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.

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.

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.

Intraoperative local hemodynamic quantitative analysis of direct revascularization in patients with moyamoya disease

Direct bypass surgery improves blood flow in patients with moyamoya disease (MMD) as well as causes local flow relocation and disturbance. This study aimed to describe the characteristics and changes of quantitative blood flow in MMD patients. Sixty-four consecutive MMD patients (67 hemispheres) who underwent STA-MCA anastomosis between August 2013 and September 2017 were included in this study. Intraoperative blood flow of superficial temporal artery and middle cerebral artery was measured with a noninvasive, ultrasound flowprobe, before and after the bypass. All data were collected prospectively. Before the bypass, 67 hemispheres were measured and 45 hemispheres acquired post-bypass measurements. Thirty-three (49.3%) had anterograde flow and 34 (50.7%) had retrograde. Retrograde blood flow was significantly higher than anterograde blood flow in MCA-M4 section (3.71 ± 2.78 ml/min vs 2.39 ± 1.71 ml/min, P = 0.023). Thirty-eight (56.7%) patients had local cerebrovascular reactivity, whereas 29 (43.3%) lost it. After bypass, blood flow was changed into three patterns: anterograde flow (1, 2.2%), retrograde flow (3, 6.7%), and bi-direction flow (41, 91.1%). Flow of M4 was significantly improved in both proximal (13.64 ± 9.16 vs 3.28 ± 2.57, P < 0.001) and distal (7.17 ± 7.21 vs 3.28 ± 2.57, P = 0.002) sides to the bypass. Postoperative infarctions occurred in 4 (8.9%) patients. All postoperative infarctions (n = 4) happened in those patients who did not have change of flow direction in M4 section distal to the bypass (P = 0.040). Direct bypass surgery improves local blood flow after bypass surgery in both sides of the anastomosis. Flow direction was usually changed after the surgery into a bi-direction pattern: anterograde flow in M4 distal to the bypass, and retrograde flow in M4 proximal to the bypass. Proximal side acquired around 5.4 times of flow than the distal side. Patients with change of flow direction in distal M4 were related with lower risks of postoperative infarctions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

Background

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

Case presentation

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

Conclusion

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

Whole-Field Indocyanine Green Intensity Analysis to Intraoperatively Predict Cerebral Hyperperfusion Syndrome Following Superficial Temporal Artery-Middle Cerebral Artery Bypass: A Retrospective Case-Control Study in 7-Year Experience With 112 Cases

BACKGROUND

Intraoperative prediction of postoperative cerebral hyperperfusion syndrome (CHS) after cerebrovascular bypass surgery is challenging.

OBJECTIVE

To conduct a retrospective case-control study with indocyanine green (ICG) intensity analysis of the superficial temporal artery-middle cerebral artery (STA-MCA) bypass and investigate whether its washout pattern might be a marker for intraoperative prediction of CHS.

METHODS

Between 2012 and 2018, 6 of 112 patients (5.4%) that underwent STA-MCA bypass exhibited CHS. We selected 5 patients with CHS (3 with atherosclerotic cerebrovascular disease [ASCVD] and 2 with moyamoya) and 15 patients without CHS (60% ASCVD and 40% moyamoya) as a matched control group. During prebypass and postbypass, washout times (WTs) for the first 10%, 25%, 50%, and 75% of maximum ICG intensity measured in the whole-camera field were compared between groups. The changes in WT (ΔWT) from prebypass to postbypass for each ICG intensity level were compared between groups. The cutoff ΔWTs, sensitivities, and specificities were also calculated.

RESULTS

Postbypass WTs were significantly longer in the CHS group than the control group at all ICG intensities (P < .05). ΔWT was significantly greater in the CHS group than the control group for the first 10%, 25%, and 50% ICG intensities (P < .001). A cutoff ΔWT of ≥2.66 s for the first 50% ICG intensity showed a sensitivity of 100% and specificity of 100%.

CONCLUSION

We found that a ΔWT ≥2.66 s for the first 50% ICG intensity could be an intraoperative predictive factor for CHS.

