Assessing success after cerebral revascularization for ischemia

Complementary role of Indocyanine green video angiography, dual-image video angiography and flow-800

BACKGROUND

Visualization of cerebral vessels, their branches and the surrounding structures are essential during cerebrovascular surgery. Indocyanine green dye-based video angiography is a commonly used technique in cerebrovascular surgery. This paper aims to analyze the real-time imaging of ICG-AG, DIVA, and the use of ICG-VA with Flow 800 to compare their usefulness in surgery.

METHODS

Intraoperative real-time identification of vascular and surrounding structures in twenty nine anterior circulation aneurysms and three posterior circulation aneurysm clipping, one STA-MCA bypass, and two carotid endarterectomies were performed in patients using ICG-VA alone, DIVA, ICG-VA with Flow 800 to analyze and compare each of these methods in details.

RESULTS

ICG-VA and DIVA couldn't visualize perforators in twenty-three cases of cerebral aneurysms clipping when used alone. Compared to that by adding Flow 800 perforators were easily visualized. In three cases, occlusion of perforators after clip application was visualized by DIVA and solved by repositioning surgical clips. In one STA-MCA bypass surgery, adequate blood flow to cortical branches of MCA (M4) from STA branches was assessed with ICG-VA, DIVA, and the use of ICG-VA with Flow 800 color mapping. ICG-VA, DIVA, and Flow 800 observed the lack of blood flow and fluttering atherosclerotic plaques in carotid endarterectomy. In one case of basilar tip aneurysm, we used ICG-VA with Flow 800; the intensity diagram drawn after determining regions of interest showed that there was no flow within the aneurysm sac after clipping.

CONCLUSION

In real-time surgery, a multimodal approach using ICG-VA, DIVA, and ICG-VA with Flow 800 colour mapping can serve as useful tools for better visualization of vascular and surrounding structures. The benefits of flow 800 color mapping, such as determining regions of interest, intensity diagrams, and color-coded images, outweigh the advantages over the ICG-VA and DIVA in the visualization of critical vascular anatomy in humans during surgical procedures.

The evaluation of intracranial bypass patency in neurosurgical practice

BACKGROUND

The patency of cranial bypasses must be carefully evaluated during and after the microsurgical procedure. Although, several imaging techniques are used to evaluate the patency of bypasses, their findings are sometimes difficult to interpret.

PURPOSE

The goal of this study was to assess the consistency of different diagnostic modalities for evaluating intracranial bypass patency.

PATIENTS AND METHOD

This prospective study included 19 consecutive patients treated with EC-IC or IC-IC bypass for MoyaMoya disease (MMD) or complex/giant aneurysms between June 2016 and June 2018. In the early postoperative period (<7 days), all patients had transcranial Doppler (TCD), CT angiography (CTA) and MRA to demonstrate patency of anastomoses and to confirm exclusion of the aneurysm. When findings of anastomosis patency differed between these techniques, conventional angiography was performed.

RESULTS

All anastomoses were patent on indocyanine green videoangiography at the end of microsurgical procedure. The results of noninvasive postoperative exams were consistent to demonstrate the patency of anastomoses in 13 patients. In 4 patients, a discrepancy in patency of anastomoses arose between TCD, CTA and MRI in the early postoperative period. In 2 other patients, the interpretation of bypass patency remained inconclusive before the decision to occlude the aneurysm. In these 6 patients, a significant edema was noted in 2 cases, a postoperative subdural hematoma in 1 case, a low flow in the anastomosis in 1 case and vasospasm in 2 cases. The anastomosis was patent on the conventional angiography in five patients.

CONCLUSION

Noninvasive imaging techniques provide useful data about the patency but their findings should be carefully interpreted due to local anatomical, physiological, and pathological factors. In case of discrepant findings, conventional angiography including supraselective catheterization of the donor vessel is suggested.

Efficacy of superficial temporal artery-middle cerebral artery bypass in cerebrovascular steno-occlusive diseases: Hemodynamics assessed by perfusion computed tomography

OBJECTIVES

Our purpose of this study was to assess the cerebral hemodynamic improvement with perfusion computed tomography (CT), before and after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery in patients with cerebrovascular steno-occlusive diseases including both moyamoya disease and nonmoyamoya steno-occlusions.

