Direct emergence of the dorsospinal artery from the aorta and spinal cord blood supply. Case reports and literature review.

Introduction: Direct emergence of a dorsospinal artery from the aorta is a rare anatomic variant, of which a total of seven cases have been reported. This report offers an additional angiographic observation and reviews the literature.

Methods: Two observations of common intercostal trunks documented during spinal angiography are described.

Results: In the first observation, the common intercostal trunk provided complete blood supply to two adjacent vertebral levels (T11 and T12). In other words, the trunk included an intercostal branch and a dorsospinal branch for each level. In the second observation, the common intercostal trunk provided an intercostal branch for each level (T9 and T10), but only one dorsospinal branch (T10). An isolated dorsospinal artery (DA) originated separately from the aorta at the T9 level, and provided a significant contribution to the anterior spinal axis.

Conclusion: The two reported cases illustrate the concept of "complete" versus "incomplete" common intercostal trunks. In instances where an incomplete trunk is documented, a separate DA originating directly from the aorta must be looked for. A review of the literature indicates a tendency for isolated DAs to participate in the blood supply to the spinal cord.