Traumatic Anterior Cerebral Artery Pseudoaneurysm

Findings:
Axial CT images show numerous right frontotemporal contusions with mass effect and effacement of the right lateral ventricle. A small amount of pneumocephalus is present posteriorly. In addition, small amount of subarachnoid hemorrhage is seen in the anterior interhemispheric fissure. Arteriography was performed initially for suspected ICA injury, which was negative. The patient developed severe headache 6 weeks later, at which time an additional CT scan was performed. This study shows a large amount of intraventricular hemorrhage, with a parenchymal hemorrhage in the right frontal lobe. Repeat cerebral arteriogram shows pooling of contrast in a moderate size pericallosal artery pseudoaneurysm.

Discussion:
The anterior cerebral artery is susceptible to traumatic injury due to increased shear forces along the genu of the corpus callosum. Posttraumatic pseudoaneurysms of the posterior cerebral artery may occur from impact on the tentorium. The intimal injury may not initially be apparent. These lesions expand over time and are at a high risk for causing catastrophic hemorrhage. In retrospect, the small amount of interhemispheric SAH may have been a clue to the presence of arterial injury, but this could not be assumed prospectively since small amounts of SAH are commonly seen in trauma.

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