What are the consequences of an extra disc in the low back?

Consequences of an Extra Disc in the Low Back

An extra disc in the low back (supernumerary lumbar disc) typically does not cause symptoms on its own and is not considered a pathological condition requiring treatment unless it contributes to specific symptoms or structural abnormalities.

Understanding Extra Discs in the Low Back

An extra disc in the lumbar spine represents an anatomical variant rather than a pathological condition. This is important to understand because:

• Anatomical variants are common in the spine and often discovered incidentally on imaging
• Many imaging findings, including disc abnormalities, are present in asymptomatic individuals
• The presence of an extra disc alone does not correlate with symptoms

Clinical Implications

Potential Consequences

• Typically asymptomatic: Most extra discs do not cause symptoms and require no treatment
• Altered biomechanics: May change load distribution across the lumbar spine
• Potential confusion in imaging interpretation: May complicate level identification during diagnostic workup
• Surgical planning considerations: Important for surgeons to identify when planning procedures

When an Extra Disc Might Become Problematic

An extra disc might become clinically relevant when:

1. It undergoes degenerative changes similar to normal discs
2. It contributes to foraminal stenosis or nerve compression
3. It affects the biomechanical stability of the spine

Diagnostic Considerations

The American College of Radiology notes that imaging findings must be correlated with clinical symptoms 1:

• MRI is highly sensitive but has low specificity for spinal pain
• Disc abnormalities are common in asymptomatic individuals
• A substantial number of people without back pain have imaging abnormalities 1
• Disc protrusion prevalence increases with age (29% at age 20 to 43% at age 80) even in asymptomatic individuals 1

Management Approach

If an extra disc is associated with symptoms:

1. Conservative management first: Similar to standard approaches for degenerative disc disease

   • Physical therapy focusing on core strengthening
   • NSAIDs for short-term pain relief
   • Activity modification

2. Interventional options: Consider only if conservative measures fail

   • Epidural steroid injections for radicular symptoms
   • Minimally invasive procedures may be considered in select cases

3. Surgical considerations: Rarely indicated unless specific criteria are met

   • Surgery should be considered only for cauda equina syndrome, progressive neurological deficits, significant motor deficits, or persistent radicular symptoms despite 6-12 weeks of conservative treatment 2
   • Fusion is not recommended for isolated findings without instability 2

Important Caveats

• The Journal of Neurosurgery guidelines emphasize that degenerative changes identified on MRI may occur in asymptomatic patients and cannot be used as the sole justification for surgery 1
• Discography is not recommended as a stand-alone test for treatment decisions in patients with low back pain and abnormal imaging studies 1
• Routine imaging for nonspecific back pain should be avoided, as it does not improve outcomes and may lead to unnecessary interventions 1, 2

Conclusion

An extra disc in the low back is generally an incidental finding rather than a cause for concern. Management should focus on symptoms rather than imaging findings, with conservative approaches as first-line treatment. Surgical intervention should be reserved for specific indications and not based solely on the presence of an extra disc.