Anterior Spinal Artery Syndrome

Anterior spinal artery syndrome, also known as anterior cord syndrome or ventral cord syndrome, is a neurologic condition that results in motor paralysis, pain, temperature sensory loss, and occasionally autonomic dysfunction due to occlusion of the anterior spinal artery. This artery supplies the anterior two-thirds of the spinal cord and runs along the entire length of the anterior surface of the spinal cord. Occlusion of the anterior spinal artery leads to reduced blood flow and eventual infarction of the spinal cord, resulting in bilateral lower extremity paresis or paraplegia with loss of pain and temperature sensation. Generally, the patient presentation varies depending on the portion of the spinal cord affected and the time to treatment. In addition to motor deficits and loss of pain and temperature sensation, clinical findings include back pain or autonomic dysfunction, such as hypotension, neurogenic bowel or bladder, and sexual dysfunction. The severity of motor dysfunction can range from paraplegia to quadriplegia, depending on the rostral level of the involved spinal cord. This clinical manifestation is known as anterior spinal artery syndrome. Typically, proprioception, vibratory sense, and fine touch are preserved. The neurological deficits manifest below the level of insult due to the anatomical distribution of the spinal cord tracts.

The anterior spinal artery forms from the bilateral vertebral arteries at the foramen magnum and runs as an uninterrupted artery within the anterior median sulcus of the spinal cord to the conus medullaris. Radicular arteries enter the spinal canal through the intervertebral foramen and primarily supply the nerve roots; however, some anastomoses contribute to the anterior spinal artery. The largest of these radicular arteries is the artery of Adamkiewicz, also known as arteria radicularis magna, which most commonly arises from a left intercostal artery between segments T9 to T12 but can vary anatomically. The anterior spinal artery branches into small sulcal and penetrating arteries that enter the body of the spinal cord. The anterior spinal artery supplies blood to the spinal cord's bilateral anterior and lateral horns and the bilateral spinothalamic and corticospinal tracts. The anterior horns and corticospinal tracts control the somatic motor system from the neck to the feet. The lateral horns, spanning levels T1 to L2 of the spinal cord, comprise the neuronal cell bodies of the sympathetic nervous system. The spinothalamic tracts relay pain, temperature, and sensory information. The anterior spinal artery, with a few radicular artery contributions, is the sole source of blood supply to these areas of the spinal cord through sulcal and penetrating arteries. Ischemia of the anterior spinal artery causes symptoms consistent with the dysfunction of these tracts. As the anterior spinal artery is formed from the more cephalad vertebral arteries and runs caudally, the more rostral the location of ischemia, the more widespread or severe the symptoms. As the lateral horns are located between the T1 and L2 of the spinal cord, autonomic symptoms are not always present if ischemia does not involve this region. Proprioception, vibratory sense, two-point discrimination, and fine touch are not affected in anterior cord syndrome and are carried by the dorsal column of the spinal cord, which is perfused by 2 posterior spinal arteries running in the posterior lateral sulci.

Anterior spinal artery syndrome is a rare cause of spinal cord acute ischemic myelopathy. However, it is the most common cause of spinal cord infarcts. The syndrome is caused by any etiology that decreases or affects blood flow to the anterior spinal artery, with aortic surgery and atherosclerotic disease being the most common causes. Diagnosis of anterior spinal artery syndrome is based on characteristic clinical features and confirmatory neuroimaging studies. The prognosis is generally poor, as no acute management is available. Management focuses on treating the underlying cause and preventing complications. Current treatment follows the same guidelines for cerebral ischemia, atherosclerotic vascular disease, and acute traumatic spinal cord injury.