Intraoperative evaluation of local cerebral hemodynamic change by laser speckle contrast imaging for predicting postoperative cerebral hyperperfusion during STA-MCA bypass in adult patients with moyamoya disease

Cerebral hyperperfusion (CHP) occurred frequently after direct superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery for moyamoya disease (MMD). We analyzed cortical microvascular density (CMD) and the change of cerebral blood flow (LΔCBF) using intraoperative laser speckle contrast imaging (LSCI) on 130 hemispheres of 95 consecutive adult patients with MMD. The demographic characteristics, cortical hemodynamic sources, bypass methods, intraoperative blood flow data, and relative CBF changes on single-photon emission computed tomography (SPECT) examination (SΔrCBF) were compared between the groups with and without CHP. The median values for CMD, LΔCBF, and SΔrCBF were significantly higher in the CHP group than in the non-CHP group (CMD 0.240 vs 0.206, P = 0.004; LΔCBF 2.285 vs 1.870, P < 0.001; SΔCBF 1.535 vs 1.260, P < 0.001). Multivariate analysis revealed that hemodynamic sources of recipient parasylvian cortical arteries from MCA (M-PSCAs), end-to-side (E-S) bypass method, CMD ≥ 0.217, and LΔCBF ≥ 1.985 were the risk factors for CHP. Intraoperative LSCI was useful for evaluating hemodynamics and predicting CHP in patients with MMD.

Hyperperfusion syndrome after superficial temporal artery-middle cerebral artery bypass for non-moyamoya steno-occlusive disease

BACKGROUND AND OBJECTIVES

Stroke is a major cause of morbidity and mortality worldwide, and intracranial stenoses increase the risk for stroke. Superficial temporal artery to middle cerebral artery bypass can be beneficial in selected patients with non-moyamoya steno-occlusive disease, however data is limited regarding the postoperative occurrence of hyperperfusion syndrome in this population. This case series describes the outcomes and complications, including hyperperfusion, in these patients who underwent bypass.

METHODS

This is a retrospective review of bypass procedures done for medically refractory intracranial stenosis at a single institution by a single surgeon between 2014 and 2021.

RESULTS

30 patients underwent 33 bypass procedures for unequivocal non-moyamoya steno-occlusive disease. All patients had immediate bypass patency on post-operative day one. Major perioperative complications (9%) included one stroke and two cases of hyperperfusion syndrome. Minor perioperative complications (12%) included two seizures, one superficial wound infection and one deep vein thrombosis. Modified Rankin Score improved in 20 patients (74%), worsened in one patient (4%), and remained stable in seven patients (22%) at the last follow up. Twenty-three patients (85%) had scores ≤ 2. The recurrent stroke rate was 3% at 30 days and 7% at two years. The bypass patency rate at one year was 87.5%.

CONCLUSION

In this series, bypass for patients with medically refractory non-moyamoya steno-occlusive disease was well tolerated and effective, with overall favorable outcomes. The occurrence of hyperperfusion syndrome is rare but significant and should be considered in post-operative management of this population.

Designing a flow-controlled STA-MCA anastomosis based on the Hagen-Poiseuille law for preventing postoperative hyperperfusion in adult moyamoya disease

Background

Technical improvements for preventing postoperative symptomatic cerebral hyperperfusion (CHP) during superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD) were seldom reported.

Objectives

The aim of this study was to investigate the significance of application of a novel flow-controlled concept which voluntarily reduces the hemodynamic difference between the donor and recipient arteries based on the Hagen-Poiseuille law when performing direct anastomoses of recipient parasylvian cortical arteries (PSCAs) with anterograde hemodynamic sources from the MCA (M-PSCAs) in adult MMD.

Design

This was a retrospective observational study.

Methods

Direct anastomoses of recipient M-PSCAs were performed on 89 symptomatic hemispheres in 82 adult MMD patients in our hospital from January 2020 to June 2021. They were divided into the flow-controlled group (patients who received direct anastomosis under designed flow-controlled principles) and non-flow-controlled group (patients who received conventional direct anastomosis to obtain maximum flow). The patients' basic characteristics and incidence of postoperative CHP were compared between the two groups. Risk factors for occurrence of postoperative CHP were analyzed.

Results

Overall, 36 hemispheres were included in the non-flow-controlled group and 53 in flow-controlled group. The incidences of postoperative focal (22.6%) and symptomatic CHP (5.7%) in the flow-controlled group were significantly lower than those (focal, 52.8%; symptomatic, 25.0%) in the non-flow-controlled group (p = 0.003 and 0.009, respectively). Multivariate analysis revealed that the flow-controlled concept was significantly associated with the development of focal (p = 0.005) and symptomatic (p = 0.012) CHP.

Conclusion

The flow-controlled STA-MCA anastomosis can significantly decrease the incidence of postoperative CHP during direct anastomoses of recipient M-PSCAs in adult MMD.

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.

Risk factors of postoperative cerebral hyperperfusion syndrome and its relationship with clinical prognosis in adult patients with moyamoya disease

BACKGROUND

To investigate the incidence, risk factors, and clinical prognosis of cerebral hyperperfusion syndrome (CHS) after superficial temporal artery-middle cerebral artery anastomosis combined with encephalo-duro-arterio-synangiosis (STA-MCA/EDAS) in adult patients with moyamoya disease (MMD).

