Microsurgical anatomy of the Adamkiewicz artery-anterior spinal artery junction.

PURPOSE: The aim of this study is to describe the anterior spinal artery-Adamkiewicz artery (ASA-AKA) junction and establish a classification allowing defining the neurological risk in either thoracoabdominal aorta aneurysm treatment and in anterior or transforaminal thoracolumbar spine surgery. METHODS: Fifteen spinal cords of fresh cadavers were dissected. Both lumbar arteries and ASA were injected with strongly diluted red-colored silicon. RESULTS: The dural crossing of AKA was located on the left side in 86 % of cases, between T8 and T10 in 73.33 % of cases and L1-L2 in 26.67 % of cases. The average diameter of the ascending branch of AKA was 1.10 mm (range 0.8-1.9 mm), and its average length was 30.27 mm (range 12.3-60 mm). The AKA's arch average diameter was 11.3 mm (range 9-20 mm) with an open downward angle average of 20.1° (range 11°-30°). The descending branch of AKA which was a continuation of ASA had an average diameter of 1.33 mm (range 0.8-1.86 mm). The ASA at the top of the arch had an average diameter of 0.74 mm (range 0.2-1.77 mm). According to these findings, we have proposed a new classification with two types of junctions. The type I and its variant correlated to high neurological risk were present in 93.33 % of cases. The type II, correlated to medium or low neurological risk, was present in 6.67 % of cases. CONCLUSION: These anatomical findings allow a planning of the neurological risk before thoracoabdominal aorta aneurysm or thoracolumbar anterior or transforaminal spine surgery.