The anterior spinal artery is formed by the union of two small branches from the vertebral arteries at the level of the foramen magnum. It descends in the anterior median fissure of the spinal cord throughout its entire length, reinforced at segmental levels by radicular arteries. It supplies the anterior two-thirds of the spinal cord including the corticospinal tracts, spinothalamic tracts, and the anterior horn cells.
The anterior spinal artery has a watershed territory in the mid-thoracic region (T4-T8) where radicular contributions are sparse, making this level vulnerable to ischaemia during hypotensive episodes, aortic surgery, and aortic dissection. Anterior spinal artery syndrome produces acute flaccid paralysis with dissociated sensory loss (loss of pain and temperature with preserved proprioception and vibration, which travel in the posterior columns supplied by posterior spinal arteries). This pattern distinguishes cord ischaemia from transverse myelitis.
Ischaemia of the anterior two-thirds of the spinal cord from aortic surgery, dissection, emboli, or sustained hypotension produces acute flaccid paraplegia with loss of pain and temperature sensation below the level, with intact proprioception, requiring neuromonitoring during aortic procedures and urgent CSF drainage when recognised post-operatively.
Type B aortic dissection occluding the critical radicular arteries feeding the anterior spinal artery causes sudden paraplegia, a devastating complication with poor prognosis managed by urgent aortic stenting and spinal cord perfusion optimisation.
