Thoracic aortic dissection is a type of traumatic aortic injury commonly seen in high-speed motor vehicle collisions ¹. Approximately 75-80% of thoracic aortic dissection occurs in motor vehicle accidents, at speeds of above 50 km/h. 

While the pathophysiology behind aortic dissection is not clear, there are three main, interplaying mechanisms for traumatic aortic injury:

1. Rapid deceleration - this may cause torsion and shearing of the aorta against its fixed segments - particular the aortic root, ligamentum arteriosum and diaphragm
2. Increased intrasvascular pressure - pressures of up to  2000 mmHg may be generated as a result of compression to the aorta which may in turn damage the vessels of the aortic wall
3. Osseous pinch - compression of the aorta between the anterior chest wall and the vertebral column may give rise to aortic injury, as well as subclavian and carotid injury

Since the 1990's, there has been a shift away from open surgical repair of aortic injury. Instead, thoracic endovascular aortic repair (TEVAR) has gradually replaced open repair as the mainstay of operative aortic injury management ². It is associated with significantly lower operative times, procedural blood loss and intraoperative blood transfusion compared to open repair.

Splenic laceration is a common occurrence occurring after blunt traumatic injury ³. In the developed world, it is usually associated with motor vehicle accidents. In one study ⁷, 45% of patients with traumatic abdominal injury demonstrated splenic laceration. 
Contrast enhanced CT is currently the diagnostic imaging tool of choice.
Features of blunt splenic injury include ⁴:

• Lacerations - irregular, linear hypodensities
• Non-perfused regions
• Hematoma (subcapsular and parenchymal) - hypodense regions which may be compressing the capsule, or within the parenchyma itself respectively
• Active hemorrhage - area of high attenuation on CTA represents active bleeding
• Hemoperitoneum - area of hypodensity due to old blood pooling in the paracolic gutters
• Vascular injury

Patients with low grade splenic lacerations, who are haemodynamically stable and have a non-peritonitic abdomen are usually managed conservatively. Recently, there has been a push to manage haemodynamically unstable patients non-surgically, but with radiological angio-embolization ⁷. 

Liver injury is a common finding in many types of trauma ⁵. This is because of its anterior location, as well as fragile parenchyma.

Investigations into traumatic liver injury involves focused assessment for trauma using ultrasound (FAST scans), CT or with diagnostic peritoneal lavage. Imaging such as radiography may reveal chest fractures or splenic lacerations, both common associated injuries.

Traumatic liver injury can be divided into six categories according to the American Association for the Surgery of Trauma ⁶. This particular patient had a grade III hepatic laceration.

• Grade I – Hematoma: subcapsular <10% surface area. Laceration: capsular tear <1 cm parenchymal depth
• Grade II – Hematoma: subcapsular 10-50% surface area intraparenchymal <10 cm in diameter. Laceration: capsular tear 1 to 3 cm parenchymal depth, <10 cm in length.
• Grade III – Hematoma: subcapsular >50% of surface area or ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma >10 cm or expanding. Laceration >3 cm in depth.
• Grade IV – Laceration: parenchymal disruption involving 25 to 75 percent of a hepatic lobe, or 1 to 3 Couinaud segments.
• Grade V – Laceration: parenchymal disruption of >75% of a hepatic lobe, >3 Couinaud segments within a single lobe. Vascular: juxtahepatic venous injuries (retrohepatic vena cava, central major hepatic veins).
• Grade VI – Hepatic avulsion.

Patients with liver injury can be managed based on their degree of hemodynamic stability. This is regardless of the grading of the injury. Stable patients are usually managed conservatively with supportive care. If there is extravasation of IV contrast, these lesions are usually embolized via hepatic embolization.

An haemodynamically compromised patient with a liver laceration is an indication for operative management. This can involve both damage control surgery, and liver resection in the severely compromised patient.

Case contributed by A/Prof. Pramit Phal.