Direct Cerebral Revascularization Research Articles

405 The Impact of Cerebral Revascularization on Pial Collateral Flow in Patients With Moyamoya Disease Using Quantitative Magnetic Resonance Angiography

INTRODUCTION: Moyamoya disease (MMD) is a chronic steno-occlusive disease primarily of the anterior circulation leading to significant pial collateralization. Changes in the distribution of intracranial blood flow after revascularization surgery are not well understood. METHODS: We conducted a retrospective chart review of 46 patients with unilateral MMD who underwent cerebral revascularization from 2011-2019. Patients who underwent pre- and post- QMRA NOVA were included in the study. Flow was measured at the M1 segment of the middle cerebral artery (MCA), P2 segment of the posterior cerebral artery (PCA), and A2 segment of the anterior cerebral artery (ACA). Pial collaterals were defined as the sum of (A2+P2) flow. Total hemispheric flow was calculated as (M1+PCA+A2) pre-operatively and (M1+PCA+A2+Bypass) post-operatively, with the incorporation of the bypass graft. RESULTS: A total of 46 patients with unilateral MMD underwent revascularization with pre and post QMRA. Total intracranial flow at baseline prior to revascularization was lower in the side of disease (214.9 ml/min vs. 269.1 ml/min). Total intracranial flow at baseline after revascularization remained lower on the ipsilateral side of disease with an increased flow in the contralateral healthy side (211.7 ml/min vs 286.1 ml/min). Pre-bypass there was a higher flow through pial collaterals on the ipsilateral diseased side (183 ml/min) than the contralateral healthy side (135 ml/min). Post-bypass this difference in pial flow between ipsilateral and contralateral sides decreased from 48 ml/min to 22 ml/min (p = 0.02). Collateral ratio decreased significantly (0.46 preoperatively vs. 0.18 postoperatively) (P < 0.01). CONCLUSIONS: The results of this study quantitatively confirm that direct cerebral revascularization decreases collateral stress in patients with moyamoya disease.

Troubleshooting the bypass: intraoperative management of initially failed anastomosis in direct cerebral revascularization surgery.

Direct cerebral revascularization is considered as one of the most technically challenging operations in neurosurgery. Technical errors are often not identified during the case, but only after the recirculation stage, making management crucial at that time of the procedure. In this study, the authors sought to describe troubleshooting of the technical errors encountered in initially failed bypass cases. A retrospective analysis describing a single-surgeon, single-institution experience between 2014 and 2021 was performed, based on operative reports and videos, including a 30-day follow-up period. Initially failed bypass was defined if the bypass was not patent or had a significant leak after recirculation, irrespective of the final result. One hundred thirty-eight bypass cases were reviewed for complex aneurysms (n = 49), moyamoya disease (n = 59), and atherosclerosis (n = 30). Fifty-one initially failed anastomoses were identified; 43 of these were the result of a technical error. Etiologies of these failed anastomoses included a clot (n = 14), vessel kinking (n = 4), spasm (n = 5), suture-related cause (n = 5), inappropriate donor or recipient (n = 3), or lack of demand (n = 8). A major leak was attributed to an uncoagulated side branch (n = 4), vessel injury due to suture/clip placement (n = 1), or inadequate suture line coverage (n = 7). Thirty-seven (86%) of 43 cases were troubleshot successfully, as salvage maneuvers included papaverine vessel massage, donor repositioning, re-anastomosis for occlusion in select cases, local hemostatic agents, and suturing or coagulating side branches in a leak. Thirty-day follow-up revealed similar rates of patency between successfully troubleshot patients (35/37) and the rest of the cases (80/87, p = 0.6). Three major patterns of a noncompatible bypass were found: a major leak, an acute occlusion, or a delayed occlusion. Based on the authors' experience, salvage strategies proved successful, showing an eventual high patency rate. The authors suggest a gradual, structured algorithm to address this stage in surgery that may contribute specifically to cerebrovascular neurosurgeons at the beginning of their careers.

