Factors of Delayed Hyperperfusion and the Importance of Repeated Cerebral Blood Flow Evaluation for Hyperperfusion After Direct Bypass for Moyamoya Disease

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.

Intraoperative Hemodynamics of Parasylvian Cortical Arteries for Predicting Postoperative Symptomatic Cerebral Hyperperfusion after Direct Revascularization in Patients with Moyamoya Disease: A Preliminary Study

Objective. The search for methods by which to predict the risks of cerebral hyperperfusion syn-drome (CHS) in adults with moyamoya disease (MMD), including those utilizing new biomarkers, still deserves further research. The objective of this study was to investigate the association between the hemodynamics of parasylvian cortical arteries (PSCAs) and postoperative CHS. Methods. A consecutive number of adults with MMD who had undergone direct bypass between September 2020 and December 2022 were recruited. Intraoperative microvascular doppler ultrasonography (MDU) was performed to evaluate the hemodynamics of PSCAs. The intraoperative flow direction, mean value of velocity (MVV) of recipient artery (RA) and bypass graft were recorded. According to flow direction after bypass, RA was divided into entering sylvian (RA.ES) and leaving sylvian (RA.LS) subtypes. Univariate, multivariate, and ROC analyses of the risk factors for postoperative CHS were performed. Results. A total of 16 (15.09%) cases in 106 consecutive hemispheres (101 patients) sat-isfied the postoperative CHS criteria. According to univariate analysis, advanced Suzuki stage, MVV of RA before bypass, and fold increase of MVV in RA.ES after bypass were significantly associated with postoperative CHS (p < 0.05). Multivariate analysis indicated that left-operated hemisphere (OR (95%CI), 4.58 (1.05-19.97), p = 0.043), advanced Suzuki stage (OR (95%CI), 5.47 (1.99-15.05), p = 0.017), and fold increase of MVV in RA.ES (OR (95%CI), 1.17 (1.06-1.30), p = 0.003) were statistically significantly associated with the occurrence of CHS. The cut-off value of fold increase of MVV in RA.ES was 2.7-fold (p < 0.05). Conclusions. Left-operated hemisphere, advanced Suzuki stage, and postoperative fold increase of MVV in RA.ES were potential risk factors for postoperative CHS. Intraoperative MDU was useful for evaluating hemodynamics and predicting CHS.

Early Surgery for Moyamoya Is Not Associated with Worse Outcomes: Analysis of a North American Adult Cohort

BACKGROUND

Patients with symptomatic moyamoya disease (MMD) or moyamoya syndrome (MMS) are at high risk of recurrent stroke. Surgical revascularization with either direct or indirect superficial temporal artery to middle cerebral artery bypass is a well-accepted treatment. However, the optimal timing and surgical technique for adult patients with MMD or MMS remain unknown.

METHODS

We performed a retrospective medical record review of patients who had undergone superficial temporal artery to middle cerebral artery bypass for MMD or MMS from January 1, 2017, to January 1, 2022. The data collected included demographics, comorbidities, complications, as well as angiographic, and clinical outcomes. Early surgery was defined as surgery performed ≤2 weeks of the last stroke and delayed surgery as surgery performed >2 weeks after the last stroke. In the statistical analysis, we compared early versus delayed surgery and direct versus indirect bypass.

RESULTS

Nineteen patients had undergone bypass surgery on 24 hemispheres. Of the 24 cases, 10 were early and 14 were delayed. In addition, 17 were direct, and 7 were indirect. No statistically significant difference was found in total complications between the early (3 of 10; 30%) and delayed (3 of 14; 21%; P = 0.67) groups. Five complications occurred in the direct group (5 of 17; 29%) and one in the indirect group (1 of 7; 14%; P = 0.63). No mortalities related to surgery occurred. Angiographic follow-up showed more extensive revascularization after early direct bypass than after delayed indirect bypass.

CONCLUSIONS

In our population of North American adults who had undergone surgical revascularization for MMD or MMS, early surgery within 2 weeks of the last stroke did not differ from delayed surgery in terms of complications or clinical outcomes. Early direct bypass showed more revascularization on angiography than did delayed indirect surgery.

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.

Effectiveness of pharmacologic interventions for prevention of cerebral hyperperfusion syndrome following bypass surgery

BACKGROUND

Cerebral hyperperfusion syndrome (CHS) following bypass surgery is a major cause of neurological morbidity and mortality. However, data regarding its prevention have not been assorted until date.

OBJECTIVE

The objective of this study was to review the literature and evaluate whether any conclusion can be drawn regarding the effectiveness of any measure on preventing bypass-related CHS.

METHODS

We systematically reviewed PubMed and Cochrane Library from September 2008 to September 2018 to collect data regarding the effectiveness of pharmacologic interventions on the refers to pretreatment (PRE) of bypass-related CHS. We categorized interventions regarding their class of drugs and their combinations and calculated overall pooled estimates of proportions of CHS development through random-effects meta-analysis of proportions.

