Extracranial-intracranial bypass in atherosclerotic cerebrovascular disease: report of a single centre experience

Extracranial-Intracranial Cerebral Revascularization for Atherosclerotic Vessel Occlusion: An Updated Systematic Review of the Literature

BACKGROUND

Atherosclerotic steno-occlusive cerebrovascular disease includes extracranial carotid occlusive and intracranial atherosclerotic disease. Despite the negative findings in Carotid Occlusion Surgery Study (COSS), many large centers continue to report favorable results for revascularization surgery in select groups of patients. The aim of our study was to perform an updated systematic review to investigate the role of revascularization surgery for atherosclerotic steno-occlusive patients in the modern era.

METHODS

Five independent reviewers performed Preferred Reporting Items for Systematic Reviews and Meta-Analyses-guided literature searches in October 2022 to identify articles reporting clinical outcomes in adult patients undergoing bypass for atherosclerotic steno-occlusive disease. Primary endpoints used were perioperative and long-term ischemic strokes, intracerebral hemorrhage, bypass patency, and favorable clinical outcomes. Study quality was evaluated with Newcastle-Ottawa, JADAD, and the Oxford Center for Evidence-Based Medicine scales.

RESULTS

A total of 6709 articles were identified in the initial search. Of these articles, 50 met the inclusion criteria and were included in the systematic review. A notable increase in the proportion of articles published over the past 10 years was observed. There were 6046 total patients with 4447 bypasses performed over the period from 1978 to 2022. The average length of follow-up was 2.75 ± 2.71 years. The average Newcastle-Ottawa was 6.23 out of 9 stars. There was a significant difference in perioperative stroke (odds ratio [OR], 0.65 [0.48-0.87]; P = 0.004), long-term ischemia (OR, 0.32 [0.23-0.44]; P < 0.0001), overall ischemia (OR, 0.36 [0.28-0.44]; P < 0.0001), and favorable outcomes (OR, 3.63 [2.84-4.64]; P < 0.0001) when comparing pre-COSS to post-COSS time frames in favor of post-COSS.

CONCLUSIONS

Based on a systematic review of 50 articles, the existing literature indicates that long-term stroke rates and favorable outcomes for surgical revascularization for steno-occlusive disease have improved over time and are lower than previously reported. Improved patient selection, perioperative care, and surgical techniques may contribute to improved outcomes.

Anemia Increases Oxygen Extraction Fraction in Deep Brain Structures but Not in the Cerebral Cortex

Sickle cell disease (SCD) is caused by a single amino acid mutation in hemoglobin, causing chronic anemia and neurovascular complications. However, the effects of chronic anemia on oxygen extraction fraction (OEF), especially in deep brain structures, are less well understood. Conflicting OEF values have been reported in SCD patients, but have largely attributed to different measurement techniques, faulty calibration, and different locations of measurement. Thus, in this study, we investigated the reliability and agreement of two susceptibility-based methods, quantitative susceptibility mapping (QSM) and complex image summation around a spherical or a cylindrical object (CISSCO), for OEF measurements in internal cerebral vein (ICV), reflecting oxygen saturation in deep brain structures. Both methods revealed that SCD patients and non-sickle anemia patients (ACTL) have increased OEF in ICV (42.6% ± 5.6% and 30.5% ± 3.6% in SCD by CISSCO and QSM respectively, 37.0% ± 4.1% and 28.5% ± 2.3% in ACTL) compared with controls (33.0% ± 2.3% and 26.8% ± 1.8%). OEF in ICV varied reciprocally with hematocrit (r ² = 0.92, 0.53) and oxygen content (r ² = 0.86, 0.53) respectively. However, an opposite relationship was observed for OEF measurements in sagittal sinus (SS) with the widely used T₂-based oximetry, T₂-Relaxation-Under-Spin-Tagging (TRUST), in the same cohorts (31.2% ± 6.6% in SCD, 33.3% ± 5.9% in ACTL and 36.8% ± 5.6% in CTL). Importantly, we demonstrated that hemoglobin F and other fast moving hemoglobins decreased OEF by TRUST and explained group differences in sagittal sinus OEF between anemic and control subjects. These data demonstrate that anemia causes deep brain hypoxia in anemia subjects with concomitant preservation of cortical oxygenation, as well as the key interaction of the hemoglobin dissociation curve and cortical oxygen extraction.