481 Troubleshooting the Bypass: Intraoperative Management of Initially Failed Anastomosis in Cerebral Extracranial – Intracranial Direct Revascularization Surgery

INTRODUCTION: Direct cerebral revascularization is considered one the most technically challenging operations in neurosurgery. Technical errors are often not identified during the completion of the anastomosis. Initial assessment and management at this moment can determine the success of the entire case, making re-circulation one of the most stressful moments in the procedure. METHODS: A retrospective analysis of direct bypass cases based on operative reports and available videos, were studied in detai. A case was defined as an “initially failed bypass”, irrespective of its final result, if after removal of the temporary clips, the bypass was not patent, or significant leak was encountered. RESULTS: 138 cases were included (109 being STA-MCA) done for flow replacement (n = 49), or for flow augmentation (n = 89). 45 initially failed anastomosis, out of which 37 were the result of a technical error encounterd. Causes were clot(n = 10), vessel kinking(n = 5), spasm(n = 6), inappropriate donor(n = 3) or recipient(n = 2), competitive flow(n = 6) or a leak(n = 5). 31/37 cases were troubleshooted successfully resulting in a working bypass. Rescue maneuvers included: Partial re-opening of the suture line and irrigation for clot, graft repositioning for kinking, papaverine-vessel massage for spasm, and partial vessel cut at the donor site for anastomosis inspection. In “local” lack of demand, a new anastomosis was done by the same donor. 30-days follow-up showed similar rates of patency between successfully troubleshooted patients and the rest of the patients (82% vs 85%, p = 0.35). CONCLUSIONS: A comprehensive approach detailing technical “corrections”, describing maneuvers and the sequence of actions done in order to “revive” the bypass, as well as their prevalence, was not previously well described. In this study we present 3 of initial failure types: a leak, acute occlusion or delayed occlusion, presenting an algorithm for intra-operative management in these cases.

Effects of Aspirin Therapy on Bypass Efficacy and Survival of Patients Receiving Direct Cerebral Revascularization.

Background: Both patency maintenance and neoangiogenesis contribute to cerebrovascular bypass efficacy. However, the combined impact of the aforementioned two indicators on postoperative revascularization following superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass has been less well elucidated. Meanwhile, there is a paucity of evidence with conflicting results about postoperative aspirin therapy. Objective: The objective of the study was to investigate the correlation between aspirin use and STA-MCA bypass efficacy, including patency, postoperative neoangiogenesis, and follow-up outcomes. Methods: A total of 181 MMD patients (201 procedures) undergoing STA-MCA bypass at our institution (2017–2019) were retrospectively reviewed. The bypass efficacy level and postoperative complications were compared between aspirin and non-aspirin groups. Results: Among 95 PS-matched pairs, the aspirin group presented a significantly more favorable bypass efficacy than the non-aspirin group [odds ratio (OR) 2.23, 95% confidence interval (CI) 1.11–4.61; p = 0.026]. Multivariate logistic regression analysis confirmed the profound impact of aspirin as an independent predictor of bypass efficacy [adjusted OR 2.91, 95% CI 1.34–6.68; p = 0.009]. A remarkable negative correlation was found between bypass efficacy and the rate of ischemic complications (Phi = −0.521). Postoperative aspirin therapy was associated with a non-significant trend toward a lower incidence of ischemic events [OR 0.73, 95% CI 0.23–2.19; p = 0.580]. No significant difference in bleeding rates was observed between aspirin and control groups [OR 1.00, 95% CI 0.12–8.48; p = 1.000]. Conclusion: Among patients undergoing STA-MCA bypass procedures, bypass efficacy is a good predictor of follow-up outcomes. Postoperative aspirin therapy can improve patency, neoangiogenesis, and overall bypass efficacy, thereby protecting against postoperative ischemic complications. Clinical Trial Registration: http://www.chictr.org.cn/, identifier CTR2100046178.

Bypass in neurosurgery-indications and techniques.

Since the introduction of cerebral bypass surgery by Professor Yasargil in 1967, a plethora of literature has been published on direct cerebral revascularization. Against this background, it is remarkable that at present, only three randomized controlled trials (RCTs) exist in the field, both dealing with extracranial to intracranial bypass surgery for flow augmentation in patients at risk to suffer ischemic or hemorrhagic stroke due to cerebrovascular disease. Next to flow augmentation, the other main indication for bypass surgery is to provide flow replacement following proximal vessel sacrifice for treatment of complex aneurysms or skull base tumors. The aim of this review was to provide a comprehensive overview of the literature regarding the indications and the techniques of cerebral bypass surgery for prevention of cerebral ischemia.

