.

CONCLUSIONS

Moyamoya disease may differ in the US and Asia, and STA-MCA bypass procedures may prevent future ischemic events in patients with this condition.

Cerebral blood oxygenation changes induced by bypass blood flow in moyamoya disease and non-moyamoya cerebral ischaemic disease

BACKGROUND

Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis has been used to prevent stroke in patients with moyamoya disease (MD) and non-moyamoya ischaemic disease (non-MD). However, little is yet known regarding the difference between these groups of patients in the extent to which the bypass contributes to maintaining adequate cerebral blood oxygenation (CBO), or the temporal changes after surgery. In the present study, we evaluated the CBO changes induced by bypass blood flow in patients with MD and non-MD during the peri-operative periods employing optical spectroscopy.

METHODS

We investigated 13 patients who underwent STA-MCA anastomosis, including 5 MD and 8 non-MD patients. We evaluated the effects of STA blood flow on the CBO in the MCA territory on the anastomosis side, employing visual light spectroscopy during surgery and near infrared spectroscopy (NIRS) at one week after surgery.

FINDINGS

In 4 MD patients and one non-MD patient, the STA blood flow increased the oxyhaemoglobin and cortical oxygen saturation (CoSO2), indicating that the bypass supplied blood flow to the ischaemic brain; the CBO changes were observed more frequently in MD than in non-MD patients (p<0.02). The pre-anastomosis CoSO2 (65.4+/-5.4%) in MD was significantly lower than that (72.8+/-7.6%) in non-MD (p<0.05). Postoperative NIRS demonstrated that the bypass began to supply blood flow to the brain in 5 non-MD patients whose bypass did not supply blood flow during surgery.

CONCLUSIONS

Although MD has vessels of small diameter as compared to non-MD, the bypass begins to supply blood flow to the ischaemic brain earlier in MD than in non-MD after anastomosis. The fact that the CoSO2 in MD was lower than that in non-MD suggested that the perfusion pressure in MD was lower than that in non-MD, and this might account for the difference in the bypass blood supply after anastomosis between MD and non-MD. Our data suggest that, even if the bypass does not supply blood to the brain during surgery in non-MD, the bypass blood flow gradually increases after surgery.

Neural Damage Caused by Cerebral Hyperperfusion after Arterial Bypass Surgery in a Patient with Moyamoya Disease: Case Report

OBJECTIVE AND IMPORTANCE:

The prognosis of cerebral hyperperfusion syndrome after vascular reconstructive surgery, including extracranial-intracranial arterial bypass, is not poor unless intracerebral hemorrhage develops secondary to hyperperfusion.

CLINICAL PRESENTATION:

A 48-year-old man with symptomatic moyamoya disease with misery perfusion in the right cerebral hemisphere underwent double right superficial temporal artery-to-middle cerebral artery bypasses. The postoperative course was uneventful until the patient developed headache and agitated delirium on the 4th postoperative day.

INTERVENTION:

Perfusion computed tomographic imaging demonstrated hyperperfusion in the right temporal lobe. The symptoms resolved by institution of intensive blood pressure control. Positron emission tomography performed 2 months after surgery demonstrated a postoperative reduction of the cerebral metabolic rate of oxygen in the right temporal lobe, where brain atrophy was observed on magnetic resonance images 3 months postoperatively. Neuropsychological testing performed 3 months postoperatively showed worsening digit span, which adversely affected the patient's quality of life.

CONCLUSION:

The current case suggests that cerebral hyperperfusion after vascular reconstructive surgery can cause irreversible neural damage, which results in cognitive impairment.

Hyperperfusion phenomenon after percutaneous transluminal angioplasty for atherosclerotic stenosis of the intracranial vertebral artery

✓ The authors report on a patient who underwent percutaneous transluminal angioplasty (PTA) for stenosis of the intracranial vertebral artery (VA). This 67-year-old man's dizziness while walking was caused by infarction of the left cerebellar peduncle. On angiograms, his left VA manifested 90% stenosis at the intracranial portion and his right VA ended at the posterior inferior cerebellar artery. Because single-photon emission computerized tomography (SPECT) showed low perfusion and poor perfusion reserve in the posterior circulation, the authors performed PTA of the left VA, which was only 35% dilated due to stenosis. Although the patient's postoperative course was uneventful, postoperative hemodynamic studies (SPECT and transcranial Doppler [TCD] ultrasonography) revealed the hyperperfusion phenomenon. A 100% increase of regional cerebral blood flow in the posterior circulation was demonstrated on SPECT studies and TCD ultrasonography revealed a doubling of blood flow velocity in the VA compared with preoperative values. Careful control of the patient's blood pressure resulted in resolution of the hyperperfusion phenomenon within 1 week post-PTA. Although hyperperfusion syndrome following carotid endarterectomy is not rare, it is seldom seen after reconstruction of the posterior circulation, and the possibility of its occurrence must be kept in mind when the posterior circulation is reconstructed.

Rational approach to treatment of moyamoya disease in childhood

Early diagnosis and treatment of moyamoya disease in children is essential to minimize residual mental and physiologic deficits. Current treatment of childhood moyamoya disease in Japan, preoperative evaluation of perfusion reserve as a surgical indication, and the role of noninvasive follow-up by magnetic resonance angiography are reported. Approximately 20% of children with definite moyamoya disease were observed or treated medically. Among surgical procedures, single indirect bypass surgery was used in approximately 30% of all patients; combinations of direct and indirect bypass surgery, 20%; and multiple-indirect bypass surgery, 18%. Both adequate understanding of the primary condition and determination of optimal treatment, including specific operative procedures, required evaluation of cerebral circulation and metabolism. Surgical indications included reduced perfusion reserve in affected brain by positron emission tomography or single photon emission tomography with administration of acetazolamide or a CO2 load. Postoperative improvements of cerebral perfusion reserve show better correlation with disappearance of ischemic attacks than does angiographically demonstrated collateral formation. Follow-up evaluation with magnetic resonance angiography has advantages over conventional angiography because it is noninvasive and avoids general anesthesia.