MATERIALS AND METHODS

Twenty-four STA-MCA bypasses were performed to 22 patients with symptomatic cerebrovascular steno-occlusive diseases, including both moyamoya disease and nonmoyamoya steno-occlusive diseases. Brain perfusion CT images were obtained before and after the bypass surgery. The relative parameters such as cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) derived from the perfusion CT were collected and analyzed to assess the efficacy of STA-MCA bypass.

RESULTS

The CBF increased, and MTT decreased after the bypass surgery in both moyamoya group and nonmoyamoya group. The increase of CBF in nonmoyamoya group and the decrease of MTT delay in moyamoya group, overall group were statistically significant (P < 0.05). No significant postoperative change in CBV was noted. During the postoperative follow-up period, none of the 22 patients experienced any repeated ischemic/hemorrhagic attacks nor any newly developed neurologic deficits.

CONCLUSION

The STA-MCA bypass is an effective surgical management for patients with cerebrovascular steno-occlusive diseases, such as moyamoya disease and internal carotid artery/MCA steno-occlusion. And perfusion CT can be used as an effective quantitative modality to assess the cerebral perfusion before and after the STA-MCA bypass surgery.

Prediction of the Long-term Efficacy of STA-MCA Bypass by DSC-PI

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass [1,2] is an important and effective type of surgical revascularization that is widely used in the treatment of ischemic cerebral artery disease. However, a means of predicting its postoperative efficacy has not been established [3,4]. The present study analyzes the correlation between preoperative perfusion parameters (obtained using dynamic susceptibility contrast-enhanced perfusion imaging, DSC-PI) and postoperative long-term prognosis (using modified Rankin Scale, mRS scores). The preoperative perfusion parameters were defined by a combination of perfusion-weighted imaging and the Alberta Stroke Program Early Computerized Tomography Score (PWI-ASPECTS) and included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. Preoperative and postoperative scores were determined for 33 patients that received a unilateral STA-MCA bypass in order to discover the most reliable imaging predictive index as well as to define the threshold value for a favorable clinical outcome. The results showed that all of the PWI-ASPECTS scores were significantly negatively correlated with clinical prognosis. Receiver operating curve (ROC) analysis of the preoperative parameters in relation to long term prognosis showed the area under curve (AUC) was maximal for the CBF-ASPECTS score (P = 0.002). A preoperative score of less than six indicated a poor postoperative prognosis (sensitivity = 74.1%, specificity = 100%, AUC = 0.843). In conclusion, preoperative PWI-ASPECTS scores have been found useful as predictive indexes for the long-term prognosis of STA-MCA bypass patients, with higher scores indicating better postoperative long-term outcomes. As the most valuable prognostic indicator, the preoperative CBF-ASPECTS score has potential for use as a major index in screening and outcome prediction of patients under consideration for STA-MCA bypass surgery.

Imaging after direct and indirect extracranial-intracranial bypass surgery

OBJECTIVE

The purpose of this article is to describe the imaging features of different types of surgical cerebral revascularization techniques.

CONCLUSION

Surgical cerebral revascularization involves direct and indirect techniques. Direct revascularization entails anastomosing a branch of the external carotid artery to a cerebral artery. Indirect revascularization involves delivering an extracranial vascular supply in proximity to the surface of the brain. The results of these techniques have distinctive imaging features.

Perfusion-weighted magnetic resonance imaging used in assessing hemodynamics following superficial temporal artery-middle cerebral artery bypass in patients with Moyamoya disease

BACKGROUND

The best strategy to assess the changes in brain hemodynamics following superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in patients with Moyamoya disease remains unknown. The purpose of the present study was to assess cerebral hemodynamics using perfusion-weighted magnetic resonance imaging (PWI) before and after STA-MCA bypass surgery in patients with Moyamoya disease.

METHODS

STA-MCA bypass surgeries were performed on 23 symptomatic cerebral hemispheres in 21 patients (11 females/10 males, age 11-62 years) with Moyamoya disease due to cerebral ischemic attacks or intracranial hemorrhages. Brain PWI images were obtained in the frontal lobes, the temporal lobes, the occipital lobes, and the basal ganglia before and after STA-MCA bypass surgery. The relative parameters cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) derived from PWI were calculated. All patients underwent CT angiography or MR angiography after surgery in order to confirm the patency of bypass.

