Cauda Equina Syndrome

Authored by , Reviewed by Dr John Cox | Last edited | Certified by The Information Standard

Cauda equina syndrome (CES) is a particularly serious type of nerve root problem. This is a rare disorder where there is pressure on the nerves at the very bottom of the spinal cord.

The collection of nerves at the bottom of the spinal cord is called the cauda equina because it is said to look like a horse's tail. Cauda equina means horse's tail in Latin.

CES may cause low back pain and problems with bowel and bladder function (usually not being able to pass urine), numbness in the saddle area, which is around the back passage (anus), and weakness in one or both legs. 

CES needs urgent investigation and treatment to prevent the nerves to the bladder and bowel from becoming permanently damaged.

See a doctor immediately if you suspect CES.

The lower back is also called the lumbosacral area of the back. It is the part of the back between the bottom of the ribs and the top of the legs.

Most of the lower back is made up from muscles that attach to, and surround, the spine. The spine is made up of many bones called vertebrae. The vertebrae are roughly circular and between each vertebra is a disc. The discs between the vertebrae are a combination of a strong fibrous outer layer and a softer, gel-like centre. The discs act as shock absorbers and allow the spine to be flexible.

Side view of lower spine

Strong ligaments also attach to nearby (adjacent) vertebrae to give extra support and strength to the spine. The various muscles that are attached to the spine enable the spine to bend and move in various ways.

The spinal cord, which contains the nerve pathways to and from the brain, is protected by the spine. Nerves from the spinal cord come out from between the vertebrae to take and receive messages to various parts of the body.

The lower end of the spinal cord is at the level of the first or second lumbar bone (vertebra). The nerves from the spinal cord then form a structure called the conus medullaris. The spinal nerves continue to branch out below the conus medullaris to form the cauda equina.

The corda equina carries nerves which control the bladder and bowel. The cauda equina also carries nerves which control movement of the legs, and nerves which sense light touch and pain in the legs or around the back passage (perineum).

CES is a particularly serious type of nerve root problem. There is pressure on the nerves at the very bottom of the spinal cord. The pressure on the nerves stops the nerves from working properly. If the pressure is not treated quickly then CES may cause permanent nerve damage.

The most common cause of CES is a prolapsed disc (often called a 'slipped disc'). Other causes include infection and bone cancer 

CES is rare. It occurs mainly in adults but can occur at any age.

The symptoms of CES usually start suddenly and progress quickly. Occasionally the symptoms start slowly.

CES may cause low back pain but not all people with CES have back pain.

The other symptoms of CES include problems with bowel (for example, constipation) and bladder function (usually unable to pass urine). Sexual problems may also occur (for example, impotence in men).

Other symptoms include numbness in the saddle area, which is around the back passage (anus), and weakness in one or both legs.

The diagnosis of CES is mainly based on the symptoms and also by a doctor's examination. Anyone with possible CES should be seen urgently in hospital.

Investigations usually include an MRI scan to confirm the diagnosis. Other investigations may include a CT scan and tests of bladder control.

Urgent surgery is often but not always needed to relieve the pressure on the nerves and prevent permanent nerve damage.

The treatment otherwise depends on the cause of CES - for example, for infection, antibiotic medicines. Radiotherapy may be used if CES has been caused by bone cancer.

The outlook depends on the cause of cauda equina syndrome (CES) and how quickly treatment can be provided.

A delay in diagnosis and effective treatment increases the risk of long-term bladder, bowel and sexual problems. Late diagnosis and a delay in treatment can also increase the risk of a permanent nerve damage affecting the bladder, bowel and legs.

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Further reading and references

When to worry about back pain

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