Initial Management

After the initial CT investigation, intravenous tissue plasminogen activator (IV-tPA) was commenced at 2.5 hours after symptom onset. Following discussion between stroke physician in admitting center and interventional neuroradiology, the patient was transferred to the regional endovascular stroke center for further management. The admitting hospital was located approximately 55 km from the regional endovascular stroke center, and the patient was transferred by ambulance.

The patient arrived in the regional endovascular stroke center at approximately 4 hours from symptom onset. At that time, tPA infusion was completed, with no improvement in patient symptoms and stable NIHSS score of 17; the patient was therefore immediately transferred to the angiosuite.

Endovascular Treatment

Procedure and Technique

Ten minutes after arrival, while patient was awake, after infiltration of soft tissues at the puncture site with local anesthetic, a single wall right CFA puncture was performed and an 8-Fr short Cordis arterial sheath placed for vascular access. A preassembled coaxial 6-Fr Weinberg through an 8-Fr Mach guide catheter was used to gain access to the left common carotid artery over a 0.035-in wire. Left common carotid angiography demonstrated patent proximal ICA with no significant atherosclerotic disease or stenosis and an unopacified column of blood distally (Fig. 8.4a, b). At this point, it was still difficult to be certain of the exact site of the occlusion. Therefore, the coaxial system was advanced into the proximal internal carotid and the 8-Fr guide catheter was positioned just above the carotid bulb by sliding it over the 6-Fr inner catheter guidewire. The system was already connected to a pressurized heparin saline flush bag via a large bore rotating hemostatic valve. Subsequently, a 5MAX-ACE intermediate catheter was placed through the guide catheter and advanced over a 0.38-in Terumo-Glide guidewire until its tip was positioned in the mid-cervical ICA. Angiographic runs via the intermediate 5MAX-ACE catheter demonstrated patency of mid to distal cervical ICA with distal cutoff of contrast filling at the level of the cavernous ICA (Fig. 8.4c, d).

A Rebar-27 microcatheter with inner Transend-EX micro-guidewire was introduced into the 5MAX-ACE intermediate catheter and initially positioned within the distal cavernous ICA. The microwire and subsequently microcatheter were advanced through the occluded segment and navigated to the level of the left M1 bifurcation. Microcatheter injection confirmed intraluminal position of microcatheter. Filling defect consistent with thrombus was seen distal to the microcatheter tip in the region of the left M1 segment bifurcation and involving proximal divisions of the left MCA (Fig. 8.5).

A 6 × 30 mm Solitaire stent retriever was deployed. Angiographic runs demonstrated minimal reconstitution through the stent with no convincing flow distally (Fig. 8.6a, b). The stent retriever was withdrawn after 2 minutes with a small volume of thrombus extracted in the stent (Fig. 8.6c); retrieval was performed with suction through the 5MAX-ACE catheter. Postretrieval angiography showed minimal improvement of flow. A second pass of Solitaire was performed; the carotid terminus was partially recanalized, with contrast opacification seen in relation to the very proximal portion of left A1 and M1, as well as filling of the left posterior communicating artery (Fig. 8.6d, e). This was followed by deployment of an EmboTrap stent retriever across the MCA bifurcation (Fig. 8.7) with further smaller clot fragments removed, and further recanalization of the carotid terminus noted on the follow-up runs.

There was, however, persistent occlusion of the left M1 segment of MCA. The 5MAX-ACE was advanced into the left M1 segment. A 3MAX reperfusion catheter was then advanced through the 5MAX-ACE to abut the proximal face of the left MCA thrombus and aspiration thrombectomy was attempted four times with a moderate amount of thrombus extracted using a 50-mL VacLok syringe. On each occasion, the 3MAX was advanced further into the superior division of the left MCA as clot removal was achieved gradually in an incremental way (Fig. 8.8). The final point of deployment of the 3MAX was to the level of the M2/M3 segment junction. This was followed by two further Solitaire passes through the other M2 branches of the superior division, with more thrombus retrieved.

At this stage, the left M1 was cleared and antegrade flow was established into the superior division; however, the inferior division and temporal branch of MCA remained occluded, and there was visible thrombus within the left A2 segment of ACA with near-complete occlusion. Therefore, a single EmboTrap retrieval was performed through the left A2 segment (Fig. 8.9) with moderate amount of thrombus removed and the artery was completely recanalized (Fig. 8.10).