Ischemic stroke following STA–MCA double bypass

Objectives

The surgical technique of STA–MCA double bypass is used to improve blood flow supplied by the distal middle cerebral artery (MCA) to the cerebral territory. This retrospective study from a single center aimed to compare the outcomes following STA–MCA double bypass in 12 patients with recurrent ischemic stroke.

Materials and methods

We retrospectively analyzed the data from patients with internal carotid artery occlusion (ICAO) who had undergone STA–MCA double bypass in our center from January 2016 to December 2020. The surgical indications, evaluation of circle of Willis (CoW), changes in cerebral hemodynamic, surgical results, and follow-up results were analyzed.

Results

Post-operative perfusion-weighted imaging showed hemodynamic improvement in all 12 patients. Ten patients (83.33%) showed clinical improvement, and 2 patients (16.67%) had stable disease. No intracranial infections or acute ischemic events occurred. The post-operative National Institutes of Health Stroke Scale score and modified Barther scores were significantly improved after 180 days of follow-up. Twenty three (96%) anastomoses maintain patency of their bypass vessels, and none had recurrent cerebral infarction during a minimum of 36 months follow-up.

Conclusion

In this small study, in patients with recurrent ischemic stroke without other types of treatment, STA–MCA double bypass surgery was more effective in the subgroup of patients with ICAO and poor blood supply to the CoW and an area of cerebral hypoperfusion that exceeded the area supplied by the MCA.

Ischemic Stroke Revascularization

Extracranial-intracranial (EC-IC) bypass is one of the most fundamental techniques for ischemic cerebrovascular disease (CVD). We describe the standard surgical strategies, advanced techniques, and controversies concerning revascularization of ischemic stroke. The standard surgical strategies and techniques emphasize how to determine surgical indication, which should be decided for symptomatic internal carotid artery or middle cerebral artery (MCA) occlusive disease with misery perfusion detected by quantitative single photon emission computed tomography. Advanced techniques are available for complex situations such as posterior circulation revascularization, Bonnet bypass for common carotid artery obstruction, and various EC-IC bypasses for ischemia in the MCA and/or anterior cerebral artery territories using inter-grafts such as femoral veins and radial arteries, illustrated by our surgical results and experiences. Controversies include endovascular treatment complementary to EC-IC bypass. Finally, we advocate emergent EC-IC bypass for progressive ischemic CVD, particularly for contraindication or unsuccessful treatment after intravenous tissue plasminogen activator administration and/or endovascular thrombolysis. EC-IC bypass surgery can be reliable for ischemic CVD under strict optimal surgical indications using safe and reliable surgical techniques.

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.

Extracranial-intracranial bypass surgery for occlusive atherosclerotic disease of the anterior cerebral circulation: protocol for a systematic review and meta-analysis

BACKGROUND

Occlusive atherosclerotic disease of the anterior cerebral circulation is one of the most common causes of anterior circulation ischemia and stroke. Treatment options include medical therapies (including antiplatelet use, blood pressure control, lipid reduction, and lifestyle modification) and extracranial-intracranial bypass surgery (such as superficial temporal artery-middle cerebral artery bypass). However, the optimal treatment remains unclear. The objective of this study will be to compare the efficacy of and extracranial-intracranial bypass surgery with that of other medical therapy in adult patients with occlusive atherosclerotic disease of the anterior cerebral circulation.

