Cauda equina syndrome is compression of the bundle of nerve roots at the lower end of the spinal canal, most often by a large central disc herniation. It is a surgical emergency, since delay can leave permanent leg weakness and loss of bladder, bowel and sexual function.
Key symptoms
- Low back pain with pain in one or both legs
- Numbness of the buttocks, genitals and inner thighs (saddle anesthesia)
- Trouble starting urination, retention or overflow incontinence
- Bowel incontinence or constipation and sexual dysfunction
- Leg weakness
What you find on exam
- Saddle area sensation to light touch and pinprick
- Lower limb strength, sensation and reflexes
- Rectal exam for anal tone and sensation
- Post-void residual with a bladder scanner
Tests
- Emergency MRI of the lumbosacral spine
- CT myelogram if MRI cannot be done
- Post-void residual over about 200 mL supports retention
- Blood count and inflammatory markers if infection or tumor is possible
Treatment basics
- Urgent neurosurgical or spine referral
- Surgical decompression, ideally within 48 hours of onset
- Bladder catheter for retention
- Pain control and rehabilitation; dexamethasone and oncology care if a tumor is the cause
Red flags
- New urinary retention or incontinence with back pain
- Saddle numbness
- Weakness in both legs or rapidly worsening leg weakness
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.