spinalcordischaemia
Table of Contents
spinal cord ischaemia / spinal TIA
see also:
Introduction
- ischaemia of the spinal cord is an uncommon presentation and may be transient (“spinal TIA”) or may be more prolonged or permanent (“spinal cord infarct”)
- only ~3% of patients with spinal cord infarcts have preceding spinal TIA
- most patients with spinal TIAs do not have a cause identified and they seem to rarely develop spinal infarct in the future
- acutely impaired blood supply may result in an acute myelopathy with onset within minutes but may be a few hours in some cases
- most patients have back or neck pain at the onset of symptoms and this is localized to the level of the lesion and ~ half were precipitated by movement which presumably compromised the blood supply to the cord 1)
- two main types:
- radicular artery territory infarct (bilateral anterior or posterior spinal artery infarcts and unilateral infarcts)
- extensive spinal cord hypoperfusion (central and transverse infarcts)
Spinal cord blood supply
- the spinal cord is supplied by 1 anterior and 2 posterior spinal arteries, which extend longitudinally in a variable fashion.
- these arteries originate from the V4 region of the vertebral arteries and anastomose at the level of the cone
- at many levels, they receive supply from the radicular arteries, which enter the canal along with the nerve roots
- each radicular artery supplies a separate functional region of the spinal arteries, particularly the anterior spinal artery
- first region extends from C1 until T3 and is supplied at the C3 level from the vertebral arteries and at the level from C6 until C7 from the cervical ascending arteries
- second region extends from T3 until T7 and sometimes receives a branch from the intercostal artery at the T7 level
- third region extends from T8 to the cone and receives a branch (Adamkiewicz artery) from the intercostal artery, most frequently between T9 and T12
- there may be a cone artery originating from the internal iliac artery (Desproges-Gotteron artery) at the L2 or L5 level
- anterior spinal artery gives rise to the central arteries, each of which enters the spinal cord to supply the anterior horn and the anterior part of the lateral column on the left or right side at each level
- most ischaemic events involve the anterior spinal artery territory, resulting in bilateral weakness and sensory loss to pain and temperature modalities while preserving vibration and position sense
- characterized by flaccidity and loss of deep tendon reflexes (if ongoing, spasticity and hyper-reflexia develop during ensuing days and weeks). Autonomic dysfunction may be present and can manifest as hypotension (either orthostatic or frank hypotension), sexual dysfunction, and/or bowel and bladder dysfunction. If C1-3 region is involved, respiration will be impaired.
- if only the anterior horns are involved (ie. incomplete anterior spinal artery syndrome) may present as either2):
- acute paraplegia (pseudopoliomyelitic form) without sensory abnormalities and without sphincter dysfunction
- painful bilateral brachial diplegia in the case of a cervical lesion (the man-in-the-barrel syndrome)
- progressive distal amyotrophy due to chronic lesions of the anterior horns; this form may be misdiagnosed as lateral amyotrophic sclerosis
- posterior spinal artery syndrome
- loss of proprioception and vibratory senses below the level of the injury and total anaesthesia at the level of the injury
- if weakness is present it is usually mild and transient;
- usually unilateral but may be bilateral
- infarction at the level of conus medullaris
- usually due to impaired Adamkiewicz artery which supplies the lower two-thirds of the spinal cord (conus medullaris)
- may be misdiagnosed as a cauda equina syndrome (CES)
- central spinal infarct (watershed infarct)
- occurs after prolonged hypotension such as post-arrest
- bilateral spinothalamic sensory deficit with sparing of the posterior columns
- motor deficit and sphincter dysfunction are usually absent
Spinal cord TIA
- these are mostly cervical and are probably caused by a transient impaired blood supply to the cord
- the cause is not found in over half of cases, other cases may be due to:
- compression or kinking of a radicular artery or spinal artery
- these tend to be associated with mechanical movement of the neck and are often preceded with upper chest/back or neck pain
- may also be caused by a cervical disc prolapse
- arterial hypotension
- arterial steal effect during upper limb exercise such as gardening causing an intermittent claudication type effect
- aortic dissection may cause a transient ischaemia
- rare: hyperextension of the thoracic spine (some of these this can be permanent):
- novice surfers (“surfers myelopathy”)
- prolonged hyperextension in yoga or pilates
- adolescents with acute hyperextension of the back eg. gymnastics
- generally present with acute pain followed by bilateral arm and leg weakness / paraethesiae which is often painful
- resolve within hours
- DDx includes periodic paralysis (eg. hypokalaemic, hyperkalaemic, thyrotoxic)
Spinal cord infarction
- these may be caused by:
- aortic surgery has a 2-8% risk for spinal cord ischaemia
- embolism
- atherosclerosis
- prolonged hypotension
- iatrogenic surgical injury to blood supply to cord or intra-operative spinal hypoperfusion or prolonged hypoxia
- eg. AAA repair, aortic dissection repair, CABG, lung cancer surgery
- prolonged hypoxia during rib retraction during thoracotomy
- posterior sectioning of intercostal vessels for chest wall resection
- direct reduction of perfusion during aortic cross-clamping, injury to artery of Adamkiewicz or other tributaries during resection of tumor
- dissection and routine ligation of intercostal vessels
- vertebral artery occlusion
- abdominal aortic aneurysm (AAA) - especially if affects the Adamkiewicz artery
- NB. infrarenal occlusion of the aorta in humans does not cause paraplegia because spinal cord at the thoracolumbar level is supplied by the artery of Adamkiewicz which arises from left posterior intercostal arteries, mostly between T8 and L1
spinalcordischaemia.txt · Last modified: 2024/09/23 06:26 by wh