CT with contrast

Diagnosis: Right ICA aneurysm with acute subarachnoid hemorrhage.

Saccular intracranial aneurysms are thought to arise from abnormal vascular hemodynamics which over time induce vascular injury. Fusiform aneurysms are more related to atherosclerosis. Other causes of aneurysms include polycystic kidney disease, fibromuscular dysplasia or connective tissue disorders. If symptomatic, patients typically present in middle age with acute subarachnoid hemorrhage or cranial nerve palsies due to mass effect if the aneurysm is in the region of the cavernous sinus or the optic chiasm. Intracranial aneurysms are multiple in up to 1/5 of patients. One third of intracranial aneurysms are at the ACOM, another 1/3 involve the ICA/PCOM, while 20% arise at the MCA trifurcation. The remainder are seen in the posterior fossa.

In the absence of subarachnoid hemorrhage, the main differential for this appearance of a para/suprasellar mass is a meningioma. Solid craniopharyngioma, or suprasellar extention of a pituitary adenoma may also resemble this. The interpeduncular cistern is a high yield location for subarachnoid blood. Diffusely increased attenuation in the basilar cisterns and involving the tentorium as well as along the falx may also be seen in acute subarachnoid hemorrhage. The falx, however, may normally have high attenuation. If contrast has been given, some enhancement along the tentorium is normal. Intraparenchymal and/or intraventricular clot may also be present depending on the location and extent of the bleed. Although it may be difficult to see the actual aneurysm without contrast, the best way to evaluate for acute subarachnoid blood is to obtain a non-enhanced CT. After SAH has been diagnosed, the definitive test is angiography. Related Cases

Meningioma ICA aneurysm ICA aneurysm