METHODS

This is the study protocol for a systematic review. We will search MEDLINE, EMBASE, Web of Science, and the Cochrane Library (from January 1980 onwards). We will include randomized controlled trials, quasi-experimental studies (non-randomized, interrupted time series), and observational studies (e.g., cohort studies and case-control studies), examining the efficacy of extracranial-intracranial bypass surgery compared to other treatments for adult patients with occlusive atherosclerotic disease of anterior cerebral circulation. Two team members will independently screen all citations, full-text articles, and abstract data. Potential conflicts will be resolved through discussion. The primary outcome will include stroke or death. The secondary outcomes will include intracranial hemorrhage, transient ischemic attack, and myocardial infarction. The study methodological quality (or bias) will be appraised using appropriate tools. If feasible, we will conduct random effects meta-analysis. Additional analyses will be conducted to explore the potential sources of heterogeneity (e.g., study design, geographical location, or risk of bias).

DISCUSSION

This review will evaluate the evidence on the efficacy of extracranial-intracranial bypass surgery for adult patients with occlusive atherosclerotic disease of the anterior cerebral circulation. We anticipate that our findings will be of interest to patients, their families, caregivers, healthcare professionals, and in making optimal treatment selection. Implications for future clinical and epidemiological research will be discussed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018105513.

[Local cerebral hemodynamics following STA-MCA bypass in patients with symptomatic carotid occlusions]

PURPOSE

To assess changes in local hemodynamic parameters in patients with symptomatic ICA occlusions and moyamoya disease after placement of extracranial-intracranial bypass (EC-IC bypass).

MATERIAL AND METHODS

The study included 112 patients who underwent surgical treatment at the National Scientific and Practical Center for Neurosurgery in the period between 1999 and 2015. Of these, 105 patients had ICA occlusions, and 7 patients had moyamoya disease. During the main stage of EC-IC bypass placement, all patients were monitored for local hemodynamic parameters using intraoperative contact Doppler ultrasonography - 89 (72%) patients (72%) and flowmetry - 56 (50%)). In 33 (29%) cases, both techniques were used. Forty two patients underwent preoperative SCT perfusion to assess the degree of perfusion deficit. Grade 1 cerebrovascular insufficiency (acute oligemia) was detected in 6 patients; grade 2 perfusion deficit (persistent oligemia) was found in 25 patients; grade 3 perfusion deficit (chronic oligemia) was present in 11 patients. Measurements were performed before bypass placement: the blood flow direction and hemodynamic parameters in the cortical arteries were evaluated; and after bypass placement: blood flow values and directions in the cortical artery, proximal and distal to the bypass area, were assessed.

RESULTS

A total of 112 EC-IC bypasses were placed without perioperative complications and deaths. Bypass functioning was confirmed in 108 (96.3%) cases; bypass thrombosis occurred in 4 (3.7%) cases. The distal blood flow direction was observed in patients with ICA occlusions (105 patients) in all cases before EC-IC bypass placement. Patients with moyamoya disease had more often the proximal blood flow direction - 5 (71%) out of 7 cases. The cerebral blood flow parameters obtained in this study differed significantly, depending on the baseline degree of perfusion deficit. The blood flow rate was minimal in patients with grade 1 cerebrovascular insufficiency. After revascularization, local hemodynamics in the cortical arteries was significantly dependent on the ability of EC-IC bypass to reverse blood flow in the proximal acceptor artery. A change in the blood flow direction was observed in 86 (77%) cases. The mean volumetric blood flow in EC-IC bypass was 34.2±5.7 mL/min.

CONCLUSION

The knowledge of baseline hemodynamic parameters and their changes after revascularization plays an important role in choosing the correct surgical technique, further bypass functioning, and, as a result, improvement of the clinical outcome after surgery.

Local Cerebral Hemodynamics after Superficial Temporal Artery-Middle Cerebral Artery Bypass in Patients with Symptomatic Carotid Occlusions

Context

Physiological insights into blood flow alterations in cortical vessels after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery are important for the prognosis of bypass sustainability and hemodynamic patency.

Aims

This study aims to assess the impact of STA-MCA bypass on local hemodynamics for patients with symptomatic carotid occlusions and Moyamoya disease.

Settings and Design

This article presents a prospective nonrandomized study of intraoperative blood flow measurements in cortical branches of MCA and donor vessel before and after cerebral revascularization.