RESULTS

Our search yielded 649 studies, of which 23 fulfilled inclusion criteria. Meta-analysis included 23 studies/2,041 cases. In Group A (blood pressure [BP] control), 202 out of 1,174 pretreated cases developed CHS (23.3% pooled estimate; 95% confidence interval [CI]: 9.9-39.4), Group B (BP control + free radical scavenger [FRS]) 10/263 (0.3%; 95% CI: 0.0-14.1), Group C (BP control + antiplatelet) 22/204 (10.3%; 95% CI: 5.1-16.7), and Group D (BP control + postoperative sedation) 29/400 (6.8%; 95% CI: 4.4-9.6)].

CONCLUSIONS

BP control alone has not been proven effective in preventing CHS. However, BP control along with either a FRS or an antiplatelet agent or postoperative sedation seems to reduce the incidence of CHS.

Five-day bed rest reduces postoperative intracerebral hemorrhage after direct bypass for Moyamoya disease

OBJECTIVES

Postoperative intracerebral hemorrhage (ICH) after direct bypass surgery for Moyamoya disease (MMD) could contribute to neurological deterioration. The aim of this study was to evaluate the effectiveness of five-day bed rest in reducing the occurrence of postoperative ICH.

METHODS

This study included 122 consecutive hemispheres in 87 Japanese adult MMD patients, comprised of 80 control hemispheres from historical data and 42 hemispheres after five-day bed rest. They all underwent direct bypass surgery. The incidence of postoperative ICH and neurological deterioration assessed via the modified Rankin Scale (mRS) were investigated and statistically analyzed.

RESULTS

Postoperative ICH was observed in 9 out of the 80 (11.3%) control patients, but not in the 42 patients with five-day bed rest. The incidence of postoperative ICH and neurological deterioration via the mRS were significantly different between the two groups (p= 0.0268 and 0.0078, respectively). Univariate logistic analysis revealed that five-day bed rest significantly reduced the incidence of postoperative ICH (p= 0.0048).

CONCLUSIONS

Five-day bed rest after direct bypass surgery dramatically can reduce the incidence of postoperative ICH and neurological deterioration after direct bypass surgery.

Diagnosis and Management of Moyamoya Disease

Moyamoya disease is an uncommon vascular disease, which causes obstruction and stenosis of arteries of the circle of Willis, and preferentially affects children and young adults. This disease is seen across the world, but is more common in East Asia. It may cause hemorrhagic or ischemic stroke, or transient ischemic attack. If symptoms or cerebral blood flow become worse, revascularization surgery is recommended. We present 2 cases of moyamoya disease who underwent bypass surgery. We also discuss the epidemiology, pathology, genomics, and symptomatology as well as diagnosis, and management of moyamoya disease.

Measurement of Intraoperative Graft Flow Predicts Radiological Hyperperfusion during Bypass Surgery in Patients with Moyamoya Disease

Introduction

Moyamoya disease (MMD) is a rare cerebrovascular disease associated with cerebral infarction or hemorrhage. Hyperperfusion is the most significant complication of direct bypass surgery. Previous research has shown that an increase in cerebral blood flow (CBF) is strongly related to symptomatic hyperperfusion and highlighted the importance of postoperative assessment of CBF.

Objective

The principal aims of this study were to quantitatively analyze the relationship between intraoperative graft flow and increase in CBF and to evaluate the effectiveness of intraoperative graft flow measurement during bypass surgery for patients with MMD.

Methods

This study included 91 surgeries in 67 consecutive adult patients with MMD who underwent direct revascularization surgery at our institution between November 2013 and September 2018. Intraoperative graft flow of the branches and main trunk was measured in all patients, after anastomosis had been established. Postoperative CBF measurements were performed under sedation, immediately after surgery. Radiological hyperperfusion was defined as focal high uptake, as determined by CBF imaging immediately after surgery. Patients were divided into two groups (radiological hyperperfusion and nonradiological hyperperfusion groups), and the relationship between intraoperative graft flow and radiological hyperperfusion was analyzed.

Results

Significant differences were observed between the radiological hyperperfusion and nonradiological hyperperfusion groups in terms of intraoperative graft flow of both the branch (median 72 vs. 42 mL/min, respectively; p < 0.01) and main trunk (median 113 vs. 68 mL/min, respectively; p < 0.01). A receiver-operating characteristic analysis was performed to test the utility of intraoperative flow as a quantitative measure. We set the cutoff values for the intraoperative branch and main trunk flow at 57 mL/min (sensitivity: 0.707, specificity: 0.702; area under the curve [AUC]: 0.773; 95% confidence interval [CI]: 0.675–0.871) and 84 mL/min (sensitivity: 0.667, specificity: 0.771; AUC: 0.78; 95% CI: 0.685–0.875), respectively.

Conclusions

Measuring intraoperative graft flow during bypass surgery may be an effective means of predicting hyperperfusion and could serve to facilitate early therapeutic intervention such as strict blood pressure control.