Direct Cerebral Revascularization: Extracranial-intracranial Bypass.

In 1967, the first extracranial to intracranial (EC-IC) arterial anastomosis was performed. Since that time, EC-IC bypass surgery has become a widely accepted surgical treatment for patients with IC stenotic or occlusive atherosclerotic lesions. This article will discuss the history, indications, types, surgical methods, and complications of the EC-IC bypass.

Intracranial angioplasty and stent placement for direct cerebral revascularization of nonacute intracranial occlusions and near occlusions

The authors reviewed their experience in 7 cases of nonacute intracranial occlusions and near occlusions in which the patients underwent intracranial angioplasty and stent implantation for direct cerebral revascularization. Between 2005 and 2008, 4 men and 3 women underwent direct cerebral revascularization of nonacute intracerebral occlusions or near occlusions. Five patients had chronic angiographically documented occlusion and 2 patients had chronic angiographically documented near occlusions. The locations of the treated vessels included 2 supraclinoid internal carotid arteries, 4 middle cerebral arteries, and 1 vertebral artery. Prior to intervention, all patients were symptomatic and experienced strokes ipsilateral to their occlusions. In addition, all patients had clinical or radiographic evidence of ongoing hemodynamic compromise. Five patients underwent successful intracranial angioplasty and stent placement and 2 patients underwent successful intracranial balloon angioplasty alone. The mean time from documented vessel occlusion to treatment was 35 days. All patients had successful revascularization determined using the Thrombolysis in Cerebral Infarction (TICI) scale: TICI Score 3, 2b, and 2a in 4, 2, and 1 patient, respectively, and the mean residual stenosis was 38%. After uneventful technical procedures, 1 patient suffered a perforator vessel stroke and 1 patient suffered a fatal hemorrhage. Mean modified Rankin Scale score of 2 (range 1-5) and mean Glasgow Outcome Scale score of 4 (range 1-6) were achieved during a mean clinical follow-up period of 399 days (range 1-840 days). Asymptomatic restenosis was documented in 4 patients, 1 underwent bypass retreatment, and 1 patient received repeated balloon angioplasty. Combined intracranial angioplasty and stent placement is a potential treatment option in selected patients for the direct revascularization of nonacute intracranial occlusions and near occlusions. Whether this represents a substantial risk reduction compared with the best medical therapy or a long-lasting treatment option is unknown.

Conduits for cerebrovascular bypass and lessons learned from the cardiovascular experience

Direct cerebral revascularization is an important procedure in the treatment of certain complex aneurysms and skull base tumors when acute sacrifice of the internal carotid artery is required. It likely remains an appropriate treatment in a small subgroup of patients with cerebral ischemia refractory to maximal medical management. Similar to cardiovascular surgery, the choice of a graft conduit is critical for a successful outcome. The standard conduits are interposition vein grafts (usually the greater saphenous vein), free arterial grafts (radial artery), and pedicled arterial grafts (superficial temporal artery). The goal of this review is to summarize the conduits commonly used in cerebral revascularization with emphasis on their patency rates and flow characteristics. Comparisons are made with similar data available in the cardiovascular literature.

Extracranial internal carotid artery dissections: noniatrogenic traumatic lesions.

Noniatrogenic traumatic extracranial internal carotid artery dissections were encountered in six patients (five men and one woman) 31 to 62 years old. All but one had overt cerebral ischemia manifest by paresis (three), sensory deficits (three), aphasia (three), or amaurosis fugax (two), One patient had an asymptomatic carotid artery bruit. Cerebral arteriography established the diagnosis in all cases. Internal carotid artery impingement between the mandible and transverse processes of the second and third cervical vertebrae, or undue stretching over these vertebral structures, were the most likely primary mechanisms of injury. Secondary complications, a result of distal thromboembolism, were evident in two patients. Direct cerebral revascularization, staged internal carotid artery constriction and ligation, as well as intensive nonoperative therapy were valid therapeutic options. There were no deaths. Treatment relieved transient ischemic symptoms or arrested progression of established neurologic deficits in each case. In select patients, early surgical intervention may lessen attending neurologic sequelae.