Partial recanalization of concomitant internal carotid-middle cerebral arterial occlusions promotes distal recanalization of residual thrombus within 24 h

Causes and Solutions of Endovascular Treatment Failure

In a meta-analysis of individual patient data from 5 randomized controlled trials, endovascular treatment (EVT) mainly using a stent retriever achieved successful recanalization in 71.1% of patients suffering from acute stroke due to anterior circulation large artery occlusion (LAO). However, EVT still failed in 28.9% of LAO cases in those 5 successful trials. Stent retriever failure may occur due to anatomical challenges (e.g., a tortuous arterial tree from the aortic arch to a target occlusion site), a large quantity of clots, tandem occlusion, clot characteristics (fresh versus organized clots), different pathomechanisms (embolic versus non-embolic occlusion), etc. Given that recanalization success is the most important factor in the neurological outcome of acute stroke patients, it is important to seek solutions for such difficult cases. In this review, the basic technique of EVT is briefly summarized and then various difficult cases with diverse conditions are discussed along with suggested solutions.

Outcomes and prognostic factors after emergent carotid artery stenting for hyperacute stroke within 6 hours of symptom onset

BACKGROUND

The optimal treatment for hyperacute stroke attributable to cervical internal carotid artery (C-ICA) occlusion remains controversial.

OBJECTIVE

This study sought to evaluate clinical outcomes and prognostic factors after carotid artery stenting (CAS) in patients with hyperacute stroke within 6 hours of onset.

METHODS

Forty-seven patients with hyperacute stroke attributable to atherosclerotic C-ICA occlusion underwent emergent CAS. Forty-two patients (89.4%) had tandem intracranial artery occlusion (TIO). When patients showed remnant M1 or proximal M2 occlusions after CAS, intracranial recanalization therapy was performed by using pharmacologic thrombolysis and mechanical thrombectomy with a Solitaire stent. Clinical and radiologic data were compared between patients with favorable (modified Rankin scale, 0-2) and unfavorable outcomes. Binary logistic regression analysis was used to find independent prognostic factors.

RESULTS

Emergent CAS was successful in all but 1 patient. Seven (16.7%) of 42 patients with TIO did not need further treatment, because thrombolysis in cerebral ischemia ≥2b was achieved immediately after CAS. Of the 35 patients who underwent intracranial recanalization therapy for remnant TIO, thrombolysis in cerebral ischemia ≥2b was achieved in 71.4% (25 of 35). Twenty-six patients (55.3%) had favorable outcomes, and mortality was 6.4% at 3 months. Time from symptom onset to carotid recanalization was inversely and independently associated with a favorable outcome for all patients and for those with TIO (P < .05).

CONCLUSION

In our patient group, emergent CAS for hyperacute stroke caused by atherosclerotic C-ICA occlusion seemed to be effective and safe. Time to carotid recanalization was inversely and independently associated with a favorable outcome.

Combined use of stent angioplasty and mechanical thrombectomy for acute tandem internal carotid and middle cerebral artery occlusion

PURPOSE

Tandem internal carotid and middle cerebral artery occlusion carries a grave prognosis, with intravenous and intra-arterial thrombolytics having low efficacy. Currently, endovascular therapy is a promising means for treatment in which the proximal carotid lesion can be treated with angioplasty and stenting, whilst mechanical thrombectomy can be used for the treatment of the distal occlusion. Two approaches can be used - the antegrade (proximal-to-distal) approach or the retrograde (distal-to-proximal) approach, although there has not yet been any consensus on which is the better approach.

CASE REPORT

We present two patients with tandem occlusions, one treated using the antegrade and one using the retrograde approach, with different revascularization outcomes, despite having similar functional outcome on follow-up.

CONCLUSION

The combined use of stent angioplasty and mechanical thrombectomy can be used to treat tandem occlusions, and with procedural modifications, the antegrade approach may more easily achieve technical success.

Outcome after mechanical thrombectomy using a stent retriever under conscious sedation: comparison between tandem and single occlusion of the anterior circulation

BACKGROUND AND PURPOSE

In acute ischemic stroke patients, internal carotid artery/middle cerebral artery (ICA/MCA) occlusion in tandem predicts a poor outcome after systemic thrombolysis. This study aimed to compare outcomes after mechanical thrombectomy for tandem and single occlusions of the anterior circulation.

MATERIALS AND METHODS

This prospective study included consecutive patients with acute ischemic stroke of the anterior circulation who had undergone mechanical thrombectomy performed with a stent retriever under conscious sedation within 6h of symptom onset. Data on clinical, imaging and endovascular findings were collected. In cases of tandem occlusion, distal thrombectomy (retrograde approach) was performed first whenever possible. Tandem and single occlusions were compared in terms of functional outcome and mortality at 3 months.

