Disruption of Cortical Arterial Network is Associated with the Severity of Transient Neurologic Events After Direct Bypass Surgery in Adult Moyamoya Disease

The Potential Role of Preoperative Posterior Cerebral Artery Involvement in Predicting Postoperative Transient Neurological Deficits and Ischemic Stroke After Indirect Revascularization in Patients With Moyamoya Disease

OBJECTIVE

Transient neurological deficits (TNDs) are known to develop after direct bypass for Moyamoya disease and may be risk factors for subsequent stroke. However, the factors involved in the development of TNDs and stroke after indirect revascularization alone, including their association with subsequent stroke, remain unclear. The purpose of this study was to investigate this issue.

METHODS

The subjects of the study were 30 patients with Moyamoya disease who underwent a total of 40 indirect revascularization procedures at our institution. Clinical and radiological data were collected retrospectively. To examine factors associated with the development of postoperative TND/stroke/asymptomatic disease, the clinical characteristics of each group were statistically compared.

RESULTS

The mean age at surgery was 7 years (range 1-63). TNDs developed after surgery in 9 out of 40 patients (22.5%). Stroke in the acute postoperative period occurred in 3 patients (7.5%), all of whom experienced cerebral infarctions. Demographic data and preoperative clinical information were not different between the groups. However, posterior cerebral artery involvement on preoperative imaging was significantly associated with the development of TNDs and stroke (P = 0.006). Furthermore, postoperative stroke was associated with unfavorable outcomes (P = 0.025).

CONCLUSIONS

Posterior cerebral artery involvement is significantly associated with the occurrence of TNDs. In contrast, TNDs after indirect revascularization have little relationship with the subsequent development of stroke. TNDs usually resolve without new strokes, and a better understanding of this particular pathology could help establish an optimal treatment regimen.

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.

The value of indocyanine green-FLOW800 in microvasculature for predicting cerebral hyperperfusion syndrome in moyamoya disease patients

Among the notable complications of direct hemodynamic reconstruction for moyamoya disease (MMD) is cerebral hyperperfusion syndrome (CHS). In this study, we evaluated hemodynamic changes in small regional microvasculature (SRMV) around the anastomosis site by using indocyanine green (ICG)-FLOW800 video angiography and verified that it better predicted the onset of CHS. Intraoperative ICG-FLOW800 analysis was performed on 31 patients (36 cerebral hemispheres) with MMD who underwent superficial temporal artery-middle cerebral artery (MCA) bypass grafting at our institution. The regions of interest were established in the SRMV and thicker MCA around the anastomosis. Calculations were made for half-peak to time (TTP1/2), cerebral blood volume (CBV), and cerebral blood flow (CBF). According to the presence or absence of CHS after surgery, CHS and non-CHS groups of patients were separated. The results showed that ΔCBV and ΔCBF were substantially greater in SRMV than in MCA (p < 0.001). Compared with the non-CHS group, ΔCBF and ΔCBV of SRMV and MCA were considerably greater in the CHS group (p < 0.001). ΔCBF and ΔCBV on the ROC curve for both SRMV and MCA had high sensitivity and specificity (SRMV: ΔCBF, AUC = 0.8586; ΔCBV, AUC = 0.8158. MCA: ΔCBF, AUC = 0.7993; ΔCBV, AUC = 0.8684). ICG-FLOW800 video angiography verified the differential hemodynamic changes in the peri-anastomotic MCA and SRMV before and after bypass surgery in patients with MMD.

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.

How I do it: combined bypass for adult moyamoya disease with maximal consideration of cosmetic aspects

BACKGROUND

Combined bypass, including direct and indirect procedures, has been recognized as the maximal revascularization to prevent further hemorrhagic or ischemic stroke in adult moyamoya disease (MMD). It is also important to consider cosmetic aspects when planning combined bypass for MMD. However, there are few reports that have described the cosmetic considerations in bypass surgery for MMD.

METHODS

We demonstrate our surgical techniques aimed at achieving extended revascularization as well as excellent cosmetic outcomes with figures and video.

CONCLUSION

Our combined bypass procedures which focus on achieving maximal cosmetic results are effective methods that require no special instruments or techniques.

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.