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.

Efficacy of superficial temporal artery-middle cerebral artery double bypass in patients with hemorrhagic moyamoya disease: surgical effects for operated hemispheric sides

The effects of superficial temporal artery to middle cerebral artery (STA-MCA) double bypass on recurrent hemorrhage in the operated hemisphere in hemorrhagic moyamoya disease (HMD) have not been clearly demonstrated. This study evaluated the effectiveness of STA-MCA double bypass in the prevention of further hemorrhagic or ischemic events in the operated hemispheric sides in comparison to the conservatively treated non-operated sides. We retrospectively analyzed 52 hemispheres of 36 patients with adult-onset HMD treated with STA-MCA double bypass. Twenty and 16 patients underwent unilateral (unilateral group) and bilateral (bilateral group) surgery, respectively. In addition, the perioperative and long-term outcomes of the 52 operated sides and 20 non-operated sides in the unilateral group were compared. All bypass surgeries were successful, but 21% of the operated sides showed hyperperfusion as estimated by our methods. Perioperative mortality and morbidity rate were 0% and 5.6%, respectively. Concerning long-term follow-up, the annual rebleeding rate (ARR) in the unilateral and bilateral group was 2.7% and 2.6%/person-year, respectively (p = 0.256). The ARR in the operated and non-operated sides was 1.1% and 1.8%/side-year, respectively (p = 0.163). Two of 20 non-operated sides suffered from ischemic infarction during the follow-up period, while none of the 52 operated sides experienced ischemic events (p < 0.05). Although the long-term rebleeding rate in the operated hemisphere tended to be lower after STA-MCA double bypass compared with that in the non-operated hemisphere, the difference was not statistically significant. In conclusion, while STA-MCA double bypass could not clearly prevent rebleeding, it can prevent further ischemic attacks in patients with HMD.

Predicting the Occurrence of Hemorrhagic Cerebral Hyperperfusion Syndrome Using Regional Cerebral Blood Flow After Direct Bypass Surgery in Patients with Moyamoya Disease

OBJECTIVE

Superficial temporal artery-middle cerebral artery anastomosis is an established treatment for moyamoya disease. However, hemorrhagic cerebral hyperperfusion syndrome (CHS) leads to poor outcomes. This study aimed to identify predictors of hemorrhagic CHS based on regional cerebral blood flow (rCBF) in patients with moyamoya disease.

METHODS

The study included 251 hemispheres in 155 patients with moyamoya disease who underwent preoperative and postoperative rCBF measurements and superficial temporal artery-middle cerebral artery double anastomosis. We used rCBF increase rate for predicting hemorrhagic CHS. rCBF increase rate was calculated by 2 methods. In method 1, the rCBF value on the operated side was compared with the rCBF value on the nonoperated side. In method 2, the postoperative rCBF value on the operated side was compared with the preoperative rCBF value on the operated side. Patients were classified into 4 groups according to rCBF increase rate to predict risk of hemorrhagic CHS.

RESULTS

Hemorrhagic CHS occurred in 7 (2.8%) hemispheres (no children). Severe hemorrhagic CHS occurred in only 1 (0.4%) hemisphere. Hemorrhagic CHS was observed in patients with ≥30% rCBF increase according to method 1 and ≥50% rCBF increase according to method 2 and was most frequently noted in ≥100% rCBF increase.

CONCLUSIONS

Predictors for hemorrhagic CHS were ≥30% rCBF increase when using method 1 and ≥50% increase when using method 2.

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

OBJECTIVE

Postoperative hyperperfusion is an important complication after direct bypass for moyamoya disease, which sometimes occurs late after initial postoperative cerebral blood flow (CBF) measurement. This study aimed to clarify the incidence of hyperperfusion with management using postoperative continuous sedation and repeated postoperative CBF measurement and to identify factors associated with delayed hyperperfusion.

