Acute Left MCA Occlusion with Chronic Right Internal Carotid Artery Occlusion: Single-Pass Stentriever-Assisted Thrombectomy—A Case of Primary and Secondary Collateral Supply Readaptation

The term “cerebral collateral circulation” refers to the subsidiary network of vascular channels that stabilize cerebral blood flow when principal conduits fail. The case presented here exemplifies primary and secondary (leptomeningeal) collateral readaptation after thrombectomy. We describe the case of a 68-year-old woman with a history of arterial hypertension, diabetes mellitus, dyslipidemia, chronic renal failure, ischemic heart disease, atrial fibrillation, and aortic valve replacement, who was under apixaban, and who presented with chronic occlusion of the right internal carotid artery (ICA). She was found unconscious at her home, where she lives alone, and had last been seen normal 30 h before admission to the hospital. Upon evaluation, she presented signs and symptoms of a major left hemisphere stroke with an initial National Institutes of Health Stroke Scale score (NIHSS) of 18. Admission noncontrast head CT showed hypodensity of the left caudate nucleus, lenticular nucleus, and internal capsule, leading to an admission Alberta Stroke Program Early CT Score (ASPECTS) of 7 points. CT angiography (CTA) revealed an occlusion of the M1 segment of the left middle cerebral artery (MCA). CT perfusion (CTP) depicted a 22 ml region with total cerebral blood flow reduction to less than 30% of expected, located predominantly in the deep zone. The region with a time-to-maximum prolongation >6 s had a volume of 207 ml. The patient underwent successful and uneventful endovascular revascularization of the left MCA/M1 occlusion. Significant neurological improvement was observed immediately after extubation, with a post-procedure NIHSS score of 6. Postprocedural head noncontrast CT revealed an ischemic area in the deep territory of the left hemisphere with no signs of hemorrhagic transformation, with an ASPECTS of 7 points. Anticoagulation with apixaban was initiated 24 h after the procedure. The patient was discharged after 9 days with an NIHSS of 2, and at a 90-day clinical follow-up, she had a modified Rankin Scale (mRS) score of 0. Collateral circulation is the main topic of this chapter.