Spine Tumors and Infections

Spinal Tumor Classification - Dural Drama

Categorized by dural/cord relationship:

• Extradural (ED): Outside dura. Most common (~60%).
  • Often vertebral metastases (breast, lung, prostate), lymphoma, chordoma.
• Intradural-Extramedullary (IDEM): Inside dura, outside cord (~30%).
  • Nerve Sheath Tumors (Schwannoma, Neurofibroma), Meningioma.
  • 📌 Mnemonic: "Spinal Meninges & Nerves" (Schwannoma, Meningioma, Neurofibroma).
• Intramedullary (IM): Within cord parenchyma. Least common (~10%).
  • Ependymoma (adults, filum), Astrocytoma (children). Cord expansion.

  ⭐ Ependymomas are the most common intramedullary tumor in adults, often with a "cap sign" (hemosiderin at poles) or hemorrhage.

Key Spinal Tumors - ID Parade

• Metastases (Mets):
  • Most common spinal tumor. Location: Extradural > Intradural Extramedullary (IDEM).
  • Vertebral: Lytic (commonest), Sclerotic, Mixed. Pedicle destruction (winking owl sign).
  • MRI: T1 ↓, T2 ↑, avid enhancement.
• Meningioma:
  • Commonest IDEM in adults. Thoracic spine, older females.
  • MRI: Isointense T1/T2. Homogeneous, avid enhancement. Dural tail sign. Calcification.
• Schwannoma:
  • Second commonest IDEM. Dumbbell shape (neural foramen) characteristic.
  • MRI: T1 iso/↓, T2 ↑. Avid, often heterogeneous enhancement. Cystic changes.
• Ependymoma:
  • Most common adult intramedullary. Central. Filum (myxopapillary variant).
  • MRI: T1 iso/↓, T2 ↑. Intense, well-defined enhancement. Hemorrhage ("cap sign"). Syrinx.

  ⭐ Myxopapillary ependymoma: most common cauda equina/filum tumor.

• Astrocytoma:
  • Most common child intramedullary. Eccentric.
  • MRI: T1 iso/↓, T2 ↑. Patchy, ill-defined enhancement. Fusiform cord expansion. Poorly demarcated.

Spinal Infections - Bug Invasion

• Pyogenic Spondylodiscitis (Vertebral Osteomyelitis):
  • Most common bug: Staphylococcus aureus.
  • MRI (gold standard):
    • T1: ↓ signal (disc, vertebral bodies).
    • T2/STIR: ↑ signal (disc, vertebral bodies - edema).
    • Post-contrast T1: Enhancement (disc, bodies, paraspinal/epidural phlegmon/abscess).
  • X-ray (late, >2 wks): Disc space narrowing, endplate erosion.
• Spinal Epidural Abscess:
  • Pus in epidural space; often from spondylodiscitis. ⚠️ Medical emergency if neuro deficits.
  • MRI: Rim-enhancing collection; DWI shows restricted diffusion (pus).
• Tuberculous Spondylitis (Pott's Spine):
  • M. tuberculosis.
  • Imaging: Anterior vertebral body destruction, relative disc preservation (early), skip lesions, large paraspinal "cold" abscess (may calcify), kyphotic (gibbus) deformity.

  ⭐ In Pott's spine, involvement of multiple vertebral bodies with relative sparing of intervertebral discs is a characteristic feature, especially in early stages.

Tuberculous Spondylitis - Tubercular Trouble

• Pott's Disease: Chronic granulomatous spinal infection by M. tuberculosis.
• Patho: Hematogenous spread, targets anterior vertebral body.
• Imaging Hallmarks:
  • Vertebral destruction (anterior wedging → kyphosis/gibbus).
  • Disc space relatively preserved initially (vs. pyogenic).
  • Subligamentous spread: Anterior Longitudinal Ligament (ALL) elevation.
  • Large paraspinal "cold" abscess; calcification common.
  • Skip lesions possible.
• MRI: Best for early changes, soft tissue (abscess, cord compression).

  ⭐ Subligamentous spread under ALL is highly characteristic, unlike pyogenic spondylodiscitis (early, prominent disc destruction).

• 📌 Pott's: Paraspinous abscess, Osteoporosis, Thoracic common, Two+ vertebrae, Subligamentous.

High‑Yield Points - ⚡ Biggest Takeaways

• Metastases: Most common adult spinal tumors; vertebral body involved, pedicle destruction ("winking owl").
• Multiple Myeloma: Presents with punched-out lytic lesions or diffuse osteopenia.
• Intradural Extramedullary: Meningioma (commonest), Neurofibroma (dumbbell appearance).
• Intramedullary: Ependymoma (adults, central, syrinx), Astrocytoma (children, eccentric).
• Pyogenic Spondylodiscitis: Staph aureus common; disc space affected first, then endplates.
• Tuberculous Spondylitis (Pott's): Disc preserved initially, subligamentous spread, large paraspinal abscess, gibbus.
• Spinal Epidural Abscess: Neurological emergency; shows peripheral ring enhancement on MRI.