Traumatic aneurysms of cerebral vessels: a case study and review of the literature.

Traumatic cerebral aneurysms (TCAs) are rare: few more than 100 cases are recorded in the world literature. TCAs are located predominantly in the supratentorial compartment and are classified as either "true" or "false." A true aneurysm is a dilation resulting from partial disruption of the arterial wall. A false aneurysm results from a full-thickness tear, with the scar from the brain tissue or an organized hematoma acting as the aneurysmal wall. The authors present a case of a false traumatic aneurysm of the pericallosal artery, which was discovered in a young patient fourteen months after a self-inflicted gunshot wound to his head. The aneurysm was an incidental finding on a CT scan performed for the investigation of his late posttraumatic seizures. Its presence was confirmed by angiography. The interval between the traumatic episode and the diagnosis of a TCA usually ranges from a few hours to a few weeks, for most are discovered by angiography performed in the acute or subacute stage of a head injury. The long interval between the injury and the diagnosis in our case is exceptional. A previous CT scan done four months after the injury did not reveal the aneurysm, which strongly suggests a protracted growth of the aneurysmal sac long after the trauma.