Incidence and Clinical Features of Symptomatic Cerebral Hyperperfusion Syndrome After Vascular Reconstruction

Prediction of Cerebral Hyperperfusion Syndrome After Combined Bypass Surgery in Moyamoya Disease Using Hemodynamic and Clinical Data

PURPOSE

Cerebral hyperperfusion syndrome (CHS) is a postoperative complication in moyamoya disease (MMD). However, limited studies have investigated the association between preoperative hemodynamic features and postoperative CHS. In this study, we aimed to identify the predictors of postoperative CHS in MMD using preoperative hemodynamic and clinical data.

PATIENTS AND METHODS

In this retrospective study, we analyzed data from 72 hemispheres of 56 adult patients with MMD who underwent combined bypass surgery. Hemodynamic features were extracted from the region of interest on preoperative arterial spin-labeling magnetic resonance imaging and basal and acetazolamide-challenged single-photon emission computed tomography (SPECT). The predictive capacity of the hemodynamic features for postoperative CHS was analyzed using a generalized estimating equation. Multivariable analysis was performed using hemodynamic and clinical data.

RESULTS

Postoperative CHS occurred in 35 operated hemispheres (48.61%). Univariable analysis revealed that the cerebrovascular reservoir capacity (CVR) in the temporal and frontal cortices on SPECT significantly predicted CHS, with a lower CVR observed in the CHS group (P<0.050). In multivariable analysis, a lower CVR in the temporal cortex [odds ratio (95% CI), 0.99 [0.98-0.99]; P=0.034], higher preoperative modified Rankin scale score [1.18 (1.05-1.33); P=0.008], and anastomosis at the left hemisphere [1.25 (1.05-1.47); P=0.010] were associated with an increased CHS risk.

CONCLUSIONS

Low preoperative CVR in the temporal cortex, poor preoperative neurological status, and surgery at dominant hemisphere are potential risk factors for postoperative CHS in MMD.

Post-Carotid Artery Stenting Hyperperfusion Syndrome in a Hypotensive Patient: Case Report and Systematic Review of Literature

Cerebral hyperperfusion syndrome (CHS) is a serious post-procedural complication of carotid artery stenting (CAS). The pathophysiological mechanisms of CHS in the absence of arterial hypertension (AH) remain only partially understood. We performed a systematic literature search of the PubMed database using the terms »cerebral hyperperfusion syndrome«, »hypotension«, »hyperperfusion«, »stroke«, »intracranial hemorrhages«, »risk factors«, »carotid revascularization«, »carotid stenting«, »carotid endarterectomy«, »blood-brain barrier«, »endothelium«, »contrast encephalopathy«, and combinations. We present a case of a normotensive female patient who developed CHS post-CAS for symptomatic carotid stenosis while being hypotensive with complete recovery. We identified 393 papers, among which 65 were deemed relevant to the topic. The weighted average prevalence of CHS after CAS is 1.2% [0.0-37.7%] with that of intracranial hemorrhage (ICH) being 0.51% [0-9.3%]. Recently symptomatic carotid stenosis or contralateral carotid revascularization, urgent intervention, acute carotid occlusion, contralateral ≥70% stenosis, and the presence of leptomeningeal collaterals were associated with CHS. A prolonged hemodynamic instability after CAS conveys a higher risk for CHS. However, none of the articles mentioned isolated hypotension as a risk factor for CHS. Whereas mortality after ICH post-CAS ranges from 40 to 75%, in the absence of ICH, CHS generally carries a good prognosis. AH is not obligatory in CHS development. Even though impaired cerebral autoregulation and post-revascularization changes in cerebral hemodynamics seem to play a pivotal role in CHS pathophysiology, our case highlights the complexity of CHS, involving factors like endothelial dysfunction and sudden reperfusion. Further research is needed to refine diagnostic and management approaches for this condition.

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.

Blood-brain barrier disruption imaging in postoperative cerebral hyperperfusion syndrome using DCE-MRI

Little has been reported about the association between cerebral hyperperfusion syndrome (CHS) and blood-brain barrier (BBB) disruption in human. We aimed to investigate the changes in permeability after bypass surgery in cerebrovascular steno-occlusive diseases using dynamic contrast-enhanced MRI (DCE-MRI) and to demonstrate the association between CHS and BBB disruption. This retrospective study included 36 patients (21 hemispheres in 18 CHS patients and 20 hemispheres in 18 controls) who underwent combined bypass surgery for moyamoya and atherosclerotic steno-occlusive diseases. DCE-MRI and arterial spin labeling perfusion-weighted imaging (ASL-PWI) were obtained at the baseline, postoperative state, and discharge. Perfusion and permeability parameters were calculated at the MCA territory (CBF(territorial), Ktrans(territorial), Vp(territorial)) and focal perianastomotic area (CBF(focal), Ktrans(focal), Vp(focal)) of operated hemispheres. As compared with the baseline, both CBF(territorial) and CBF(focal) increased in the postoperative period and decreased at discharge, corresponding well to symptoms in the CHS group. Vp(focal) was lower in the postoperative period and at discharge, as compared with the baseline. In the control group, no parameters significantly differed among the three points. In conclusion, Vp at the focal perianastomotic area significantly decreased in patients with CHS during the postoperative period. BBB disruption may be implicated in the development of CHS after bypass surgery.

[Moyamoya disease in adults: treatment methods in modern era]

Moyamoya angiopathy is a chronic progressive cerebrovascular disease characterized by stenosis and occlusion of the distal segments of the internal carotid arteries and/or proximal segments of the middle and anterior cerebral arteries, with a gradual compensatory restructuring of the cerebral circulation to the system of the external carotid arteries. Today, the main treatment method for Moyamoya angiopathy is surgical revascularization of the brain. A search and analysis of publications on the treatment of adult patients with Moyamoya angiopathy was carried out in the PubMed and Medscape databases over the past 10 years. We present a case of an adult female patient with a hemorrhagic form of Moyamoya angiopathy stage IV according to J. Suzuki, who underwent staged combined revascularization of both cerebral hemispheres. Surgical revascularization included the creation of a low-flow extra-intracranial shunt combined with a combination of indirect synangiosis. The combination of direct and indirect methods of surgical revascularization enables to achieve the development of an extensive network of collaterals and fully compensate for cerebral circulatory disorders both in the early and late postoperative periods, which is confirmed by instrumental diagnostic data. Combined revascularization is the most effective modern method of treating patients with Moyamoya angiopathy due to the complementary influence of direct and indirect components of revascularization.

ABO blood types may affect transient neurological events after surgical revascularization in patients with moyamoya disease: a retrospective single center study

BACKGROUND

Moyamoya disease (MMD) is a cerebrovascular disease with unknown cause. Patients with MMD disease usually experience transient neurological events (TNEs) after revascularization surgery. This retrospective single-center study was aimed to explore the risk factors of postoperative TNEs after surgical revascularization in patients with MMD.

METHODS

We selected 324 patients who underwent surgical revascularization between January 2017 and September 2022 in our center. The perioperative characteristics of the patients were recorded and the outcome was TNEs after surgery. An analysis of risk factors contributing to postoperative TNEs by using logistic regression model.

RESULTS

Three hundred twelve patients were enrolled, and the incidence of postoperative TNEs was 34% in our study. Males were more likely to suffer from postoperative TNEs (OR = 2.344, p = 0.002). Preoperative ischemic presentation (OR = 1.849, p = 0.048) and intraoperative hypotension (OR = 2.332, p = 0.002) were associated with postoperative TNEs. Compared to patients with blood type O, patients with blood type A (OR = 2.325, p = 0.028), B (OR = 2.239, p = 0.027) and AB (OR = 2.938, p = 0.019) had a significantly higher incidence of postoperative TNEs. A risk prediction model for postoperative TNEs was established, and the established risk prediction area under the receiver operating characteristic curve (ROC) of the model was 0.741.