Materials and Methods

Evaluation of local hemodynamic parameters was established for 112 patients with symptomatic carotid occlusive disease and cerebrovascular insufficiency during STA-MCA bypass surgery. We used intraoperative Doppler ultrasonography (89 patients - 72%), flowmetry (56 cases - 50%), and in 33 cases both methods. For physical justification of observed facts, we performed computational simulation with OpenFOAM CFD framework using Navier-Stokes nonstationary hemodynamic model.

Statistical Analysis Used

All calculations were performed with IBM SPSS Statistics version 10.0 software. We used parametric (Z-test and Student's t-test) and nonparametric models (Wilcoxon, Mann-Whitney). For categorical values, we used Fisher's exact test.

Results

Local cerebral hemodynamics after revascularization surgery significantly depended on initial perfusion deficit and the ability of bypass to reverse the blood flow in proximal parts of cortical artery (86 cases, 77%). Mechanism of cortical blood flow alteration was related to donor vessel cut flow value and potential consumption threshold of acceptor artery.

Conclusions

Knowledge of hemodynamic principles of flow redistribution after STA-MCA bypass is important to improve bypass stainability and leads to better revascularization results.

Long-Lasting Symptomatic Cerebral Hyperperfusion Syndrome following Superficial Temporal Artery-Middle Cerebral Artery Bypass in a Patient with Stenosis of Middle Cerebral Artery

Cerebral hyperperfusion syndrome (CHPS) is a complication that can occur after cerebral revascularization surgeries such as superficial temporal artery- (STA-) middle cerebral artery (MCA) anastomosis, and it can lead to neurological deteriorations. CHPS is usually temporary and disappears within two weeks. The authors present a case in which speech disturbance due to CHPS lasted unexpectedly long and three months was taken for full recovery. A 40-year-old woman, with a history of medication of quetiapine, dopamine 2 receptor antagonist as an antipsychotics for depression, underwent STA-MCA anastomosis for symptomatic left MCA stenosis. On the second day after surgery, the patient exhibited mild speech disturbance which deteriorated into complete motor aphasia and persisted for one month. SPECT showed the increase of cerebral blood flow (CBF) in left cerebrum, verifying the diagnosis of CHPS. Although CBF increase disappeared one month after surgery, speech disturbance continued for additionally two months with a slow improvement. This case represents a rare clinical course of CHPS. The presumable mechanisms of the prolongation of CHPS are discussed, and the medication of quetiapine might be one possible cause by its effect on cerebral vessels as dopamine 2 receptor antagonist, posing the caution against antipsychotics in cerebrovascular surgeries.

Effect of Adventitial Dissection of Superficial Temporal Artery on the Outcome of Superficial Temporal Artery-Middle Cerebral Artery Bypass in Moyamoya Disease

Superficial temporal artery-middle cerebral artery (STA-MCA) has been used for the treatment of occlusive cerebrovascular disease including moyamoya disease. The effect of STA-MCA bypass depends not only on the patency of anastomosis, but also on integrity and functional capacity of the donor artery. In the present prospective study, we investigated the effect of extensive stripping STA adventitia and fasciae on hemodynamic function in STA-MCA bypass of moyamoya disease patients. Twenty patients (n=8 in control group, n=12 in stripping group) of moyamoya disease were subjected to STA-MCA end-to-side direct anastomosis. Perfusion unit (PU) values of the cortex were measured and recorded using a Laser Doppler flowmetry (LDF) for 5 days. Computed tomography perfusion was performed to determine blood flow before and after bypass. No patient experienced significant neurologic deficits associated with neurosurgical complications. LDF demonstrated that adventitial stripping group had higher cerebral blood flow increase than control group. The adventitia stripping group tends to have higher rate of increased cerebral perfusion after bypass than non-stripping group. Furthermore, the ultrasound examination at 3 days after bypass demonstrated that the adventitial stripping group has a tendency of bigger STA and higher peak systolic velocity than control group. Our result suggests that stripping adventitia of STA improves hemodynamics of STA-MCA bypass in moyamoya disease.

Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery for Refractory Symptomatic Intracranial Atherosclerotic Stenosis

OBJECTIVE

To evaluate blood flow changes after bypass surgery for refractory symptomatic intracranial atherosclerotic stenosis (ICAS).