Three more retrievals were performed through the left MCA superior and inferior divisions and temporal branch with more thrombus extracted; however, eventually only the superior division of MCA and the proximal segment of the anterior temporal branch were reopened. Total number of stent retriever passes was 9 with the resultant thrombolysis in cerebral infarction (TICI) 2a recanalization of the arteries. Angiographic runs from the cervical carotid showed no residual thrombus, with patent bifurcation, and no significant stenosis; therefore, no carotid intervention was needed (Fig. 8.10). The procedure took 109 minutes from the first to the last run.

Postprocedural Care/Outcome

Patient was cooperative during the procedure and his clinical condition remained relatively stable with no significant neurological change during the procedure. At the end of the procedure, groin hemostasis was achieved using an 8-Fr Angio-Seal. Postprocedure, the patient was stable, and transferred by ambulance back to the referring hospital escorted by a stroke physician and a nurse.

Blood pressure control was instigated with a target mean arterial pressure of less than 120 mm Hg to prevent reperfusion injury. However, the patient gradually deteriorated overnight with drop in Glasgow Coma Scale (GCS). A repeat NCCT of the brain was performed 24 hours postthrombectomy demonstrating a large left MCA territory infarct with multiple regions of hemorrhagic transformation (Fig. 8.11a).

Following further discussion and consultation with neurosurgeon, the patient was transferred back to the regional endovascular stroke center for further management. An external ventricular drain was inserted and the patient underwent left hemispheric decompressive craniectomy and duraplasty the same day (Fig. 8.11b, c) with gradual resolution of the resultant mass effect, and moderate improvement in GCS. Subsequently a ventriculoperitoneal shunt was inserted.

The patient remained hemiplegic with no further significant change in the clinical status and was transferred to a rehabilitation facility with moderate but consistently improving functional capabilities, and plan for later cranioplasty and replacement of the bone flap (Fig. 8.12).

Background

Despite the relative success of intravenous thrombolysis, limitations in recanalization of proximal intracranial arterial occlusion of less than 50% have spurred development of various endovascular techniques. ^{1 ,​ 2} The introduction of stent retrievers was a major advancement; however, despite their high recanalization rate, up to approximately 90%, ³ they are not perfect and interventionalists sometimes encounter thrombus which is not retrievable by applying conventional techniques. ⁴

Nevertheless, this is of great importance, considering the overwhelming result of recent randomized controlled trials which undeniably confirmed superiority of endovascular intervention in terms of final clinical outcome. ^{5 ,​ 6} In fact meta-analyses of the randomized controlled trials comparing adjunct endovascular therapy versus medical management alone in acute ischemic stroke have shown superior functional outcomes in subjects receiving endovascular therapy, with noninferiority to medical management in terms of important clinical end points of mortality and symptomatic intracerebral hemorrhage. ⁷ This supports recommendations for including earlier endovascular therapy in patients with imaging-demonstrated large-vessel occlusions.

It is important to remember that recanalization is likely the strongest predictor of at-risk-tissue rescue and patient outcome in acute large artery occlusive stroke. A meta-analysis showed an odds ratio of approximately 5 for having a good functional outcome at 3 months poststroke for those patients with near-complete recanalization, TICI 2b/3, compared with poor or no recanalization after intervention. ⁸ Recanalization of the occluded artery depends on multiple different factors including thrombus type, location, and the extent of the occlusion. ⁹ It is well known that when using IV thrombolysis, recanalization rates are lower in proximal versus distal arteries ^{2 ,​ 8 ,​ 10 ,​ 11 ,​ 12} ; hence, the best IV-tPA outcome in patients with anterior circulation stroke is usually seen in those with distal MCA occlusion compared to occlusion of the carotid terminus ¹³ who are likely the group with poor prognosis if not fully recanalized.

It has been well established that the clot length is also an independent predictor of the outcome in IV thrombolysis. ¹⁴ There is now emerging evidence that clot burden can be also considered a predictor for outcome in those who received endovascular treatment. ¹⁰ There have been attempts in proposing standard methods in quantifying thrombus burden in patients, assisting prognostication based on site and extent of the intracranial occlusion. ^{10 ,​ 15}

Clinical trials have also shown that the likelihood of recanalization negatively correlates with the thrombus burden, with those having a clot less than 8 mm in length having a much better chance to achieve recanalization. ^{9 ,​ 16}

Clot composition may also determine effectiveness of thrombolysis. A study found that fibrin-rich cardioembolic thrombus achieved faster and more frequent recanalization with tPA compared to large-vessel atherosclerotic lesions. ¹⁷ In a case series with complete or partial MCA recanalization after IV-tPA, 20% of patients had early reocclusion, and risk factors for this include NIHSS score more than 16 at baseline and severe ipsilateral carotid artery disease, which was defined as more than 70% stenosis in this study. ¹⁸