Dr. Lazaridis of University of Chicago has no relevant financial relationships to disclose.)
Dr. Levine of the SUNY Health Science Center at Brooklyn has no relevant financial relationships to disclose.)
Traumatic intracranial aneurysms result from either penetrating head trauma causing direct injury to the vascular wall or from severe closed head injury producing torsion or stretching of an intracranial vessel against the hard edge of dural membranes, bony protrusions, or fractured bones. As traumatic intracranial aneurysms have a high rate of growth and rupture, they need to be detected early and treated aggressively. Experience from the military conflict in the Iraq war has provided the most extensive descriptions of traumatic aneurysms. However, other series from civilian populations have also emerged.
• Traumatic intracranial aneurysms result from severe penetrating head trauma or closed head injuries, causing direct mural injury or indirect stretching injury to arterial walls.
• Although traumatic aneurysms constitute a small fraction of all aneurysms in adults, they carry a high risk of progressive growth and rupture and, therefore, are important to detect and treat in the setting of head trauma.
• Surgical risks of treatment of traumatic aneurysms are high, often requiring sacrifice of the parent vessel for effective exclusion of the aneurysm from the circulation.
• Developing endovascular therapies are increasingly used to treat traumatic aneurysms and can be effective with preservation of the parent artery.
Historical note and terminology
An autopsy-proven case of a middle meningeal artery aneurysm after head injury was first recorded in 1829 (Smith 1829). Later, in 1891, Bollinger postulated that 4 cases of "delayed apoplexy" after head injury were due to the rupture of a traumatic aneurysm (Bollinger 1891). Guibert reported a case involving the infraclinoid internal carotid artery, but Birley and Trotter were the first to describe a case of an intracranial aneurysm after severe head injury (Guibert 1895; Birley and Trotter 1928). Tonnis demonstrated the first case proven by angiography and Cairns provided a comprehensive description of these aneurysms (Tonnis 1934; Cairns 1942). Aneurysm formation after a depressed skull fracture was described by Krauland in 1949, and angiographically demonstrated after a closed head injury in 1962 (Hirsch et al 1962).
It may be that detection of traumatic aneurysms has decreased from the 1970s to the present due to reliance on noncontrast computerized tomography, rather than traditional angiography, for screening evaluation of head-injured patients with traumatic aneurysms sometimes overlooked. Vigilance is required in patients with high-risk injuries; with awareness of the need for screening for vascular injury in appropriate patients, high rates of detection of traumatic aneurysms are reported (Cohen et al 2008).
Traumatic aneurysms have been traditionally divided into "true," "false," and "mixed," depending on whether the arterial wall is partially injured with ballooning of all layers ("true") or ruptured in intimal and medial layers with thin fibrous tissue, organized clot, or brain tissue forming the outer membrane containing the vascular space ("false"). “Pseudoaneurysm” is now a preferred term for false aneurysm. When a true aneurysm ruptures and forms a pseudoaneurysm outside the true one, the aneurysm is "mixed." Whatever the histologic classification, traumatic aneurysms have high risk of growth and rupture and call for urgent management.
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