CONCLUSIONS

Males, preoperative ischemic presentation and intraoperative hypotension were associated with postoperative TNEs. We also found a possible link between postoperative TNEs and ABO blood types after surgical revascularization for moyamoya patients.

Screening of postoperative cerebral hyperperfusion syndrome in moyamoya disease: a three-dimensional pulsed arterial-spin labeling magnetic resonance imaging approach

Introduction

Moyamoya disease (MMD) is associated with a risk of postoperative cerebral hyperperfusion syndrome (CHS) after revascularization surgery. This study aimed to explore the feasibility of using three-dimensional pulsed arterial spin labeling (3D PASL) and phase contrast (PC) magnetic resonance imaging (MRI) for predicting CHS occurrence in patients with MMD before revascularization surgery.

Methods

Overall, 191 adult patients (207 hemispheres) with MMD who underwent combined revascularization surgery were included in this study. Preoperative 3D PASL-MRI and PC-MRI were performed before surgery. The PASL-MRI data were analyzed using SPM12. Patient clinical information, average flow, and preoperative cerebral blood flow (CBF) were compared between the non-CHS and CHS groups.

Results

Among the patients, 45 (21.74%) developed CHS after revascularization surgery. No significant differences were noted in age, sex, clinical symptoms, hypertension, diabetes, surgical side, or history of revascularization surgery between the non-CHS and CHS groups. However, the average flow in the superficial temporal artery was significantly lower in the CHS group than in the non-CHS group (p < 0.05). Furthermore, 11 clusters of preoperative CBF values were significantly greater in the CHS group than in the non-CHS group [p < 0.05, false discovery rate (FDR) corrected]. A significant correlation was also observed between the preoperative time-to-flight MR angiography (MRA) scores and CBF values in patients with MMD (p < 0.05).

Conclusion

Compare patients with lower preoperative CBF and higher preoperative average flow in the STA, patients with higher preoperative CBF and lower preoperative average flow in the STA are more likely to develop postoperative CHS Preoperative PASL-MRI and PC-MRI examinations may help to screen patients at high risk of developing CHS after revascularization surgery.

Flow volume mismatch dramatically affects transient neurologic symptoms after direct bypass in Moyamoya disease

Transient neurological events (TNEs) occur after bypass surgery in Moyamoya disease (MMD); however, their pathology remains unknown. To elucidate the pathophysiology of TNEs, we investigated their relationship with perioperative superficial temporal artery (STA) blood flow volume, which was evaluated using ultrasonography. Forty-nine patients with MMD, who underwent direct bypass surgery, were included and stratified into TNE and non-TNE groups, respectively. The STA blood flow volume was evaluated at four time points (preoperatively and 2-4, 7, and 10-14 days postoperatively), and a change in volume during the postoperative period was defined as a flow volume mismatch. We investigated the association between ultrasonographic findings of flow volume mismatch and TNEs and magnetic resonance imaging findings, such as the cortical hyperintensity belt (CHB) sign, using univariate and path analyses. The STA blood flow volume increased immediately postoperatively, gradually decreasing over time, in both groups. The TNE group showed a significant increase in blood flow volume 2-4 days postoperatively (P = 0.042). Flow volume mismatch was significantly larger in the TNE group than in the non-TNE group (P = 0.020). In the path analysis, STA flow volume mismatch showed a positive association with the CHB sign (P = 0.023) and TNEs (P = 0.000). Additionally, the CHB sign partially mediated the association between STA flow volume mismatch and TNEs. These results suggest that significantly high STA blood flow volume changes occurring during the acute postoperative period after direct bypass surgery in MMD are correlated with TNEs and the CHB sign, suggesting involvement in the pathophysiology of TNEs.

Transient ischemic attack after indirect revascularization surgery for pediatric patients with moyamoya disease: A retrospective study of intraoperative blood pressure

BACKGROUND

This study aimed to investigate the association between intraoperative blood pressure and postoperative transient ischemic attacks (TIAs) in pediatric patients with moyamoya disease after indirect revascularization surgery.

METHODS

We retrospectively reviewed the medical records of patients with moyamoya disease younger than 15 years who underwent indirect revascularizations under general anesthesia from 2013 to 2019. Perioperative clinical factors and intraoperative blood pressure data were collected and analyzed. Univariate and multivariable mixed-effect logistic regressions were used to identify predictors of postoperative TIA and symptom progression.

RESULTS

Among 444 hemispheres in 296 pediatric patients, 70 cases (16%) experienced postoperative TIAs within 2 weeks after surgery, and 34 cases (7.7%) developed postoperative symptom progression. Baseline mean blood pressure (MBP) (adjusted odds ratio, 1.261; 95% confidence interval, 1.037-1.528; P < 0.001), Average mean arterial pressure (MAP) (adjusted odds ratio, 1.137; 95% confidence interval, 1.052-1.228; P = 0.006), and Ipsilateral magnetic resonance angiography (MRA) score (adjusted odds ratio, 1.464; 95% confidence interval, 0.886-2.419; P = 0.012) were statistically significant risk factors for postoperative TIA. Average real variability of MAP (ARV-MAP), which were measures of intraoperative MAP variability (adjusted odds ratio, 4.731; 95% confidence interval, 1.419-15.257; P = 0.003) and maximum MAP declination (MaxD-MAP) (adjusted odds ratio, 1.271; 95% confidence interval, 1.013-1.520; P = 0.010) were statistically significant risk factors for postoperative symptom progression.

CONCLUSION

Higher pre-induction baseline blood pressure and ipsilateral MRA score were independent risk factors predicting postoperative TIA in pediatric patients with moyamoya disease after indirect revascularization. The high variability and drastic decline in intraoperative MAP showed predictive value in postoperative symptom progression.

Transient neurological events in childhood moyamoya disease

OBJECTIVE

Patients sometimes experience transient neurological events (TNEs) during the early postoperative period after revascularization surgery for childhood moyamoya disease. The clinical background and pathophysiology of TNEs remain unclear. This study aimed to evaluate the incidence rate of TNEs and discuss the factors associated with pediatric moyamoya disease.

METHODS

The authors retrospectively reviewed 110 cerebral hemispheres of 61 pediatric patients younger than 15 years who were treated from 2011 to 2020. All children underwent either simple double-direct or combined revascularization surgery. Of these 61 patients, 52 underwent bilateral surgery and 9 underwent unilateral surgery. The authors calculated the incidence of TNEs in accordance with a previously reported TNE definition. Cerebral blood flow (CBF) was evaluated in all eligible cases with xenon CT immediately after revascularization surgery.

RESULTS

The incidence rate of TNEs in patients with childhood moyamoya disease was 26.4%. TNEs occurred after an average (range) of 6.26 (2-12) days postoperatively without triggers, and all identified TNEs spontaneously resolved within 2 weeks. The most common symptoms were dysarthria, facial palsy, and numbness around the mouth, followed by sensory disturbance of the upper extremities. The presence of focal hyperperfusion on xenon CT performed immediately after revascularization surgery was strongly correlated with the incidence of TNEs (p = 0.0001). Focal hyperperfusion was observed in 43 of 110 operative sides (39.1%). Notably, only 25.6% of patients with focal hyperperfusion showed numerical global hyperperfusion. In addition, a decrease in CBF compared with the thalamic region in the contralateral side was observed in TNE-affected cases (p = 0.0443).

