Cauda equina syndrome 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.
The condition 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. It needs urgent investigation and treatment to prevent the nerves to the bladder and bowel from becoming permanently damaged.
See a healthcare professional immediately if you suspect CES.
Understanding the lower back
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.
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.
What is the cauda equina?
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).
What is cauda equina syndrome?
Cauda equina syndrome (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.
How common is cauda equina syndrome?
CES is rare. It occurs mainly in adults but can occur at any age.
Symptoms of cauda equina syndrome?
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.
CES may cause pain, numbness or weakness in both legs.
Other symptoms include numbness in the saddle area, which is around the back passage (anus), and weakness in one or both legs.
How is cauda equina syndrome diagnosed?
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.
Cauda equina treatment
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.
Cauda equina recovery
The outlook (prognosis) depends on the cause of 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.
Further reading and references
Sciatica (lumbar radiculopathy); NICE CKS, December 2020 (UK access only)
Gitelman A, Hishmeh S, Morelli BN, et al; Cauda equina syndrome: a comprehensive review. Am J Orthop (Belle Mead NJ). 2008 Nov37(11):556-62.
Ma B, Wu H, Jia LS, et al; Cauda equina syndrome: a review of clinical progress. Chin Med J (Engl). 2009 May 20122(10):1214-22.
Gardner A, Gardner E, Morley T; Cauda equina syndrome: a review of the current clinical and medico-legal position. Eur Spine J. 2011 May20(5):690-7. doi: 10.1007/s00586-010-1668-3. Epub 2010 Dec 31.
Tamburrelli FC, Genitiempo M, Bochicchio M, et al; Cauda equina syndrome: evaluation of the clinical outcome. Eur Rev Med Pharmacol Sci. 201418(7):1098-105.