EC-IC bypass for stroke: is there a future perspective?

[EC-IC bypass for occlusion of the internal carotid artery]

BACKGROUND

There are barely any alternative treatment options to the drug treatment of hemodynamically caused cerebral ischemia, as in occlusion of the internal carotid artery.

OBJECTIVE

For secondary prevention of an ischemic stroke due to carotid occlusion and hemodynamic instability, extracranial-intracranial (EC-IC) bypass surgery can be an important option in selected patients.

MATERIAL AND METHODS

The development, study situation, indications and surgical technique for placement of an EC-IC bypass in cases of occlusion of the internal carotid artery are presented.

RESULTS

With appropriate expertise and strict selection of patients, the placement of an EC-IC bypass enables stabilization of cerebral perfusion with a low rate of complications.

CONCLUSION

The study situation is controversially discussed; nevertheless, surgical treatment in a specialized neurovascular center should at least be considered.

Cross-Comparison of 4-Dimensional Flow Magnetic Resonance Imaging and Intraoperative Middle Cerebral Artery Pressure Measurements Before and After Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery

BACKGROUND

The hemodynamic changes after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery are unclear.

OBJECTIVE

To clarify the hemodynamics by comparing flow parameters obtained by 4-dimensional (4D) flow magnetic resonance imaging (MRI) and intraoperative MCA pressure measurement.

METHODS

We recruited 23 patients who underwent STA-MCA bypass surgery for internal carotid artery (ICA) or MCA stenosis. We monitored intraoperative MCA, STA, and radial artery (RA) pressure. All patients underwent 4D flow MRI preoperatively and 3 wk after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFViICA), contralateral ICA (BFVcICA), basilar artery (BFVBA), ipsilateral STA (BFViSTA), and contralateral STA (BFVcSTA). The sum of intracranial BFV was defined as BFVtotal. We compared BFV parameters and intraoperative pressure.

RESULTS

BFViSTA significantly increased after surgery (P < .001). BFViICA and BFVBA significantly decreased after surgery (BFViICAP = .005; BFVBAP = .02). No significant difference was observed between BFVcICA before and after surgery. As a result, BFVtotal postoperatively increased by 6.8%; however, no significant difference was observed. Flow direction at M1 changed from antegrade to unclear after surgery in 5 patients. Intraoperative MCA pressure and MCA/RA pressure ratio significantly increased after surgery (P < .001). We found a stronger positive correlation between MCA pressure increase ratio and BFVtotal increase ratio in patients with lower pre-MCA pressure (r = 0.907, P < .001).

CONCLUSION

The visual and quantitative assessment of 4D flow MRI revealed that intracranial blood flow changes complementarily after STA-MCA bypass surgery. 4D flow MRI may detect the improvement of cerebral perfusion pressure.

Cortical Venous Reddening Predicts Remote Cerebral Infarction Post Superficial Temporal Artery-Middle Cerebral Artery Bypass in Atherosclerotic Occlusive Cerebrovascular Disease

BACKGROUND

The superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis (STA-MCA bypass) currently is performed to prevent atherosclerotic occlusive cerebrovascular disease. However, the benefits of the bypass surgery remain controversial. To ensure consistent surgical benefits, understanding the mechanisms of perioperative cerebral infarction (CI) is required. Moreover, appropriate patient selection procedures must be determined to decrease the rate of perioperative stroke. We retrospectively investigated patients who underwent bypass surgery at our institution and determined that the patients who presented with cortical venous reddening after anastomosis during the surgery developed perioperative CI.

METHODS

A total of 45 consecutive patients who underwent bypass surgery were retrospectively investigated. Twenty-five of the 45 patients underwent bypass for atherosclerotic occlusion or stenosis of the internal carotid artery or middle cerebral artery. Preoperative iodine-123-N-isopropyl-iodoamphetamine single-photon emission computed tomography was performed with and without acetazolamide administration. Change in color of the cortical veins was observed on recorded surgical videos, and its correlation with perioperative CI was investigated.

RESULTS

We experienced 2 cases of perioperative extensive CI at a region remote from the site of anastomosis. In both cases, retrospective investigation of surgical videos demonstrated reddening of cortical veins soon after the anastomosis procedure. Of all 45 patients, postoperative CI and venous reddening were observed in only these 2 cases.

CONCLUSIONS

We determined that patients presenting with cortical venous reddening after anastomosis developed perioperative CI. Cortical venous reddening may be an important predictor for the occurrence of CI after STA-MCA bypass surgery for patients with atherosclerotic occlusive cerebrovascular disease.

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.

Stroke in patients with occlusion of the internal carotid artery: options for treatment

Ischemic stroke may occur in patients in whom vascular imaging shows the ipsilateral internal carotid artery (ICA) to be occluded. In younger patients this is often due to carotid artery dissection, while in older people this most likely results from cardiac embolism or thrombosis secondary to high-grade stenosis at the carotid bifurcation. Interventional techniques aim at recanalization of the carotid artery for early restoration of cerebral blood flow and secondary prevention of future strokes. In chronic ICA occlusion the ischemic infarct may be related to hemodynamic compromise. In this situation, extracranial-intracranial bypass surgery was introduced, but its role remains still unclear. Ischemic stroke may also occur in patients with a chronic occlusion of the contralateral ICA. This situation demands the usual stroke treatment, but surgical and neuroradiological interventions face a higher risk than unilateral vascular pathology. Medical treatment supports stroke prevention in carotid artery occlusion.

The Role of MCA-STA Bypass Surgery After COSS and JET: The European Point of View

The results of the previously published Carotid Occlusion Surgery Study (COSS) and the Japanese EC-IC Bypass Trial (JET) seem to influence the position towards surgical treatment for ischemic cerebrovascular disease (Ogasawara and Ogawa, Nihon Rinsho 64(Suppl 7):524-527, 2006; Powers et al., JAMA 306:1983-1992, 2011).The goal of this article is to give the European point of view after COSS and JET on behalf of the Cerebrovascular Section of the European Association of Neurological Surgeons (EANS).