CONCLUSIONS

TNEs occurred more frequently in childhood moyamoya disease patients than expected. The clinical background, including symptoms, timing, and duration, was almost identical to TNEs in adults. Focal hyperperfusion, rather than numerical global hyperperfusion, was strongly correlated with the incidence of TNEs. Furthermore, the authors advocate the notion that a clinical course where symptoms occur without triggers may be a unique characteristic of TNEs, especially in childhood moyamoya disease.

Hemodynamic changes of donor artery after combined revascularization in adult Moyamoya disease

To explore the hemodynamic changes of the superficial temporal artery in adult Moyamoya Disease (MMD) who underwent combined revascularization surgery. A number of 40 patients with MMD were enrolled, and all of them underwent a direct superficial temporal artery (STA)-middle cerebral artery (STA-MCA) bypass combined with an encephalo-duro-arterio-synangiosis (EDAS). Hemodynamic parameters were detected by Color Doppler Ultrasonography (CDUS) at the preoperative, perioperative and follow-up time, including peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI). The control group were selected randomly during the same period. Researchers applied the SPSS 21 to conduct the two-sample analysis, Chi-Squared test and one-way repeated measures ANOVA between groups. P < 0.05 was considered statistically significant. In this study, 21 males and 19 females with an average age of 44.9 years (Range 28 y-56 y) were enrolled in the MMD group. Among them, 21 patients (52.5%) had perioperative complications, and all symptoms were transient neurological dysfunctions. Intermittent speech disorder was the most common complication during the period of operation. The preoperative hemodynamic of STA showed no significant difference between MMD and the control group. The perioperative hemodynamics had significant carnages compared with preoperative, and there was a trend of fluctuation. The perioperative PSV in the group with complications was significantly higher than the group without complications, except for EDV and RI. In the follow-up ( X ¯ = 5 months), PSV (60.21 ± 22.24 cm/s, P = 0.712) showed no difference compared with baseline data, while EDV (25.12 ± 9.94 cm/s, P = 0.000) and RI (0.575 ± 0.092, P = 0.000) showed significant difference between MMD and control group. The blood flow spectrogram showed high resistance in preoperative, but most patients showed a low resistance pattern during the follow-up time. It was the first time to demonstrate that the hemodynamic changes of STA fluctuated significantly within one week and eventually remained stable after combined revascularization. The PSV may play a more important role in postoperative complications. In the follow-up, PSV had no significant difference, EDV increased significantly, and RI decreased significantly. The blood flow spectrogram mainly shows a low resistance pattern when the hemodynamic is stable.

Intravoxel Incoherent Motion Magnetic Resonance Imaging Used in Preoperative Screening of High-Risk Patients With Moyamoya Disease Who May Develop Postoperative Cerebral Hyperperfusion Syndrome

Objective

This study aimed to investigate the feasibility of preoperative intravoxel incoherent motion (IVIM) MRI for the screening of high-risk patients with moyamoya disease (MMD) who may develop postoperative cerebral hyperperfusion syndrome (CHS).

Methods

This study composed of two parts. In the first part 24 MMD patients and 24 control volunteers were enrolled. IVIM-MRI was performed. The relative pseudo-diffusion coefficient, perfusion fraction, apparent diffusion coefficient, and diffusion coefficient (rD*, rf, rADC, and rD) values of the IVIM sequence were compared according to hemispheres between MMD patient and healthy control groups. In the second part, 98 adult patients (124 operated hemispheres) with MMD who underwent surgery were included. Preoperative IVIM-MRI was performed. The rD*, rf, rADC, rD, and rfD* values of the IVIM sequence were calculated and analyzed. Operated hemispheres were divided into CHS and non-CHS groups. Patients’ age, sex, Matsushima type, Suzuki stage, and IVIM-MRI examination results were compared between CHS and non-CHS groups.

Results

Only the rf value was significantly higher in the healthy control group than in the MMD group (P < 0.05). Out of 124 operated hemispheres, 27 were assigned to the CHS group. Patients with clinical presentation of Matsushima types I–V were more likely to develop CHS after surgery (P < 0.05). The rf values of the ipsilateral hemisphere were significantly higher in the CHS group than in the non-CHS group (P < 0.05). The rfD* values of the ACA and MCA supply areas of the ipsilateral hemisphere were significantly higher in the CHS group than in the non-CHS group (P < 0.05). Only the rf value of the anterior cerebral artery supply area in the contralateral hemisphere was higher in the CHS group than in the non-CHS group (P < 0.05). The rf values of the middle and posterior cerebral artery supply areas and the rD, rD*, and rADC values of the both hemispheres were not significantly different between the CHS and non-CHS groups (P > 0.05).

Conclusion

Preoperative non-invasive IVIM-MRI analysis, particularly the f-value of the ipsilateral hemisphere, may be helpful in predicting CHS in adult patients with MMD after surgery. MMD patients with ischemic onset symptoms are more likely to develop CHS after surgery.

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.

Non-invasive assessment of cerebral microvascular changes for predicting postoperative cerebral hyperperfusion after surgical revascularisation for moyamoya disease: an arterial spin labelling MRI study

PURPOSE

Cerebral hyperperfusion syndrome (CHPS) can result after anastomotic surgery as the reperfusion is established in chronically ischemic cerebral territories in patients of moyamoya disease (MMD). In this study, we have evaluated the feasibility of arterial spin labelling (ASL) perfusion MRI to predict cerebral hyperperfusion syndrome based on changes of cerebral blood flow (CBF) after revascularisation surgery in patients of MMD.

METHODS

Our prospective study included 25 patients with MMD who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass with or without dural/muscle synangiosis. ASL MRI was performed before and 1-7 days after surgery. On the side planned for operation, 5-mm ROI circle was drawn on the predetermined regions in frontal lobe, temporal lobe, parietal lobe and basal ganglia in proximal and distal territories of MCA to calculate ipsilateral CBF values (CBFi). An attempt was made to select the same location on contralateral side (non-operative) (CBFc) for each measurement for calculation of hemispheric normalised CBF (nCBFh) ratios. To adjust for inter individual variation among MR imagers and CBF, additional regions of interest were drawn within the cerebellum (CBFcbl) for cerebellar CBF normalised ratios (nCBFCbl).

RESULTS

Of the 25 patients (26 operated hemispheres), 5 patients showed significant immediate postoperative symptoms suggestive of CHPS. Based on our findings, sensitivity and specificity of ASL perfusion to detect CHPS were evaluated. ASL was found to have 47-100% sensitivity and 45-88% specificity to detect CHPS. We have tried to calculate the prevalence of CHPS in postoperative patients of moyamoya disease, which in our study ranged from 6.83 to 40.70%.

CONCLUSION

Based on our results, we concluded that ASL perfusion is an appropriate alternative to standard nuclear medicine studies to monitor the changes in perfusion after STA-MCA bypass surgery in moyamoya patients. ASL MR perfusion can be used to identify changes in cerebral blood flow (CBF) for early detection of cerebral hyperperfusion syndrome in patients with otherwise normal conventional MRI sequences with very high sensitivity but moderate specificity.

Decreased cortical perfusion in areas with blood-brain barrier dysfunction in Moyamoya disease

BACKGROUND

Recently, several studies have focused on the relationship between blood-brain barrier (BBB) impairment and the etiology of Moyamoya disease (MMD). However, in vivo studies investigating about BBB impairment and cortical perfusion in MMD patients were really rare.