METHODS

The clinical data of 160 adult patients with MMD treated by STA-MCA/EDAS from January 2016 to January 2017 were retrospectively analyzed. According to CHS diagnosis, MMD patients were divided into CHS and non-CHS group. Univariate and multivariate analysis of risk factors and Kaplan-Meier curve of stroke-free survival for CHS were performed.

RESULTS

A total of 12 patients (7.5%) developed postoperative CHS, of which 4 patients (2.5%) presented with cerebral hemorrhage. Univariate and multivariate analysis showed moyamoya vessel on the surgical hemisphere (OR = 3.04, 95% CI = 1.02-9.03, P = 0.046) and left operated hemisphere (OR = 5.16, 95% CI = 1.09-21.34, P = 0.041) were independent risk factors for CHS. The other variables, such as age, gender, presentation, hypertension, diabetes, smoking, mean mRS score on admission, modified Suzuki stage and pre-infarction stage on surgical hemisphere, and bypass patency, had no association with postoperative CHS (P > 0.05). At final follow-up with average 38 months, there were 18 out of 133 patients (13.5%, 4.91% per person year) presented with newly developed complications. There was no significant difference between newly developed complications, mean mRS scores, and Kaplan-Meier curve of stroke-free survival in patients with and without CHS (P > 0.05).

CONCLUSION

The concentration of moyamoya vessels and left operated hemisphere was independent risk factors for CHS, which could not affect the clinical prognosis if treated timely and properly. The current study offers a new perspective of moyamoya vessels and supporting data for choosing MMD candidates on cerebral revascularization.

Expression of hypoxia-inducing factor-1α and matrix metalloproteinase-9 in the recipient parasylvian cortical arteries with different hemodynamic sources in adult moyamoya disease

Objective

In our latest research, we have demonstrated that the recipient parasylvian cortical arteries (PSCAs) with hemodynamic sources from the middle cerebral artery (M-PSCAs) has a higher risk of postoperative cerebral hyperperfusion (CHP) syndrome than those from non-M-PSCAs in adult moyamoya disease (MMD) patient. However, whether there are differences between M-PSCAs and non-M-PSCAs in vascular specimens characteristics has not been studied. In this study, we further investigate the vascular specimen of recipient PSCAs by histological and immunohistochemical methods.

Methods

50 vascular specimens of recipient PSCAs were obtained from 50 adult MMD patients during the combined bypass surgeries in our departments of Zhongnan hospital. 4 recipient PSCAs samples were also obtained in the same way from the middle cerebral artery occlusion patients. The samples were received the pathological sectioning, hematoxylin and eosin staining, and immunohistochemistry, then the vascular wall thickness, matrix metalloproteinase-9 (MMP-9) and hypoxia-inducing factor-1α (HIF-1α) were analyzed.

Results

M-PSCAs adult MMD patients had a thinner intima than non-M-PSCAs in the recipient PSCAs specimens. In recipient non-M-PSCAs vascular specimens, the immunoreactivity indicating HIF-1α and matrix metalloproteinase-9 (MMP-9) was significantly higher than M-PSCAs groups. The logistic regression analyses showed that the M-PSCAs was an independent risk factor of postoperative cerebral hyperperfusion (CHP) syndrome (OR 6.235, 95% CI1.018-38.170, P = 0.048) in MMD.

Conclusion

Our results indicate that M-PSCAs adult MMD patients had thinner intima than non-MCAs adult MMD patients in the PSCAs. More importantly, HIF-1α and MMP-9 were overexpressed in non-M-PSCAs vascular specimens.

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.

A flow self-regulating superficial temporal artery–middle cerebral artery bypass based on side-to-side anastomosis for adult patients with moyamoya disease

OBJECTIVE

Side-to-side (S-S) superficial temporal artery–middle cerebral artery (STA-MCA) bypass was reportedly used to treat a special moyamoya disease (MMD) patient with collaterals arising from the donor STA. However, the S-S technique is not routinely performed to date, and its benefits are still unknown for adult MMD. The purpose of this study was to investigate the possibility of routine use of the S-S technique for adult MMD.

METHODS

The authors retrospectively analyzed the clinical data of 50 adult patients (65 hemispheres, including 30 in the end-to-side [E-S] group and 35 in the S-S group) with MMD who underwent STA-MCA bypass. The patient demographic characteristics, clinical courses, technical details, intraoperative blood flow data, postoperative and preoperative relative cerebral blood flow (rCBF) values, modified Rankin Scale (mRS) scores, and short-term revascularization results were compared between the 2 groups.

RESULTS

There were no significant differences observed in terms of the baseline characteristics, bypass patency rates, postoperative/preoperative rCBF values, incidence of cerebral hyperperfusion syndrome (CHS), mRS scores, and short-term revascularization results between the 2 groups (all p > 0.05). Intraoperative blood flow analysis showed that the increase of STA flow in the E-S group was significantly higher than that of proximal STA flow in the S-S group (p = 0.008). Although the increases of proximal and distal recipient flow in the E-S group seemed greater than those in the S-S group, the results were not statistically significant (p = 0.086 for proximal flow and p = 0.076 for distal flow). CHS symptoms in the S-S group were milder and with much shorter duration. The follow-up angiographic data of the representative case demonstrated that both frontal and parietal STA branches and the occipital artery participated in postoperative collateralization.

