MSD Manual

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Cauda Equina Syndrome


Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Last full review/revision Jan 2020| Content last modified Jan 2020
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Cauda equina syndrome occurs when the nerve roots at the caudal end of the cord are compressed or damaged, disrupting motor and sensory pathways to the lower extremities and bladder.

Cauda equina syndrome is not a spinal cord syndrome. However, it mimics conus medullaris syndrome, causing similar symptoms.

Cauda equina syndrome most commonly results from a herniated disk in the lumbar spine. Other causes include congenital neurologic anomalies (eg, spina bifida), spinal cord infection, spinal epidural abscess, spinal cord tumor, spinal cord traumaspinal stenosis, arteriovenous malformation, and complications after spinal surgery. Many of these conditions cause swelling, which contributes to compression of the nerves.

Symptoms and Signs

Cauda equina syndrome (like conus medullaris syndrome) causes distal leg paresis and sensory loss in and around the perineum and anus (saddle anesthesia), as well as bladder, bowel, and pudendal dysfunction (eg, urinary retention, urinary frequency, urinary or fecal incontinence, erectile dysfunction, loss of rectal tone, abnormal bulbocavernosus and anal wink reflexes). Urinary retention or incontinence results from loss of sphincter function.

In cauda equina syndrome (unlike in spinal cord injury), muscle tone and deep tendon reflexes are decreased in the legs.

Without treatment, cauda equina syndrome can cause complete paralysis of the lower extremities.


  • MRI or CT myelography

If symptoms suggest cauda equina syndrome, MRI should be done immediately if available. If MRI is unavailable, CT myelography should be done.

If traumatic bone abnormalities (eg, fracture, dislocation, subluxation) that require immediate spinal immobilization are suspected and advanced imaging is not immediately available, plain spinal x-rays can be done. However, CT detects bone abnormalities better.


  • Surgery

  • Usually corticosteroids

Usually, treatment focuses on the disorder causing cauda equina syndrome, usually by relieving compression.

If cauda equina syndrome is causing sphincter dysfunction (eg, causing urine retention or incontinence), immediate surgery (eg, diskectomy, laminectomy) is required.

Analgesics should be used as needed to relieve pain. If symptoms are not relieved with nonopioid analgesics, corticosteroids can be given systemically or as an epidural injection; however, analgesia tends to be modest and temporary. Corticosteroids can also reduce swelling.

Key Points

  • The most common cause of cauda equina syndrome is a herniated disk.

  • If cauda equina syndrome is possible, immediately do MRI, or if it is not available, do CT myelography.

  • Surgically evaluate patients with symptoms of cauda equina syndrome (eg, urinary retention, frequency, or incontinence) immediately.

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NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version

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