Endovascular Stroke Therapy

Abstract

Ischemic stroke is a leading cause of death and disability throughout the world and is both preventable and treatable. This review focuses on the treatment of the most severe form of ischemic stroke, namely large-vessel ischemic stroke, using endovascular techniques. Such therapies were proven effective in 2015. These therapies are among the most beneficial surgical therapies ever subjected to randomized clinical trials. Recent research has explored treating patients up to 24 h following the onset of stroke using advanced imaging techniques to select patients with brain tissue still at risk. These new findings suggest there exists a tissue clock rather than a time clock when selecting patients for therapy. Stroke systems throughout the world are now embracing endovascular stroke therapy. Improving regional stroke systems of care and expanding eligibility for patients are a major focus of current research.

Keywords: Thrombectomy; ischemic penumbra; large-vessel stroke; penumbral imaging; systems of care.

Fig. 1

Clinical outcomes of patients based on blood vessel size. Some patients were treated with IV tPA but did not receive endovascular treatment [2].

Fig. 2

Illustration of mechanical thrombectomy. (a) CTA of a patient with a left middle cerebral artery (MCA) occlusion (arrow). (b) Anterior-posterior (AP) digital subtraction angiogram (DSA) of the left internal carotid artery performed 21 min after the CTA, confirming the left MCA occlusion. (c) AP fluoroscopic view showing a suction catheter in the intracranial internal carotid artery with stent deployed through the MCA clot; below is a cartoon of the anatomy drawn to scale of the image in (c). (d) Photograph of the stent/suction catheter removed from the brain, revealing clot engaged in the stent interstices. (e) AP DSA of the left internal carotid artery, confirming complete recanalization of the left MCA. The procedure time was 35 min from groin puncture to restoration of blood flow.

Fig. 3

Time dependency of clinical outcome from mechanical thrombectomy. The solid line is the odds ratio of improved clinical outcome and the dashed lines are the 95% confidence intervals for that estimate. The solid circle indicates the point beyond which benefit is uncertain. Reproduced with permission [38].

Fig. 4

Illustration of CT Perfusion (CTP) imaging for a patient with an acute left MCA stroke. This shows a small area of decreased cerebral blood flow (CBF, 8 ml) and a larger volume of perfusion delay (71 ml). This patient has a 63 ml volume of mismatch. The region of low CBF is predictive of the brain that is irreversibly injured while the region of perfusion delay is predictive of the region of the brain at risk of infarction if the left MCA is not opened. CTP is not as accurate at predicting core infarct as MRI DWI adding caveats to interpretation; however, CTP is preferred due to ease and patient tolerance.

Fig. 5

Receiver operating characteristic curves for each neurological exam-based scale. ROC = receiver operating characteristic; SAVE = Speech Arm Vision Eyes; EMSA = Emergency Medical Stroke Assessment; FAST-ED = Field Assessment Stroke Triage for Emergency Destination; mNIHSS = modified National Institutes of Health Stroke Scale; NIHSS = National Institutes of Health Stroke Scale; CPSS = Cincinnati Prehospital Stroke Scale; C-STAT = Cincinnati Stroke Triage Assessment Tool; G-FAST = Gaze, Face, Arm, Speech, and Time; PASS = Prehospital Acute Stroke Severity; VAN = Vision, Aphasia, and Neglect; 3ISS = 3-Item Stroke Scale; reproduced with permission [47].