METHODS

We examined a cohort of consecutive patients with symptomatic ICAS. Superficial temporal artery-middle cerebral artery (MCA) bypass was performed in refractory patients with poor perfusion. Angiograms were graded systematically for antegrade, collateral, and bypass flow, and clinical variables were collected preoperatively, at 7 days postoperatively, and 3, 6, and 12 months postoperatively.

RESULTS

Among 185 consecutive cases with ICAS, 15 patients who were unsuitable for or did not respond to the best medical therapy or stenting underwent bypass surgery. No patients had new ischemic deficits within 7 days postoperatively. The mean follow-up period was 30.2 ± 12.3 months. Within this period, all anastomoses were patent by methods of ultrasound or computed tomography angiography. In 2 patients, stenotic lesions exhibited early postoperative occlusion conversion at 7 days on digital subtraction angiography. In 2 patients, stenotic lesions showed progression of occlusion at 6 and 8 months. The 2 lesions with early occlusion were both located in the MCA. The extent of retrograde blood flow via bypass anastomosis was correlated with early occlusion conversion.

CONCLUSIONS

For refractory ICAS in patients with compromised hemodynamics, direct bypass might induce early occlusion of a stenotic area. MCA lesions may have a greater tendency toward early occlusion conversion.

Assessment of Hemodynamic Compromise Using Computed Tomography Perfusion in Combination with 123I-IMP Single-Photon Emission Computed Tomography without Acetazolamide Challenge Test

OBJECTIVES

The acetazolamide challenge test in conjunction with ¹²³I-IMP single-photon emission computed tomography (SPECT) is a known method of assessing cerebrovascular reserve capacity. In this study, we investigated whether CT perfusion in combination with resting state ¹²³I-IMP SPECT could be used instead of the acetazolamide challenge test to evaluate hemodynamic compromise in patients with atherosclerotic occlusive disease.

METHODS

Twenty consecutive patients with unilateral internal carotid artery or middle cerebral artery steno-occlusive disease were enrolled. ¹²³I-IMP SPECT was performed with and without the acetazolamide challenge test, and with CT perfusion. Cerebral blood flow (CBF), cerebral blood volume, and mean transit time (MTT) obtained by CT perfusion were compared with CBF and cerebrovascular reactivity (CVR) obtained by ¹²³I-IMP SPECT.

RESULTS

The asymmetry ratio of MTT as measured by CT perfusion showed a strong correlation with the CVR to acetazolamide as measured by ¹²³I-IMP SPECT (ρ = -.780, P <.001). Based on the CBF obtained through ¹²³I-IMP SPECT and the MTT obtained through CT perfusion, hemodynamic compromise was detected with high sensitivity (1.000) and specificity (.929), and a cutoff value of 30% was found to be suitable for the asymmetry ratio of MTT. MTT prolongation was significantly improved after revascularization surgery in hemodynamic compromise (P = .028).

CONCLUSION

MTT as measured by CT perfusion in combination with CBF as measured by resting state ¹²³I-IMP SPECT may be useful for evaluating hemodynamic compromise as an alternative to the acetazolamide challenge test.

Determination of oxygen extraction fraction using magnetic resonance imaging in canine models with internal carotid artery occlusion

Perfusion of the penumbra tissue below the flow threshold for functional disturbance but above that for the maintenance of morphological integrity is the target for therapy in acute ischaemic stroke. The measurement of the oxygen extraction fraction (OEF) may provide a direct assessment of tissue viability, so that irreversible tissue damage and penumbra can be reliably identified. By using an asymmetric spin echo single-shot echo planar imaging (ASE-SSEPI) sequence, the quantitative OEF was obtained in the ischaemic brain tissues of canine models with internal carotid artery occlusion. TTC staining, which delineated the regions of infarct and penumbra, was used for defining the corresponding regions on OEF maps. The threshold of the OEF to discriminate the infarct cores and penumbral tissues was then determined according to the OEF values at different times. With repeated-measures ANOVA, the OEF of the infarcted regions was found to be time dependent. An OEF greater than 0.48 best predicted cortical infarction at 1.5 hr, with an area under the receiving operating characteristic curve of 0.968, a sensitivity of 97.5%, and a specificity of 92.5%. Our results may be helpful in the evaluation of tissue viability during stroke events.

