What are the symptoms of cauda equina syndrome?

Symptoms of Cauda Equina Syndrome

The most critical symptoms of cauda equina syndrome are urinary retention (90% sensitivity), bowel dysfunction, saddle anesthesia, and bilateral motor weakness of the lower extremities. 1

Core Clinical Presentation

Primary Symptoms

• Urinary dysfunction

  • Urinary retention is the most sensitive finding (90% sensitivity)
  • New-onset urinary symptoms in context of low back pain require urgent evaluation

• Bowel dysfunction

  • Fecal incontinence
  • Decreased rectal tone (often a late finding)

• Sensory abnormalities

  • Saddle anesthesia (numbness in perineal/genital region)
  • Bilateral sensory changes in lower limbs

• Motor deficits

  • Bilateral lower extremity weakness
  • Motor deficits at multiple levels

• Pain patterns

  • Low back pain (most common physical finding)
  • Sciatica (radiating pain below knee)

• Sexual dysfunction

  • Impaired sexual function

Associated Findings

• Absent or diminished lower limb reflexes 1
• Progressive neurological deficits
• Symptoms refractory to standard pain management

Etiology and Pathophysiology

Cauda equina syndrome results from compression of the sacral and lumbar nerve roots within the vertebral canal. The most common causes include:

1. Lumbar disc herniation (most frequent at L4-L5 and L5-S1 levels)
2. Neoplasms (primary or metastatic)
3. Infection or inflammation
4. Spinal stenosis
5. Hemorrhage 1, 2

The pathophysiology involves direct mechanical compression of nerve roots and potential venous congestion or ischemia of the cauda equina 3.

Diagnostic Considerations

Red Flags

• In patients without urinary retention, the probability of cauda equina syndrome is approximately 1 in 10,000 1
• Postoperative spine patients with back/leg pain refractory to analgesia plus urinary retention require high suspicion 3
• New-onset urinary symptoms with low back pain or sciatica warrant urgent MRI assessment 1

Diagnostic Approach

1. Focused neurological examination including:

   • Perineal/saddle sensation
   • Rectal tone assessment
   • Lower extremity motor strength
   • Reflexes
   • Bladder function assessment

2. Imaging:

   • MRI lumbar spine without IV contrast is the preferred initial study
   • CT can be used if MRI is unavailable (50% thecal sac effacement on CT predicts significant spinal stenosis) 1

Management Implications

When cauda equina syndrome is diagnosed, urgent surgical decompression of the spinal canal is required to prevent permanent neurological damage 3. Delayed diagnosis and treatment can lead to permanent disability and significant medicolegal consequences 4.

Common Pitfalls

1. Attributing early signs of cauda equina syndrome to common postoperative findings
2. Failing to recognize subtle initial presentations
3. Delaying imaging in patients with new urinary symptoms and back pain
4. Not maintaining high suspicion in patients with multiple neurological deficits

Remember that cauda equina syndrome is rare (approximately 0.04% among patients with low back pain) but represents a true spinal emergency requiring prompt recognition and intervention 1.