Cauda equina syndrome may begin with generalised lower back pain and sciatica, but may then progress to cauda equina compression. The point at which a patient develops cauda equina syndrome is determined by the onset of bladder, bowel and rectal dysfunction.
Time of onset
The time of onset of cauda equina syndrome is generally taken to be the time that symptoms of disturbed urinary, rectal and perineal function appear. This might represent reduced bladder, perineal and bowel sensation, and/or the disturbed ability to pass urine or open the bowels.
Thus according to the commonly accepted definition of CES, a patient with a prolapsed intervertebral disc with back pain and sciatica (a pain that runs down the back of the thigh and leg to the foot) does not have cauda equina syndrome until he/she develops urinary and/or rectal symptoms, and/or the symptom of saddle anaesthesia. Saddle anaesthesia indicates the compression of the S3-5 nerve roots which enable sensation in the ‘saddle’ area.
Symptoms of cauda equina syndrome
The urinary, rectal and saddle symptoms that indicate the onset of cauda equina syndrome include:
- Altered urethral sensation (e.g. the patient only knows when micturition has stopped when they hear the flow of urine stop)
- Loss of desire to void
- Hesitancy and poor urinary flow
- Loss of sensation of bladder fullness
- Feeling of retention or incomplete voiding
- Need to strain to void
- Perirectal numbness
- Loss of rectal control
- Sensory abnormalities in the rectum/anal canal (e.g. inability to differentiate between faeces and flatus due to altered rectal and anal sensitivity)
- Loss of ability to achieve or maintain an erection
- Loss of sensation of orgasm
- Saddle anaesthesia i.e. loss of sensation in the area around the anus, vulva and buttocks (representing that area of skin supplied by the 3rd to 5th sacral nerve roots)
Out of all of these, medical professional should be alert to three main symptoms, known as the ‘red flag symptoms’. The red flags are an indication that CES has started. They are:
- Saddle anaesthesia
- Recent onset of bowel or bladder dysfunction
- Severe or progressive neurological deficit
The development of the red flag symptoms is an indication for urgent (meaning within hours) MRI scan to determine whether or not there is an acute cauda equina compression.
Failure to spot red flag symptoms of CES
If doctors fail to spot the red flag symptoms of cauda equina syndrome, resulting in a delay in diagnosis and treatment, there will be grounds for a compensation claim.