What are the symptoms of Cauda equina syndrome?

Symptoms of Cauda Equina Syndrome

Cauda equina syndrome (CES) is characterized primarily by urinary retention (90% sensitivity), saddle anesthesia, bilateral motor weakness of the lower extremities, and fecal incontinence, requiring urgent surgical decompression to prevent permanent neurological damage.

Key Clinical Features

Cardinal Symptoms

• Urinary retention/dysfunction - The most frequent and sensitive finding (90% sensitivity) 1
• Saddle anesthesia - Numbness in the perineal/genital region 1, 2
• Bowel dysfunction - Including fecal incontinence or decreased rectal tone 2
• Bilateral lower extremity symptoms - Though can sometimes present unilaterally 3
  • Motor weakness
  • Sensory changes/numbness
  • Pain (sciatica)
• Low back pain - Often present but nonspecific 1, 2

Additional Symptoms

• Decreased rectal tone (often a late finding) 2
• Sexual dysfunction 1
• Absent lower limb reflexes 1

Etiology and Prevalence

CES is rare, with an estimated prevalence of only 0.04% among patients with low back pain 1. The most common causes include:

1. Lumbar disc herniation - Most commonly at L4-L5 and L5-S1 levels 1
2. Neoplasms - Both primary and metastatic 4
3. Trauma - Including vertebral dislocations 5
4. Infection/inflammation 1
5. Spinal stenosis 1
6. Hemorrhage 1

Diagnostic Challenges

Atypical Presentations

• May present with unilateral symptoms initially, making diagnosis challenging 3
• Can rarely present as abdominal pain 6
• Postoperative CES symptoms may be mistaken for common postoperative findings 2

Red Flags Requiring Urgent Evaluation

• New-onset urinary symptoms in the context of low back pain or sciatica 1
• Progressive neurologic deficits 1
• Refractory back/leg pain, especially with urinary retention 2

Diagnostic Approach

When CES is suspected, urgent imaging is required:

• MRI lumbar spine without contrast is the preferred initial study 1
• CT lumbar spine without contrast can be used if MRI is unavailable 1

Clinical Significance

CES represents a true neurological emergency. Without prompt surgical decompression, patients may suffer permanent:

• Paralysis
• Bowel/bladder incontinence
• Sexual dysfunction
• Chronic pain

The probability of CES in patients with low back pain but without urinary retention is approximately 1 in 10,000 1, highlighting the importance of this key symptom in the diagnostic process.