Cauda Equina Syndrome
The cauda equina is formed by nerve roots caudal to the level of spinal cord termination. Cauda equina syndrome is caused by compression of the nerves causing a combination of low back pain, unilateral or more usually bilateral sciatica, saddle (perineal) sensory disturbances, bladder and bowel dysfunction, and variable lower extremity motor and sensory loss.
Cauda equina syndrome is a medical emergency and immediate referral for investigation and treatment is required to prevent
permanent neurological damage.
Cauda equina syndrome is rare. It occurs mainly in adults between the age of 30 and 40 but can occur at any age.
A congenitally narrow spinal canal or acquired spinal stenosis arising from a combination of degenerative changes of the disc and the segmental posterior joints may predispose to cauda equina syndrome.
The commonest cause of cauda equina syndrome is compression arising from large central lumbar disc herniation at the L4/5 and L5/S1 level.
Tumours: metastases, lymphomas, spinal tumours.
Infection, including epidural abscess.
Congenital, eg congenital spinal stenosis, kyphoscoliosis and spina bifida.
Late-stage ankylosing spondylitis.
Inferior vena cava thrombosis.
Clinical diagnosis of cauda equina syndrome is not easy to make and can be missed until it has become severe. Most cases are rare and progress rapid within hours or days. However that said cauda equina syndrome can also evolve slowly over a few weeks and patients do not always complain of pain at the beginning but the pain and symptons will become progessively worse.
Pain in one leg (unilateral) or both legs (bilateral) that starts in the buttocks and travels down the back of the thighs and legs and in to the foot(sciatica)
Numbness in the groin or area of contact if sitting on a saddle (perineal or saddle paresthesia)
Bowel and bladder disturbances
Lower extremity muscle weakness and loss of sensations
Reduced or absent lower extremity reflexes
Low back pain can be divided into local and radicular pain.
Local pain is generally a deep, aching pain resulting from soft tissue and vertebral body irritation.
Leg pain (radicular pain) is generally a sharp, stabbing pain resulting from compression of the nerve roots. Radicular pain
projects along the specific areas controlled by the compressed nerve (known as a dermatomal distribution).Bladder disturbance (urinary manifestations) related to cauda equina syndrome include the following:
Inability to urinate (urinary retention)
Difficulty initiating urination (urinary hesitancy)
Decreased sensation when urinating (decreased urethral sensation)
Inability to stop or control urination (incontinence)
Bowel disturbances may include the following:
Inability to stop or feel a bowel movement (incontinence)
Loss of anal tone and sensation
The diagnosis is usually possible from the history and examination.
Further investigations are focused on localising the site of compression and the underlying cause.
MRI scan is the preferred investigation to confirm the diagnosis and determine the level of the compression and any underlying cause.
Myelography and CT are also sometimes used.
Conus medullaris syndrome (the conus medullaris is located above the cauda equina at T12-L1; nerve root pain is less prominent and the main features are urinary retention and constipation.
Mechanical back pain or prolapsed lumbar disc.
Fracture of lumbar vertebrae due to trauma.
Spinal cord compression.
Patients should be referred immediately for a neurosurgical consultation.
Urgent surgical spinal decompression is indicated for most patients to prevent permanent neurological damage.
Immobilise spine if cauda equina syndrome is due to trauma.
Surgery is indicated to remove blood, bone fragments, tumour, herniated disc or abnormal bone growth.
For patients with a herniated disk as the cause of cauda equina syndrome, early surgical decompression is recommended.
Lesion debulking is required for space occupying lesions, eg tumours, abscess.
If surgery cannot be performed, radiotherapy may relieve cord compression caused by malignant disease.
Other treatment options may be useful in certain patients, depending on the underlying cause of the cauda equina syndrome:
Anti-inflammatory agents, including steroids, can be effective in patients with inflammatory causes, eg ankylosing spondylitis.
Infection causes should be treated with appropriate antibiotic therapy.
Patients with spinal neoplasms should be evaluated for chemotherapy and radiation therapy.
Postoperative care includes addressing lifestyle issues, eg obesity, and also physiotherapy and occupational therapy, depending on residual lower limb dysfunction.
Complications are increasingly likely if diagnosis and appropriate management is delayed, and include residual:
Bladder, bowel, and sexual dysfunction
Prognosis is dependent on the aetiology and the time taken before effective treatment is provided.
A degree of bladder and bowel function may be permanently lost.
Late diagnosis and treatment increases the risk of a permanent neurological deficit.
Patients with bilateral sciatica or complete perianal anaesthesia have a less favourable prognosis than patients with unilateral pain.
Please note that the above is RARE!