METHODS

This study included 16 patients diagnosed with MMD and 9 patients with atherosclerotic cerebrovascular disease (ACVD); all of who were treated with superficial temporal artery-middle cerebral artery (STA-MCA) bypass. Cortical perfusion was assessed using intraoperative indocyanine green (ICG) videoangiography by calculating the blood flow index (BFI). In addition, we used sodium fluorescein (NaFl) to evaluate the permeability of BBB in vivo during operation.

RESULTS

The results showed that BBB impairment in MMD patients was more significant than that in ACVD patients, whereas, the cortical perfusion was comparable between two groups. BFI was significantly improved after STA-MCA bypass both in the MMD group (post-operation vs pre-operation: 109.2 ± 67.7 vs 64.3 ± 35.0, p = 0.004) and the ACVD group (post-operation vs pre-operation: 137.6 ± 89.6 vs 90.8 ± 58.3, p = 0.015). Moreover, BFI was significantly decreased in the cortex with BBB impairment as compared with that in the cortex with intact BBB (impaired BBB vs intact BBB: 55.7 ± 26.5 vs 87.6 ± 55.1, p = 0.025). Following bypass, the cortical perfusion significantly improved in the area of BBB impairment (post-operation vs pre-operation: 93.8 ± 75.2 vs 55.7 ± 26.5, p = 0.004), which was not observed in the BBB intact area (post-operation vs pre-operation: 92.4 ± 50.4 vs 87.6 ± 55.1, p = 0.58).

CONCLUSION

In summary, we observed that BBB impairment in MMD patients was more significant than that in ACVD patients. This study also demonstrated for the first time that cortical perfusion was significantly decreased in the cortex with BBB impairment as compared with that in the cortex with intact BBB in MMD patients. We also observed that After STA-MCA bypass, the cortical perfusion was significantly improved in the cortex with BBB impairment. These results may provide a new insight for BBB impairment and cortical perfusion in the etiology of MMD.

Severe cerebral edema induced by watershed shift after bypass in a patient with chronic steno-occlusive disease: a case report and short literature review

Background

Carotid occlusive disease is a type of progressive disease resulting in ischemic stroke. Extracranial-intracranial bypass surgery represents a valid therapeutic option when medical treatment does not make effects. The appearance of cerebral edema following bypass is common during acute stage. Additionally, there are many causes of mild cerebral edema, such as hemodynamic changes, venous congestion and others. However, severe edema involving large brain tissue, which presents as reversible aphasia and hemiplegia, remains to be elucidated.

Case presentation

A 55-year-old man was admitted to the neurosurgery department for repeated dizziness for over a year and sudden onset of syncope 1 month prior, and he was diagnosed with carotid occlusive disease. After surgical contraindications were excluded, dual bypass and encephalo-duro-myo-synangiosis were performed. Although blood pressure and fluid management were strictly under control promptly after surgery, massive cerebral edema involving the left anterior cerebral artery and middle cerebral artery territories occurred from the 6th day after surgery. Additionally, no discernible cerebral infarction or hemorrhage occurred. Moreover, the cerebral blood flow of the middle cerebral artery displayed an early decrease followed by delayed elevation on the left side. Without restricting the spreading of cerebral edema, life-threatening cerebral herniation could develop at any time. Mannitol and furosemide were administered for impending cerebral herniation. The amelioration of symptoms was noticed on the 16th day after surgery. The patient felt relief on the 21st day after surgery. Digital subtraction angiography performed on the 180th day after surgery demonstrated the patency of dual anastomosed vessels, and the patient recovered without any permanent neurological deficit.

Conclusion

Based on changes in cerebral blood flow and reversible symptoms, the “watershed shift” phenomenon could explain such a severe deficit. However, this deficit was not the same as the classical presentation of the “watershed shift”, which involves a moderate amount of brain tissue and presents significant increases in cerebral blood flow. In addition to the “watershed shift”, a swollen temporal muscle may also participate in the progression of focal edema.

Detection of Transient Increase of Cerebral Blood Flow and Reversible Neuronal Dysfunction by Iodine-123-Iomazenil Single Photon Emission Computed Tomography After Cerebral Hyperperfusion Syndrome After Revascularization Surgery for Moyamoya Disease

BACKGROUND

Early and late images of single photon emission computed tomography (SPECT) using ¹²³I-iomazenil (¹²³I-IMZ) can demonstrate cerebral blood flow and cortical neuronal viability. Hyperperfusion syndrome is one of the serious complications after revascularization surgery for moyamoya disease; therefore, the real-time observation of the hemodynamics and neuronal viability is important for the treatment after the revascularization. Here we report, a case of moyamoya disease where ¹²³I-IMZ SPECT had a significant efficacy to delineate the hemodynamics and transient neuronal dysfunction in hyperperfusion state after revascularization.

CASE DESCRIPTION

A 47-year-old woman presented with motor aphasia 3 days after superficial temporal artery-middle cerebral artery anastomosis with indirect revascularization. Magnetic resonance imaging (MRI) on the same day showed no new ischemic changes but high intensities along the left frontal sulci observed on fluid-attenuated inversion recovery images, and ¹²³I-IMZ SPECT demonstrated the increased uptake on the early images and the decreased uptake on the late images around the anastomosis site. The patient was completely recovered 1 month after surgery, and abnormal changes on MRI and ¹²³I-IMZ SPECT returned to normal along with the symptom withdrawal.

CONCLUSIONS

These findings indicate that ¹²³I-IMZ SPECT could be the index for the treatment of revascularization for obstructive vascular diseases such as moyamoya disease.

Postoperative Functional Outcomes and Prognostic Factors in Two Types of Adult Moyamoya Diseases

BACKGROUND

To determine the functional outcomes in each period for adult ischemic and hemorrhagic Moyamoya disease (MMD) patients and identify prognostic factors.

METHODS

The current retrospective study reviewed consecutive adult MMD patients surgically treated from January 2012 to June 2017. Perioperative clinical data were collected and follow-up was conducted via telephone interviews. Functional outcomes and prognostic factors were analyzed.

RESULTS

A total of 219 ischemic MMD patients (268 hemispheres) and 157 hemorrhagic patients (193 hemispheres) were included. The median follow-up time was 18 months (3-69 months). MMD type had no significant effect on the modified Rankin Scale(mRS) score at discharge. Perioperative complications (P = 0.004) and the mRS score at baseline (P < 0.001) were risk factors correlated with the short-term functional outcomes in both groups, while diabetes mellitus (DM, P = 0.022) also played a role in the ischemic group. During the follow-up period, functional outcomes obviously improved in both groups, but two groups showed nonproportional cumulative curves for favorable functional outcomes (log-rank test, P = 0.483). Stroke recurrence (P < 0.001) and mRS at discharge (P < 0.001) were common factors related with long-term functional outcomes in two types of MMD patients. Particularly, female patients with ischemic MMD were more likely to have higher mRS scores (P = 0.028) and Suzuki stage was positively associated with long-term functional outcomes in hemorrhagic group (P = 0.044).

CONCLUSIONS

MMD type had no significant effect on prognosis while both types of MMD patients showed overall significant improvements in functional outcomes after surgery. Different types of MMD patients have distinct prognostic factors for short-term and long-term functional outcomes.

