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

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.

Factors Influencing Long-Term Blood Flow in Extracranial-to-Intracranial Bypass for Symptomatic Internal Carotid Artery Occlusive Disease: A Quantitative Study

BACKGROUND

Maintaining the patency of extracranial-to-intracranial (EC-IC) bypass is critical for long-term stroke prevention. However, reports on the factors influencing long-term bypass patency and quantitative assessments of bypass patency are limited.

OBJECTIVE

To quantitatively evaluate blood flow in EC-IC bypass using four-dimensional (4D) flow magnetic resonance imaging (MRI) and investigate factors influencing the long-term patency of EC-IC bypass.

METHODS

Thirty-six adult Japanese patients who underwent EC-IC bypass for symptomatic internal carotid or middle cerebral artery occlusive disease were included. We examined the relationships between decreased superficial temporal artery (STA) blood flow volume and perioperative complications, long-term ischemic complications, patient background, and postoperative antithrombotic medications in patients for whom STA flow could be quantitatively assessed for at least 5 months using 4D flow MRI.

RESULTS

The mean follow-up time was 54.7 ± 6.1 months. One patient presented with a stroke during the acute postoperative period that affected postoperative outcomes. No recurrent strokes were recorded during long-term follow-up. Two patients died of malignant disease. Seven cases of reduced flow occurred in the STA, which were correlated with single bypass (P = .0294) and nonuse of cilostazol (P = .0294). STA occlusion was observed in 1 patient during the follow-up period. Hypertension, age, smoking, dyslipidemia, and diabetes mellitus were not correlated with reduced blood flow in the STA.

CONCLUSION

Double anastomoses and cilostazol resulted in long-term STA blood flow preservation. No recurrence of cerebral infarction was noted in either STA hypoperfusion or occlusion cases.

Vessel-selective 4D MRA based on ASL might potentially show better performance than 3D TOF MRA for treatment evaluation in patients with intra-extracranial bypass surgery: a prospective study

OBJECTIVES

To compare bypass patency and intracranial collaterals from the external carotid artery (ECA) by four-dimensional MR angiography (MRA) based on super-selective pseudo-continuous arterial spin labeling (pCASL) combined with the keyhole and view-sharing techniques (4D-sPACK) versus three-dimensional time-of-flight (3D TOF) MRA in patients with extra-intracranial revascularization.

METHODS

The MR data of 45 patients administered bypass surgery were collected. The image quality of 4D-sPACK was evaluated using a 4-point grading system according to whether the diagnosis of intracranial collaterals was affected. Anastomosis patency and intracranial collateral visualization from ECA were assessed by two radiologists on 4D-sPACK and 3D TOF MRA, with digital subtraction angiography (DSA) findings as reference. Intracranial collateral assessment employed another 4-point grading system according to the number of vessels shown. Interobserver agreement was assessed with the weighted kappa statistic.

RESULTS

Fifty hemispheres in 43 patients were included. The image quality of 4D-sPACK was good in 47 (47/50, 94.0%) hemispheres. 4D-sPACK had a higher sensitivity than 3D TOF MRA (97.73% vs 79.55%) for visualizing anastomoses. There were significant differences between 4D-sPACK (scores, 3.22 ± 1.15) and 3D TOF MRA (scores, 1.80 ± 0.67) in the visualization of intracranial collaterals from ECA (p < 0.001). The interobserver agreement was substantial for intracranial collateral assessment (κ_4D-sPACK = 0.788; κ_{3D TOF MRA} = 0.800) and almost perfect for bypass patency (κ_4D-sPACK = 0.912; κ_{3D TOF MRA} = 0.816; κ_DSA = 0.811).

CONCLUSION

This pilot study shows that, 4D-sPACK has a better performance than 3D TOF MRA in treatment evaluation of patients after bypass surgery, and has high consistency with DSA.

KEY POINTS

• 4D-sPACK is a non-contrast-enhanced dynamic MRA method for the visualization of intracranial vessels. • 4D-sPACK has higher specificity for the diagnosis of anastomosis occlusion. • 4D-sPACK is better than 3D TOF MRA in the visualization of intracranial collaterals in patients after bypass surgery.

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.

Revascularization of Moyamoya Angiopathy in Older Adults

BACKGROUND

Moyamoya angiopathy most often manifests in patients in the second and third decades of life. Although uncommon, it can also manifest later in life. We present our results in patients >50 years old with moyamoya angiopathy who were treated with surgical revascularization via either direct bypass or indirect bypass (encephaloduroarteriosynangiosis).

METHODS

A retrospective review was conducted to identify patients with moyamoya disease who were treated with surgical revascularization at our institution between 2002 and 2015. Outcomes and complications were analyzed.

RESULTS

We identified 33 patients with moyamoya angiopathy >50 years old (mean age 59.0 years ± 7.6) who were treated with surgical revascularization of 45 affected hemispheres. Of the affected hemispheres, 27 (60%) were treated with indirect bypasses and 18 (40%) were treated with direct bypasses. Neurologic complications occurred in 4 (12%) patients. The mean length of follow-up was 18.7 months ± 18.6; 4 patients were lost to follow-up. At last follow-up, 11 of 18 (61%) direct bypasses were patent. Treatment failed in 5 of 45 (11%) treated hemispheres (stroke in 2 and persistent transient ischemic attacks in 3). In terms of functional outcome at last follow-up, 16 of 29 (55%) patients were the same as before surgery, 10 (35%) were better, and 3 (10%) were worse (including 1 death).

CONCLUSIONS

Although uncommon, moyamoya angiopathy can manifest in older adults. Surgical revascularization is a reasonable treatment option with good functional outcomes and an acceptable complication rate.

Radial Artery Grafts as Rescue Strategy for Patients with Moyamoya Disease for Whom Conventional Revascularization Failed

BACKGROUND

Failure of direct revascularization with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for Moyamoya disease (MMD) is comparatively rare. However, for those cases where a bypass fails to prevent further ischemic attacks, safe and efficient rescue strategies are needed. We present our experience with radial artery grafts for secondary revascularization of MMD.

METHODS

Between April 2007 and April 2014, we have performed STA-MCA bypass in 182 patients diagnosed with Moyamoya vasculopathy. Four patients with typical MMD who had an unsuccessful STA-MCA bypass required additional revascularization because they remained symptomatic. Digital subtraction angiography revealed delayed STA graft failure in these patients, who continued to have transient ischemic attacks after the initial surgery. Cerebral blood flow studies confirmed persistent impairment of cerebrovascular reserve capacity. As an escape strategy, we performed radial artery graft bypass surgery from the external carotid artery to the M2 or M3 portion of the MCA.

RESULTS

The median duration between the 2 surgeries was 10 months. The mean follow-up period after rescue revascularization was 8.5 ± 3.3 months. Revascularization with the radial artery graft was successful in all cases without perioperative complications. Postoperatively, none of the patients experienced further cerebrovascular events. After 3 months, digital subtraction angiography revealed patent radial artery grafts and adequate revascularization in 3 patients; 1 patient presented with bypass graft failure but had developed transdural collateral vessels contributing to the filling of the cerebral vasculature.

CONCLUSIONS

Rescue bypass with a radial artery graft provides a useful function. Although delayed graft failure may occur, this procedure is successful if the patients remain symptom free with the development of collateral flow.