METHODS

This retrospective study evaluated 72 consecutive hemispheres in 56 adult Japanese patients with moyamoya disease who underwent direct bypass. Postoperative continuous sedation was routinely administered based on CBF evaluation. First, the incidence of symptomatic hyperperfusion was investigated. Second, radiologic hyperperfusion (RHP), which was strictly defined as >30% increase in CBF compared with the contralateral side, and factors associated with delayed RHP were statistically analyzed.

RESULTS

Postoperative symptomatic hyperperfusion occurred in 3 hemispheres (4.2%), including subarachnoid hemorrhage in 1 hemisphere (1.4%). RHP immediately after surgery was identified in 16 hemispheres (22.2%). In 8 hemispheres (11.1%), RHP appeared or worsened several days after initial CBF study. In univariate logistic regression analysis, decreased preoperative cerebral vasoreactivity was significantly associated with delayed RHP.

CONCLUSIONS

The incidence of symptomatic hyperperfusion was 4.2% with management. Delayed hyperperfusion was significantly associated with decreased cerebral vasoreactivity. Therefore, repeated CBF measurements evaluating preoperative cerebral vasoreactivity may decrease complications.

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.

Progressive Cortical Neuronal Damage and Extracranial-Intracranial Bypass Surgery in Patients with Misery Perfusion

BACKGROUND AND PURPOSE

Misery perfusion may cause selective neuronal damage in atherosclerotic ICA or MCA disease. Bypass surgery can improve misery perfusion and may prevent neuronal damage. On the other hand, surgery conveys a risk for neuronal damage. The purpose of this retrospective study was to determine whether progression of cortical neuronal damage in surgically treated patients with misery perfusion is larger than that in surgically treated patients without misery perfusion or medically treated patients with misery perfusion.

MATERIALS AND METHODS

We evaluated the distribution of benzodiazepine receptors twice by using PET and ¹¹C-labeled flumazenil in 18 surgically treated patients with atherosclerotic ICA or MCA disease (9 with misery perfusion and 9 without) and no perioperative stroke before and after bypass surgery; in 8 medically treated patients with misery perfusion and no intervening ischemic event; and in 7 healthy controls. We quantified abnormal decreases in the benzodiazepine receptors of the cerebral cortex within the MCA distribution and compared changes in the benzodiazepine receptor index among the 3 groups.

RESULTS

The change in the benzodiazepine receptor index in surgically treated patients with misery perfusion (27.5 ± 15.6) during 7 ± 5 months was significantly larger than that in surgically treated patients without misery perfusion (-5.2 ± 9.4) during 6 ± 4 months (P < .001) and in medically treated patients with misery perfusion (3.2 ± 15.4) during 16 ± 6 months (P < .01).

CONCLUSIONS

Progression of cortical neuronal damage in surgically treated patients with misery perfusion and no perioperative stroke may occur and may be larger than that in medically treated patients with misery perfusion and no intervening ischemic event.

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

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

Intraoperative middle cerebral artery pressure measurements during superficial temporal artery to middle cerebral artery bypass procedures in patients with cerebral atherosclerotic disease

OBJECTIVE

No previous study has monitored middle cerebral artery (MCA) pressure during the superficial temporal artery (STA)-MCA bypass procedure for cerebral atherosclerotic disease. In this paper, the authors describe their method of monitoring MCA pressure and report their initial data on intraoperative MCA pressure and its relationship with hemodynamics prior to and after the bypass procedures.

METHODS

The results from a total of 39 revascularization procedures performed between 2004 and 2014 were analyzed. The patient group included 27 men and 12 women, and their mean age at surgery was 67.6 years (range 39–83 years). The authors investigated the MCA pressure via the STA during STA-MCA bypass procedures. After one branch of the STA was anastomosed to the MCA, the other branch was connected to an arterial line, and a clip was placed temporally on the main STA trunk to monitor the pre-anastomosis MCA pressure. Simultaneously, the radial artery (RA) pressure was determined before removing the temporal clip to measure the post-anastomosis MCA pressure. The relationship between MCA pressures and single photon emission computed tomography findings and the risk factors for hyperperfusion after STA-MCA bypass were analyzed.