Applications of Microscope-Integrated Indocyanine Green Videoangiography in Cerebral Revascularization Procedures

Indocyanine green videoangiography (ICG-VA) is a near-infrared range fluorescent marker used for intraoperative real-time assessment of flow in cerebrovascular surgery. Given its high spatial and temporal resolution, ICG-VA has been widely established as a useful technique to perform a qualitative analysis of the graft patency during revascularization procedures. In addition, this fluorescent modality can also provide valuable qualitative and quantitative information regarding the cerebral blood flow within the bypass graft and in the territories supplied. Digital subtraction angiography (DSA) is considered to be the gold standard diagnostic modality for postoperative bypass graft patency assessment. However, this technique is time and labor intensive and an expensive interventional procedure. In contrast, ICG-VA can be performed intraoperatively with no significant addition to the total operative time and, when used correctly, can accurately show acute occlusion. Such time-sensitive ischemic injury detection is critical for flow reestablishment through direct surgical management. In addition, ICG has an excellent safety profile, with few adverse events reported in the literature. This review outlines the chemical behavior, technical aspects, and clinical implications of this tool as an intraoperative adjunct in revascularization procedures.

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.

Predictors and clinical features of transient neurological events after combined bypass revascularization for moyamoya disease

OBJECTIVE

Transient neurological events (TNEs) are frequently observed after revascularization surgery for moyamoya disease (MMD). However, clinical features and pathophysiology of TNEs in MMD are still unclear. This study was aimed to clarify the incidence and time course of TNEs and to determine the independent predictors of TNEs in MMD.

PATIENTS AND METHODS

A total of 195 hemispheres in 171 consecutive patients with MMD who had undergone combined direct and indirect bypass surgery were analyzed. Preoperative clinical characteristics and radiographic features were recorded. The incidence and clinical feature of postoperative TNEs were evaluated. Multivariate logistic regression analyses were performed to identify the risk factors for postoperative TNEs. Outcomes were compared between patients who had TNEs with those without TNEs at the time of discharge.

RESULTS

Postoperative TNEs were detected in 40 (20.5%) of 195 operated hemispheres, including 17 (42.5%) aphasia, 9 numbness of the extremities (22.5%), 6 seizures (15%), 5 motor weakness (12.5%), 4 dysarthria (10%) and 6 others (15%). The incidence of TNEs was significantly higher in adult patients than in pediatric ones. Multivariate analysis revealed that female, left-sided surgery and the presence of the edematous lesion was an independent predictor of TNEs after surgery in MMD (OR, 3.0; 95% CI, 1.1-8.2; P = 0.03, OR, 2.9; 95% CI, 1.2-7.0; P = 0.02 and OR, 17.4; 95% CI, 5.7-53.0; P < 0.01, respectively). DSA stage (OR 0.05, 95% CI 0.0-0.5, p = 0.005; OR 0.08, 95% CI 0.0-0.4, p = 0.008), PCA involvement (OR 2.75, 95% CI 1.0-7.4, p = 0.046), left-sided surgery (OR 2.73, 95% CI 1.2-6.5, p = 0.022) and edematous lesion (OR 21.2, 95% CI 7.6-59.7, <0.001) were significantly associated with TNE severity. Compared with patients without postoperative TNEs, no significant differences in mRS score between the two groups were detected.

CONCLUSIONS

Female, left-sided surgery and edematous lesion were independent risk factors for postoperative TNEs; the left-sided surgery and edematous lesion were also independently associated with the severity of TNE. Although patients with postoperative TNEs had worse neurological status during the perioperative period, postoperative TNEs had no associations with worse mRS score at the time of discharge.

Development of bilateral dural arteriovenous fistulae following pial synangiosis for moyamoya syndrome: case report

Moyamoya syndrome predisposes patients to ischemic or hemorrhagic stroke due to progressive narrowing of intracranial vessels with subsequent small-vessel collateralization. Dural arteriovenous fistulae (DAVFs) are most commonly noted after venous sinus or cortical vein thrombosis and are believed to be primarily due to venous hypertension and elevated sinus pressures, although there is no known association with moyamoya syndrome, or with surgical treatment for moyamoya disease (MMD). The authors present the case of a 14-year-old girl with Down syndrome treated using pial synangiosis for MMD who subsequently was noted to have bilateral DAVFs. This case provides a new perspective on the origins and underlying pathophysiology of both moyamoya syndrome and DAVFs, and also serves to highlight the importance of monitoring the moyamoya population closely for de novo cerebrovascular changes after revascularization procedures.

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.

Intraoperative evaluation of local cerebral hemodynamic change by indocyanine green videoangiography: prediction of incidence and duration of postoperative transient neurological events in patients with moyamoya disease

OBJECTIVE

Transient neurological events (TNEs) occur frequently in the acute phase after direct bypass surgery for moyamoya disease (MMD), but there is currently no way to predict them. FlowInsight is a specialized software for analyzing indocyanine green (ICG) videoangiography taken with a surgical microscope. The purpose of this study was to investigate whether intraoperative evaluation of local hemodynamic changes around anastomotic sites using FlowInsight could predict the incidence and duration of TNEs.

METHODS

From patients who were diagnosed with MMD in our hospital between August 2014 and March 2017 and who underwent superficial temporal artery-middle cerebral artery bypass surgery, we investigated 25 hemispheres (in 22 patients) in which intraoperative ICG analysis was performed using FlowInsight. To evaluate the local cerebral hemodynamics before and after anastomosis, regions of interest were set at 3 locations on the brain surface around the anastomotic site, and the mean cerebral blood flow (CBF), mean gradation (Grad), mean transit time (MTT), and mean time to peak (TTP) were calculated from the 3 regions of interest. Furthermore, the change rate in CBF (ΔCBF [%]) was calculated using the formula (postanastomosis mean CBF - preanastomosis mean CBF)/preanastomosis mean CBF. ΔGrad (%), ΔMTT (%), and ΔTTP (%) were similarly calculated.

RESULTS

Postoperative stroke without TNE occurred in 2 of the 25 hemispheres. These 2 hemispheres (in 2 patients) were excluded from the study, and data from the remaining 23 hemispheres (in 20 patients) were analyzed. For each parameter (ΔCBF, ΔGrad, ΔMTT, and ΔTTP) calculated by FlowInsight, the difference between the groups with and without TNEs was significant. The median values for ΔCBF and ΔGrad were significantly higher in the TNE group than in the no-TNE group (ΔCBF 30.13 vs 3.54, p = 0.0106; ΔGrad 62.05 vs 10.78, p = 0.00435), whereas the median values for ΔMTT and ΔTTP were significantly lower in the TNE group (ΔMTT -16.90 vs -7.393, p = 0.023; ΔTTP -29.07 vs -7.02, p = 0.00342). Comparison of the area under the curve (AUC) for each parameter showed that ΔTTP had the highest AUC and was the parameter with the highest diagnostic accuracy (AUC 0.857). The Youden index revealed that the optimal cutoff value of ΔTTP was -11.61 (sensitivity 77.8%, specificity 71.4%) as a predictor of TNEs. In addition, Spearman's rank correlation coefficients were calculated, and ΔCBF, ΔGrad, ΔMTT, and ΔTTP each showed a strong correlation with the duration of TNEs. The larger the change in each parameter, the longer the TNEs persisted.

CONCLUSIONS

Intraoperative ICG videoangiography findings were correlated with the occurrence and duration of TNEs after direct bypass surgery for MMD. Screening for cases at high risk of TNEs can be achieved by ICG analysis using FlowInsight.

