Cauda Equina Syndrome



Cauda equina syndrome is a combination of symptoms caused by pressure on the bundle of nerves within the lumbar canal (cauda equina). This bundle also contains the bowel and bladder nerves. Cauda equina syndrome can be the result of a variety of causes and needs immediate medical attention! The most common cause is a large disc protrusion. Other causes include infection (discitis), tumour, trauma or following spinal surgery.


The classical symptoms are bilateral leg pain (sciatica), incontinence of urine and/or faeces and numbness in the area of the anus and genitalia (saddle  anaesthesia or perianal numbness). It is possible to have only some  and not all of these symptoms. Cauda equina syndrome without any pain, however, is very unusual. Many patients with severe back pain or sciatica find it difficult to pass urine because of the pain rather than pressure on the bowel and bladder nerves but if there is any doubt, patients need to be assessed by a doctor urgently. Patients also may have weakness or numbness of the leg or foot or sexual dysfunction.


If untreated cauda equina syndrome can lead to permanent incontinence of bowel and bladder.


Patients should have a MRI scan urgently. It is normally not essential to have this immediately (i.e. in the middle of the night) but as soon as possible during daylight. If there is no out of hours MRI service at the hospital available, the patient must be referred to a hospital which provides this.

Treatment and Outlook

Immediate diagnosis and treatment are essential to prevent long term damage. Decompressive surgery should be done within 48 hours of onset of the symptoms. This might not be possible or difficult if there is a complex underlying problem like a collapsed vertebra from a spinal tumour but in the majority of cases the cause is a disc protrusion. Any patient with cauda equina syndrome and a compressive lesion should be referred immediately to a neurosurgeon or spinal orthopaedic surgeon. Sometimes, patients have severe compression of the cauda equina on MRI but have not developed the clinical symptoms. There is a risk that this might occur at a later stage and the patient should be seen and assessed by a spinal surgeon as soon as possible.

large disc protrusion causing cauda equima syndrome

large disc protrusion causing cauda equina syndrome