CONCLUSIONS

S-S anastomosis can achieve comparable clinical effects to standard E-S construction. S-S anastomosis used in adult MMD demonstrated mild CHS symptoms with short duration and had the potential to arouse all scalp arteries as donor sources for revascularization through the intact distal STA branch via flow self-regulation.

Symptomatic hyperperfusion after combined revascularization surgery in patients with pediatric moyamoya disease: patient series

BACKGROUND

Symptomatic hyperperfusion after cerebral revascularization for pediatric moyamoya disease (MMD) is a rare phenomenon. The authors report a series of patients with this condition.

OBSERVATIONS

In all three patients in this case series, the combined revascularization was on the left side, the patency of bypass grafts was confirmed after surgery, and focal hyperemia around the anastomotic site was observed on single photon emission computed tomography (SPECT). On the first to eighth days after surgery, all of the patients developed neurological manifestations, including motor aphasia, cheiro-oral syndrome, motor weakness of their right upper limbs, and severe headaches. These symptoms disappeared completely approximately 2 weeks after surgery, and all patients were discharged from the hospital. Quantitative SPECT was performed to determine the proportional change in cerebral blood flow (ΔRCBF) (to ipsilateral cerebellar ratio (denoted ΔRCBF) in the region of interest around the anastomoses, and the mean value was 1.34 (range, 1.29–1.41).

LESSONS

This rare condition, which develops soon after surgery, requires an accurate diagnosis by SPECT. One indicator is that the ΔRCBF has risen to 1.3 or higher. Subsequently, strategic blood pressure treatment and fluid management could prevent the development of hemorrhagic stroke.

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.

The First 24 h Hemodynamic Management in NICU after Revascularization Surgery in Moyamoya Disease

Objective

To evaluate whether hemodynamic factors are risk factors for prognosis in moyamoya disease (MMD).

Materials and Methods

The retrospective study reviewed a single-center MMD cohort in Huashan Hospital from August 2017 to January 2020. Stroke events in 30 days and follow-up modified Rankin Scale (mRS) grade were recorded. Systematic assessments with perioperative mean arterial pressure (MAP), red blood cell (RBC) parameters, and fluid management were also conducted. Logistic regressions were applied to evaluate the predictors of worse outcomes. Data was analyzed using SPSS 24.0.

Results

Admission to neurological intensive care unit (NICU) totalled about 347 after revascularization surgery. The result showed that the higher the postoperative MAP level (favorable group 95.7 ± 11.4 mmHg vs. unfavorable group 103.6 ± 10.4 mmHg, p < 0.001) and the greater the MAP variability (favorable group 0.26 ± 13.2 vs. unfavorable group 7.2 ± 13.5, p = 0.006) were, the higher the patient's follow-up mRS grade was. What is more, a higher early postoperative Hb level also seemed to predict a worse long-term clinical outcome (favorable group 116.9 ± 17.1 g/L vs. unfavorable group 123.7 ± 13.0 g/L, p = 0.03), but the difference disappeared after adjusting sex and age. Logistic regression analyses showed that a higher level of postoperative MAP (β = 0.024, 95% CI (0.004, 0.044), and p = 0.02) within the first 24 h in NICU might be the short-term risk factor. For long-term outcome, a higher level (β = 1.058, 95% CI (1.022, 1.096), and p = 0.001) and a greater variability (β = 30.982, 95% CI (2.112, 454.414), and p = 0.01) of postoperative MAP might be the negative predictors of mRS grade.

Conclusions

The early postoperative hemodynamic management might be extremely critical for patients with MMD. Both high postoperative MAP levels and large MAP variability might affect the prognosis. What is more, we also found that a higher postoperative Hb level might be related with a worse outcome.

Prolonged/delayed cerebral hyperperfusion in adult patients with moyamoya disease with RNF213 gene polymorphism c.14576G>A (rs112735431) after superficial temporal artery-middle cerebral artery anastomosis

OBJECTIVE

Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis is the standard surgical management for moyamoya disease (MMD), whereas cerebral hyperperfusion (CHP) is one of the potential complications of this procedure that can result in delayed intracerebral hemorrhage and/or neurological deterioration. Recent advances in perioperative management in the early postoperative period have significantly reduced the risk of CHP syndrome, but delayed intracerebral hemorrhage and prolonged/delayed CHP are still major clinical issues. The clinical implication of RNF213 gene polymorphism c.14576G>A (rs112735431), a susceptibility variant for MMD, includes early disease onset and a more severe form of MMD, but its significance in perioperative pathology is unknown. Thus, the authors investigated the role of RNF213 polymorphism in perioperative hemodynamics after STA-MCA anastomosis for MMD.

METHODS

Among 96 consecutive adult patients with MMD comprising 105 hemispheres who underwent serial quantitative cerebral blood flow (CBF) analysis by N-isopropyl-p-[123I]iodoamphetamine SPECT after STA-MCA anastomosis, 66 patients consented to genetic analysis of RNF213. Patients were routinely maintained under strict blood pressure control during and after surgery. The local CBF values were quantified at the vascular territory supplied by the bypass on postoperative days (PODs) 1 and 7. The authors defined the radiological CHP phenomenon as a local CBF increase of more than 150% compared with the preoperative values, and then they investigated the correlation between RNF213 polymorphism and the development of CHP.

