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Cauda equina syndrome (CES) occurs when the nerve roots of the cauda equina are compressed and disrupt motor and sensory function to the lower extremities and bladder. Patients with this syndrome are often admitted to the hospital as a medical emergency. CES can lead to incontinence and even permanent paralysis.

The collection of nerves at the end of the spinal cord is known as the cauda equina, due to its resemblance to a horse's tail. The spinal cord ends at the upper portion of the lumbar (lower back) spine. The individual nerve roots at the end of the spinal cord that provide motor and sensory function to the legs and the bladder continue along in the spinal canal. The cauda equina is the continuation of these nerve roots in the lumbar region. These nerves send and receive messages to and from the lower limbs and pelvic organs.


CES most commonly results from a massive herniated disc in the lumbar region. A single excessive strain or injury may cause a herniated disc. However, disc material degenerates naturally as you age, and the ligaments that hold it in place begin to weaken. As this degeneration progresses, a relatively minor strain or twisting movement can cause a disc to rupture.

The following are other potential causes of CES:

Spinal lesions and tumors
Spinal infections or inflammation
Lumbar spinal stenosis
Violent injuries to the lower back (gunshots, falls, auto accidents)
Birth abnormalities
Spinal arteriovenous malformations (AVMs)
Spinal hemorrhages (subarachnoid, subdural, epidural)
Postoperative lumbar spine surgery complications
Spinal anesthesia

Symptoms and Diagnosis

CES symptoms mimic those of other conditions. Its symptoms may vary in intensity and evolve slowly over time. CES is accompanied by a range of symptoms, the severity of which depend on the degree of compression and the precise nerve roots that are being compressed. Besides a herniated disc, other conditions with similar symptoms to CES include peripheral nerve disorder, conus medullaris syndrome, spinal cord compression, and irritation or compression of the nerves after they exit the spinal column and travel through the pelvis, a condition known as lumbosacral plexopathy.

"Red Flag Symptoms"

Patients with back pain should be aware of the following "red flag" symptoms that may indicate CES:

Severe low back pain
Motor weakness, sensory loss, or pain in one, or more commonly both legs
Saddle anesthesia (unable to feel anything in the body areas that sit on a saddle)
Recent onset of bladder dysfunction (such as urinary retention or incontinence)
Recent onset of bowel incontinence
Sensory abnormalities in the bladder or rectum
Recent onset of sexual dysfunction
A loss of reflexes in the extremities

Medical history implications:

Recent violent injury to the back
Recent lumbar spine surgery
A history of cancer
Recent severe infection

The following tests may be helpful in diagnosing CES:

Magnetic resonance imaging (MRI): A diagnostic test that produces three-dimensional images of body structures using magnetic fields and computer technology. MRI produces images of the spinal cord, nerve roots, and surrounding areas.

Myleogram: A myleogram is an x-ray of the spinal canal following injection of a contrast material into the surrounding cerebrospinal fluid spaces; can show displacement on the spinal cord or spinal nerves due to herniated discs, bone spurs, tumors, etc.


Once the diagnosis of CES is made, and the etiology established, urgent surgery is usually the treatment of choice. The goal is to reverse the symptoms of neural dysfunction. Left untreated, CES can result in permanent paralysis and incontinence.

Those experiencing any of the red flag symptoms should consult a neurosurgeon or orthopedic spine surgeon as soon as possible. Prompt surgery is the best treatment for patients with CES. Treating patients within 48 hours after the onset of the syndrome provides a significant advantage in improving sensory and motor deficits as well as urinary and rectal function. But even patients who undergo surgery after the 48-hour ideal timeframe may experience considerable improvement.

Although short-term recovery of bladder function may lag behind reversal of lower extremity motor deficits, the function may continue to improve years after surgery. Following surgery, drug therapy coupled with intermittent self-catheterization can help lead to slow, but steady recovery of bladder and bowel function.