What should I do if I suspect cauda equina syndrome or a severe herniated disc?

Management of Suspected Cauda Equina Syndrome or Severe Herniated Disc

If you suspect cauda equina syndrome (CES) or a severe herniated disc, obtain an emergency MRI within 1 hour of presentation and arrange urgent surgical consultation, as delays in diagnosis and treatment can lead to permanent neurological damage and poor quality of life outcomes. 1, 2

Recognition of Red Flags

True Red Flags (Early Warning Signs)

• Bilateral radiculopathy (bilateral radicular pain and/or sensory disturbance or motor weakness) 3
• New changes in bladder function with preserved control (hesitancy, poor stream, urgency) 3, 1
• Subjective or objective loss of perineal sensation 3
• Progressive neurological deficits in the legs 3

White Flags (Signs of Late, Often Irreversible Damage)

• Complete urinary retention or incontinence 3
• Fecal incontinence 3
• Complete perineal anesthesia 3
• Patulous anus (reduced anal tone) 3, 1

Diagnostic Algorithm

1. Targeted Physical Examination:

   • Assess perineal/saddle sensation
   • Check anal tone
   • Evaluate lower extremity strength, sensation, and reflexes
   • Note that urinary retention has 90% sensitivity for CES 1

2. Immediate Imaging:

   • First choice: MRI lumbar spine without contrast - gold standard 3, 1
   • If MRI unavailable: CT lumbar spine without IV contrast (≥50% thecal sac effacement on CT predicts significant spinal stenosis) 3
   • For MRI-incompatible patients: CT myelography 3

3. Surgical Referral:

   • Urgent surgical consultation if any red flags are present 1, 2
   • Do not delay for imaging results if clinical suspicion is high 3

Treatment Approach

• Timing is critical: Surgical decompression should be performed as an emergency, ideally within 48 hours of symptom onset 4
• Better outcomes are associated with surgery at the Incomplete CES (CESI) stage before progression to Complete CES with Retention (CESR) 3
• Even with delayed presentation, surgery within 12-72 hours post-CESR may still improve outcomes 3

Important Considerations

• CES is rare (0.04% of patients with low back pain) but devastating if missed 1
• Most common cause is lumbar disc herniation (45% of cases), particularly at L4-L5 and L5-S1 levels 3, 1, 4
• Other causes include neoplasm, infection/inflammation, spinal stenosis, and hemorrhage 3, 5
• No single symptom or sign has sufficient positive predictive value for diagnosing CES; a combination of symptoms must be evaluated 1
• MRI cannot diagnose CES (which is a clinical diagnosis) but can identify cauda equina compression 3
• Recovery of bladder function may be slow (months to years), but long-term outcomes can be favorable with proper management 6

Pitfalls to Avoid

• Do not wait for complete urinary retention or perineal anesthesia to diagnose CES - these are late signs with poor prognosis 3
• Do not delay MRI - it should be performed within 1 hour of presentation 2
• Do not attribute symptoms solely to common back pain without thorough evaluation of red flags 5
• Do not catheterize patients before neurological assessment as this may mask urinary retention 3