RESULTS

CHP at POD 1 was observed in 23 hemispheres (23/73 hemispheres [31.5%]), and its incidence was not statistically different between groups (15/41 [36.6%] in RNF213-mutant group vs 8/32 [25.0%] in RNF213-wild type (WT) group; p = 0.321). CHP on POD 7, which is a relatively late period of the CHP phenomenon in MMD, was evident in 9 patients (9/73 hemispheres [12.3%]) after STA-MCA anastomosis. This prolonged/delayed CHP was exclusively observed in the RNF213-mutant group (9/41 [22.0%] in the RNF213-mutant group vs 0/32 [0.0%] in the RNF213-WT group; p = 0.004). Multivariate analysis revealed that RNF213 polymorphism was significantly associated with CBF increase on POD 7 (OR 5.47, 95% CI 1.06-28.35; p = 0.043).

CONCLUSIONS

Prolonged/delayed CHP after revascularization surgery was exclusively found in the RNF213-mutant group. Although the exact mechanism underlying the contribution of RNF213 polymorphism to the prolonged/delayed CBF increase in patients with MMD is unclear, the current study suggests that genetic analysis of RNF213 is useful for predicting the perioperative pathology of patients with MMD.

Intraoperative transit-time ultrasonography combined with FLOW800 predicts the occurrence of cerebral hyperperfusion syndrome after direct revascularization of Moyamoya disease: a preliminary study

BACKGROUND

Cerebral hyperperfusion syndrome (CHS) is a common complication after direct bypass surgery in patients with Moyamoya disease (MMD). Since preventive measures may be inadequate, we assessed whether the blood flow difference between the superficial temporal artery (STA) and recipient vessels (△BF) and the direct perfusion range (DPR) are related to CHS.

METHODS

We measured blood flow in the STA and recipient blood vessels before bypass surgery by transit-time probe to calculate △BF. Perfusion changes around the anastomosis before and after bypass were analyzed with FLOW800 to obtain DPR. Multiple factors, such as △BF, DPR, and postoperative CHS, were analyzed using binary logistic regression.

RESULTS

Forty-one patients with MMD who underwent direct bypass surgery were included in the study. Postoperative CHS symptoms occurred in 13/41 patients. △BF and DPR significantly differed between the CHS and non-CHS groups. The optimal receiver operating characteristic (ROC) curve cut-off value was 31.4 ml/min for ΔBF, and the area under the ROC curve (AUC) was 0.695 (sensitivity 0.846, specificity 0.500). The optimal cut-off value was 3.5 cm for DPR, and the AUC was 0.702 (sensitivity 0.615, specificity 0.750).

CONCLUSION

Postoperative CHS is caused by multiple factors. △BF is a risk factor for CHS while DPR is a protective factor against CHS.

Hemodynamic analysis of the recipient parasylvian cortical arteries for predicting postoperative hyperperfusion during STA-MCA bypass in adult patients with moyamoya disease

OBJECTIVE

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a common approach for treating moyamoya disease (MMD); however, the selection of recipient vessels is still controversial, and its relationship with postoperative cerebral hyperperfusion (CHP) has not been revealed. The aim of the study was to investigate the relationship between the hemodynamic sources of the recipient parasylvian cortical arteries (PSCAs) and the occurrence of postoperative CHP.

METHODS

The authors retrospectively analyzed the clinical data from 68 adult patients (75 hemispheres) with MMD who underwent STA-MCA bypass. Based on their hemodynamic sources from the MCA and non-MCAs, the PSCAs were classified as M-PSCAs and non-M-PSCAs, and their distributional characteristics were studied. Moreover, the patients' demographics, incidence of postoperative CHP, and post- and preoperative relative cerebral blood flow values were examined.

RESULTS

The digital subtraction angiography analysis demonstrated that 40% (30/75) of the recipient PSCAs had no hemodynamic relationship with the MCA. The post- and preoperative relative cerebral blood flow values of the M-PSCA group were significantly higher than those of the non-M-PSCA group (p < 0.001). Multivariate analysis revealed that the hemodynamic source of PSCAs from the MCA was significantly associated with the development of focal (p = 0.003) and symptomatic (p = 0.021) CHP. Twelve (85.7%) of the 14 patients with symptomatic CHP and all 4 (100%) patients with postoperative hemorrhage were from the M-PSCA group.

CONCLUSIONS

This study revealed that direct anastomoses of PSCAs with anterograde hemodynamic sources from the MCA had a high risk of postoperative CHP during STA-MCA bypass in adult patients with MMD.

Cerebral Hyperperfusion and Concomitant Reversible Lesion at the Splenium after Direct Revascularization Surgery for Adult Moyamoya Disease: Possible Involvement of MERS and Watershed Shift Phenomenon

