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Discitis and Osteomyelitis


  • Usually the result of blood–borne agents
    • Especially from lung and urinary tract
    • Average age of onset is in children around 6 years
    • Most common pathogen is staphylococcus
    • Also Streptococcus
    • Gram-negative rods in IV drug abusers or immunocompromised patients
      • E. Coli
      • Proteus
      • Non-pyogenic
        • Tuberculosis
        • Coccidioidomycosis
  • May occur as a result of invasive procedure
    • Surgery
    • Discography
    • Myelography
  • Pathogenesis
    • In children, probably begins in still vascularized disc
    • In adults, in anterior inferior corner of vertebral body with spread across disk to adjacent vertebral endplate
  • Site of involvement
    • L3/4
    • L4/5
    • Unusual above T9
    • Usually involvement of one disk space (occasionally 2)
  • Bacteria destroy disk and both contiguous end-plates
  • Imaging Findings
    • Narrowing and destruction of an intervertebral disk
      • Earliest plain film sign
    • Indistinctness of adjacent endplates with destruction
    • Often associated with bony sclerosis of the two contiguous vertebral bodies
    • Paravertebral soft tissue mass
    • Endplate sclerosis (during healing phase beginning anywhere from 8 weeks to 8 months after onset)
    • Bone fusion after 6 months to 2 years

Frontal and lateral radiographs of the thoracic spine demonstrate destruction of the endplates
of two contiguous vertebral bodies with considerable endplate sclerosis, findings characteristic of discitis

  • MRI
    • Decreased marrow intensity on T1-weighted images in two contiguous vertebrae
    • High signal intensity on T2
      • Because of associated edema
    • Disk space and paravertebral soft tissues enhance on MRI
  • Clinical
    • Pain is present if disease  is acute
    • Point tenderness
    • Malaise
    • Irritability in children
    • Referred hip pain
    • Inability to bear weight
    • Course of discitis is frequently more benign in children than adults
      • Disk space is narrowed but no destruction of contiguous vertebral bodies
  • Osteomyelitis of the vertebral body
    • Usually the result of discitis
    • But can occur from direct involvement from hematogenous dissemination to body
    • MRI findings are similar to discitis
  • Bone scan will be positive
  • Gallium scan or Indium-111 scan will be positive
  • Renal spondyloarthropathy
    • May resemble discitis
    • Usually involves cervical spine
    • Destruction of disk space and adjacent vertebral bodies
    • Signal on T2 is low rather than high
    • No clinical evidence of infection
  • Complication of disease
    • Kyphosis
  • Treatment
    • Bone fusion after 6 months to 2 years

Radiologic Clinics, Imaging of the Spine, 1991
The Requisites, Neuroradiology
Dahnert, 4th Ed