Mechanism of infarction involving ipsilateral carotid and posterior cerebral artery territories.

BACKGROUND: We investigated the potential mechanism of infarction involving the territories of both the internal carotid artery (ICA) and the ipsilateral posterior cerebral artery (PCA).

METHODS: Among consecutive patients with an ischemic stroke who had undergone both diffusion-weighted magnetic resonance imaging (DWI) and cerebral angiography, those who were found to have acute lesions in the ipsilateral ICA and PCA territories on DWI were selected for this study. The mechanism of infarction was sought by investigating angiographic findings and DWI lesion patterns. The frequency of patency between the ICA and PCA in the patient group was compared with that in the normal control group.

RESULTS: Infarctions involving ipsilateral ICA and PCA territories were rare (21 of 1,388 patients, 1.5%). Sixteen of those 21 patients (76%) demonstrated steno-occlusive lesions of the relevant ICA. Cardioembolic sources were rarely found. All but 1 patient with fetal-type PCA (fPCA) or the posterior communicating artery demonstrated significant ICA stenosis. The fPCA was more frequently found in the ipsilateral hemisphere of patients with an infarction than in the control group (44.4 vs. 18.5%, p = 0.006). Ischemic lesions in the ICA territory were usually small but multiple, and those in the PCA territory were single and located in the cortex.

CONCLUSIONS: Large artery atherosclerosis of the carotid artery was very common in patients with infarctions involving the ipsilateral ICA and PCA territories. Extracranial cervical artery evaluation is indispensable in those patients.