Superficial temporal artery (STA)–middle cerebral artery (MCA) bypass is the standard surgical treatment for moyamoya disease (MMD). Local cerebral hyperperfusion (CHP) is one of the potential complications, which could enhance intrinsic inflammation and oxidative stress in MMD patients and accompany concomitant watershed shift (WS) phenomenon, defined as the paradoxical decrease in the cerebral blood flow (CBF) near the site of CHP. However, CHP and simultaneous remote reversible lesion at the splenium have never been reported. A 22-year-old man with ischemic-onset MMD underwent left STA–MCA bypass. Although asymptomatic, local CHP and a paradoxical CBF decrease at the splenium were evident on N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography 1 day after surgery. The patient was maintained under strict blood pressure control, but he subsequently developed transient delirium 4 days after surgery. MRI revealed a high-signal-intensity lesion with a low apparent diffusion coefficient at the splenium. After continued intensive management, the splenial lesion disappeared 14 days after surgery. The patient was discharged without neurological deficits. Catheter angiography 2 months later confirmed marked regression of posterior-to-anterior collaterals via the posterior pericallosal artery, suggesting dynamic watershed shift between blood flow supplies from the posterior and anterior circulation. Mild encephalitis/encephalopathy with a reversible splenial lesion could explain the pathophysiology of the postoperative splenial lesion in this case, which is associated with generation of oxidative stress, enhanced inflammation, and metabolic abnormalities. Rapid postoperative hemodynamic changes, including local CHP and concomitant WS phenomenon, might participate in the formation of the splenial lesion.

A novel model of cerebral hyperperfusion with blood-brain barrier breakdown, white matter injury, and cognitive dysfunction

OBJECTIVE

Cerebral hyperperfusion (CHP) is associated with considerable morbidity. Its pathophysiology involves disruption of the blood-brain barrier (BBB) with subsequent events such as vasogenic brain edema and ischemic and/or hemorrhagic complications. Researchers are trying to mimic the condition of CHP; however, a proper animal model is still lacking. In this paper the authors report a novel surgically induced CHP model that mimics the reported pathophysiology of clinical CHP including BBB breakdown, white matter (WM) injury, inflammation, and cognitive impairment.

METHODS

Male Sprague-Dawley rats were subjected to unilateral common carotid artery (CCA) occlusion and contralateral CCA stenosis. Three days after the initial surgery, the stenosis of CCA was released to induce CHP. Cortical regional cerebral blood flow was measured using laser speckle flowmetry. BBB breakdown was assessed by Evans blue dye extravasation and matrix metalloproteinase-9 levels. WM injury was investigated with Luxol fast blue staining. Cognitive function was assessed using the Barnes circular maze. Other changes pertaining to inflammation were also assessed. Sham-operated animals were prepared and used as controls.

RESULTS

Cerebral blood flow was significantly raised in the cerebral cortex after CHP induction. CHP induced BBB breakdown evident by Evans blue dye extravasation, and matrix metalloproteinase-9 was identified as a possible culprit. WM degeneration was evident in the corpus callosum and corpus striatum. Immunohistochemistry revealed macrophage activation and glial cell upregulation as an inflammatory response to CHP in the striatum and cerebral cortex. CHP also caused significant impairments in spatial learning and memory compared with the sham-operated animals.

CONCLUSIONS

The authors report a novel CHP model in rats that represents the pathophysiology of CHP observed in various clinical scenarios. This model was produced without the use of pharmacological agents; therefore, it is ideal to study the pathology of CHP as well as to perform preclinical drug trials.

Pre-operative higher hematocrit and lower total protein levels are independent risk factors for cerebral hyperperfusion syndrome after superficial temporal artery-middle cerebral artery anastomosis with pial synangiosis in adult moyamoya disease patients-case-control study

Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is a standard treatment for adult moyamoya disease (MMD) patients. Cerebral hyperperfusion (CHP) syndrome is one of the most serious complications of this procedure that can result in deleterious outcomes, but predicting CHP before revascularization surgery remains challenging. Furthermore, the hematological/serological factors associated with CHP syndrome are unknown. To investigate the correlation between pre-operative hematological/serological factors and the development of CHP syndrome after STA-MCA anastomosis with encephalo-duro-myo-synangiosis (EDMS) for MMD., a pre-operative peripheral blood test was performed within 5 days before surgery. Local cerebral blood flow (CBF) at the site of anastomosis was quantified by N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography 1 and 7 days after surgery, and the pre-operative CBF value at the corresponding area was measured. We defined CHP syndrome as a local CBF increase over 150% compared with the pre-operative value, which was responsible for delayed intracranial hemorrhage, transient focal neurological deterioration, and/or seizure. Then, we retrospectively investigated the correlation between peripheral blood test results and the development of CHP syndrome. CHP syndrome 1 day after STA-MCA anastomosis with EDMS was observed in nine patients (9/114 hemispheres; 7.9%). Multivariate analysis with multiple imputation revealed that higher hematocrit value and lower total protein level were significantly associated with the development of CHP syndrome (p value: 0.028 and 0.043, respectively). Higher pre-operative hematocrit levels and lower pre-operative total protein levels are novel risk factors for CHP syndrome after direct revascularization surgery in adult MMD patients.

Prediction of Cerebral Hyperperfusion after Superficial Temporal Artery-Middle Cerebral Artery Anastomosis by Three-Dimensional-Time-of-Flight Magnetic Resonance Angiography in Adult Patients with Moyamoya Disease

