Cauda equina syndrome
Cauda equina syndrome is compression of the lumbosacral nerve roots below the spinal cord causing saddle anesthesia, bladder or bowel dysfunction, bilateral leg weakness with areflexia, and low tone, most often from a large central lumbar disk herniation. It is a surgical emergency diagnosed by emergent MRI of the lumbar spine and treated with urgent decompression.
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What this article covers
- Overview
Definition: cauda equina syndrome is compression of the bundle of lumbosacral nerve roots that occupies the spinal canal below the termination of the spinal cord, producing saddle sensory loss…
- Epidemiology
Uncommon but critical: one of the three most common atraumatic spinal emergencies, alongside spinal epidural abscess and spontaneous spinal epidural hematoma, and clinicians who see it first…
- Risk factors
Large central or paracentral disk herniation: the dominant risk factor, most often at L4-L5 or L5-S1.
- Pathophysiology
Anatomic substrate: the spinal cord terminates at the conus medullaris (typically around the L1-L2 vertebral level in adults), below which the canal contains only the cauda equina, a bundle of lumbar…
- Clinical features
No single lab or imaging value defines it; diagnosis rests on a clinical symptom-and-sign complex confirmed by imaging: the constellation below is the basis for suspecting and diagnosing cauda equina syndrome.
- Differential diagnosis
Conus medullaris syndrome: compression at the very tip of the spinal cord, presenting with a mix of upper and lower motor neuron signs and more symmetric, earlier sphincter involvement; MRI localizes…
- Diagnosis
Established by MRI showing a compressive lesion of the cauda equina correlating with the clinical syndrome: the diagnosis is confirmed when MRI demonstrates a compressive lesion (most often a large…
- Management
Initial step: treat cauda equina syndrome as a surgical emergency; obtain immediate neurosurgical or orthopedic spine surgery consultation as soon as the diagnosis is suspected clinically, in…
- Complications
Permanent urinary retention or incontinence: the most feared complication, more likely with delayed decompression or complete cauda equina syndrome (absent bladder sensation) at presentation.
- Prognosis
Time to decompression is the dominant prognostic factor: decompression within 24 to 48 hours of symptom onset is associated with better recovery of bladder, bowel, sexual, and motor function than delayed surgery.
- Prevention
No population-level screening exists, since cauda equina syndrome usually arises acutely from an unpredictable large disk herniation, hematoma, abscess, or fracture.
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