Compression of Central Nervous System

• Compression may arise within or outside the spinal cord.
• Causes of compression include:
  • Abscess
    • Abscesses may be extradural, vertebral or intervertebral.
  • Fracture of vertebral bodies
    • Traumatic fracture
    • Pathological fracture, due to abscess, metabolic causes or neoplasia.
  • Neoplasia
  • Intervertebral disk disease
    • Prolapsed disks can cause acute or chronic compression.
  • Malformations
    • Wobbler horses
      • Caused by stenotic myelopathy.
      • The vertebral canal narrows due to malformation and malarticulation of the cervical vertebrae (usually C3-C4)
    • Cervical vertebral malformation-malarticulation in dogs has a similar pathogenesis to wobbler horses
    • Atlantoaxial subluxation of toy dogs.
      • A hypoplastic dens leads to subluxation.

Pathology

• Lesions associated with focal compressive spinal cord injury are similar regardless of cause.

Gross

• The spinal cord may be indented or flattened.

Histological

• The myelin sheath may balloon in all funiculi.
• Axonal swelling and loss is seen.
• Macrophages appear within days and remove debris within myelin "digestion chambers".
• Neuronal loss, gliosis, malacia and oedema may also be apparent.