Neurosurgery notes/Spine/Spinal vascular diseases/Fibro-cartilagenous stroke

Fibro-cartilagenous stroke

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Spinal vascular diseases

Definition

  • The migration of fibrocartilaginous nucleus pulposus material through the nearby vasculature to embolize into one of the spinal cord vessels

Numbers

  • female predominance (63.5% female vs 36.5% male)
  • Age
    • Range 14-78 years
    • Average 41years
      • Half of the patients were under 40 years of age

Clinical presentation

  • Like any spinal cord infarction
    • onset of dull transient neck or back pain followed by or accompanying a syndrome of myelopathy.
  • Has a sensory level
    • A pathognomonic clinical finding for anterior spinal artery infarction is the sparing of proprioception and vibratory sensation below the sensory level.
  • bladder and/or bowel dysfunction
  • Paraplegia or Quadriplegia
  • Possible respiratory compromise for higher than C5 cervical cord disease.
  • Temporal
    • Infarction versus Inflammatory
      • Infarction has rapid course of symptoms to nadir, typically over hours.
    • A characteristic clinical symptom that may point to FCE as a cause for this spinal cord infarction is a temporal correlation with a minor or even unnoticed incident that triggers the increased intra-disc or intra-vertebral body pressure as described above in the “Mechanisms” section.
  • In our review of tissue diagnosed FCE
    • 61% of the cases presented following such an event.
    • The duration between this trigger event and the onset of symptoms varied from minutes to days, but averaged at 2.4 days.
    • The weakness was asymmetric in 15% of the cases.
    • There was associated neck or back pain in 76%.
    • Nearly 40% of deaths were due to preventable respiratory complications ( pulmonary embolism 20%, pneumonia 17%, aspiration 2%).

Localization

  • Spine (most commo)
  • Lung
  • Brain
  • Vertebrae and ribs

Clinical anatomy

  • Disc
    • In adults
      • Largest avascular structure in the body
        • It has also been postulated that remnants of vascular channels can persist in the inter-vertebral disc beyond the second decade of life.
      • Normally
        • Neo-vascularization reappears in the normal adult inter-vertebral disc at the circumferential edges at around 50 years of age.
      • Degenerative disc disease
        • Neo-revascularization
          • occur earlier than 50
          • is more pronounced
    • In neonates
      • highly vascular structure with large thin walled blood channels running mainly in the cartilage end plate
      • Vascular tissue
        • quickly starts to regress after 2 months old
        • By age 11–16 years will have completely disappeared
    • Can indeed be the source of embolic material as evidenced by histopath
    • Annulus fibrosus
      • Outer
      • Mesodermally
    • Nucleus pulposus
      • Endodermally
  • Vertebral body and the spinal cord
    • have a fixed blood supply throughout life.
    • Spinal cord
      • from medulla to conus has
        • One anterior longitudinal spinal arteries
        • Two posterior longitudinal spinal arteries
      • Radicular arteries (Ka) supply both the spinal cord and then vertebral body
  • Schmorl’s nodes
    • Focal masses of fibrocartilage found within the bone of vertebrae
    • lie in close proximity to the vascular supply of the vertebral body.
    • Common
      • present in 38% to 79% of the adult population
      • Developed due to herniation of nucleus pulposus material into the body of the adjacent vertebra as a consequence of degenerative disc changes

Mechanisms

  • The fibrocartilaginous disc material gains vascular access via any of three pathways:
    • Revascularization of the inter-vertebral disc
      • by
        • Normal aging
        • Degenerative disc disease especially herniation;
      • Initial trigger for break off of fibro-cartilaginous nucleus pulposus material is increased intra-disc or intra-vertebral body pressure by axial loading forces applied to the spine
        • Such as
          • Heavy lifting
          • Straining
          • Falls or minor traumatic events to the neck and back.
    • Formation of Schmorl’s nodes
    • Persistence of inter-vertebral disc vasculature into adulthood.
  • Once in the vasculature, the fibrocartilaginous embolus can enter the spinal cord via either an
    • Arterial route
      • The fibrocartilaginous material travels retrograde through the arterial system supplying the spinal column, to reach the radicular artery which carries it into the spinal cord arterial system in a normal anterograde fashion
    • Venous route
      • The fibrocartilaginous material gain access to the venous system of the spinal column and travel initially in a normal anterograde fashion where they would enter the caval system, but then travel retrograde to the venous plexus of Batson and the parenchyma of the spinal cord.
      • Retrograde flow in the venous route is postulated to be aided by concomitant increases in the intra-thoracic or intra-abdominal pressure as may occur with lifting, straining, coughing or valsava

Imaging

Sagital (a) and axial (b) T2 sequence MRIs showing hyper-intense lesions in the distribution of the Anterior spinal artery in a 63-year-old man clinically diagnosed with spinal cord infarction due to FCE. The lesions are characteristically opposite to disc protrusions at T4–5 and T6–7 thoracic levels.
Sagital (a) and axial (b) T2 sequence MRIs showing hyper-intense lesions in the distribution of the Anterior spinal artery in a 63-year-old man clinically diagnosed with spinal cord infarction due to FCE. The lesions are characteristically opposite to disc protrusions at T4–5 and T6–7 thoracic levels.

Reference