Aneurysm is the medical term for an abnormal bulge or ballooning that occurs in the wall of a blood vessel. This weakening allows the pressure of flowing blood to push outward, creating a dilated sac that can potentially rupture and cause life-threatening internal bleeding. While aneurysms are often linked to pre-existing conditions like hypertension, a severe car accident can absolutely cause an aneurysm, which is specifically known as a traumatic aneurysm. This risk is primarily associated with the intense forces of blunt trauma or rapid deceleration experienced during a collision.
The Mechanism of Traumatic Aneurysm Formation
Traumatic aneurysms are typically classified as pseudoaneurysms, or false aneurysms, which differ structurally from true aneurysms caused by disease. A true aneurysm involves the dilation of all three layers of the arterial wall, but a pseudoaneurysm forms when all layers of the vessel wall are breached. Blood leaks out of the artery and is contained by the surrounding soft tissue, forming a hematoma that maintains communication with the main vessel. This contained pool of blood is what constitutes the false aneurysm.
The physics of a high-speed car accident creates the forces necessary to damage these strong vessel walls. Rapid deceleration, such as hitting a fixed object, causes organs and structures to move forward suddenly. The aorta, the body’s largest artery, is particularly vulnerable where it is tethered and fixed in the chest, such as at the aortic isthmus. This sudden stop creates immense shearing forces that can tear the inner lining of the artery, an injury known as dissection, or completely rupture the wall.
In the head and neck, blunt force or violent movement can lead to the formation of a cerebral aneurysm. A severe closed head injury, even without skull fracture, can cause the brain to rotate or shift within the skull. This motion subjects the intracranial vessels to torsion and stretching, which can tear the inner layer of the artery. Blood then flows into the damaged wall, weakening the structure and leading to a focal dilation.
The thoracic aorta and the arteries of the brain are the most common and dangerous sites. A tear in the inner lining allows blood to pool, which can eventually form a pseudoaneurysm that expands over time. This structural weakness means it is at risk of expanding or rupturing, sometimes days or weeks after the initial collision.
Recognizing Warning Signs After an Accident
The symptoms of a traumatic aneurysm can be immediate, masked by other injuries, or dangerously delayed, appearing as the blood vessel injury worsens. For an aneurysm in the brain, the most recognizable warning sign is often a sudden, severe headache, sometimes described as the “worst headache of life.”
Neurological deficits may also occur as the growing aneurysm presses on brain tissue or if a small rupture occurs. These symptoms include vision changes, nausea, vomiting, dizziness, or weakness and numbness on one side of the body.
When the thoracic aorta is involved, the symptoms relate to the vessel’s location in the chest and back. An aortic pseudoaneurysm can cause intense, persistent chest or upper back pain that may feel like a ripping or tearing sensation. If the growing aneurysm presses on nearby nerves or structures, a patient may experience difficulty swallowing or a new onset of hoarseness. These symptoms require emergency medical attention.
Medical Assessment and Management
If a traumatic aneurysm is suspected following a collision, a thorough medical assessment using advanced imaging is necessary for diagnosis. The primary tool for visualization is Computed Tomography Angiography (CTA), which uses a contrast dye to highlight blood vessels and precisely locate the injury. Cerebral angiography or a specialized Duplex ultrasonography may also be used to confirm the size, location, and nature of the aneurysm.
The treatment pathway depends heavily on the aneurysm’s location, size, and stability. For many traumatic pseudoaneurysms, particularly those in the extremities, a non-surgical approach may be attempted first. Smaller, stable pseudoaneurysms can sometimes be monitored to see if the body’s clotting mechanisms will allow them to spontaneously thrombose, or clot off.
For larger or unstable aneurysms, intervention is required to prevent rupture. Endovascular repair is a common, minimally invasive procedure that involves navigating a catheter through blood vessels to the site of the aneurysm. For a cerebral aneurysm, a procedure like coiling can be performed, which fills the sac with tiny platinum wires to promote clotting and seal it off from blood flow.
In the case of a thoracic aortic pseudoaneurysm, Thoracic Endovascular Aortic Repair (TEVAR) is often utilized. This involves deploying a stent-graft—a fabric tube supported by a metal mesh—inside the damaged section of the aorta to reinforce the vessel wall and redirect blood flow away from the injury. Open surgical repair, while more invasive, may still be necessary for highly complex aneurysms or those involving multiple major branch vessels.