Evaluation of Hemodynamic Change by Indocyanine Green-FLOW 800 Videoangiography Mapping: Prediction of Hyperperfusion Syndrome in Patients with Moyamoya Disease

Objective

Hyperperfusion syndrome (HPS) after bypass surgery for moyamoya disease (MMD) mainly results from redistribution of blood flow, which leads to poor outcomes, while effective methods to predict HPS are still lacking. Indocyanine green (ICG) videoangiography can assess regional cerebral blood flow changes semiquantitatively with the application of FLOW 800 software. The purpose of this study was to investigate whether the intraoperative evaluation of local hemodynamic changes around anastomotic sites using FLOW 800 videoangiography mapping can predict the incidence of HPS and clinical outcomes.

Methods

Of the patients who were diagnosed with MMD in our hospital between August 2018 and December 2019, who underwent superficial temporal artery-middle cerebral artery bypass surgeries, we investigated 65 hemispheres (in 62 patients) in which intraoperative ICG analysis was performed using FLOW 800 (Zeiss Meditec, Oberkochen, Germany) to evaluate the local cerebral hemodynamics before and after anastomosis. Regions of interest were set at more than 2 points on the brain surface according to the location and situation of recipient arteries in the surgical area. Peak cerebral blood volume (CBV), regional cerebral blood flow (CBF), and time to peak (TTP) were calculated from the selected points. As the data were available intraoperatively, anastomoses were performed in a suitable area. According to the occurrence of HPS, patients were divided into the asymptomatic and symptomatic groups, from which hemodynamic parameters were compared. Furthermore, ROC analysis was performed to determine the diagnostic accuracy of change rates in CBV, CBF, and TTP (i.e., ΔCBV, ΔCBF, and ΔTTP) for predicting HPS.

Results

Data from the 62 patients were analyzed, and all patients were closely assessed during hospitalization after the procedures. The values of ΔCBV and ΔCBF were significantly higher in the symptomatic group (p < 0.01), while ΔTTP is slightly lower in the symptomatic group with no statistical differences (p = 0.72). Hemodynamic parameters including ΔCBV and ΔCBF, calculated by FLOW 800, had high sensitivity and specificity according to the ROC curve (ΔCBV: AUC = 0.743, 95% CI, 0.605-0.881, p = 0.002; ΔCBF: AUC = 0.852, 95% CI, 0.750-0.954, p < 0.01), which could be used as predictors for HPS.

Conclusions

Intraoperative ICG-FLOW 800 videoangiography mapping is a safe method which can reflect hemodynamic characteristics in the surgical area for MMD, the findings of which correlate with the occurrence of HPS. Parameters including ΔCBV and ΔCBF are proven to be efficient in the prediction of HPS.

Flow evaluation of STA-MCA bypass using quantitative ultrasonography: An alternative to standard angiography for follow up of bypass graft

PURPOSE

To date, digital subtraction angiography (DSA) has been considered as the gold imaging modality for assessing graft patency after extracranial-intracranial bypass. The utility of a noninvasive and quantitative method of assessing graft flow postoperatively was evaluated by using quantitative ultrasonography.

METHOD

All STA-MCA bypass surgery performed over a 5-year period at a single institution were reviewed. Measured by duplex ultrasonography, pre-operative (day1) and post-operative (day1, day7, 3month and 6 month) graft blood flow rates were recorded and analyzed. Results were correlated to Matsushima grade determined by DSA performed within 24 h when ultrasonography was conducted to confirm the graft function.

RESULTS

100 patients with 131 operated hemispheres were included in this study. The mean flow rates in the STA graft on pre-operative day1, post-operative day 1 and 7, at 3- and 6-month postoperatively were 24.1, 106.7, 112.6, 97.4 and 79.7 ml/min respectively. The mean post-operative flow in the STA graft graded as A/B/C were significantly different (168.0 ± 34.8 ml/min, 91.0 ± 15.5, 42.1 ± 17.2 ml/min, respectively, p = 0.000). 124.5 ml/min and 65.5 ml/min are good cut-off value for predicting post-operative graft Matsushima grade. The analysis also showed excellent agreement between ultrasonography and DSA for assessing bypass function (κ = 0.78).

CONCLUSIONS

The patency of the STA grafts can be assessed noninvasively by quantitative ultrasonography, which results are comparable to those of conventional DSA. This, therefore, suggest that quantitative ultrasonography may be an alternative method to standard DSA for serial follow up of STA grafts.

