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Cauda Equina Syndrome

Updated: Nov 26, 2020

Cauda equina syndrome is a rare but serious condition that describes extreme pressure and swelling of the nerves at the end of the spinal cord. 

Cauda equina syndrome is a medical emergency that calls for urgent surgical intervention.

If patients with cauda equina syndrome do not get Surgery done urgently, adverse results can include paralysis, impaired bladder, and/or bowel control, difficulty walking, and/or other neurological and physical problems which can remain permanently.

Patients should be aware that acute cauda equina syndrome that results in nerve damage is fairly common and one should consult a Medical Doctor (Neurosurgeon or Ortho-Spine Surgeon) urgently if anyone develops symptoms suggestive of Cauda Equina.

Onset of Cauda Equina Syndrome

Symptoms of cauda equina syndrome usually develop suddenly and the onset of the condition is often described using the following distinctions:

  • Acute onset is marked by a rapid development of symptoms that often includes severe low back pain and significant loss of bladder and bowel function. In an acute onset, sensory and motor deficits in the lower body typically develop within 24 hours.

  • Gradual onset can develop over progressively, and symptoms may come and go over the course of several weeks or months. Gradual onset usually typically includes partial or intermittent loss of bowel and bladder function, as well as recurring low back pain in combination with muscle weakness and numbness and bladder and/or bowel incontinence or dysfunction. Sciatica may also occur in one or both legs.

Loss of bowel or bladder function may include incontinence (inability to retain urine or stool), and/or constipation (inability to eliminate urine or stool).

It is possible for a patient to develop cauda equina syndrome with no history of back pain, or in a patient with a long or recent history of low back pain or sciatica.

The Cauda Equina and Its Function

The cauda equina gets its name from Latin for "horse’s tail," because the nerves at the end of the spine visually resemble a horse’s tail as they extend from the spinal cord, through the lumbar spine and down the back of each leg.

The cauda equina consists of about 10 pairs of nerve roots, some of which combine to form larger nerves in the lower body—one example of which is the sciatic nerve.

The cauda equina is responsible for sensory and motor innervation to the pelvis and lower limbs, as well as bowel and bladder function. If the cauda equina is damaged by inflammation or compression in the low back, symptoms may be severe and may develop quickly. Early medical attention and treatment are crucial for making as full a recovery as possible.

Cauda Equina Syndrome Symptoms

The severity of cauda equina syndrome symptoms varies depending on the degree of nerve compression. For most of the patients, cauda equina syndrome (CES) develops suddenly while some patients experience a gradual onset of symptoms.

Typical symptoms of cauda equina syndrome include: 

  • Neurological symptoms in the lower body. Weakness, tingling, or numbness in the legs, and/or feet on one or both sides of the body is a common symptom. Lower body weakness or numbness may make it difficult to walk or stand. 

  • Altered sensation in the “saddle region,” or saddle anesthesia. The saddle region is the area of the body that would be in contact with a saddle when sitting on a horse. This region includes the groin, the buttocks and genitals, and the upper inner thighs. With cauda equina syndrome, all or parts of this region may have neurological symptoms of numbness, tingling, and/or weakness. 

  • Bladder or bowel incontinence. Recent onset of bowel or bladder dysfunction, including incontinence and retention, is one of the primary red-flag symptoms of cauda equina syndrome. Bladder/bowel dysfunction typically consists of a poor urinary stream, an altered or lack of sensation while urinating, urinary retention, loss of rectal control, and/or the need to strain in order to urinate. 

  • Sharp or stabbing pain in the legs or lower extremities. Compression of the cauda equina may lead to sciatic nerve pain felt on both sides of the body, and may be experienced as a sharp, hot pain felt down the backs of the thighs and possibly into the lower legs and feet. 

  • Localized lower back pain. A dull, steady ache may be felt across the lower back and/or pelvis, potentially causing discomfort or stiffness. 

Patients who experience any combination of the above symptoms should seek immediate medical treatment, as the condition can progress suddenly and requires prompt medical treatment. 

Causes of Cauda Equina Syndrome

Cauda equina syndrome occurs when any mechanical or inflammatory issue causes cauda equina compression to the point of neurological disruption or damage. 

Lumbar Herniated Disc Is A Typical Cause

Nerve compression leading to cauda equina syndrome is most often caused by a lumbar herniated disc. A lumbar disc can herniate in a single injury when excessive pressure is placed on the lower spine, or can occur when an already weakened disc is strained and ruptures.

Other Causes of Cauda Equina Syndrome

In addition to lumbar herniated disc, it is possible for the following factors to impinge on the cauda equina and cause symptoms.

  • Lumbar spinal stenosis. If the lumbar stenosis put pressure on the spinal canal, cauda equina may result

  • Inflammatory conditions can contribute to cauda equina syndrome if bony overgrowth or inflamed tissues press on lumbar nerve roots. One example of an inflammatory condition that may possibly lead to cauda equina syndrome is ankylosing spondylitis.

  • Infections of the spinal canal (osteomyelitis) such as a spinal epidural abscess, which in turn may potentially press into the spinal canal, producing neurological symptoms.

  • Tumors/neoplasms near the spine may put pressure on the spinal canal. Tumors may originate in the spine, but it is more common that cancer from another part of the body spreads toward the spine. 

  • Trauma to the lumbar spine. Trauma such as a car accident, fall, or a penetrative injury such as gunshot or knife wound, can damage the cauda equina and produce neurological symptoms. 

Risk factors for the condition are similar to risk factors for spinal stenosis and lumbar herniated disc, including overall health and lifestyle (such as nicotine use, obesity, and low activity level), being between 30 and 50 years old, and labor-intensive work.

Diagnosing Cauda Equina Syndrome

Magnetic Resonance Imaging (MRI) is the standard method of confirming the presence of cauda equina syndrome and for planning surgical treatment. The sooner cauda equina syndrome can be diagnosed, the better chance the patient has to make a sound recovery and experience as few lingering symptoms of nerve damage as possible.

Treatments for Cauda Equina Syndrome 

Cauda equina syndrome typically requires urgent surgical decompression in order to reduce or eliminate pressure on the impacted nerves. Most surgeons recommend decompression as soon as possible, within about 8-24 hours of the onset of symptoms if symptoms develop suddenly.

While there are conflicting reports in the literature regarding the timing of treatment, it is generally thought that surgery within 24 hours gives the maximum potential for improvement of sensory and motor deficits. In one meta-analysis, patients who underwent surgery within 24 hours of onset were found to have a significant improvement in sensory/motor deficits and bowel and bladder function over patients who received treatment after 24 hours. In patients who undergo surgery after 24 hours may experience no improvement in their urinary and rectal function, and neurologic deficits.

Surgical Decompression

Cauda equina syndrome is best treated with surgery like decompression by a lumbar laminectomy, or a lumbar microdiscectomy may be used given a patient’s unique situation.

The patient will likely be kept in the hospital for a few days following the surgery to monitor recovery of motor and sensory function.

Post-Surgical outcome

The outcome for cauda equina syndrome depends on a variety of factors, such as how promptly the nerve is decompressed and the degree of nerve damage at the time of surgery.

Following surgery, the extent of recovery is variable. Patients may continue to experience some low back or leg pain, bladder or bowel dysfunction, and other physical problems depending on the duration of nerve compression and the severity of symptoms at the time of surgery.

While it is generally thought that neurological damage caused by cauda equina syndrome is permanent, some studies have reported that long-term management may allow patients with initially poor prognosis following surgery to eventually regain some functional voiding of the bladder with little daily interruption.

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