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Thoracolumbar Intervertebral Disc Prolapse N043

Last amended 
9 July 2023
Current RMA Instruments
Reasonable Hypothesis SOP
68 of 2023
Balance of Probabilities SOP
69 of 2023
Changes from previous Instruments

SOP Bulletin 237

ICD Coding

ICD-10-AM codes M51.0, M51.1 or M51.2

Brief description

Between each pair of vertebral bodies in the spine there is a cushion-like structure known as an intervertebral disc.  These discs (help to) hold the vertebrae together, allow movement between vertebrae and provide shock absorption in the spine.  Discs are comprised of an outer fibrous layer (the annulus fibrosis) surrounding an inner gel-like centre (the nucleus pulposus).  Injury or degeneration of a disc can lead to tearing of the outer layer and protrusion/herniation of the disc contents into the spinal canal.  This can result in local pain and/or nerve compression.  Thoracolumbar intervertebral disc prolapse can occur in isolation (typically in a younger person), or as part of a wider spinal degenerative process. The thoracolumbar intervertebral disc prolapse (IVDP) SOP is appropriate for isolated (single level) disc disease/injury.  The thoracolumbar spondylosis SOP should usually be applied (instead, not as well) when more generalised degeneration in the thoracolumbar spine is present (see further information, below).

Confirming the diagnosis:

To confirm the diagnosis there needs to be evidence on radiological imaging of disc prolapse (i.e. more than just bulging of an intact disc) together with clinical manifestations in the form of:

  • pain or stiffness at the involved level; or
  • symptoms and signs of nerve root compression; or
  • clinical evidence of spinal cord compression; and
  • the clinical manifestations need to be attributable to the disc prolapse and not some other pathology. 

Either symptoms/signs alone or radiological evidence alone is insufficient for diagnosis, both components must be present.

This SOP applies when disc prolapse occurs in isolation (i.e. single level disease without more widespread degenerative changes (osteophytes, facet joint arthritis).  More generalised spinal degenerative disease is more appropriately covered by the thoracolumbar spondylosis SOP.

The relevant medical specialist is an orthopaedic surgeon or neurologist.

Additional diagnoses covered by the SOP
  • Thoracolumbar intervertebral disc herniation
  • Thoracolumbar intervertebral disc protrusion
  • Extrusion or ruptured thoracolumbar intervertebral disc
Related conditions that may be covered by the SOP (further information required)
  • Slipped disc
  • Sciatica
Conditions not covered by SOP
  • Bulging intervertebral disc (generally within normal range – not a disease)
  • Thoracic or lumbar spondylosis*
  • Musculoligamentous strain or sprain of the thoracic or lumbar spine* - sprain and strain SOP  
  • Schmorl’s nodes
  • Scheuermann’s disease*

* another SOP applies

# non-SOP condition

Clinical onset

To establish clinical onset the diagnosis first needs to be confirmed and symptoms need to be located at the right level of the thoracolumbar spine and attributable to a disc prolapse.  Clinical onset can then be backdated to the time of first onset of relevant symptoms.  This may have been at the time of, or shortly after, an acute injury, provided the same symptoms of pain or nerve entrapment have persisted from the time of injury.

Clinical worsening

The clinical course is variable and symptoms may progress, remain or diminish over time.  Initial treatment is generally conservative and focused on pain relief.  Injections into the spine do not have any long term benefits.  Surgery (discectomy) is usually a last resort and is more likely to be effective to alleviate neurological symptoms (from nerve root compression) than for local pain.  Surgery is unlikely to provide any benefit in the longer term (5 to 10 years).  Worsening of prolapse can occur with further injury or continuation of activity that led to the problem.  This may be manifest by a persisting increase in symptoms or radiological evidence of more pronounced prolapse.  Progression to more widespread degeneration may be better dealt with as an onset of thoracolumbar spondylosis rather than a worsening of thoracolumbar IVDP.

Further comments on diagnosis

Thoracolumbar intervertebral disc prolapse may be an initially acute event, in which there is sudden onset of symptoms at a particular level in the spine.  This typically occurs in young adults.  It needs to be distinguished from intervertebral disc degeneration as part of a wider process (thoracolumbar spondylosis).  Generally one or other diagnosis will apply, but in certain circumstances both diagnoses may apply to the same area of the spine.

Note that IVDP is a factor in the spondylosis SOPs but not vice versa.

When degenerative disc disease with prolapse is present:

1. If thoraolumbar IVDP predates thoracolumbar spondylosis:

IVDP may give rise to disc degeneration at the involved level.  When degenerative disc disease is present and there is a history of old thoracolumbar IVDP at the involved level (predating the spondylosis), a diagnosis of thoracolumbar spondylosis (identifying the region involved) should be made.  Causes of thoracolumbar IVDP will then still be considered as potential causes for the diagnosed thoracolumbar spondylosis, via propagation.

2. If thoracolumbar IVDP postdates the onset of thoracolumbar spondylosis:

Protrusion/rupture/herniation of a thoracolumbar intervertebral disc that develops in the setting of wider degenerative change is usually part of the degenerative process and is covered by a diagnosis of thoracolumbar spondylosis.  A separate diagnosis of thoracolumbar IVDP will generally not be warranted.

If degenerative disease is present and there is then a separate event, e.g. a trauma, that leads to the onset of new disc prolapse, then in that setting an additional diagnosis of thoracolumbar IVDP may be warranted.