Epidural block or epidural steroid injection is a common technique to relieve chronic spinal pain. It may be Lumber Epidural Block, Caudal Epidural Block, Cervical Epidural Block or Thoracic Epidural Block depending on the site of intervention.
It reduces inflammation, blocks transmission of nociceptive C-fibre input and prevents ectopic discharge from axon & dorsal root ganglion. Immediate relief is more than 85% but long-term relief is nearly 50%. Earlier it is done long-term relief is more. It may be done through Lumber or Caudal approach, later being slightly more effective. Most of the studies showed positive results for short-term and long-term pain relief. Best results are obtained in disc herniation with poor outcome in non-specific neck/back pain.
Here non-ionic water-soluble radio-opaque dye is injected in the epidural space under fluoroscopy and distribution of dye is noted. Normal Epidurogram looks like an inverted Christmas tree where dye enters into the dural extension of each nerve root. In cases of nerve root oedema/inflammation or epidural fibrosis the dye does not enter into the root / filling defect in epidural spread of dye. Epidural fibrosis is better diagnosed with Epidurogram than CT/MRI. Epidural fibrosis may account for as much as 20% to 36% of all cases of failed back surgery syndrome (FBSS).
Epidurolysis/ epidural adhesiolysis/ neuroplasty is done in epidural fibrosis with normal saline/hypertonic saline with/without hyaluronidase. It may be done with Racz catheter after performing an Epidurogram. Epidural fibrosis is seen in failed back surgery syndrome or in post-inflammatory adhesion following extrusion/ sequestration of nucleus pulposus.