RESULTS

According to preoperative PWI, there was significant hypoperfusion in the symptomatic temporal and frontal lobes. According to postoperative PWI, the regional CBF had increased in both the temporal and frontal lobes on the operative side (p < 0.05, versus preoperative data). In the postoperative CBV maps, there was a significant decrease in the occipital lobe on the operative side (p < 0.05, versus preoperative data). The postoperative MTT in the temporal lobe, frontal lobe and basal ganglia area on the operative side was short, relative to the preoperative MTT (p < 0.05). The CT angiography or MR angiography imaging demonstrated patency of the bypass in all patients after surgery. During the follow-up period, all patients showed significant improvement in neurological function postoperatively.

CONCLUSIONS

This study demonstrates that STA-MCA bypass is a safe and effective surgical treatment for Moyamoya disease. PWI enables an effective and objective assessment of hemodynamics before and after STA-MCA bypass surgery in patients with Moyamoya disease.

Effect of carotid endarterectomy on cognitive function in patients with asymptomatic carotid artery stenosis

BACKGROUND

This study was conducted to determine if patients with asymptomatic carotid artery stenosis show cognitive function decline, and if they experience any changes in cognitive function after carotid endarterectomy (CEA).

METHOD

Cognitive function was examined in 15 patients (12 males and three females, 70.0 ± 6.5 years) with asymptomatic carotid artery stenosis before and 3 months after CEA. Cognitive function was assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), two subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R 2 subtests), and the Japanese version of National Adult Reading Test (JART). The patients' average scores were compared with the normal average by one-sample t-tests, and the before and after scores were compared with paired t-tests. Changes in each patient were calculated from difference before and after CEA using 95 % confidence intervals.

RESULTS

Before surgery, patients showed significant cognitive decline in RBANS total scale and immediate memory, language, and attention. At 3 months after CEA, the total scale and the immediate memory were not significantly different from the normal average. The average total scale score, the immediate memory and attention, and the WAIS-R 2 subtests scores were increased after treatment. Changes in each patient were calculated from the scores before and after CEA. At 3 months after CEA, the rate of increase in RBANS scores were 60.0 % of the patients for immediate memory, 26.7 % for visuospatial/constructional, 33.3 % for language and attention, 26.7 % for delayed memory, 47.7 % for total scale and 26.7 % for WAIS-R 2 subtests. Thus, so-called asymptomatic patients exhibit mild cognitive impairment before surgery, but after CEA, patients recover normal memory abilities.

CONCLUSIONS

Our findings of mild cognitive dysfunction in asymptomatic patients suggest that they might be symptomatic after all.

The impact of early perfusion CT measurement after extracranial-intracranial bypass surgery: results of a pilot study

OBJECTIVE

The early postoperative period after extracranial-intracranial bypass surgery carries the risk of hypo- as well as hyperperfusion. The purpose of this study is to evaluate early perfusion computerized tomography (PCT) after revascularization to assess the hemodynamic balance.

METHODS

Standard cerebral bypass surgery was performed on ten patients, and PCT measurement within 6 h after surgery was performed and analyzed.

RESULTS

The hemisphere with reduced cerebral vascular reserve (CVR) showed a regional cerebral baseline blood flow (CBF) of 5.58 ± 1.69 and a regional cerebral baseline blood volume (CBV) of 2.41 ± 0.76 before surgery. Mean transit time (MTT) was 4.16 ± 0.9 s and time to peak (TTP) 3.25 ± 1.62 s. After the procedure values changed significantly (p < 0.05) in eight patients who had no complications. Patency rate was documented in all patients by angiography. One patient showed a decrease of CBF and CBV and an increase of MTT and TTP. Clinically the patient developed a transient hemiparesis immediately after surgery. Another patient showed the expected increase in CBF and CBV; however, MTT and TTP also increased. A delayed hemiparesis probably related to hyperperfusion occurred with improvement in the follow-up.