Subtraction of arterial spin-labeling magnetic resonance perfusion images acquired at dual post-labeling delay: Potential for evaluating cerebral hyperperfusion syndrome following carotid endarterectomy

Arterial spin-labeling magnetic resonance perfusion imaging is a promising tool for the diagnosis of cerebral hyperperfusion syndrome after carotid endarterectomy. However, arterial spin-labeling with a single post-labeling delay has been reported to show a higher incidence of increased arterial spin-labeling signals in the bilateral hemisphere, probably due to a shortening of the arterial transit time or an arterial transit artifact caused by intravascular stagnant magnetically-labeled spin. To overcome these shortcomings, we used two post-labeling delay settings (1.0 and 1.5 s) in 8 patients who had undergone carotid endarterectomy. In addition, we created a subtraction image between the mean perfusion maps at post-labeling delays of 1.0 and 1.5 s. This also decreased arterial transit artifacts, as these appeared in nearly the same configuration in both post-labeling delay settings. In all eight cases examined, increased arterial spin-labeling signals were observed bilaterally on both dual post-labeling delay settings. Subtraction images revealed that these increased signals were attributable to arterial transit artifacts in seven cases. However, in one patient who developed clinical symptoms, the subtraction method demonstrated post-carotid endarterectomy hyperperfusion. This preliminary study demonstrates that the subtraction method might decrease arterial transit artifacts and yield a map that can better represent true perfusion, thus enabling the detection of post-carotid endarterectomy hyperperfusion.

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.

Intracranial Hemorrhage After Superficial Temporal Artery-Middle Cerebral Artery Direct Anastomosis for Adults with Moyamoya Disease

BACKGROUND

Intracranial hemorrhage, such as intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and intraventricular hemorrhage (IVH), is an extremely rare complication after surgical revascularization for moyamoya disease (MMD). However, the incidence, timing, prognosis, possible mechanism, and prevention are not well known.

METHODS

Adult patients with MMD who underwent direct bypass or combined bypass and experienced ICH, SAH, or IVH within 7 days postoperatively were enrolled in this study. The medical records and radiologic findings of these patients, together with their intraoperative video recordings, were reviewed retrospectively.

RESULTS

Direct superficial temporal artery (STA)-middle cerebral artery (MCA) bypass or combined bypass was performed for 222 hemispheres in 193 adult patients with MMD between January 2001 and December 2016. Intracranial hemorrhage occurred perioperatively in 8 hemispheres (3.6%) in 8 patients. The hemorrhages developed immediately after STA-MCA direct anastomosis during surgery in 3 patients. Hemorrhage on computed tomography and neurologic deterioration were also observed immediately postoperatively in 2 patients and during the postoperative period in 3 patients. Although 4 patients received medical management, neurosurgical treatment was needed in the other 4 patients. One patient died, and 6 patients were left with moderate or severe disabilities.

CONCLUSIONS

Intracranial hemorrhage (ICH, IVH, or SAH) after direct bypass for adult patients with MMD is an extremely rare but fatal complication. Although these hemorrhages can be associated with hyperperfusion syndrome, no effective prevention has been established.

Surgical Treatment of Adult Moyamoya Disease

PURPOSE OF REVIEW

Moyamoya disease (MMD) is being increasingly diagnosed with the development of radiological surveillance technology and increased accessibility to medical care. Accordingly, there have been several recent reports on treatment outcomes in MMD. In this review, we summarize recent advances in surgical treatment and outcomes of adult MMD, while addressing related controversies.

RECENT FINDINGS

Recent studies suggest that revascularization surgery leads to significantly more favorable outcomes for stroke prevention, angiographic and hemodynamic changes, and clinical outcomes than does conservative treatment for adult patients with ischemic MMD. Moreover, direct revascularization methods should be considered as the first-line treatment over indirect methods, although the latter may be considered if a direct method is not possible. In cases of hemorrhagic MMD, several studies have demonstrated that surgical treatment is more effective than conservative treatment in preventing further hemorrhage. In addition to revascularization surgery, endovascular treatment is emerging as a breakthrough therapy for hemorrhagic MMD. Accumulating evidence regarding the surgical treatment of adult MMD suggests the benefit of revascularization over conservative management for both ischemic and hemorrhagic patients. However, the benefit of revascularization in asymptomatic adult MMD remains unclear.

Assessment of Hemodynamic Changes and Hyperperfusion Risk After Extracranial-to-Intracranial Bypass Surgery Using Intraoperative Indocyanine Green-Based Flow Analysis

BACKGROUND

Intraoperative blood flow assessments during cerebral bypass would ideally assess vessel patency, downstream perfusion, and risk of postoperative hyperperfusion syndrome (HPS). Previous studies using indocyanine green-based flow analyses (ICG-BFA) have identified multiple parameters that can intraoperatively track bypass-related changes in cerebral perfusion and potentially predict postoperative risk of HPS. Herein, we determine the most robust parameter and anatomic location for intraoperative ICG-BFA assessment of bypass-related perfusion changes and prediction of postoperative risk of HPS.

METHODS

Retrospective analysis of an institutional review board-approved prospective database identified patients undergoing superficial temporal artery-to-middle cerebral artery bypass. Demographic and clinical information, as well as manually calculated and automated pre- and postbypass intraoperative ICG-BFA data from cortical, arterial, and venous regions of interest were recorded and analyzed.

RESULTS

Seven patients underwent superficial temporal artery-to-middle cerebral artery bypass (4 Moyamoya, 3 carotid occlusions). Average age was 48.2 ± 13.9 years (3 female, 4 male). Although all parameters measured showed trends toward improvement postbypass, only changes in arterial and venous automated ICG-BFA slope (also known as blood flow index [maximum intensity/rise time]) reached significance. None of the patients experienced symptomatic HPS, despite 5 of 7 (71.4%) having an increased HPS risk based on previously published ICG-BFA data.

CONCLUSIONS

ICG-BFA has utility for the intraoperative assessment of bypass-related changes in cerebral perfusion, with automated blood flow index being the most robustly affected parameter. Although previously published ICG-BFA indices did not predict the development of symptomatic postoperative HPS, larger-scale studies correlating observed ICG-BFA changes with risk of HPS are warranted.

Moyamoya Disease in an 18-Month-Old Female Caucasian Complicated by Cerebral Hyperperfusion Syndrome Following Indirect Revascularization

BACKGROUND Cerebral hyperperfusion syndrome is a rare complication of indirect revascularization due to moyamoya disease, but has not been reported previously in the pediatric population. We present a case of an 18-month-old girl with moyamoya disease that was treated with bilateral pial synangiosis and had complications consistent with cerebral hyperperfusion syndrome. This case report discusses the pathophysiological mechanisms involved in cerebral hyperperfusion in moyamoya syndrome. CASE REPORT An 18-month-old female Caucasian presented with seizures and weakness of the left side. Angiography confirmed bilateral cerebral moyamoya disease that was worse on the right side. Indirect revascularization with pial synangiosis was first performed on the right side to allow for healing. Five months later, pial synangiosis was then performed on the left side. Postoperatively, the patient experienced increased intracranial pressure (ICP), suggesting cerebral hyperperfusion syndrome. She was treated with a repeat lumbar puncture, a lumbar drain, and a lumbar shunt. CONCLUSIONS This report demonstrates a case of cerebral hyperperfusion syndrome as a complication of moyamoya disease in a pediatric patient. Although the patient progressed well after placement of a lumbar shunt, this case demonstrates the occurrence of cerebral hyperperfusion syndrome as a complication of revascularization in pediatric patients and highlights the need for further research in this area.

