Cauda equina syndrome
Background
- Compression of the cauda equina nerve roots (below the conus medullaris, typically L1-L2)
- A surgical emergency — delayed treatment (>48 hours) associated with permanent neurologic deficit[1]
- Most common cause: large central lumbar disc herniation (70%)
- Other causes: spinal epidural abscess, tumor, spinal epidural hematoma, spinal stenosis
Clinical Features
- Red flags (must screen for in any patient with back pain):
- Urinary retention or incontinence (most consistent finding; post-void residual >200 mL)
- Fecal incontinence or decreased rectal tone
- Saddle anesthesia (perineal/perianal numbness)
- Bilateral lower extremity weakness or radiculopathy
- Progressive neurologic deficit
- Sexual dysfunction
- Low back pain is present in most cases but may be minimal
- Bilateral sciatica is more concerning than unilateral
- Decreased ankle reflexes bilaterally
Differential Diagnosis
- Conus medullaris syndrome (upper motor neuron signs, more symmetric)
- Lumbar disc herniation without cauda equina involvement
- Spinal cord compression (non-traumatic)
- Epidural abscess
- Transverse myelitis
- Guillain-Barré syndrome
Evaluation
- MRI lumbar spine with and without contrast — imaging modality of choice[2]
- Emergent MRI — do not delay for other workup
- CT myelography if MRI unavailable or contraindicated
- Post-void residual (bladder scan) — >200 mL supports diagnosis
- Rectal exam — assess sphincter tone (decreased in CES)
- Labs: CBC, ESR/CRP (if infection suspected), coagulation studies
Management
- Emergent neurosurgical or spine surgery consultation
- Surgical decompression within 24-48 hours of symptom onset improves outcomes
- Earlier decompression (<24h) associated with better recovery of bladder function
- If epidural abscess suspected: blood cultures, IV antibiotics before imaging
- Pain management: NSAIDs, acetaminophen, opioids as needed
- Foley catheter if urinary retention present
- Dexamethasone 10 mg IV if tumor-related compression suspected
Disposition
- Admit for emergent surgical evaluation
- Do NOT discharge patients with suspected CES — missed diagnosis carries significant medicolegal risk[3]
See Also
References
- ↑ Ahn UM, et al. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. Spine. 2000;25(12):1515-1522. PMID 10851100.
- ↑ Fairbank J, Mallen C. Cauda equina syndrome: implications for primary care. Br J Gen Pract. 2014;64(619):67-68. PMID 24567577.
- ↑ Todd NV. Cauda equina syndrome: the timing of surgery probably does matter. Br J Neurosurg. 2005;19(4):301-306. PMID 16455534.