How to Recognize Cauda Equina Syndrome

It’s nerve compression, but not just run-of-the-mill nerve compression. Cauda equina syndrome is an emergency that needs to be treated quickly.

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Back pain can often be nothing more than a minor inconvenience after sitting in an uncomfortable chair or lifting something too heavy. In fact, according to experts, 50 to 80% of people will experience at least one episode of back pain in their lives. And as the National Institute of Neurological Disorders and Stroke says, most low back pain is acute and usually resolves itself within a few days. By two weeks (or so) later, you’re good as new.

Recognize cauda equinaCauda equina syndrome is an emergency; learn to recognize the signs.

But every once in a while, that low back pain can be a sign of something more serious. One of those conditions is known as cauda equina syndrome. It’s not a condition as readily known as, say, sciatica or arthritis, but it does have specific signs and symptoms that are helpful to be aware of.

What Is Cauda Equina Syndrome?

Latin for “horse’s tail,” the cauda equina “is the group of nerves that runs through the lumbar spinal canal,” according to  Eeric Truumees, M.D., professor of orthopaedic surgery and neurological surgery at the University of Texas’ Dell Medical School, 2020-21 president of the North American Spine Society, and SpineUniverse Editorial Board member.

Although Dr. Truumees says that there is no “official definition,” of cauda equina syndrome, generally, the condition implies two things:

  • Compression of most of the lumbar spinal canal
  • Symptoms consistent with compression, such as numbness or weakness in a limb

You may be wondering how cauda equina syndrome differs from typical compression of the lumbar spinal canal.

“As with run-of-the-mill nerve compression, cauda equina syndrome can be caused by a number of different problems, from fractures to tumors to infections,” Dr. Truumees says. “Most commonly, however, disc herniations cause both problems. The key differences are the degree to which the nerves are compressed, and the number of nerves compressed. For example, compression of any single nerve will not cause loss of bladder function. Compression of many nerves, especially the sacral nerves, may.”  

He points out that another key difference is the urgency of treatment. While nerve compression leading to pain or numbness may be treated a number of ways, surgery is reserved for those nerve compression problems that are severe and fail to get better non-operatively.

“When the nerve compression leads to weakness, a more urgent surgery may be required, but it is not an emergency,” Dr. Truumees shares. “Cauda equina syndrome, on the other hand, is an emergency.  Surgery to decompress the nerves is undertaken on a ‘sooner is better than later basis’ with a goal of surgery within 48 hours at most. Even early surgery may not reverse the bowel and bladder dysfunction but delays only increase the risk of residual problems.”

Cauda equina locationIn most adults, the cauda equina begins below where the spinal cord ends, usually around the top of the lumbar vertebrae--L1 or L2--according to Dr. Truumees.

Can Cauda Equina Syndrome Sneak Up on You?

Since one of the factors that can bring on cauda equina is long-term compression, is it possible to not know that you’re living with it? Well, yes and no. You’ll likely be aware of the symptoms of another spinal condition that crowds the spinal canal before cauda equina syndrome materializes.

“Usually, cauda equina syndrome comes about relatively quickly,” Dr. Truumees says. “Even in patients with arthritis leading to spinal stenosis, the final step to getting cauda equina is often an acute change like a disc herniation in an already tight spinal canal. With that, there is usually a sudden increase in pain and decrease in function.”

Even though the condition itself can happen in the blink of an eye, other overlapping back problems can sometimes mask cauda equina syndrome. Dr. Truumees notes that this tends to be most common in severely ill patients, like those with spinal infection, epidural abscesses, or systemic cancers with tumor in the spinal canal.

Causes of Cauda Equina

“Cauda equina syndrome can arise from anything that compresses the nerves,” Dr. Truumees says. Most commonly, it’s caused by root compression that comes from degenerative processes, mainly lumbar disc herniations. Other possible causes include:

  • Bleeding (an epidural hematoma)
  • Trauma (fractures or penetrating trauma)
  • Tumors (either from tumors growing into the canal or the collapse of a tumor-affected bone)

“Disc herniations may gradually grow in size, thereby leading to a slowly-evolving cauda equina syndrome, though this has only rarely been reported,” Dr. Truumees adds. “Similarly, overgrowth of arthritic joints or bone spurs into the spinal canal can theoretically lead to long-term compression. However, even in these cases, there is often an acute or chronic aspect contributing to the cauda equina syndrome itself. This could be an enlarging disc herniation or synovial cyst further compromising already compressed nerves.”

Cauda Equina Symptoms

Here are some cauda equina symptoms you and/or your doctor can be on lookout for if you suspect you may have cauda equina syndrome. These symptoms vary based on the level that the spinal canal has been affected:

  • Neurogenic bladder dysfunction. This can range from retention (difficulty starting a urinary stream) or incontinence (limited or non-voluntary control over urination).
  • Bowel dysfunction
  • Sexual dysfunction
  • Saddle numbness with numbness that extends into other parts of the legs
  • Back and leg pain

Cauda Equina Diagnosis

How will your doctor pinpoint a diagnosis of cauda equina syndrome?

“Any significant change in bowel, bladder, or leg function serve as ‘red flags’ that should lead to an early, complete assessment,” Dr. Truumees says.

He explains that a physician will want to get a detailed history of the onset and the evolution of symptoms. Next will come a close physical examination which will include testing sensation and strength but also a rectal exam to assess voluntary contraction. Your doctor may also check your reflexes, and if possible, assess your gait and alignment.

If you are presenting most or all of these symptoms, Dr. Truumees says that this will generally set in motion spinal imaging, or a cauda equina MRI.

“If the symptoms, exam, and imaging match, it will typically lead to emergency admission to the hospital and surgical intervention,” Dr. Truumees states.

Updated on: 12/04/20
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Eeric Truumees, MD
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