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)
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