Bilateral paramedian thalamic and mesencephalic infarcts after basilar tip aneurysm coiling: role of the artery of Percheron.

Aneurysm embolization using Guglielmi detachable coils (GDC) is gaining acceptance as a viable alternative for surgery in the treatment of aneurysms. Recent reports describe a significant rate of thromboembolic complications. Thalamic and midbrain blood supply can arise from complex anatomical variations. The rare variation: "artery of Percheron", is a solitary arterial trunk arising from one of the proximal segments of a posterior cerebral artery and supplies the paramedian thalami and rostral midbrain bilaterally. We describe a patient that underwent elective endovascular treatment for a basilar tip aneurysm using GDC and stents in each PCA; 12 hours later patient was comatose and not following commands. Sequential magnetic resonance imaging (MRI) of brain showed bilateral paramedian thalamic and mesencephalic infarcts presumably secondary to artery of Percheron occlusion. Thromboembolic event related to the use of the GDC embolization and stents is a rare clinical sequelae, but catastrophic. The use of antiplatelets agents should be reinforced in the scenario. When bilateral medial thalamic and midbrain infarcts are found, occlusion of the artery of Percheron should be considered. Angiography may not b helpful and lack of visualization of the artery does not exclude its presence. In this case the MRI findings confirmed the presence of the infarction based on the anatomical distribution.