Uncommon Etiology for Seizure: Cerebral Hyperperfusion Syndrome

Cerebral hyperperfusion syndrome (CHS) is a rare life-threatening complication of carotid endarterectomy (CEA) and carotid artery stenting (CAS) for carotid artery stenosis. The incidence varies between 0 and 3%, depending on the severity of the stenosis, perioperative hypertension, and contralateral carotid stenosis. This case report reports a 53-year-old female patient presenting with decreased alertness and multiple tonic-clonic seizures, in the background of bilateral CEA. She was found to have bilateral carotid stenosis. Her left CEA was performed three months prior and right CEA was four days prior to her current presentation with seizures. After bilateral CEA, the imaging showed extensive pathologic process involving primarily the subcortical white matter and overlying cortex, more on the right cerebral hemisphere. On follow-up six weeks later, she reported no recurrent seizures and imaging showed decrease in abnormal signal intensity of the grey and white matter. This was indicative of near complete resolution of hyperperfusion damage. CHS is a rare complication due to the loss of autoregulation of the cerebrovascular system and increased blood flow status after bilateral CEA. This case is reported because of a rare and unique presentation of seizures in the background of bilateral CEA.

Signal changes on magnetic resonance perfusion images with arterial spin labeling after carotid endarterectomy

BACKGROUND

Cerebral hyperperfusion after carotid endarterectomy (CEA) is defined as an increase in ipsilateral cerebral blood flow (CBF). Practically, however, prompt and precise assessment of cerebral hyperperfusion is difficult because of limitations in the methodology of CBF measurement during the perioperative period. Arterial spin labeling (ASL) is a completely noninvasive and repeatable magnetic resonance perfusion imaging technique that uses magnetically-labelled blood water as an endogenous tracer. To clarify the usefulness of ASL in the management of cerebral hyperperfusion, we investigated signal changes by ASL with a single 1.5-s post-labeling delay on visual inspection.

METHODS

Thirty-two consecutive patients who underwent CEA were enrolled in this retrospective study.

RESULTS

On postoperative day 1, 22 (68.8%) and 4 (12.5%) patients exhibited increased ASL signals bilaterally (Group A) and on the operated side (Group B), respectively. Follow-up ASL showed improvement in these findings. Six (18.8%) patients showed no change (Group C). There was no apparent correlation between ASL signals on postoperative day 1 and the preoperative hemodynamic state, including the cerebrovascular reserve (P = 0.2062). Three (9.4%) patients developed cerebral hyperperfusion syndrome (two in Group A and one in Group B). Coincidence in the localization of increased ASL signals and electroencephalographic abnormalities was noted in these patients.

CONCLUSION

Visual analysis of ASL with a single post-labeling delay overestimates CBF and cannot identify patients at risk of cerebral hyperperfusion syndrome probably because of the strong effect of the shortened arterial transit time immediately after CEA. However, ASL may be used as for screening.

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.

Moyamoya Disease: Treatment and Outcomes

Although the pathogenesis of moyamoya disease (MMD) has not been fully elucidated, the effectiveness of surgical revascularization in preventing stroke has been addressed by many studies. The main mechanism of surgical revascularization is augmenting the intracranial blood flow using an external carotid system by either direct bypass or pial synangiosis. This can improve resting cerebral blood flow as well as vascular reserve capacity. For direct revascularization, the superficial temporal artery is used as the donor artery in most cases, although the occipital artery may be used in limited cases. Usually, the cortical branch of the middle cerebral artery is selected as the recipient of direct anastomosis. As for indirect revascularization, various techniques using different kinds of connective tissues have been introduced. In some cases, reinforcing the anterior cerebral artery and the posterior cerebral artery territories can be considered. The effectiveness of surgical revascularization for preventing ischemic stroke had been generally accepted by many studies. However, for preventing hemorrhagic stroke, new evidence has been added by a recent randomized controlled trial. The incidence of peri-operative complications such as stroke and hyperperfusion syndrome seems to be high due to the nature of the disease and technical demands for treatment. Preventing and adequately managing these complications are essential for ensuring the benefits of surgery.

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.

Significance of Cerebral Blood Flow Analysis in the Acute Stage after Revascularization Surgery for Moyamoya Disease

Moyamoya disease is a chronic, occlusive cerebrovascular disease with unknown etiology characterized by steno-occlusive changes at the terminal portion of the internal carotid artery, either bilaterally or unilaterally, and an abnormal vascular network at the base of the brain. Surgical revascularization such as extracranial-intracranial (EC-IC) bypass is the preferred procedure for moyamoya disease. Despite the favorable long-term outcome, cerebral infarction and hyperperfusion syndrome are potential complications of this procedure, which can lead to neurological deterioration in the acute stage. In light of the similar clinical presentations between perioperative ischemia and hyperperfusion, it is essential to attempt a prompt cerebral blood flow (CBF) measurement in the acute stage after EC-IC bypass for moyamoya disease to differentiate these distinct pathologies, because the management of cerebral ischemia and hyperperfusion is contradictory to each other. Routine CBF analysis by single-photon emission computed tomography and/or magnetic resonance imaging not only facilitated a safer perioperative management but also provided important information about dynamic pathology of the hemodynamic conversion in the acute stage after revascularization surgery for moyamoya disease. We represent the current status of CBF analysis during the perioperative period of revascularization surgery for moyamoya disease, and sought to discuss its significance and efficacy to avoid surgical complications.

An Alternative Display Could Lead to Earlier Diagnosis of Intracerebral Pathology with a Hemedex Flow Probe In Situ

OBJECTIVE

To report 2 cases of patients who had an ischemic stroke and an intracerebral hematoma after a superficial temporal artery-middle cerebral artery bypass with a thermal diffusion blood flow probe in situ and emphasize how a change in the way the data are presented could have led to an earlier diagnosis.

METHODS

Both patients had flow probes within 2 cm of the graft site and were thus close enough to be representative of local or regional rather than global perfusion. Data smoothening was applied to the raw data that were available and displayed on the monitor. Both the smoothed plots and the raw plots were analyzed.

RESULTS

Good clinical correlation was observed between the flow probe data and the clinical condition of both patients. This was more apparent when viewing the smoothed plots.

CONCLUSIONS

Although there was good clinical correlation, data displayed on the perfusion monitor can be incorrectly interpreted because the signal-to-noise ratio is small. We therefore suggest an alternative presentation of perfusion data for clinicians to recognize hypoperfusion and to take informed action before a stroke or hematoma is clinically manifest.

Hemichorea-hemiballismus caused by postoperative hyperperfusion after clipping of a giant unruptured middle cerebral artery aneurysm

Background:

Movement disorders after the clipping for an unruptured giant aneurysm are rare. The information on the pathogenesis and treatment options for this condition is largely unknown.

Case Description:

An 82-year-old female with no neurological deficits underwent a clipping for a giant middle cerebral artery (MCA) aneurysm. Immediately after surgery, she presented with hemichorea–hemiballismus (HC–HB) on the left side. Postoperative angiograms and single-photon emission computed tomography demonstrated the hyperperfusion in the right frontal cortex and the decreased perfusion in the basal ganglia, indicating that the abrupt hemodynamic changes due to the obliteration of the giant aneurysm caused the dysfunction of the frontal cortical and subcortical pathway and the basal ganglia. Administration of tiapride hydrochloride was dramatically effective in controlling the HC–HB until the hyperperfusion resolved. Single-photon emission computed tomography obtained 8 weeks after surgery revealed that the cerebral blood flow had been normalized in the right frontal cortex. The relative hypoperfusion of the right basal ganglia was also resolved. Then tiapride hydrochloride was discontinued without a relapse of HC–HB.