CONCLUSION

This pilot study demonstrates that early PCT parameters can provide immediate and detailed information about hemodynamic parameters and seems to have a predictive value regarding the morbidity of hypo- or hyperperfusion in patients after cerebral bypass surgery.

Cerebral misery perfusion diagnosed using hypercapnic blood-oxygenation-level-dependent contrast functional magnetic resonance imaging: a case report

Introduction

Cerebral misery perfusion represents a failure of cerebral autoregulation. It is an important differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately.

Case presentation

A 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion.

Conclusions

Blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited.

Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.

The evolution of cerebral revascularization surgery

Among the relatively few surgeons to be awarded the Nobel Prize was Alexis Carrel, a French surgeon and pioneer in revascularization surgery at the turn of the 20th century. The authors trace the humble beginnings of cerebral revascularization surgery through to the major developments that helped shape the modern practice of cerebral bypass surgery. They discuss the cornerstone studies in the development of this technique, including the Extracranial/Intracranial Bypass Study initiated in 1977. Recent innovations, including modern techniques to monitor cerebral blood flow, microanastomosis techniques, and ongoing trials that play an important role in the evolution of this field are also evaluated.

Intracranial arterial stenting for symptomatic stenoses: a Latin American experience

BACKGROUND

The proportionally higher incidence of intracranial atherosclerosis among Asian and black patients and a greater proclivity for intracranial artery stenosis in the Hispanic population merit drawing attention to a Latin American experience with intracranial arterial stenting.

METHODS

This is a retrospective analysis of an observational study of 33 intracranial lesions (each >50% stenosis) in 32 patients treated by intracranial angioplasty in 6 Latin American centers over a 3-year period. The investigation used a unique device, a balloon-expandable stent (Lekton Motion stent system, now Pharos, Biotronik, AG, Bülach, Switzerland).

RESULTS

The treated patients ranged in age from 30 to 81 years (mean, 59.3 years; SD, 12 years), including 24 male and 8 female patients (sex ratio, 4:1). Two were Asians, 4 were blacks, and the rest were white Hispanic. Our mean follow-up is of 10.2 months (SD, 7.84 months), with a mortality rate of 9.4% (3/32), a nonfatal complication rate of 6.2%, and a stroke rate (rate of recurrence) of 0%. The mean pretreatment stenosis of 68.75% (SD, 14%) was reduced to a residual of 5.16% (SD, 16%) (P = .000; 95% confidence interval, 56.8%-70.3%). A control angiogram was performed in 82% of patients, and in that case, the restenosis 50% or greater was of 8.7% during the follow-up period.

CONCLUSION

The treatment of intracranial stenosis with the Lekton Motion stent (Pharos) is feasible with a high technical success rate. Restenosis as well as the rate of new neurologic events during follow-up suggests some efficacy of stroke prevention by using the latest-generation, highly trackable, balloon-expandable stents.

Limb-shaking Transient Ischemic Attacks: case report and review of literature

Background

Limb shaking Transient Ischemic Attack is a rare manifestation of carotid-occlusive disease. The symptoms usually point towards a seizure like activity and misdiagnosed as focal seizures. On careful history the rhythmic seizure like activity reveals no Jacksonian march mainly precipitated by maneuvers which lead to carotid compression. We here present a case of an elderly gentleman who was initially worked up as suffering from epileptic discharge and then later on found to have carotid occlusion.

Case presentation

Elderly gentleman presented with symptoms of rhythmic jerky movements of the left arm and both the lower limbs. Clinical suspicion of focal epilepsy was made and EEG, MRI-Brain with MRA were done. EEG and MRI-Brain revealed normal findings but the MRA revealed complete occlusion of right internal carotid artery. On a follow-up visit jerky movements of the left arm were precipitated by hyperextension and a tremor of 3–4 Hz was revealed. Based on this the diagnosis of low flow TIA was made the patient was treated conservatively with adjustment of his anti-hypertensive and anti-platelet medications.

Conclusion

Diagnosis of limb-shaking TIA is important and should be differentiated from other disorders presenting as tremors. Timely diagnosis is important as these patients are shown to benefit from reperfusion procedures either surgical or radiological reducing their risk of stroke.