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Imaging of Spinal Stroke. Institute of Neuroradiology, University of Zurich, Switzerland. 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
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Imaging of Spinal Stroke Institute of Neuroradiology, University of Zurich, Switzerland
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
T3 T8 T8 Lazorthes, G. et al. Rev Neurol 1966;115:1055-1068. Arteries supplying the spinal cord Novy, J. et al. Arch Neurol 2006;63:1113-1120.
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
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
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 2006;63:1113-1120.
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.
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 1955;18:170-188.
Th4 70 y, history aortic dissection, status after grafting, hypertension, coronary artery disease presents with acute paraplegia.
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
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
26-year-old man left-sided neck pain, acute onset lower limb weakness and difficulty voiding.
2 w follow-up 2 m follow-up Zhang J., et al. J Spinal Disord Tech. 2005; 18:277-282
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