Conclusion:

This case appears consistent with the theory that the connecting fibers responsible for the development of HC–HB are also located in the frontal lobe. The treatment of giant aneurysms involving the M1 portion can cause abrupt hemodynamic changes in both frontal cortex and the basal ganglia, which can potentially induce postoperative movement disorders.

Indocyanine green videoangiography for assessment of postoperative hyperperfusion in moyamoya disease

BACKGROUND

Postoperative cerebral hyperperfusion (HP) is a notable complication that occurs more frequently in moyamoya disease (MMD) than in atherosclerosis. This study aimed to clarify the characteristics of intraoperative indocyanine green (ICG) videoangiography in MMD and atherosclerotic disease in terms of postoperative HP.

METHODS

This prospective study included 47 patients with 60 sides that underwent superior temporal artery (STA)-middle cerebral artery (MCA) single bypass. ICG videoangiography was performed after revascularization. The ICG time intensity curve was recorded in the STA, proximal MCA, distal MCA, and superficial Sylvian vein, and the angiographic differences among adult MMD, pediatric MMD, and atherosclerosis were analyzed.

RESULTS

Twenty-two patients (27 sides) had adult MMD, 14 patients (22 sides) had pediatric MMD, and 11 patients (11 sides) had atherosclerosis. Postoperative HP was significantly higher in adult MMD (40.7 %) than in pediatric MMD (18.2 %) and atherosclerosis (0 %). Adult MMD with HP was associated with a longer ICG peak time (P < 0.001). There was no correlation between the ICG peak time and preoperative cerebral blood flow or vascular reserve. The ratio of the vessel caliber was also higher in adult MMD with HP (P < 0.001).

CONCLUSIONS

ICG videoangiography provides different characteristics of bypass flow among adult MMD, pediatric MMD, and atherosclerosis. Poor run-off and stagnation of blood flow from the STA might contribute to postoperative HP in MMD. The occurrence of postoperative HP in MMD could depend on two factors: donor STA size and poor run-off and integrity of the blood brain barrier in the recipient MCA.

Venous reddening as a possible sign of hyperperfusion after superficial temporal artery-middle cerebral artery anastomosis for moyamoya disease: case report

Here we report a case of moyamoya disease in which cortical veins reddened after superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis, following postoperative hyperperfusion. A 37-year-old man with moyamoya disease suffered cerebral infarction in his right hemisphere. Single photon emission computed tomography (SPECT) showed impaired cerebral blood flow (CBF) in both cerebral hemispheres. The patient underwent STA-MCA anastomosis in the right cerebral hemisphere. During operation, soon after declamping the STA, cortical veins near the anastomosis site changed its color from blue to red. This change was repeatable by clamping and declamping of the STA. Postoperative SPECT and computed tomography (CT) demonstrated increased CBF and subarachnoid hemorrhage at the anastomosis site, suggesting the occurrence of postoperative hyperperfusion. By strictly controlling the patient's blood pressure, the syndrome resolved 1 week after the operation. We propose that the venous reddening after STA-MCA anastomosis may be a sign of postoperative hyperperfusion.

Cerebral hyperperfusion syndrome following the excision of a mycotic aneurysm with superficial temporal artery-to-middle cerebral artery bypass: case report

The authors report a rare case of cerebral hyperperfusion syndrome (HPS) following the excision of a mycotic aneurysm with superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass. A 74-year-old woman with infective endocarditis presented with progressive cerebral infarction and subarachnoid hemorrhage due to a mycotic aneurysm, which was excised with a STA-MCA bypass. Postoperatively, the patient developed HPS that was considered to be exacerbated by a previous ischemic event. Therefore, cerebral hemodynamics should be evaluated before bypass surgery to prevent subsequent hyperperfusion.

Monitoring Flow in Extracranial-Intracranial Bypass Grafts Using Duplex Ultrasonography: A Single-Center Experience in 80 Grafts Over 8 Years

BACKGROUND:

High-flow extracranial-intracranial (EC-IC) bypass is performed by using radial artery graphs (RAGs) or saphenous vein grafts (SVGs) for various pathologies such as aneurysms, ischemia, and skull-base tumors. Quantifying the acceptable amount of blood flow to maintain proper cerebral perfusion has not been well established, nor have the variables that influence flow been determined.

OBJECTIVE:

To identify the normative range of blood flow through extracranial-intracranial RAGs and SVGs as measured by duplex ultrasonography. Multiple variables were evaluated to better understand their influence of graft flow.

METHODS:

All EC-IC grafts performed at Harborview Medical Center from 2005 to 2012 were retrospectively reviewed for this cohort study. Daily extracranial graft duplex ultrasonography with flow volumes and transcranial graft Doppler were examined, as were short- and long-term outcomes. Both ischemic and hyperemic events were evaluated in further detail.

RESULTS:

Eighty monitorable high-flow EC-IC bypasses were performed over the 8-year period. Sixty-five bypasses were performed by using RAGs and 15 were performed with SVGs. The average flow was 133 mL/min for RAGs and 160 mL/min for SVGs (P = .25). For both RAG and SVG groups, the donor and recipient vessel selected significantly impacted flow. For the RAG group only, preoperative graft diameter, postoperative hematocrit, and postoperative date significantly influenced flow. A 1-week average of &gt;200 mL/min was 100% sensitive to cerebral hyperemia syndrome.

CONCLUSION:

This study establishes the normative range of duplex ultrasonographic flow after high-flow EC-IC bypass, as well the usefulness and practicality of such monitoring as a surrogate to flow in the postoperative period.

Cerebral Hyperperfusion Syndrome After Superficial Temporal Artery-middle Cerebral Artery Bypass for Severe Intracranial Steno-occlusive Disease: A Case Control Study

BACKGROUND:

Intracranial stenoses carry increased risk for cerebral ischemia. We perform external carotid-internal carotid (EC-IC) artery bypass in our patients with severe stenosis of the intracranial internal carotid (ICA) or middle cerebral artery (MCA) with impaired cerebral vasodilatory reserve (CVR).

OBJECTIVE:

To evaluate cerebral hemodynamics and cerebral hyperperfusion syndrome (HPS) in patients who develop focal neurological deficits after EC-IC bypass surgery.

METHODS:

Patients with severe intracranial ICA or MCA stenosis and impaired CVR on transcranial Doppler (TCD) derived breath-holding index (BHI) were evaluated with acetazolamide-challenged technetium-99m hexamethylpropyleneamineoxime–single-photon emission computed tomography (SPECT). EC-IC bypass surgery was offered to patients with impaired CVR on SPECT. Close monitoring was performed in patients developing focal neurological deficits within 7 days of surgery.

RESULTS:

Of 112 patients with severe intracranial ICA/MCA stenosis, 77 (69%) showed impaired CVR and 46 (41%) underwent EC-IC bypass. Transient neurological deficits within 7 days of surgery developed in 8 (17%). HPS was confirmed by CT perfusion and/or SPECT in 7 cases. A strong correlation was observed between HPS and preoperative TCD-BHI values (0%, 6.3%, and 41% in patients with BHI 0.3-0.69, 0-0.3 and &lt;0, respectively; P = .012). HPS patients showed more than a 50% increase in MCA flow velocity on TCD (compared with preoperative values) on the operated side (63.3% vs 3.3% on control side, P &lt; .001). Meticulous control of blood pressure and hydration led to rapid and complete resolution of neurological deficits in all cases.

CONCLUSION:

Symptomatic cerebral HPS is common in the early postoperative period after EC-IC bypass surgery. Early diagnosis and appropriate management might prevent the complications of this syndrome.