The spinal cord receives vascular supply through three major arteries. The single anterior spinal artery and two paired posterior spinal arteries. Segmented medullary arteries are supplied by the unbranched arteries that join the anterior spinal artery or the posterior spinal artery compared to radicular arteries that supply the nerve roots.
Most radicular arteries disappear before birth; however, several dominant radiculomedullary ones remain, including the artery of Adamkiewicz. They also result in important collateral vessels for the spinal cord by forming anastomoses with the anterior and two posterior spinal arteries resulting in their common name of booster/feeder vessels.
The cord is dependent upon three longitudinal arterial trunks or channels. The anterior and posterior spinal artery longitudinally runs along the whole spinal cord and often anastomose with each other forming plexuses.
Cord ischemia, primarily secondary to vascular insults in the mid-thoracic region, is common as the diameter of the spinal cord and its resulting arteries undergo significant narrowing here. Damage of any kind to the anterior spinal artery can cause significant motor symptoms, as it supplies the anterior two-thirds of the spinal cord. The majority of the corticospinal tracts, which are responsible for motor function, are also affected by insults to the anterior spinal artery. While ischemia to the posterior spinal artery results in a sensory and proprioceptive loss due to its supply to the dorsal roots.
Muscles have little to no effect on the spinal cord supply except in the case of minor anastomoses as there is an extensive network of epidural arterial and minor vessels that supply the paraspinal musculature. These vessels are interconnected and anastomose with the subclavian arteries cranially and the lumbar/hypogastric arteries caudally. These anastomoses are especially useful in providing a minor collateral network that can supply some flow to the spinal cord in occlusion of the larger routes.
The origins, course, and position are common. However, variations of size are not.
The thoracic spine from T2 to T10 has increased stiffness due to intervertebral disks, coronal plane articulation of the facet joints, and articulation with the ribs, which in turn articulate with the sternum. The inherent kyphosis in the thoracic spine also concentrates the axial load on the anterior column improving rigidity. Therefore, fractures are generally less common. However, when they do occur, it is increasingly worrisome since the mid-thoracic spine is a known vascular watershed area. Extensive dissection and periosteal stripping during surgical exposure should be avoided around the mid-thoracic region since even minor vascular insults can lead to cord ischemia.
The artery of Adamkiewicz is the only significant arterial supply feeding the anterior spinal artery along the lower thoracic, lumbar, and sacral spinal cord. This vessel is clinically relevant, as injury to this vital artery can occur during various procedures, most notably descending/thoracoabdominal aortic repairs. Injury to this artery can cause consequential neurologic damage manifesting as anterior spinal cord syndrome.
With sudden blockage of blood supply, the common symptoms are sudden back pain that can quickly lead to numbness/weakness or pain that radiates along the nerves branching from the affected area.
Symptomatic treatment and physical therapy are recommended unless a clot or stenosis is identified, in which case surgery is recommended.
There are three major syndromes due to blockage of the spinal arteries.
Venous infarctions are rare but rapidly progress with near-certain fatality within 36 hours.
Infarcts in the spinal arteries often lead to an irreversible motor/sensory loss; however, new treatments have found that improving oxygen exposure/blood flow over extended periods to damaged areas may improve previous injuries that were at one time thought to be irreversible.
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