Double-barrel bypass for cerebral ischemia: technique, rationale, and preliminary experience with 10 consecutive cases

BACKGROUND

In selected patients, extracranial-intracranial bypass remains an important treatment for the prevention of stroke. Traditionally, superficial temporal artery-middle cerebral artery (STA-MCA) bypass uses 1 STA branch. We have adopted a "double-barrel" technique in which both branches are joined with MCA recipients in distinct vascular territories.

OBJECTIVE

To assess the feasibility of routinely using both branches of the STA for cerebral revascularization.

METHODS

Ten consecutive patients underwent double-barrel bypass. Patients were selected if they demonstrated symptomatic MCA hypoperfusion resistant to medical therapy or had symptomatic moyamoya disease. Flow-directed bypass was performed to augment flow to the territories most at risk in each case, based on preoperative and intraoperative data. Computed tomography perfusion was routinely performed to evaluate baseline deficits and postoperative augmentation. Clinical data were analyzed to assess patient demographics and outcomes.

RESULTS

The double-barrel bypass was no more difficult technically than the traditional approach, with the second branch harvested through a small satellite incision. By isolating temporary occlusion to each territory, there was no additional ischemia to each brain region. No intraoperative complications or wound-healing issues occurred. Postoperative computed tomography perfusion studies all showed improvement, and delayed vascular imaging demonstrated universal graft patency. Nine of 10 patients have been asymptomatic since surgery, whereas 1 patient demonstrated symptoms in a separate vascular distribution.

CONCLUSION

Double-barrel STA-MCA bypass is both feasible and potentially advantageous. In our series, both bypass branches remained patent, augmenting flow to the territories most at need.

Neurocognitive improvement after carotid artery stenting in patients with chronic internal carotid artery occlusion: a prospective, controlled, single-center study

Symptomatic internal carotid artery (ICA) occlusion with hemodynamic impairment remains a dismal disease when untreated. In this prospective, single-center, controlled study, we investigated the feasibility, safety, and long-term outcome of stenting by endovascular recanalization for patients with chronic ICA occlusion. Forty patients with symptomatic chronically occluded ICA were assigned to receive endovascular recanalization (group A, n = 18) or conservative management (group B, n = 22). The primary end point was 100% complete recanalization of the primary occlusion at 60 minutes, and secondary end points were improvement in neurologic function and cognitive function. Patients in the 2 groups were comparable in demographic and baseline characteristics. Successful recanalization was achieved in 88.9% (16 of 18) of patients with the restoration of Thrombolysis in Myocardial Ischemia/Thrombolysis in Cerebral Ischemia 2 or 3 flow. There was no procedural or new cerebral ischemic event. Improvement in brain perfusion was observed in 12 (12 of 18, 75%) patients on single-photon emission computed tomography. Improvement in neurologic function defined as a reduction of ≥4 points on the National Institutes of Health Stroke Scale (NIHSS) at 6 months was observed in group A (baseline, 6.83 ± 3.01 vs 6 months, 2.61 ± 1.20; P < .01) and group B (baseline, 6.05 ± 2.75 vs 6 months, 4.77 ± 1.69; P < .05). A significant difference in NIHSS scores was noted between group A and B at 1, 3, and 6 months (P < .05 or .001). Improvement in cognitive function defined as an increase of ≥8 on the Montreal Cognitive Assessment (MoCA) was observed in group A at 3 and 6 months (baseline, 14.67 ± 3.56 vs 3 months, 24.17 ± 3.55 and 6 months, 24.72 ± 2.85; P < .01). Significant improvement in MoCA was also observed in group B (P < .01). Furthermore, a significant difference in MoCA scores was noted between group A and B at 1, 3, and 6 months (P < .05 or .001). Endovascular recanalization is feasible and safe for patients with symptomatic chronic carotid artery occlusion. Successful carotid artery stenting can improve neurological function and global cognitive function than nonrevascularization.

