Imaging of Spinal Stroke

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Imaging of Spinal Stroke
Institute of Neuroradiology, University of
Zurich, Switzerland
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Spinal cord infarction frequency

• not established, large clinical investigations
  are lacking
• 1 of all strokes, annual incidence of 12 in
  100,000
• occurrence rate at death 0.23 (9/3784)
  autopsies
• small arterial vessels with low flow rates
• extensive collateral network between the main
• medullary arteries at the spinal cord surface

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Arteries supplying the spinal cord
Novy, J. et al. Arch Neurol 2006631113-1120.
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Spinal cord infarction clinical symptoms

• acute onset, severe back pain
• bilateral weakness, paresthesias and sensory loss
• loss of sphincter control evident within a few
  hours
• confounding diagnoses (acute transverse
  myelopathy, viral myelitis, Guillain-Barré, mass
  lesions), develop over 24-72 h with slower
  evolution, rarely painful
• epidural/subdural hematomas need exclusion by MRI
• symptoms and degree of deficits depend on the
  affected level and size of the vascular
  territories

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Spinal cord infarction etiology

• Classification according to location of vascular
  pathology
• intrinsic cord vessels arteritis (SLE,
  granulomatous),
• emboli of atheroma, disc compression
• ASA occlusion arteritis, trauma, spondylosis,
  adhesive
• arachnoiditis, spinal DSA, anesthesia
• aortic disease dissecting aneurysm, surgery,
  aortic
• thrombosis, atherosclerotic embolization
• uncommon causes decompression sickness,
  circulatory
• failure (cardiac arrest, hypotension)
• no identifiable cause 50-75 of cases

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Spinal cord infarction pathogenesis

• a) mechanical triggering factor
• - anterior, posterior
• - unilateral or bilateral coincides with the
  level of the involved radicular artery
• b) hypoperfusion factor
• - central and transverse
• involve several levels in the thoracolumbar
  region

Novy, J. et al. Arch Neurol 2006631113-1120.
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Imaging of spinal cord infarction MRI

• T2-w imaging not sensitive in the first hours
  after
• symptoms onset (abnormal signal in 45-67)
• snake-eyes on axial T2-w images indicate
• involvement of the ventral gray matter
• contrast enhancement in the subacute stage
• hemorrhagic transformation seen as hyperintense
  signal
• on the T1-weighted images.

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Vulnerability of spinal cord to anoxia

• The gray matter is predominantly affected due to
  its high vulnerability to anoxia
• Motorneurons lose electrophysiological reflex
  responses 1.5 times faster as interneurons and 3
  times faster as dorsal column neurons
• terminal ischemia (failure of conduction) occurs
  after 20 minutes of asphyxia
• abrupt anoxia shortens the survival time of all
  structures

Gelfan S, Tarlov IM. J Neurophysiol
195518170-188.
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Th4
70 y, history aortic dissection, status after
grafting, hypertension, coronary artery disease
presents with acute paraplegia.
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DW-MRI of the spinal cord

• Challenges
• fine structure and elasticity of the SC
• requirement for high in-plane resolution
• Artifacts related to motion
• CSF pulsations
• respiratory motion
• swallowing
• Spatially rapid changes in susceptibility

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Imaging of spinal cord infarction DW-MRI

• demonstration of intracelullar, cytotoxic edema
• diffusion abnormality reported 4-30 h following
  onset, always in the presence of T2-w signal
  abnormality
• decrease (75) of the calculated ADC values
• in follow-up performed 5-20 d following
  infarction, early normalization of ADC with
  persistent T2-w abnormality

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26-year-old man left-sided neck pain, acute
onset lower limb weakness and difficulty voiding.
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2 w follow-up
2 m follow-up
Zhang J., et al. J Spinal Disord Tech. 2005
18277-282
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Zhang J, et a. JMRI 200726848-854
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Spinal cord infarction

• Prognosis and outcome
• substantial motor, sensory, bladder and bowel
  dysfunction
• short-term mortality rate 20-25
• vascular, infectious and other medical
  complications
• long term prognosis is determined by the degree
  of cord
• sparing (unilateral infarcts have better
  prognosis)
• early diagnosis may contribute to improved
  patient
• management

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