Postinfectious Cerebellitis

Hyperammonemic Encephalopathy

• MRI
  • Focal ventral deviation of the spinal cord from the level of the inferior endplate of T4 through the mid T5 vertebral body with a C-shaped concavity along the dorsal margin of the cord at this level and likely dural defect with no CSF signal visualized along the ventral aspect of the deviated cord
  • Thin CSF signal ventral epidural collection immediately cranial and caudal to the cord contour abnormality extending throughout the thoracic spine
  • Mild multilevel degenerative disc disease with a small posterior disc bulge at T7-T8 and multilevel mild facet hypertrophy and ligamentum flavum thickening. No significant spinal canal or neural foraminal stenosis
  • No abnormal cord signal
  • No abnormal marrow signal
  • Normal alignment

• CT myelogram
  • Status post multilevel midthoracic laminectomies
  • Persistent focal ventral deviation of the spinal cord from the level of the inferior endplate of T4 through the mid T5 vertebral body with a C-shaped concavity along the dorsal margin of the cord at this level and likely dural defect with no CSF signal visualized along the ventral aspect of the deviated cord

• Spinal cord herniation

• Unlike patients with dorsal arachnoid cysts and webs, patients with ventral cord herniation will not benefit from exploration/fenestration of the dorsal thecal sac
• Given the potential overlapping imaging appearances of these entities, patients with cord herniation are at risk for surgical mismanagement
• CT myelography can be a useful problem-solving tool in these cases because a dorsal arachnoid cyst should have delayed filling with contrast material compared to the remainder of the thecal sac
• Given that cord herniation involves the spinal cord (which lives in the subarachnoid space) extending through the dura, cord herniation may be accompanied by a CSF leak, so patients with cord herniation can present with signs and symptoms of intracranial hypotension

Images