RESULTS

The MCA/RA (%) pressure was significantly correlated with that of the resting stenotic/normal side cerebral blood flow (CBF) ratio (%) in the linear regression analysis (slope 1.200, r2 = 0.3564, F = 20.49, p < 0.0001). The intraoperative MCA pressure was 39.3% of RA pressure in patients with Powers' Stage 2 cerebral atherosclerotic disease. After 1 branch of the STA was anastomosed, the intraoperative MCA pressure increased to 75.3% of the RA pressure. The rate of increase in pressure was significantly correlated with the increase in the STA diameter in the linear regression analysis (slope 2.59, r2 = 0.205, F = 9.549, p = 0.0038). Hyperperfusion occurred in 2 cases. When mean values for these 2 patients were compared with those for the 37 patients without hyperperfusion, significant differences were found in the stenotic/normal side CBF ratio (p = 0.0001), pre-anastomosis MCA pressure (p = 0.02), rate of increase in pressure (p = 0.02), pre-anastomotic MCA/RA pressure ratio (p = 0.01), vascular reserve (p = 0.0489), and STA diameter (p = 0.0002).

CONCLUSIONS

The measurement of intraoperative MCA pressure may be a useful technique to assess cerebral perfusion and for predicting the risk of hyperperfusion. Monitoring MCA pressure is recommended during STA-MCA bypass procedures for atherosclerotic disease.

Postoperative transient neurological symptoms and chronic subdural hematoma after extracranial-intracranial bypass for internal carotid/middle cerebral atherosclerotic steno-occlusive diseases: negative effect on cognitive performance

BACKGROUND

The mechanisms underlying post-extracranial to intracranial (EC-IC) bypass neurocognitive changes are poorly understood.

METHODS

Data from 55 patients who underwent a unilateral EC-IC bypass for atherosclerotic internal carotid artery (ICA)/middle cerebral artery (MCA) steno-occlusive disease were retrospectively evaluated. These patients underwent neuropsychological examinations (NPEs), including assessment by the Wechsler Adult Intelligence Scale-Third Edition and Wechsler Memory Scale-Revised (WMS-R) before and 6 months after EC-IC bypass. Results of NPEs were converted into Z-scores from which preoperative cognitive composite scores (CSpre) and postoperative cognitive composite scores (CSpost) were obtained. The association between the change of composite score between pre- and postoperative NPEs (CSpost-pre = CS post - CS pre) and various variables were assessed. These latter variables included occluded artery (ICA or MCA), preexisting ischemic lesion as verified in preoperative T2WI, robust bypass patency as verified by MRA performed approximately 6 months postoperatively, and postoperative transient neurological symptoms and/or postoperative chronic subdural hematoma (CSDH), both of which were dichotomized as postoperative events.

RESULTS

Postoperative MRI follow-up (median, 6 months; interquartile range, 5-8 months) confirmed successful bypasses in all patients, with no additional ischemic lesions on T2WI when compared with preoperative imaging. Further, MRA showed patent bypasses in all patients. A nearly statistically significant CS post-pre decrease was observed in patients with postoperative events when compared with those without postoperative events (-0.158 vs. 0.039; p = 0.069). A multiple regression model predicting CSpost-pre was performed. After controlling for occluded arteries, postoperative events were identified as an independent predictor of a decline in CSpost-pre (p = 0.044). In the group rate analysis, three of four postoperative NPE scores (Performance IQ, WMS-memory, WMS-attention) were significantly improved relative to preoperative NPE scores.

CONCLUSIONS

Postoperative transient neurological symptoms and/or CSDH might play a significant role in the subtle decline in cognition following an EC-IC bypass. However, this detrimental effect was small, and based on the group rate analysis, we concluded that a successful unilateral EC-IC bypass does not adversely affect postoperative cognitive function.

