Comparing computed tomography (CT) angiography versus digital subtraction angiography for the screening of traumatic pseudoaneurysms in transcranial stab injuries

Introduction: Transcranial stab injuries among the civilian population in South Africa are more common than in the West. In a study conducted in Durban, South Africa, in 1992, transcranial stab injuries accounted for 6% of all head injuries admitted to the neurosurgical unit. Digital subtraction angiography (DSA) has been the gold standard for diagnosing traumatic pseudoaneurysms. Its use as a screening tool is, however, limited and carries risks of neurological deficits. We postulate that the newer generation computed tomography (CT) scanner would serve as a better screening tool for traumatic pseudoaneurysms following transcranial stab injuries with the blade removed, provided the image quality is good. Methods: All patients admitted with a stab to the head with total calvarial penetration from September 2014 to January 2016 were included in the study. Those with a retained metallic fragment, incomplete imaging protocols, no penetration of the blade into the brain parenchyma or other causes of penetrating head injury were not included in the study. A retrospective chart review was then done on a prospectively recruited patient cohort. All CT angiograms were performed using a dual source CT scanner. Results: A total of 26 patients met the inclusion criteria. There were seven vascular injuries identified on DSA: three traumatic pseudoaneurysms and four vessel cut-offs. One traumatic pseudoaneurysm was missed on computed tomography angiography (CTA) because of a poor quality scan. The average sensitivity and specificity of CTA compared with DSA was 67% and 95.5%, respectively. Negative predictive value for CTA was 99.5%. Conclusion: A good quality CTA carried out on the newer generation CT scanners allows for use of CTA as a screening tool for patients with a transcranial stab injury and no retained blade or metallic foreign bodies.