Mechanical Thrombectomy for Internal Carotid Artery Occlusion with Accessory Middle Cerebral Artery: A Case Report

The accessory middle cerebral artery (AMCA) is a relatively rare normal variant of the middle cerebral artery (MCA). Mechanical thrombectomy (MT) for internal carotid artery (ICA) occlusion with AMCA is very rare, and the initial diagnosis can be difficult. We illustrate a case of ICA occlusion with AMCA in which delayed diagnosis led to delayed MT.

An 80-year-old man suddenly presented with only mild sensory aphasia. The National Institutes of Health Stroke Scale score was 6. Head MRI showed new punctate acute ischemic lesions. Head MRA demonstrated the left ICA occlusion and visualization of the left MCA via the anterior communicating artery. Since there were few findings that would positively suggest cardioembolic cerebral embolism, including the absence of atrial fibrillation, the patient was diagnosed with the progression of ICA stenosis to acute occlusion. Antiplatelet therapy was initiated, but 10 h later, the patient developed a progressive stroke and underwent MT, which resulted in complete recanalization, during which an AMCA was identified. The patient was transferred to a rehabilitation hospital with a modified Rankin Scale of 4.

A high-signal-intensity area in the main MCA on FLAIR MRI, suggesting flow stagnation, along with absent signal in the same region on time-of-flight MRA, suggesting occlusion, may be a clue to the diagnosis of ICA occlusion with a normal MCA variant.