Extracranial to intracranial by-pass anastomosis: Review of our preliminary experience from a low volume center in Egypt

Background:

Cerebral revascularization is a useful microsurgical technique for the treatment of steno-occlusive intracranial ischemic disease, complex intracranial aneurysms that require deliberate occlusion of a parent artery and invasive skull base tumors. We describe our preliminary experience with extracranial-to-intracranial by-passes at a low volume center; and discuss clinical indications and microsurgical techniques, challenges in comparison to large advanced referral centers.

Materials and Methods:

Twenty-seven patients with hemodynamic ischemia or complex aneurysms or skull base tumors were operated at Cairo University Hospitals in the period between May 2009 and June 2014. All patients operated by a low flow by-pass were operated through a superficial temporal artery to middle cerebral artery (MCA) anastomosis. All patients chosen for a high flow by-pass were operated using a radial artery graft interposed between the MCAs distally and the common or the external carotid artery proximally. Patency was confirmed at the end of surgery using appearance on the table and confirmed after surgery by transcranial color-coded duplex or computed tomography angiography. All patient data were prospectively collected and retrospectively analyzed at the end of surgery.

Results:

Nineteen patients (70.4%) were operated upon for flow augmentation and eight patients (29.6%) were operated upon for flow replacement. A total of 30 anastomoses were performed. All except one were patent which gives a patency rate of 96.3%. There was one death in the present series resulting from a hyperperfusion syndrome. 89.5% of patients with hemodynamic ischemia stopped having symptoms after surgery. All but one patient operated for hemodynamic ischemia showed a considerable cognitive improvement after surgery. None of the patients operated upon for flow replacement showed improvement of oculomotor nerve function in spite of adequate intraoperative decompression. All patients treated for flow replacement showed the absence of recurrence on follow-up.

Conclusion:

Our initial results for both low and high flow by-pass procedures in our low volume center indicate that such complex surgical procedures are possible with results comparable to those obtained in other larger referral centers throughout the world. This procedure not only represents a more definitive treatment when compared to other endovascular or radiation treatments but is also much less costly when compared to other treatment modalities.

Moyamoya disease concurrent with Graves' disease treated by direct bypass: clinical features and treatment strategies

BACKGROUND

Moyamoya disease (MMD) concurrent with Graves' disease (GD) is rare. There is no guideline about optimizing thyroid hormones and the appropriate timing of surgical treatment for MMD with GD.

METHODS

We encountered eight patients with MMD and GD presenting with cerebral ischemia who were treated by direct bypass. Thyroid hormones [free thyroxin (fT4) and free triiodothyronine (fT3)], thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb) were measured sequentially. After thyrotoxic conditions were medically optimized, revascularization surgery was performed by superficial temporal artery-middle cerebral artery (STA-MCA) double bypass in all cases. Clinical outcomes were estimated by modified Rankin scale (mRS) at discharge and 3 months after surgery.

RESULTS

In six patients with thyrotoxicosis, the fT4, fT3, and TRAb (range) at the onset of cerebral ischemia were 4.81-10.30 pg/ml, 13.08-31.90 pg/ml, and 3.5-83.8 IU/l, respectively. At surgery, mean (range) fT3 and fT4 were optimized to 3.02 (1.01-4.87) pg/ml and 1.09 (0.41-1.68) ng/dl, respectively. In the thyrotoxic cases, it took 70-310 days (mean, 142 days) to optimize thyroid hormones before surgery. There was no neurological aggravation after surgery, and outcome was excellent at 3 months with mRS scores ≤2 in all cases.

CONCLUSIONS

For MMD concurrent with GD, optimizing thyroid hormones followed by STA-MCA double bypass was successful to prevent cerebral ischemic events.

Two-stage carotid saphenous vein interposition graft and superficial temporal artery bypass for acute carotid occlusion

The safety and efficacy of bypass surgery to achieve cerebral revascularization for cerebral hypoperfusion are controversial. However, bypass surgery still plays an important role for a select group of patients. The indication to perform a high-flow or low-flow bypass in cases of acute symptomatic artery occlusion is not defined. Neurologic symptoms in acute symptomatic occlusion are usually blood pressure dependent, and acute blood flow restoration may be considered. This report reviews the case of a patient with an acute carotid occlusion in which a two-stage bypass technique was used to achieve revascularization and discusses the issues influencing the decision-making.

