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 as 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 run longitudinally 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 the event of 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 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 a variety of 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, as well as physical therapy, is 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.
|||Ali F,Dublin AB, Anatomy, Back, Anterior Spinal Artery 2018 Jan; [PubMed PMID: 30422558]|
|||Källén K,Mastroiacovo P,Castilla EE,Robert E,Källén B, VATER non-random association of congenital malformations: study based on data from four malformation registers. American journal of medical genetics. 2001 Jun 1; [PubMed PMID: 11343333]|
|||Moon BJ,Choi KH,Shin DA,Yi S,Kim KN,Yoon DH,Ha Y, Anatomical variations of vertebral artery and C2 isthmus in atlanto-axial fusion: Consecutive surgical 100 cases. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia. 2018 Jul; [PubMed PMID: 29724649]|
|||Wang MX,Smith G,Albayram M, Spinal cord watershed infarction: Novel findings on magnetic resonance imaging. Clinical imaging. 2019 Jan 31; [PubMed PMID: 30763904]|
|||Awad H,Ramadan ME,El Sayed HF,Tolpin DA,Tili E,Collard CD, Spinal cord injury after thoracic endovascular aortic aneurysm repair. Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2017 Dec; [PubMed PMID: 29019146]|
|||Chakravorty BG, Arterial supply of the cervical spinal cord and its relation to the cervical myelopathy in spondylosis. Annals of the Royal College of Surgeons of England. 1969 Oct; [PubMed PMID: 4980920]|
|||Muradov JM,Ewan EE,Hagg T, Dorsal column sensory axons degenerate due to impaired microvascular perfusion after spinal cord injury in rats. Experimental neurology. 2013 Nov; [PubMed PMID: 23978615]|
|||Martirosyan NL,Feuerstein JS,Theodore N,Cavalcanti DD,Spetzler RF,Preul MC, Blood supply and vascular reactivity of the spinal cord under normal and pathological conditions. Journal of neurosurgery. Spine. 2011 Sep; [PubMed PMID: 21663407]|