A complex abnormality of the circle of Willis. Case presentation

Abstract

Objective. We report a case of a patient with medium ACI stenosis and border zone infarct that occurred under normal hemodynamic conditions (normal BP, sinus rhythm), as normal supply mechanisms through the circle of Willis were absent. The circle of Willis was practically absent: the right ICA ramified in right MCA and a single ACA. Left ICA ramified in MCA and PCA. Right PCA was a branch of BA. Case presentation. A 75 year old patient was admitted in emergency with dressing apraxia. CT scan and MRI disclosed a 5/4 cm infarction in the temporo-parieto-occipital junction on the right side. Doppler ultrasonography of the precerebral vessels revealed medium stenosis of right ICA. 3D TOF MRA reconstruction disclosed a complex abnormality of the circle of Willis: absence of A1 and P1 on the left side, absence of PCoA on the right side, a single and fenestrated ACA originating in right ICA. The circle was practically absent; there was no possibility of circulatory supply. The territories of distribution of the precerebral vessels suffered severe modifications: right ICA ramified in MCA and a single ACA, left ICA ramified in MCA and PCA, right PCA was a branch of basilar artery. The infarction occurred between the boundaries of the right ICA (MCA respectively) and the posterior territory (PCA respectively). Conclusion. We report a complex and extremely rare abnormality of the circle of Willis that became clinically manifest because of a severe hemodynamic compromise.