Introduction: Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is an effective surgical procedure for adult patients with moyamoya disease (MMD) and is known to have the potential to prevent cerebral ischemia and/or hemorrhagic stroke. Cerebral hyperperfusion (CHP) syndrome is one of the serious complications of this procedure that can result in deleterious outcomes, such as delayed intracerebral hemorrhage, but the prediction of CHP before revascularization surgery remains challenging. The present study evaluated the diagnostic value of preoperative three-dimensional (3D)-time-of-flight (TOF) magnetic resonance angiography (MRA) for predicting CHP after STA-MCA anastomosis for MMD. Materials and Methods: The signal intensity of the peripheral portion of the intracranial major arteries, such as the anterior cerebral artery (ACA), MCA, and posterior cerebral artery (PCA) ipsilateral to STA-MCA anastomosis, on preoperative MRA was graded (0–2 in each vessel) according to the ability to visualize each vessel on 97 affected hemispheres in 83 adult MMD patients. Local cerebral blood flow (CBF) at the site of anastomosis was quantitatively measured by N-isopropyl-p-[123I]-iodoamphetamine single-photon emission computed tomography 1 and 7 days after surgery, in addition to the preoperative CBF value at the corresponding area. Then, we investigated the correlation between the preoperative MRA score and the development of CHP. Results: The CHP phenomenon 1 day after STA-MCA anastomosis (local CBF increase over 150% compared with the preoperative value) was evident in 27 patients (27/97 hemispheres; 28%). Among them, 8 (8 hemispheres) developed CHP syndrome. Multivariate analysis revealed that the hemispheric MRA score (0–6), the summed ACA, MCA, and PCA scores for the affected hemisphere, was significantly associated with the development of CHP syndrome (p = 0.011). The hemispheric MRA score was also significantly correlated with the CHP phenomenon, either symptomatic or asymptomatic (p < 0.001). Conclusion: The signal intensity of the intracranial major arteries, including the ACA, MCA, and PCA, on preoperative 3D-TOF MRA may identify adult MMD patients at higher risk for CHP after direct revascularization surgery.

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.

[Cerebral hyper perfusion syndrome after carotid artery stenting]

OBJECTIVE

To explore the risk factors, clinical characteristics, precaution and treatment of hyper perfusion syndrome (HPS) after carotid artery stenting (CAS).

METHODS

From September 2014 to March 2018, the clinical data of 226 patients with severe carotid stenosis (70%-99%) treated with carotid artery stenting (CAS)at Department of Interventional Radiology and Vascular Surgery, Peking University Third Hospital, were analyzed retrospectively．Five of them developed HPS after CAS．The relationship between the clinical baseline data, imaging characteristics, perioperative management and HPS were assessed.

RESULTS

In this group, 5 patients of them (2.21%, 5/226) developed HPS after CAS, and 2 patients of them (0.88%, 2/226) were hyper perfusion induced intracranial hemorrhage (HICH). The 5 patients consisted of 4 men and 1 woman whose age ranged from 58 to 74 years. The symptoms of HPS occurred within 4 hours to 3 days after CAS. Among the 5 cases, the clinical manifestations were that 2 cases with headache, 1 case with delirium,1 case with hemiparesis of left limbs, and 1 case with coma(died ultimately).The main manifestations of case 1 and case 2 were headache in the frontal parietal temporal region of the operative side, accompanied by nausea and vomiting. The symptoms were relieved after blood pressure lowering treatment and mannitol dehydration. The main manifestations of case 3 were excitement and delirium. The symptoms were relieved by a small dose of sedatives, also with blood pressure lowering treatment and mannitol dehydration. The initial symptoms of case 4 were excitement and delirium, accompanied by mild headache of the operative side, and hemiplegia of the contralateral limb occurred within a short time. The main manifestation of case 5 was severe headache and went into deep coma within a short time. This patient died of massive cerebral hemorrhage ultimately.

CONCLUSION

HPS is an uncommon but serious complication after CAS. Improving our understanding and heightening vigilance of HPS is necessary. The earlier diagnosis, the earlier treatment.

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.

Single Vessel Double Anastomosis for Flow Augmentation – A Novel Technique for Direct Extracranial to Intracranial Bypass Surgery

BACKGROUND

A double anastomosis using a single superficial temporal artery (STA) donor branch for both a proximal side-to-side (S2S) and a distal end-to-side anastomosis is a novel direct bypass technique for use in selected patients necessitating flow augmentation.

OBJECTIVE

To describe the single-vessel double anastomosis (SVDA) technique, including its indications, advantages, and limitations, in addition to reporting our cases series of patients who underwent a SVDA bypass surgery.

METHODS

Patients undergoing a SVDA bypass at a single institution between January 2010 and February 2016 were retrospectively reviewed. Intraoperative flow data was collected, including STA cut-flow, bypass flows, and cut flow index (CFI). Bypass patency was assessed by cerebral angiography and quantitative magnetic resonance angiography with noninvasive optimal vessel analysis. Adverse events occurring during the hospital stay and clinical status at last follow up was recorded.

RESULTS

Seven patients underwent SVDA bypass. Mean follow-up was 14.5 mo. Initial CFI for the S2S bypasses averaged 0.56 ± 0.25 and CFI after the SVDA averaged 1.15 ± 0.24. There was a statistically significant average difference in CFI before and after the SVDA bypass (p < .013). Thirteen bypasses (93%) were patent postoperatively, and remained patent at last follow up. Four patients experienced various postoperative complications. None of the patients had a new stroke since hospital discharge.

CONCLUSION

SVDA is a novel technique that can be advantageous for selected cases of extracranial-to-intracranial bypass. Expertise in bypass procedures is a necessary prerequisite. Graft patency rates and complications appear comparable to other bypass techniques.

Biphasic Development of Focal Cerebral Hyperperfusion After Revascularization Surgery for Adult Moyamoya Disease Associated With Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

Cerebral hyperperfusion (CHP) syndrome is a potential complication of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD), but its biphasic and delayed development is extremely rare.