Quantitative cerebral perfusion assessment using microscope-integrated analysis of intraoperative indocyanine green fluorescence angiography versus positron emission tomography in superficial temporal artery to middle cerebral artery anastomosis

Background:

Intraoperative qualitative indocyanine green (ICG) angiography has been used in cerebrovascular surgery. Hyperperfusion may lead to neurological complications after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. The purpose of this study is to quantitatively evaluate intraoperative cerebral perfusion using microscope-integrated dynamic ICG fluorescence analysis, and to assess whether this value predicts hyperperfusion syndrome (HPS) after STA-MCA anastomosis.

Methods:

Ten patients undergoing STA-MCA anastomosis due to unilateral major cerebral artery occlusive disease were included. Ten patients with normal cerebral perfusion served as controls. The ICG transit curve from six regions of interest (ROIs) on the cortex, corresponding to ROIs on positron emission tomography (PET) study, was recorded. Maximum intensity (I_MAX), cerebral blood flow index (CBFi), rise time (RT), and time to peak (TTP) were evaluated.

Results:

RT/TTP, but not I_MAX or CBFi, could differentiate between control and study subjects. RT/TTP correlated (|r| = 0.534-0.807; P < 0.01) with mean transit time (MTT)/MTT ratio in the ipsilateral to contralateral hemisphere by PET study. Bland–Altman analysis showed a wide limit of agreement between RT and MTT and between TTP and MTT. The ratio of RT before and after bypass procedures was significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.60 ± 0.032 and 0.80 ± 0.056, respectively; P = 0.017). The ratio of TTP was also significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.64 ± 0.081 and 0.85 ± 0.095, respectively; P = 0.017).

Conclusions:

Time-dependent intraoperative parameters from the ICG transit curve provide quantitative information regarding cerebral circulation time with quality and utility comparable to information obtained by PET. These parameters may help predict the occurrence of postoperative HPS.

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

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

Minocycline Prevents Focal Neurological Deterioration Due to Cerebral Hyperperfusion After Extracranial-Intracranial Bypass for Moyamoya Disease

BACKGROUND:

Cerebral hyperperfusion (CHP) is a potential complication of superficial temporal artery–middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD), and optimal postoperative management has not yet been established. Minocycline, a neuroprotective antibiotic agent, plays a role in blocking matrix metalloproteinase 9 (MMP-9), which contributes to edema formation and hemorrhagic conversion after cerebral ischemia-reperfusion. Patients with MMD have been shown to have increased serum MMP-9 levels.

OBJECTIVE:

To examine the effect of minocycline on the prevention of postoperative CHP after STA-MCA anastomosis for MMD.

METHODS:

N-isopropyl-p-[123I]iodoamphetamine single-photon emission computed tomography was performed 1 and 7 days after STA-MCA anastomosis on 109 hemispheres in 86 consecutive patients with MMD (ages, 9-69 years; mean, 37.2 years). Postoperative systolic blood pressure was strictly maintained at lower than 130 mm Hg in all 109 surgeries. The most 60 recent hemispheres were managed by the intraoperative and postoperative intravenous administration of minocycline hydrochloride (200 mg/d). The incidence of focal neurological deterioration (FND) due to CHP was then compared with that in 36 patients undergoing 49 surgeries managed without minocycline.

RESULTS:

FND due to CHP was observed in 4 operated hemispheres in patients treated without minocycline (4/49, 8.16%), and in none in the minocycline-treated group (0/60) (P = .0241). Multivariate analysis revealed that minocycline administration (P &lt; .001), surgery on the left hemisphere (P = .031), and a smaller recipient artery diameter (P &lt; .001) significantly correlated with FND due to CHP.

CONCLUSION:

The administration of minocycline with strict blood pressure control may represent secure and effective postoperative management to prevent symptomatic CHP after STA-MCA anastomosis for MMD.

