Mechanical Thrombectomy for Isolated Anterior Cerebral Artery (A2 Segment) Occlusion with Major Left Hemispheric Ischemic Stroke: First-Pass Recanalization, Leptomeningeal Readaptation, and Rapid Clinical Improvement

Several randomized control trials have demonstrated the efficacy of large vessel thrombectomy in the proximal intracranial circulation. However, the clinical benefit of thrombectomy in medium-sized vessels has not been fully evaluated. By consensus definition, vessels in an adult with a diameter of 0.75−2.0 mm are defined as medium-sized. This definition encompasses the M3-4, A2-4, and P2-4 segments. These more distal, smaller, and weaker vessels have longer catheter trajectories and increased vessel tortuosity, potentially increasing procedural risk. Isolated anterior cerebral artery (ACA) territory occlusion is a rare phenomenon and is known to have distinct clinical features. Clinically, the neurological deficits associated with medium-sized vessel occlusions are generally thought to be less severe than those associated with occlusions in larger vessels. However, patients with isolated ACA embolic occlusions may present with significant neurological morbidity comparable to that resulting from more proximal occlusions. We present our experience with an 82-year-old woman who had a history of arterial hypertension, gout, ischemic heart disease, and a right hemispheric ischemic stroke 2 years earlier resulting in left hemiparesis, but with nearly complete neurological recovery. She had recently been diagnosed with atrial fibrillation and was taking apixaban. She was admitted to the emergency room (ER) 2 h after stroke onset. On admission, she was drowsy with leftward gaze deviation, anarthria with global aphasia, and moderate-to-severe right hemiparesis, corresponding to an initial National Institutes of Health Stroke Scale (NIHSS) score of 18. She alternated between drowsiness and agitation. Her admission arterial blood pressure was 220/115 mmHg, and she was given a low dose of intravenous nicardipine. Admission cranial CT revealed advanced microvascular brain disease and an Alberta Stroke Program Early CT Score (ASPECTS) of 10. CT perfusion (CTP) imaging showed that there was no brain area with a reduction in cerebral blood flow to <30% of expected levels (core), but there was an extended 89 ml area with a time-to-maximum prolongation >6 s (penumbra) corresponding to left ACA territory. CT angiography (CTA) images showed occlusion of the left ACA in the A2 segment. Although the patient was in the early therapeutic window, she did not receive intravenous thrombolysis due to uncontrolled arterial hypertension. Stentriever-assisted mechanical thrombectomy (MT) allowed rapid recanalization of the left ACA in a single pass. The patient was transferred to the intensive care unit. She remained intubated, ventilated, and deeply sedated with a normotensive nicardipine drip. A contrast-enhanced CT obtained 20 h after thrombectomy showed a left prefrontal infarct. After this CT, the patient’s sedation was discontinued, and she was extubated. Neurological examination 24 h after thrombectomy showed almost complete neurological recovery with only mild hemiparesis (NIHSS 3), which continued to improve during her hospital stay. Electrocardiographic (ECG) monitoring revealed atrial fibrillation. Oral non-vitamin K anticoagulation (NOAC) was started on day 3 after thrombectomy. The patient was discharged home on post-thrombectomy day 7 with no neurological deficit. This chapter discusses an unusual condition: primary, isolated, embolic ACA occlusion and the emerging role of MT.