Membrane Retraction Technique in Bypass Surgery for the Treatment of Adult Moyamoya Disease with Deep-Seated Recipient Artery

OBJECTIVE

To introduce a membrane retraction technique that can provide good exposure of deep-seated recipient arteries in cortical sulci and simplify the anastomosis procedure.

METHODS

Only those adult patients with moyamoya disease who underwent superficial temporal artery to middle cerebral artery bypass surgery during which the suitable recipient arteries were located deep in cortical sulci were included in this retrospective study. By placing 10-0 prolene sutures to the arachnoid membrane of the 2 banks of sulcus, arachnoid retraction was applied to pull the sulcus apart and then the deep-seated recipient arteries were exposed. Standard end-to-side anastomosis was completed. The mean occlusion time and successful rate were recorded and compared with those of the normal procedure.

RESULTS

From June to November 2019, 124 superficial temporal artery to middle cerebral artery bypass surgeries for the treatment of moyamoya disease were performed in Nanfang Hospital. The membrane retraction technique was used in 5 patients (5/110, 4.5%) and the success rates were 100%. The mean temporary occlusion time was 27.2 minutes. No procedure-related complications were observed. All patients recovered uneventfully. The postoperative angiograms confirmed good patency of bypass grafts in all 5 cases.

CONCLUSIONS

The membrane retraction technique is an effective and safe method for the treatment of adult patients with moyamoya disease with deep-seated recipient arteries within the sulci.

dl-3-n-butylphthalide for alleviation of neurological deficit after combined extracranial-intracranial revascularization for moyamoya disease: a propensity score-matched analysis

OBJECTIVE

Postoperative neurological deficits impair the overall outcome of revascularization surgery for patients with moyamoya disease (MMD). dl-3-n-butylphthalide (NBP) is approved for the treatment of ischemic stroke in China. This pilot study evaluated the effect of NBP on perioperative stroke and neurological deficits in patients with MMD.

METHODS

The authors studied cases in which patients underwent combined revascularization surgery for MMD at their institution, with or without NBP administration. The overall study group included 164 patients (213 surgically treated hemispheres), including 49 patients who received NBP (25 mg twice daily) for 7 postoperative days. The incidence of perioperative stroke and transient neurological deficit (TND) and the severity of neurological deficits were compared between 49 propensity score-matched case pairs with or without NBP treatment. Subgroup analyses by type of onset and preoperative neurological status were also performed to determine specific characteristics of patients who might benefit from NBP administration.

RESULTS

In the overall cohort, baseline characteristics differed with respect to preoperative stroke and modified Rankin Scale (mRS) score between patients who received NBP and those who did not receive it. In the 49 propensity score-matched pairs, postoperative stroke was observed in 11 patients and TND occurred in 21 patients, with no significant difference in incidence between the 2 groups. However, the TND was less severe in the NBP-treated group (p = 0.01). At 1 month after surgery, the neurological outcome was more favorable (p = 0.001) and the disability-free recovery rate was higher in patients with NBP treatment (p < 0.001). The number of patients who experienced an improved neurological function, compared to preoperative function, as measured by mRS, was greater in the NBP group than in the no-NBP group (p < 0.001). Multivariable analysis revealed that NBP administration was associated with decreased severity of TND (OR 0.28, p = 0.02), improved neurological function (OR 65.29, p = 0.04), and lower postoperative mRS score (OR 0.06, p < 0.001). These beneficial effects of NBP remained significant in ischemic type MMD and patients with preoperative mRS scores of 2 or greater.

CONCLUSIONS

Postoperative administration of NBP may alleviate perioperative neurological deficits after revascularization surgery for MMD, especially in patients with ischemic MMD and unfavorable preoperative status. The results of this study suggest that randomized controlled trials to assess the potential benefit of NBP in patients with MMD may be warranted.

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.

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.

2017 Yearbook of Neurorestoratology

In 2016 we published the first Yearbook of Neurorestoratology, which summarized pathogenesis in nervous system disease and damage, as well as neurorestorative mechanisms and neurorestorative therapeutic results. Given the progress and achievements occurring in 2017, we have put together those major progresses as the “2017 Yearbook of Neurorestoratology”, which can help readers to easily follow the latest developments in Neurorestoratology.