This causes back and radicular leg pain, commonly lower back and buttock pain, posterior leg pain with or without pins and needles, numbness and weakness in the affected leg.
In most cases, the pain is caused by disc herniation and the associated inflammation. More rarely, it is a consequence of spondylolythesis, infection, spinal stenosis and the associated degenerative changes to the spine, or a space-occupying lesion.
Problems with the sacroiliac joint can also irritate the L5 nerve root.
Peripheral parts of the nerve can be compressed and the piriformis muscle may also impinge on the sciatic nerve in the gluteal area.
The history can give clues to the cause. Traumatic disc injuries are often preceded by sudden-onset low back pain after lifting, in particular from loading in lumbar flexion and rotation. Pins and needles, numbness and leg pain may follow.
Pain or neurological symptoms from coughing and sneezing can indicate disc pathology. Patients may report an insidious onset of numbness and pins and needles in a dermatome pattern with leg pain, with or without lower back pain.
The GP's examination
A full neurological examination is necessary to exclude cauda equina syndrome and establish the degree to which the nerve is affected.
This should include testing of lower limb reflexes, myotomes and dermatomes. The highly specific straight leg raise test can indicate a disc herniation if positive between 30-70 degs and a positive crossover test can indicate a herniated nucleus pulposus.
Lumbar range of motion can be assessed to establish movements that are provocative of symptoms. Combined with the history this can point towards the nature of the nerve root irritation.
Symptom-provoking forward flexion with side flexion is often indicative of a disc bulge or herniation. Neurogenic symptoms provoked by lumbar extension may be more indicative of facet joint dysfunction and in the older patient, could indicate a stenotic pattern.
Pain control, such as NSAIDs and opiates, may help to settle low back pain and in some cases, neuropathic medications can help.
If pain has resulted in muscle spasm with inhibited functional movement, a muscle relaxant could be considered.
Healthcare professionals should encourage patients to pace their daily activities while staying active. Prolonged bed rest is not encouraged, although finding a pain-free position and resting for short periods throughout the day can help the nerve to settle.
If the patient's job is manual in nature, they may require time off to allow a disc injury to heal and the nerve to settle down. Typically, the leg pain will resolve within 12 weeks. Patients requiring more treatment and guidance can be referred to a physiotherapist.
Understanding the patient's view of their condition is vital to developing an effective management strategy. Tools such as STaRT Back (see Resources) are used to categorise patients according to their risk of developing chronic pain.
Physiotherapists will generally follow the NICE guidelines on low back pain, while taking into account their own clinical findings.
Patients at low risk may only need advice and education. Those at medium risk may benefit from joint manipulation or mobilisation, acupuncture and ergonomic advice, with an exercise programme, to facilitate their return to normal functional levels.
Patients identified as being at high risk of chronic pain should be seen by an experienced clinician and may be offered the treatment above, but with more frequent, longer sessions, incorporating basic CBT techniques to reduce disability and pain.
Who to refer
Patients whose symptoms are improving and who are continuing with normal daily activities may only need basic pain relief. Those who would benefit from further ergonomic or exercise advice and manual therapy should be referred to a physiotherapist. Patients at risk of developing chronic pain should be referred to a physiotherapist immediately.
Communication between GP, therapist and patient is vital. It is helpful to ensure patients understand how to use their medication before their initial physiotherapy assessment.
A clear, unified opinion on the condition and any imaging results will help to reassure patients.
Exercise advice should be patient-specific because of the varied causes of symptoms, but assuring patients they can move around as their pain allows helps to prevent problems.
GPs and therapists can help to relieve the stress caused by patients having to take time off work by communicating with each other and the patient's employer about the nature of their condition and the tasks they may or may not be able to complete.
- Dr Raymond is a GP in east London and Mr Turpin is a physiotherapist in Lymington, Hampshire
- Hill JC, Dunn KM, Main CJ et al. Eur J Pain 2010; 14(1): 83-9.
- Savigny P, Kuntze S, Watson P et al. Low back pain: early management of persistent non-specific low back pain. London, National Collaborating Centre for Primary Care and RCGP, 2009.
- STarT Back screening tool. www.keele.ac.uk/startback