T1 pre-gad T2 MRA

Diagnosis: Thrombosed saccular MCA aneurysm with MCA infarction

Abnormal vascular hemodynamics are believed to induce saccular intracranial aneurysms. Fusiform aneurysms are usually due to atherosclerosis. Saccular aneurysms are associated with polycystic kidney disease, fibromuscular dysplasia, and connective tissue disorders. Symptoms are usually related to the mass effect or subarachnoid hemorrhage from rupture. They are multiple in up to 1/5 of patients. 20% arise at the MCA trifurcation while 1/3 are at the ACOM and another 1/3 involve the ICA/PCOM. The remainder are in the posterior fossa.

This patient had a left MCA trifurcation aneurysm wrapped in 1985. The dark rim around the lesion on T2 suggests that there is clot with hemosiderin in the periphery. The lack of flow void, no phase encoding artifact and no flow on MRA proves that the aneurysm is thrombosed. The surrounding region of encephalomalacia with no flow in the left MCA on MRA is compatible with MCA occlusion and infarct. Related Cases

Supraclinoid ICA Aneurysm Cavernous ICA Aneurysm AICA aneurysm