Teaching Case

The patient, affected by transrenal aortic aneurysm, was sent to our department for a preoperative evaluation of the Adamkiewicz artery (AKA). Computed Tomography Angiography (CTA) was performed.

The patient was affected by transrenal aortic aneurysm (58x59 mm) extended for 14 cm over the aortic carrefour, with a maximal patent lumen of 24 mm and thrombotic apposition (Fig.1). A surgical treatment was planned but a preoperative CTA, with volume rendering reconstruction, was required to study the AKA and minimise the risk of spinal cord ischaemia.
The AKA joins the anterior spinal artery (ASA) between T11 and T12, with a characteristic hairpin turn (Fig.2). The AKA is supported by the left intercostal artery that originates from aorta at the level of T11 but it is obstructed at the ostium (for a calcified plaque) and it is supported retrogradely by the cranial (hypertrofic) intercostal artery (Fig.3, 4).

Spinal cord ischaemia, resulting in paraplegia and paraparesis, is the most serious complication that can occur after thoracoabdominal aortic aneurysm repair (it has been reported to occur in 5-10% of patients) and it is mainly caused by interruption of blood supply to the spinal cord during the aortic operation [1].
Blood supply of the spinal cord derived from three to ten intercostal and lumbar arteries, which coalesce to form the anterior spinal artery (ASA) and the two posterior spinal arteries (PSAs). The ASA extends the length of the spinal cord and it is the major supplier of the anterior two-thirds of the spinal cord; the remainder is supplied by the PSAs [2]. The AKA is the principal arterial supply of the ASA in the lower thoracic and lumbar level and originates from the left side in 72% of cases [3]. It is the largest radiculomedullary artery with a characteristic hairpin turn, and with continuity from the aorta to the ASA. In 75% of cases it joins the ASA between T9 and T12 but in 10% of cases it joins it between LI and L2. In the remaining 15% of the cases the AKA joins the anterior spinal artery between T5 and T8.
Preoperative AKA identification and display of intercostal and lumbar arteries is very important to minimise the risk of postoperative spinal cord ischaemia and to aid the planning of surgery.
Several angiographic techniques have been used. Conventional angiography shows these arteries, but this invasive technique carries greater risk for complications (including spinal cord injury) and it is time consuming. Magnetic resonance (MR) and computed tomography angiography (CTA) have been proposed as an alternative to non-invasive techniques. MR can display segmental arteries and the AKA but does not provide a clear contour of the vertebral body as 3D-CTA images [4]. Particularly CTA with intra-arterial contrast injection could track the AKA to the aorta because of high contrast, necessary to detect small vessels.
Osseous structures sometimes interfere with visualisation of arteries. It may be difficult to visualise the AKA that runs into an intervertebral foramen and it is also very thin. Another difficult point is the differentiation of the AKA and the ASA from the spinal veins.
This imaging technique has an incremental benefit in reducing post-operative complications: the surgeon can reanastomose these arteries onto an aortic graft or potentially avoid those levels when placing endostents.