Background: Infarcts in the territory of the posterior cerebral arteries (PCAs) are common. Although associated clinical symptoms and signs are known, the mechanisms of stroke and the anatomical distribution of PCA territory lesions caused by the various stroke mechanisms are less well defined. Published reports have selected only special subgroups of patients.
Patients and methods: We studied stroke mechanisms, infarct distribution, and clinical findings among 79 patients in the New England Medical Center Posterior Circulation Registry in whom brain imaging scans showed infarcts that involved 1 or more cortical territories of the PCA.
Results: Forty-eight patients (61%) had infarcts limited to the PCA territory (pure PCA), while 31 (39%) also had infarcts in other territories (PCA+). Infarcts were in the cortical territory of the PCA in 47 patients (59%) and were cortical and deep in 32 (41%). Infarcts that were cortical and deep were more common in PCA+ lesions. Stroke mechanisms were embolism of cardiac origin (32 [41%]), proximal arterial disease (25[32%]), cryptogenic embolism (8[10%]), intrinsic PCA disease (7[9%]), vasoconstriction (4[5%]), and coagulopathy (3[4%]). Patients with cardiogenic embolism and intrinsic PCA disease often had pure PCA territory infarcts, while patients with proximal arterial disease more often had PCA+ infarcts. Visual abnormalities were present in 66 patients (84%). Motor weakness, cognitive and behavioral abnormalities, and ataxia were found in 20 patients (25%); only 12 (15%) had sensory signs.
Conclusions: The great majority of pure PCA and PCA+ territory infarcts are caused by cardiac or intra-arterial embolism. Intrinsic PCA disease, vasoconstriction, and coagulopathy are less common causes of infarction.