RESULTS

From May 2010 to April 2012, 42 patients with acute ischemic stroke attributable to MCA and/or ICA occlusion were treated. Eleven patients (26.2%) presented with tandem occlusions and 31 patients (73.8%) had a single anterior circulation occlusion. Baseline characteristics were similar between the two groups. Recanalization status also did not differ significantly (P=0.76), but patients with tandem occlusions had poorer functional outcomes (18.2% vs. 67.7% for single occlusions; P=0.01), a higher mortality rate at 3 months (45.5% vs. 12.9%, respectively; P=0.03) and more symptomatic intracranial hemorrhages at 24h (9.7% vs. 0%, respectively; P=0.01). A high rate of early proximal re-occlusion or severe residual stenosis (66%) was also observed in the tandem group.

CONCLUSION

Tandem occlusions had poor clinical outcomes after mechanical thrombectomy compared with single occlusions. The retrograde approach (treatment of distal occlusion first) used in patients under conscious sedation may have contributed to these poor outcomes.

What is meant by "TICI"?

BACKGROUND

In 2003, Higashida et al proposed the Thrombolysis In Cerebral Infarction scale to evaluate angiographic intracranial flow. Our aim is to review how subsequently published studies define TICI.

MATERIALS AND METHODS

We used the ISI Web of Knowledge and SciVerse Scopus databases to search for "TICI" and "thrombolysis in cerebral infarction" and for articles that cited the original TICI paper from January 2004 through May 2012. Articles were categorized according to their definition of the TICI categories, typically grades 0-4, with grade 2 (partial reperfusion) subdivided into 2a and 2b, and rate of contrast entry to the perfused area. In addition, we catalogued the type of redefinitions of TICI subcategory 2 and additions of new categories.

RESULTS

Of 236 articles screened, 74 were included. Eight (11%) explicitly followed the TICI scale as originally defined. Thirty-seven (50%) cited Higashida but did not define their scale. Fifteen (21%) used and explained modified scales. Thirteen (18%) used the term TICI, but did not define the scale and did not cite Higashida. Eighteen (24%) specified a 2a subcategory. Nine defined grade 2a as <67% filling, 6 defined it as <50%, and 3 did not offer a percentage. Two studies added a 2c subcategory. Fifty-two (70%) used a cutoff level to define "successful reperfusion." Of these, 65% used TICI ≥2, 33% used TICI ≥2b, and 2% used TICI = 3.

CONCLUSIONS

There is substantial variability in the definition and/or application of the TICI scale in the literature. This variability could considerably impact our understanding of results of revascularization studies.

Incomplete mechanical recanalization of middle cerebral artery occlusions facilitates endogenous recanalization within 5 h

BACKGROUND AND PURPOSE

Successful revascularization can often improve functional outcome after large intracranial arterial occlusions. However, incomplete or unsuccessful recanalization is often the end result after attempted mechanical thrombectomy. A study was undertaken to determine whether partial recanalization of proximal isolated middle cerebral artery (MCA) occlusions facilitates endogenous thrombolysis and spontaneous recanalization.

METHODS

We retrospectively analyzed consecutive patients with acute ischemic stroke undergoing mechanical thrombectomy using the Merci Retriever System for occlusions involving any portion of the M1 segment of the MCA. Only those patients with a residual obstruction of the proximal MCA segments were included. The rates of facilitated endogenous recanalization (FER₅) by imaging within the 5 h following intervention were compared in patients with partial proximal recanalization and those in whom recanalization was unsuccessful.

RESULTS

Forty-two patients were included in the analysis. Twenty-six patients had good recanalization of the proximal aspect of the target lesion with an arterial occlusive lesion score of 2 or 3 but a residual partial or total occlusion of the MCA, while 16 patients failed to recanalize any portion of the target occlusion. Twelve patients (46%) in the first group and only one (5.9%) in the second group had facilitated endogenous recanalization on interval imaging 5 h after intervention (OR 12.9, 95% CI 1.5 to 112.2). Nine patients with proximal recanalization had good clinical outcomes at discharge (mRS ≤2) compared with none without recanalization (p=0.01), but FER did not have a relationship with clinical outcome.

CONCLUSIONS

Despite initially incomplete proximal mechanical thrombectomy, nearly half of all patients with residual M1 occlusions will undergo further endogenous recanalization within the subsequent 5 h.