Middle cerebral artery stenosis: endovascular and surgical options

Extracranial-to-Intracranial Bypass for Distal Internal Carotid Artery and/or Proximal Middle Cerebral Artery Steno-Occlusive Disease: A Case Series of Clinical Outcomes at a Single, High-Volume Cerebrovascular Center

BACKGROUND

Extracranial-to-intracranial (EC-IC) bypass was first described by Yasargil in the 1960s for treatment of symptomatic distal internal carotid artery (ICA) and/or proximal middle cerebral artery (MCA) steno-occlusive disease through direct anastomosis. Subsequent bypass trials failed to demonstrate benefit for overall outcomes and stroke rates compared with best medical therapy. However, the procedure remained in the neurosurgeon's armament, with studies showing benefits in select patient populations. With advancements in technology, patient selection has become more comprehensive.

OBJECTIVE

To provide a contemporary evaluation of EC-IC bypass from our high-volume cerebrovascular center, focusing on associated clinical outcomes.

METHODS

Consecutive patients who underwent direct EC-IC bypass surgeries for symptomatic distal ICA and/or proximal MCA steno-occlusive disease between April 2015 and September 2019 were identified retrospectively. Medical records were reviewed to collect demographics, clinical presentation, computed tomography perfusion imaging findings, transcranial Doppler results, procedure indication, donor vessel types, anastomosis site, bypass patency, periprocedural complications, postprocedural complications, symptom recrudescence, repeat or new interventions, subjective improvements, and modified Rankin Scale scores.

RESULTS

We identified 27 patients who underwent 32 EC-IC bypass procedures. The rate of ipsilateral stroke was 9.4%, with a median follow-up of 8 months (IQR, 4-13 months). Patients experienced a 22.3% improvement in modified Rankin Scale scores, and 70.3% of patients reported subjective improvement and satisfaction at follow-up.

CONCLUSION

Direct EC-IC bypass remains a viable option for revascularization in symptomatic patients with distal ICA and/or proximal MCA steno-occlusive disease.

Comparison of outcomes and utilization of extracranial-intracranial bypass versus intracranial stenting for intracranial stenosis

Background:

Extracranial–intracranial (EC-IC) bypass and intracranial stenting (ICS) are both revascularization procedures that have emerged as treatment options for intracranial atherosclerotic disease (ICAD). This study describes and compares recent trends in utilization and outcomes of intracranial revascularization procedures in the United States using a population-based cohort. It also investigates the association of ICS and EC-IC bypass with periprocedural morbidity and mortality, unfavorable discharge status, length of stay (LOS), and total hospital charges.

Methods:

The National Inpatient Sample (NIS) was queried for patients with ICAD who underwent EC-IC bypass or ICS during the years 2004–2010. Patient characteristics, demographics, perioperative complications, outcomes, and discharge data were collected.

Results:

There were 627 patients who underwent ICS and 249 patients who underwent EC-IC bypass. Patients who underwent ICS were significantly older (P < 0.001) with more comorbidities (P = 0.027) than those who underwent EC-IC bypass. Patients who underwent EC-IC bypass experienced higher rates of postprocedure stroke (P = 0.014), but those who underwent ICS experienced higher rates of death (P = 0.006). Among asymptomatic patients, the rates of postprocedure stroke (P = 0.341) and death (P = 0.887) were similar between patients who underwent ICS and those who underwent EC-IC bypass. Among symptomatic patients, however, there was a higher rate of postprocedure stroke in patients who underwent EC-IC bypass (P < 0.001) and a higher rate of death among patients who underwent ICS (P = 0.015).

Conclusion:

The ideal management of patients with ICAD cannot yet be defined. Although much data from randomized and prospective trials on revascularization have been collected, many questions remain unanswered. There still remain cohorts of patients, specifically patients who have failed aggressive medical management, where not enough evidence is available to dictate decision-making. In order to further elucidate the safety and efficacy of these intracranial revascularization procedures, further clinical trials are needed.

Graft selection in cerebral revascularization

Cerebral revascularization constitutes an important treatment modality in the management of complex aneurysms, carotid occlusion, tumor, and moyamoya disease. Graft selection is a critical step in the planning of revascularization surgery, and depends on an understanding of graft and regional hemodynamics, accessibility, and patency rates. The goal of this review is to highlight some of these properties.

Endovascular therapy of symptomatic intracranial stenosis in patients with impaired regional cerebral blood flow or failure of medical therapy

BACKGROUND AND PURPOSE

Symptomatic intracranial stenoses have a high risk for a recurrent stroke if treated medically. Although angioplasty and stent placement are proposed treatment options, data on longer-term outcome are limited.

MATERIALS AND METHODS

We analyzed all endovascular procedures on symptomatic intracranial stenosis at our institution from January 1998 to December 2005. We retrospectively assigned patients to group A (symptoms despite antithrombotic therapy) or group B (impaired regional cerebral blood flow [rCBF]). Primary outcome events were periprocedural major complications or recurrent ischemic strokes in the territory of the treated artery. We used the Kaplan-Meier method to calculate survival probabilities.

RESULTS

The procedural technical success rate was 92% (35/38) with periprocedural major complications in 4 cases (10.5%; group A [8.3%, 2/24], group B [14.3%, 2/14]). Median (range) follow-up for the 33 patients with technically successful procedures was 21 (0-72) months. Recurrent ischemic strokes occurred in 15% (3/20) of patients in group A and 0% (0/13) of patients in group B. Overall, there were 21% (7/33) primary outcome events (group A [25%, 5/20], group B [15%, 2/13]). There was a nonsignificant trend for better longer-term survival free of a major complication or recurrent stroke in patients with impaired rCBF compared with patients who were refractory to medical therapy treatment (Kaplan-Meier estimate 0.85 [SE 0.10] vs 0.72 [SE 0.11] at 2 years, respectively).

CONCLUSION

Interventional treatment of symptomatic intracranial stenosis carries significant risk for complications and recurrent stroke in high-risk patients. The observation that patients with impaired rCBF may have greater longer-term benefit than medically refractory deserves further study.

Assessing success after cerebral revascularization for ischemia

Cerebral revascularization continues to evolve as an option in the setting of ischemia. The potential to favorably influence stroke risk and the natural history of cerebrovascular occlusive disease is being evaluated by the ongoing Carotid Occlusion Surgery Study and the Japanese Extracranial-Intracranial Bypass Trial. For those patients who undergo bypass in the setting of ischemia, four key areas of follow-up include functional neurological status, neurocognitive status, bypass patency, and status of cerebral blood flow and perfusion. Several stroke scales that can be used to assess functional status include the National Institutes of Health Stroke Scale, Bathel Index, Modified Rankin Scale, and Stroke Specific Quality of Life. Neurocognition can be checked using the Repeatable Battery for the Assessment of Neuropsychological Status, among other tests. Bypass patency is checked intraoperatively using various flow probes and postoperatively using magnetic resonance angiography (MRA) or computed tomographic angiography (CTA). Cerebral blood flow and perfusion can be assessed using a host of modalities that include positron emission tomography (PET), xenon CT, single photon emission computed tomography (SPECT), transcranial Doppler (TCD), CT, and MR. Paired blood flow studies after a cerebral vasodilatory stimulus using one of these modalities can determine the state of autoregulatory vasodilation (Stage 1 hemodynamic compromise). However, only PET with oxygen extraction fraction measurements can reliably assess for Stage 2 compromise (misery perfusion). This article discusses the various clinical, neuropsychological, and radiographic techniques available to assess a patient's clinical state and cerebral blood flow before and after cerebral revascularization.