CASE REPORT

A 47-year-old woman with autosomal dominant kidney disease (ADPKD) presented with transient ischemic attacks due to MMD, and underwent left STA-MCA anastomosis. N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography (¹²³IMP-SPECT) 1 day after surgery revealed asymptomatic CHP at the site of anastomosis. Strict blood pressure control and minocycline hydrochloride relieved CHP at postoperative day 7. However, 2 days later, the patient complained of sensory aphasia, and ¹²³IMP-SPECT demonstrated significant focal CHP at the site of anastomosis accompanying high-intensity signal on magnetic resonance (MR) imaging of fluid attenuated inversion recovery (FLAIR) in her left temporal lobe near the site of anastomosis. We continued strict blood pressure control and additionally administered free radical scavenger (Edaravone) and antiepileptic agents, which gradually improved sensory aphasia. MR imaging and ¹²³IMP-SPECT also confirmed the amelioration of the FLAIR-high lesion and focal CHP in her left temporal lobe. Two months later, the patient underwent right STA-MCA anastomosis without complications.

CONCLUSIONS

Although the underlying mechanism is unknown, biphasic development of focal CHP after revascularization surgery in an MMD patient with ADPKD is unique. Due to the potential vulnerability of the systemic vessels in ADPKD, it is conceivable that intrinsic vascular wall fragility in MMD could be enhanced by ADPKD and have partly led to this rare complication.

Noninvasive Assessment of Hemodynamic Stress Distribution after Indirect Revascularization for Pediatric Moyamoya Vasculopathy

BACKGROUND AND PURPOSE

Indirect revascularization surgery is an effective treatment in children with Moyamoya vasculopathy. In the present study, we hypothesized that DSC-PWI may reliably assess the evolution of CBF-related parameters after revascularization surgery, monitoring the outcome of surgical pediatric patients with Moyamoya vasculopathy. Thus, we aimed to evaluate differences in DSC-PWI parameters, including the hemodynamic stress distribution, in surgical and nonsurgical children with Moyamoya vasculopathy and to correlate them with long-term postoperative outcome.

MATERIALS AND METHODS

Pre- and postoperative DSC parameters of 28 patients (16 females; mean age, 5.5 ± 4.8 years) treated with indirect revascularization were compared with those obtained at 2 time points in 10 nonsurgical patients (6 females; mean age, 6.9 ± 4.7 years). We calculated 4 normalized CBF-related parameters and their percentage variance: mean normalized CBF of the MCA territory, mean normalized CBF of the proximal MCA territory, mean normalized CBF of cortical the MCA territory, and hemodynamic stress distribution. The relationship between perfusion parameters and postoperative outcomes (poor, fair, good, excellent) was explored using 1-way analysis of covariance (P < .05).

RESULTS

A significant decrease of the mean normalized CBF of the proximal MCA territory and hemodynamic stress distribution and an increase of the mean normalized CBF of the cortical MCA territory were observed after revascularization surgery (P < .001). No variations were observed in nonsurgical children. Postoperative hemodynamic stress distribution and its percentage change were significantly different in outcome groups (P < .001).

CONCLUSIONS

DSC-PWI indices show postoperative hemodynamic changes that correlate with clinical outcome after revascularization surgery in children with Moyamoya disease.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Revascularization of Concurrent Renal and Cerebral Artery Stenosis in a 14-Year-Old Girl with Takayasu Arteritis and Moyamoya Syndrome

Concurrent involvement of bilateral renal and cerebral arteries, usually incurred as stenosis, is rare in childhood-onset Takayasu arteritis (c-TA). We report the case of a 14-year-old girl, with c-TA, presenting with transient ischemic attack after endovascular revascularization for renal artery stenosis and cerebrovascular stroke after surgical revascularization for cerebral artery stenosis associated with childhood-onset moyamoya syndrome. We deem that decrease of blood pressure by endovascular revascularization and improvement of cerebral perfusion by surgical revascularization may have jeopardized the cerebral deep watershed zone to cerebral ischemia followed by cerebral hyperperfusion syndrome and caused transient ischemic attack and cerebrovascular stroke in our patient. Revascularization could be a double-edge sword for c-TA patients presenting with concomitant renal artery stenosis and cerebral artery stenosis, and should be performed with caution. Quantitative analysis of cerebral blood flow by brain magnetic resonance imaging and angiography should be performed within 48 hours after surgical revascularization in c-TA.

CT perfusion in predicting the morbidity and prognosis of hypoxic-ischemic encephalopathy after off-pump coronary artery bypass grafting

OBJECTIVE

To investigate the perfusion parameters of computed tomography (CT) in hypoxicischemic encephalopathy (HIE) after off-pump coronary artery bypass grafting (OPCABG), and its potential in predicting the occurrence and prognosis of hypoxic-ischemic encephalopathy.

METHODS

We selected 830 patients. The patients were grouped into: HIE and no HIE. HIE patients were further divided into two groups: poor prognosis and better prognosis.