Semiquantitative analysis of indocyanine green videoangiography for cortical perfusion assessment in superficial temporal artery to middle cerebral artery anastomosis

BACKGROUND

Postoperative hyperperfusion may lead to severe neurological complications after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. However, there are no reliable modalities to predict the occurrence of postoperative hyperperfusion during surgery. The purpose of this study is to evaluate whether a semiquantitative analysis of indocyanine green (ICG) videoangiography could be useful in predicting postoperative hyperperfusion after STA-MCA anastomosis.

METHODS

This study included seven patients who underwent STA-MCA anastomosis due to occlusive carotid artery diseases. During surgery, ICG videoangiography was performed before and after bypass procedures, and ICG intensity-time curves were semiquantitatively analyzed to evaluate hemodynamic changes by calculating maximum intensity, time to peak (TTP), and blood flow index (BFI).

RESULTS

Maximum intensity significantly increased from 252.6 ± 132.5 to 351.7 ± 151.9 after bypass (p < 0.001). TTP was significantly shortened from 12.9 ± 4.4 s to 9.8 ± 3.7 s (p < 0.001). Furthermore, BFI significantly increased from 33.9 ± 28.1 to 74.6 ± 88.4 (p < 0.05). Postoperative hyperperfusion was observed in five of seven patients 1 day after surgery. The ratio of BFI before and after bypass procedures was significantly higher in patients with postoperative hyperperfusion than those without, 2.5 ± 1.1 and 1.5 ± 0.4, respectively (p = 0.013).

CONCLUSIONS

These findings suggest that semiquantitative analysis of ICG videoangiography is helpful in predicting occurrence of hyperperfusion after STA-MCA anastomosis in patients with occlusive carotid artery diseases.

Hemodynamics and changes after STA-MCA anastomosis in moyamoya disease and atherosclerotic cerebrovascular disease measured by micro-Doppler ultrasonography

Moyamoya disease (MMD) and atherosclerotic cerebrovascular disease (ACVD) differ in angiographic appearance and probably hemodynamics. Pediatric MMD (PMMD) usually presents with cerebral ischemia, while intracranial hemorrhage is more common in adult MMD (AMMD), suggesting differences in cerebral hemodynamics. We analyzed the cortical flow velocity and direction of recipient arteries using micro-Doppler ultrasonography to evaluate the cortical circulation before and after anastomosis in MMD and ACVD. Twenty-eight patients with adult MMD (AMMD), 7 with pediatric MMD (PMMD), 16 with ACVD, and 12 control patients were studied. A micro-Doppler probe was applied on the cortical recipient artery (A4 or M4) before and after anastomosis. Systolic maximum flow velocity (V max) and blood flow direction were investigated at proximal and distal parts of anastomosed sites in recipient arteries. Pre- and postoperative regional cerebral blood flow was measured by cold xenon-computed tomography (Xe-CT). Before anastomosis, retrograde cortical flow was significantly more common in PMMD patients, and V max in cortical artery was significantly lower in AMMD patients. Bypass surgery changed the direction of blood flow from the anastomosis site to proximal and distal sites of the recipient artery in most patients, but pre-anastomosis flow direction was preserved more frequently in PMMD patients. The rate of V max increase after anastomosis was significantly higher in AMMD than in PMMD (11.6 ± 9.8 vs. 3.9 ± 1.8; P = 0.01). Micro-Doppler ultrasonography identified differences in cortical circulation among AMMD, PMMD, and ACVD. In AMMD, significantly low velocity in the cortical artery was observed before anastomosis, and bypass surgery reversed the flow and significantly increased flow velocity. The data of PMMD showed unique hemodynamics of the cortical artery before anastomosis, characterized by a higher frequency of retrograde flow and preserved velocity. The V max increase rate was significantly higher in patients with postoperative cerebral hyperperfusion on Xe-CT, and further study is warranted to validate the clinical use of intraoperative micro-Doppler monitoring to predict postoperative hyperperfusion.