Relationship between ischaemic symptoms during the early postoperative period in patients with moyamoya disease and changes in the cerebellar asymmetry index

OBJECTIVE

The aim of this study was to clarify the relationship between ischaemic symptoms during the early postoperative period in patients with moyamoya disease and changes in the cerebellar asymmetry index (AI), a parameter used to quantitatively identify crossed cerebellar diaschisis (CCD).

PATIENTS AND METHODS

We analysed the data of 18 patients with moyamoya disease who underwent quantitative IMP-cerebral blood flow SPECT at least once during the follow-up period. Cerebellar AI scores were calculated using the CBF of the cerebellum calculated automatically from multiple slices of SPECT images with automated ROI setup software and categorized and statistically examined according to the presence or absence of ischaemic symptoms.

RESULTS

The cerebellar AI calculated from SPECT performed in the patients who presented with ischaemic symptoms was 0.094 ± 0.023 (mean ± SD), which was significantly elevated compared to the value of 0.013 ± 0.025 (mean ± SD) calculated from SPECT performed when the patients did not present with ischaemic symptoms (p < 0.0001). Limiting the time of SPECT to calculate the cerebellar AI to be compared to the acute phase within 2 weeks after surgery did not change this trend, and again, the cerebellar AI was statistically significantly elevated in the presence of ischaemic symptoms (0.094 ± 0.023 (mean ± SD)) compared to the AI in the absence of ischaemic symptoms (0.000081 ± 0.026 (mean ± SD)) (p = 0.0003). In patients who underwent quantitative SPECT in the acute phase during the first postoperative week, the cerebellar AI values calculated from the results of SPECT performed during the preoperative period as well as multiple times during postoperative period were followed over time in each case. The cerebellar AI increased in patients who presented with symptoms of ischaemia postoperatively but then tended to decrease reversibly and approach zero with the disappearance of symptoms of ischaemia.

CONCLUSIONS

Since the cerebellar AI reflects the symptom of ischaemia in patients with moyamoya disease, especially in the early stage after revascularization surgery, and is a parameter that improves with symptom improvement, it seems to be useful for understanding the state of cerebral blood flow after bypass surgery in patients with moyamoya disease.

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.

Direct double bypass using the posterior auricular artery as initial surgery for moyamoya disease: technical note

Surgical treatments for moyamoya disease (MMD) include direct revascularization procedures with proven efficacy, for example, superficial temporal artery (STA) to middle cerebral artery (MCA) bypass, STA to anterior cerebral artery bypass, occipital artery (OA) to MCA bypass, or OA to posterior cerebral artery bypass. In cases with poor development of the parietal branch of the STA, the posterior auricular artery (PAA) is often developed and can be used as the bypass donor artery. In this report, the authors describe double direct bypass performed using only the PAA as the donor in the initial surgery for MMD.In the authors' institution, MMD is routinely treated with an STA-MCA double bypass. Some patients, however, have poor STA development, and in these cases the PAA is used as the donor artery. The authors report the use of the PAA in the treatment of 4 MMD patients at their institution from 2013 to 2016. In all 4 cases, a double direct bypass was performed, with transposition of the PAA as the donor artery. Good patency was confirmed in all cases via intraoperative indocyanine green angiography and postoperative MRA or cerebral angiography. The mean blood flow measurement during surgery was 58 ml/min. No patients suffered a stroke after revascularization surgery.

Clinical factors influencing the development of extracranial-intracranial bypass graft for steno-occlusive cerebrovascular disease

OBJECTIVE

Effectively retaining the patency of the extracranial-intracranial (ECIC) bypass is one of the most important factors in improving long-term results; however, the factors influencing bypass patency have not been discussed much. Therefore, the authors investigated factors influencing the development of the bypass graft.

METHODS

In this retrospective study, the authors evaluated 49 consecutive hemispheres in 47 adult Japanese patients who had undergone ECIC bypass for chronic steno-occlusive cerebrovascular disease. To evaluate objectively the development of the ECIC bypass graft, the change in the area of the main trunk portion of the superficial temporal artery (STA) from before to after bypass surgery (postop/preop STA) was measured. Using the interquartile range (IQR), the authors statistically analyzed the factors associated with excellent (> 3rd quartile) and poor development (< 1st quartile) of the bypass graft.

RESULTS

The postop/preop STA ranged from 1.08 to 6.13 (median 1.97, IQR 1.645–2.445). There was a significant difference in the postop/preop STA between the presence and absence of concurrent diabetes mellitus (p = 0.0432) and hyperlipidemia (0.0069). Furthermore, logistic regression analysis revealed that only concurrent diabetes mellitus was significantly associated with poor development of the bypass graft (p = 0.0235).

CONCLUSIONS

Diabetes mellitus and hyperlipidemia influenced the development of the ECIC bypass graft. In particular, diabetes mellitus is the only factor associated with poor development of the bypass graft.