RESULTS

(1) Patients with HIE, who had a history of stroke and hypertension, showed more severe stenosis on CTA and more perfusion abnormalities compared to non-HIE patients (p < 0.05). (2) The differences in frontal, temporal, occipital lobe rTTP, and occipital lobe rMTT in patients with or without HIE were statistically significant (p < 0.05). (3) Logistic regression analysis showed that the difference in occipital lobe rTTP was an independent risk factor for the morbidity in HIE. (4) HIE patients, if they had a history of an abnormal CT, showed poor prognosis (p < 0.05). Furthermore, in these patients, CT images showed significant differences in right frontal, occipital, basal ganglia rTTP, as well as left temporal, occipital, basal ganglia rTTP, as well as frontal lobe rMTT. (5) Three principal components (F1, F2, F3) can be used to generalize all indexes.

CONCLUSION

The difference in occipital lobe rTTP on CTA perfusion may be a potential predictor of HIE. Furthermore, abnormal CT and rTTP may be used for predicting the prognosis in HIE patients. Three principal components (F1 as a reflection of CBF, F2 as reflection of TTP, F3 as a reflection of MTT) can be used to generally describe perfusion parameters.

Hemodynamic Changes after Unilateral Revascularization for Moyamoya Disease: Serial Assessment by Quantitative Magnetic Resonance Angiography

BACKGROUND: Ultrasonic flow meters and quantitative magnetic resonance angiography quantitatively assess flow during hemodynamic evaluation of cerebral ischemia. Although their reliability and reproducibility have been verified, their clinical impact in moyamoya disease has rarely been reported.

OBJECTIVE: To investigate flow measurement outcomes in moyamoya disease patients pre- and postoperatively through a retrospective observational study.

METHODS: We evaluated 41 patients undergoing their first revascularization surgery who were followed ≥6 mo. Hemodynamic parameters were recorded preoperatively, at 1 and 6 mo postoperatively, and at the last follow-up. Demographic factors, Suzuki stage, and stroke development were also analyzed.

RESULTS: Patients’ median age was 37 yr (interquartile range [IQR], 27-43), and 16 (39.0%) patients were men. During follow-up, 9 (22.0%) patients experienced postoperative stroke (4 major strokes). Hemodynamic status was improved in 34 (82.9%) patients at the 6-mo follow-up. Median intraoperative flow was 41 mL/min (IQR, 25-59). Bypass flow peaked at 6 mo (median, 67 mL/min; IQR, 35-99). At the 1- and 6-mo follow-ups, ipsilateral hemispheric flow was significantly increased. The median proportion of posterior circulation at 6 mo was 44.4%, significantly lower than the preoperative proportion (50.1%). Abundant intraoperative bypass flow was associated with hemodynamic improvement, while low contralateral hemispheric flow was related with immediate postoperative ischemic stroke.

CONCLUSION: Ipsilateral hemispheric flow was increased during 6-mo follow-up, and posterior circulation flow burden was diminished. Abundant intraoperative bypass flow was associated with postoperative hemodynamic improvement. Low preoperative contralateral hemispheric flow was related with immediate postoperative ischemic stroke.

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.

Clinical features and outcomes in 154 patients with haemorrhagic moyamoya disease: comparison of conservative treatment and surgical revascularization

OBJECTIVES

Rebleeding is an unsatisfactory outcome for patients with haemorrhagic MMD. This study mainly investigated clinical features and outcomes in haemorrhagic MMD.

METHODS

A retrospective review was performed on a total of 154 patients with haemorrhagic MMD comprising 126 surgically treated and 28 conservatively treated patients.

RESULTS

There were 102 female and 52 male patients with a mean age at the initial bleeding of 33.95 years. Preoperative rebleeding occurred in 37 patients, and multivariate Cox regression analysis demonstrated that age at the time of initial bleeding (P < 0.001, HR = 1.093) was a risk factor for preoperative rebleeding. Of 124 patients with surgical revascularization, perioperative ischaemic stroke occurred in five (4.03%) and intracranial bleeding in four (3.23%). The mean follow-up period was 36.12  months. Recurrent bleeding occurred in six (10.17%) of 59 patients treated with direct revascularization, seven (20.69%) of 34 patients treated with indirect revascularization, two (6.45%) of 31 patients treated with combined revascularization and six (21.43%) of 28 patients treated conservatively. Kaplan-Meier analysis revealed no statistical differences in preventing rebleeding between direct, indirect and combined revascularization and conservative treatment (P = 0.311).

CONCLUSIONS

Age at the initial bleeding is a risk factor for rebleeding in haemorrhagic MMD. Although surgical revascularization show the tendency to decrease the rebleeding rate, there is no statistical difference between direct revascularization, indirect revascularization, combined revascularization and conservative treatment in preventing rebleeding. Further study is needed to determine whether surgical revascularization is effective in select population or with certain techniques.

NIR fluorescent small molecules for intraoperative imaging

Recent advances in bioimaging and nanomedicine have permitted the exploitation of molecular optical imaging in image-guided surgery; however, the parameters mediating optimum performance of contrast agents are not yet precisely determined. To develop ideal contrast agents for image-guided surgery, we need to consider the following criteria: (1) excitation and emission wavelengths in the near-infrared (NIR) window, (2) optimized optical characteristics for high in vivo performance, (3) overcoming or harnessing biodistribution and clearance, and (4) reducing nonspecific uptake. The design considerations should be focused on optimizing the optical and physicochemical property criteria. Biodistribution and clearance should first be considered because they mediate the fate of a contrast agent in the body such as how long after intravenous injection a contrast agent reaches the peak signal-to-background ratio (SBR) and how long the signal lasts (retention).