Extra-intracranial standard bypass in the elderly: perioperative risk, bypass patency and outcome

BACKGROUND

Patients with chronic atherosclerotic vessel occlusion and cerebrovascular hemodynamic insufficiency may benefit from extra-intracranial (EC-IC) bypass surgery. Due to demographic changes, an increasing number of elderly patients presents with cerebrovascular hemodynamic insufficiency. So far, little data for EC-IC bypass surgery in elderly patients suffering occlusive cerebrovascular disease are available. We therefore designed a retrospective study to address the question whether EC-IC bypass is a safe and efficient treatment in a patient cohort ≥70 years.

METHODS

50 patients underwent EC-IC standard bypass surgery with translocation of the superficial temporal artery to an M2 segment of the medial cerebral artery. Criteria for bypass surgery were presence of symptomatic occlusive cerebrovascular disease of the anterior circulation and proof of a severely restricted or abrogated reserve capacity (detected by H2O-photon emission tomography or single photon emission computer tomography - before and after forced vessel dilatation by diamox). The incidence of perioperative neurological and surgical complications, bypass patency, bypass function and short-term outcome were retrospectively analyzed.

RESULTS

The study cohort consisted of 16 patients ≥70 years (mean = 74.3 years, SE 1.3). It was compared to a cohort of 34 patients <70 years (mean = 61.2 years, SE 1.0). Both groups underwent EC-IC bypass surgery after careful preoperative work-up. Both patient groups did not differ significantly in gender, vascular pathology, previous history of diseases/comorbidity or clinical symptoms. The number of patients which underwent stenting or other endovascular treatments of the internal or common carotid artery prior to EC-IC bypass surgery was significantly higher in the group of patients ≥70 years (37.5 vs. 0%, p < 0.001). Perioperative stroke rate was 0% in both groups and mild morbidity occurred in 18.8 and 14.7%, respectively (p = 0.699). One 84-year-old female patient died due to perioperative endocarditis. Initial bypass patency was 93.8% in patients above the age of 70 years and 97.1% in the younger group (p = 0.542). Secondary occlusion rate was low in both groups (≥70 years: 0% vs. <70 years 3.7%). No new neurologic deficit occurred in patients with a patent bypass during the follow-up period (median 18 ± 13.1 months). Two patients with an initially occluded bypass and one with a secondary bypass occlusion suffered from new neurological symptoms.

CONCLUSIONS

Our data show comparable safety and efficiency of EC-IC bypass surgery in patients under and above the age of 70 years due to a careful preoperative work-up and a strict indication for 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.

Dynamic changes in blood flow of a bypassed superficial temporal artery with unstable internal carotid artery stenosis

Background:

There are limited indications for superficial temporal artery to middle cerebral artery (STA–MCA) bypass in the treatment of cerebral atherosclerotic disease. However, recent reports emphasize that STA–MCA bypass may be beneficial for select patients. In this report, we describe a case in which a flow-dependent STA–MCA bypass was achieved in a patient with unstable internal carotid artery (ICA) stenosis.

Case Description:

A 51-year-old woman presented with left ICA occlusion. A severely elongated mean transit time (MTT) indicated misery perfusion. STA–MCA bypass was performed immediately and blood flow through the graft appeared excellent on magnetic resonance angiography (MRA). Two weeks later, MRA revealed normal anterograde ICA blood flow and the bypass graft was not visible. Three years later, the left ICA stenosis again became severe and the patient developed contralateral hemiparesis. She underwent endovascular surgery and the ipsilateral MCA became occluded during the procedure. The STA–MCA bypass graft appeared immediately after the MCA occlusion and became a major provider of blood flow to the ipsilateral MCA area. She recovered with almost no deficit.

Conclusion:

This is a rare case which shows that dynamic flow changes through an STA–MCA bypass can occur with variable ICA blood flow. STA–MCA bypass can be beneficial for the treatment of unstable ICA stenosis.