Case Study: An apparently routine case of back pain

It is essential to examine patients thoroughly upon hearing of back pain. Dr Honor Merriman reports

Maria works at the local post office and has had several episodes of back pain. She also looks after her grandson and has had a complex family life.

She usually comes in to see me but sometimes requests a home visit, so I was not surprised to receive a phone call from her one day from work.

She had suddenly developed back pain and was on her way home because she knew my usual approach to back pain (painkillers and gentle activity). I advised that a repeat prescription for painkillers could be collected from the surgery later the same day.

The following day Maria phoned to tell me that her pain had increased. On visiting her I perceived an odour of urine in the bedroom. I took a more detailed history from her and asked her about numbness in her legs and perineal area.

Reluctantly she let me check sensation in these areas. She could not feel anything around her perineum.

Hospital admission
I arranged hospital admission later that day and the orthopaedic team investigated her quickly. An MRI scan showed a herniated inter-vetebral disc and a diagnosis of a cauda equina lesion was made. Maria had surgery and has made a slow but complete recovery. She is now back at work.

The cauda equina is the term for the spinal nerves that emerge from the lower end of the spinal cord (the lumbosacral enlargement).

Herniated lumbar discs can press on these nerves so that there is a loss of motor control to the bladder, bowel and leg.

If the pressure to these nerves is not relieved urgently the nerve damage can become permanent, with devastating effects on the patient. This is why it is important to ask about bowel and bladder control when taking a history from patients with back pain.

An MRI scan is the most useful investigation for patients with ‘red flag' symptoms. Plain X-rays of the spine are only indicated in older patients who are suspected of having osteoporotic crush vertebral fractures. In cases where there may be bone destruction due to metastases or infection a nuclear medicine scan can be used.

Blood tests can be helpful in older patients who may have underlying disease causing their back pain.

Full blood count, electrolytes, creatinine, bone profile and possibly a prostate-specific antigen (PSA) test should be considered.

Common complaint
Back pain is a common problem in general practice, but a full history and examination should always be taken, including questions about bladder and bowel control.

Patients who have stressful lives and ‘yellow flags' indicating psychosocial sources for their pain may also have significant pathology.

The simplest way to consider whether a patient with back pain needs referral or not is to keep the NICE referral guidelines in mind.

Patients aged under 20 or over 55 are more likely to have sinister cause for symptoms. Other criteria include a history of injury, pain that is constant and progressive, thoracic pain, widespread neurological signs and symptoms, other signs of generalised illness such as weight loss and past medical history of carcinoma.

The majority of back pain cases need analgesia and advice about exercises that encourage relief of muscle spasm and maintenance of mobility. However, the risk of not taking a full enough history and examining the patient thoroughly can be high.

Every year cases of missed cauda equina syndrome lead to medical litigation.

It is advised that all doctors ask the patient information about bladder, bowel and sexual function and that a thorough examination is taken.

Dr Merriman is a GP in Oxford

LESSONS LEARNT
When treating a case of back pain, the following questions should always be asked:

  • Have you noticed any numbness or strange sensations around your buttocks or between your legs?
  • Has your bladder been working normally? Can you tell when it is full? Have you had any loss of control, or have you felt you want to use the toilet all the time?
  • Have you experienced any unusual problems with your bowels recently?
  • Have you noticed any differences in sexual function, for example loss of feeling in your genitals or not being able to get an erection or ejaculate?

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