What Is Cauda Equina Syndrome?

By Vickie Wolfe

The cauda equina area is not the true spinal cord. The true spinal cord ends at L1/2. The area below the true spinal cord is called the conus medullaris. Immediately below that is the cauda equina area. The cauda equina are the nerves that leave the lower spinal cord and travel inside the spinal canal BELOW where the true spinal cord stops (at about L1/2) before leaving the canal and going to the legs, bowel, bladder and genitals.

A cauda equina syndrome is what you get when you impair the function of many or all of the nerve roots in the cauda equina area. Since these nerve roots serve sphincter and sexual function, sensation around the perineum (anus, genitalia) sensation in the legs, muscles throughout the legs, etc., it is possible to get pain and numbness as well as bladder and bowel dysfunction, sexual dysfunction and muscle weakness in the legs. Simply put, CES is damage to these nerve roots.

Centuries ago, anatomists who dissected cadavers thought that this area, with itís collection of nerve roots, looked like the tail of a horse, thus the Latin name, Cauda Equina. Looking at the picture below you can see why it looked like the tail of the horse to them.

(click image for larger version)

Below is an illustration* of the cauda equina area. You can see the disc herniation at L5- S1 compressing the nerves in the cauda equina area.

(click image for a larger version)

There are many of us that ended up with CES from a centrally herniated disc, usually at L4/5 S1. In too many cases, for one reason or another, our doctors didnít act soon enough and by the time we did have surgery to relieve the compression it was too late and we are left with what may be permanent nerve damage. The time before surgery, when it may still be possible to relieve this compression and avoid permanent nerve damage is the acute stage of cauda equina syndrome. Once we have the surgery and are left with the nerve damage we are in the chronic stage of cauda equina syndrome. Our hope is to reach patients and doctors and teach them to recognize the acute stage, act quickly to relieve the compression and avoid the chronic stage of Cauda Equina Syndrome.

How CES is Accquired?
I am going to explain first how most of us came to have chronic CES. For most of us this started out as a pain in the low back, maybe the legs, mine started out more in my left hip area. However it started, it got worse. For some of us it took a while to develop into an emergency. For others it happen QUICKLY. It was an emergency almost from the beginning.

Before I explain HOW a disc ruptures I will quickly explain the areas of the spinal column. The spinal column is made up of 33 vertebrae separated by 23 intervertebral discs. The spinal column had 3 distinct areas, the cervical, thoracic and lumbar areas. There are also five sacral vertebrae and coccyx. The lumbar area is where the cauda equina nerves are located.

Each vertebrae is separated by an intervertebral disc. These discs are sometimes called the "shock absorbers" of the spine. They cushion and stabilize the vertebrae.

The nucleus pulposus is the inner core of the disc which consists of a gelatinous material. The annulus fibrosis is the outer layer of the disc which is the strongest portion of the disc and provides strength to prevent disc herniations. People sometimes say they have a "slipped disc" in their back. In reality, a disc can't slip out of place. But discs can be injured. Sometimes the outer layer, the annulus fibrosis can tear and this allows the inner pulposus (the jelly like substance) to leak out. What causes the disc to rupture? Well it could be any type of accident perhaps simple wear and tear or the effects of aging.

Discs rupture all the time and we usually don't even know it. The rupture can be very small, a tiny tear with only a small amount of pulposus coming out. Usually when a disc ruptures, the inside pulpous goes to either the right or the left side of the spinal canal. Look at this illustration*:

(click image for a larger version)

This illustration shows the various stages of a disc rupture. Note the cauda equina area, where our nerves are.

The top two illustrations show first a normal disc, next to that the start of a bulging disc and the next illustration the disc on the bottom left shows a ruptured disc where the pulposus goes to the side. This is normally how discs rupture. There can be some nerve damage, but not the devastating damage that we get with CES.

Finally look at the illustration on the bottom right side. You can see where the red is the herniated disc and all that pulposus is going INTO the spinal column where all our cauda equina nerves are. This is crushing our nerves and cutting off the oxygen and blood supply. So it stands to reason that the longer we go with these nerves being crushed the more damage we are going to have.

For most of us, when you read our stories the one thing we all have in common is that we had a HUGE, CENTRALLY herniated disc. Remember I said some ruptures can be small, only a small amount of pulposus comes out. With us the rupture is very large and the amount of pulposus is large. All that goo, that pulpous, goes into the spinal canal, where our nerves are and crushes our nerves. In my case when my neurosurgeon saw the MRI films, the area where the disc was herniated was so large that there was no light coming through on the film. These nerves were totally crushed. Most of us, that have CES this way, were exactly the same. Is it any wonder that the longer we went with our nerves being crushed like this, the worse our damage was? Even patients that were treated relatively quickly have some nerve damage, but nothing compared to us, the ones who couldn't get our doctors to listen to us, until it was too late and the damage had been done.

This is basically how we end up with CES from a centrally herniated disc. We have a ruptured disc, but it is a centrally herniated disc, the tear is large with much pulposus and it (meaning the jelly like goo) goes into the spinal canal, where our cauda equina nerves are, and crushes those nerves.

When this happens, when we have a centrally herniated disc we MUST have surgery as soon as possible to relieve the compression. Our nerves in the cauda equina area are being crushed. How much permanent damage we have will depend on how long our nerves are crushed.

Red Flag Signs of CES
How can our doctors tell if we do have CES? Well partly from our symptoms. The following are the Red Flag signs of possible CES:

  • Severe pain in radicular (nerve root) pattern: back, buttocks, perineum (saddle area),genitalia, thighs, leg.

  • Loss of sensation: often tingling or numbness in the saddle area.

  • Weakness: in legs, often asymmetric.

  • Bladder/bowel/sexual dysfunction: incontinence/retention of urine; incontinence of faeces; impotence/loss of ejaculation or orgasm.

  • Loss of reflexes: knee/ankle reflexes may be diminished, as may anal and bulbocavernosus.

If we have the above symptoms we need, immediately, an MRI or a Myelogram with CT scan. Since a myelogram is an invasive procedure I would always opt for the MRI. If it shows that we do have a centrally herniated disc we need to have surgery immediately. Remember, the longer the nerves are crushed the more likely we will be to have permanent nerve damage.


Nerve regeneration will depend on how long those nerves were crushed and how much damage has been done. The only way to know is to wait. Doctors tell us that if the nerves are going to regenerate it can take as long as two years.

When a nerve is crushed there are three possible outcomes. The nerve may be "asleep" when there is enough pressure to cause it to completely shut down. It will come back if the pressure is removed soon enough.

The second possibility is when there is a little more pressure and the nerve branch, called an axon, is destroyed, but the insulation, called the myelin is still intact. The nerve can re-grow it's axon if the myelin sheath is still there to give it a guide back to where it is supposed to go. The rate of growth under the best conditions is 1mm per day. That is about one inch per month.

The third condition occurs when the axon is crushed and the myelin sheath is disrupted. The nerve will try to grow it's axon, but doesn't have a guide to find it's way back to where it belongs. In this case nerve regeneration is not possible, at least not at this time.

*Many thanks to The Doe Report (www.doereport.com) for allowing CESSG to use the above illustrations.