Back pain is estimated to affect up to 85% of adults at some time in their lives. In most cases the cause is non-specific and is due to simple strains or sprains with symptoms resolving within one to three months.
Despite this, it can be quite debilitating and ranks as one of the commonest medical reasons given for work absences. Indeed, at any point in time up to 10% of adults may have activity-limiting lower back pain lasting for more than one day.
Of those attending general practice, less than 10% will have a clear cause identified but this can include disc lesions, trapped nerves, osteoarthritis and spinal fractures.
Reassuringly, in only about 1% of cases back pain is associated with serious illness such as cancer and bone disorders involving the spine.
Physical injuries sustained from contact sports, lifting heavy items or falls are common causes of back pain, though in many instances there is no clear history of a trauma. Pain can also be aggravated or caused by factors such as poor posture, incorrect footwear, badly-designed seating, poor lifting techniques and a lack of exercise.
Lower back pain due to lumbar spine disease is commonest as it bears the most weight and is subjected to more twisting, turning and straining than any other part of the back. So when should one worry about back pain or get it investigated? This will depend on the severity of pain, whether there is a history of trauma and the nature and duration of symptoms.
Acute back pain (lasting for up to 4-6 weeks) that is localised around the vertebral column is often due to strain or minor injures to the muscles that run longitudinally along the spine and support it. In the absence of other symptoms, it often resolves of its own accord and can be treated with topical anti-inflammatories and simple pain killers.
You may need to go your GP if it’s very troublesome, though in most cases further investigations such as blood tests or imaging of the spine will not be required.
Pain which radiates from the lower back into the groin and down the leg or into the foot is consistent with nerve root impingement.
This happens when the space in the lateral part of the spine where the nerve lies is narrowed due to degenerative changes in the vertebrae and/or disc protrusion. It may be felt as ‘sharp and shooting’ or as a dull ache or heaviness and is often intermittent and aggravated in different positions. In particular, sciatica refers to a sharp or burning pain radiating down from the buttock along the course of the sciatic nerve (the posterior or lateral aspect of the leg and usually to the foot).
Compression of nerve roots that comprise the sciatic nerve or the nerve itself gives rise to symptoms.
Pain in the upper back which spreads along the line of the ribs and into the chest is also suggestive of nerve entrapment.
If not resolving within 4-6 weeks, imaging of the spine with MRI should be considered. This will establish if there is narrowing of the nerve exit space due to slipped discs and/or arthritis that could be causing nerve entrapment. It is also sensitive at detecting other pathologies such as a spinal muscle tear, narrowing of the spinal canal and vertebral fractures.
When symptoms are mild and no major findings are identified on MRI, then the nerve pain can be treated with specific painkillers and will usually resolve of its own accord. If sciatica or symptoms of a trapped nerve persist, then spinal injections around the local area of nerve root irritation can help to reduce inflammation and reduce pain.
In addition, a procedure to deactivate the nerve under local anaesthetic (rhizotomy or rhizolysis) can be performed. For more severe disease such as due to significant disc protrusions, surgery to remove part or all of the disc may be required.
If back pain is associated with new bowel or bladder dysfunction, limb weakness, numbness in the buttock/spine or bilateral leg symptoms then imaging with an MRI should be done urgently.
In older adults with a history of osteoporosis or fragility fractures, central back pain may indicate a vertebral collapse/fracture. These can happen with minimal trauma or spontaneously and can be evaluated with a plain x-ray. Pain usually settles within about 4-6 weeks but when persistent, injection of a cement into the area of collapse (vertebroplasty) under local anaesthetic can help.
Make sure to try and avoid aggravating activities, however, as far as is possible. Keeping active and gradually returning to usual activities, including work and hobbies is important in aiding recovery.
For chronic back pain, a variety of medications which are safe and effective are available. Physiotherapy may also help in optimising correct spinal posture.
Back pain may also occasionally be due to problems outside the spine such as kidney infections/stones, pancreatic disease and shingles. If you have persistent back pain or concerning symptoms make sure to get it checked out with your GP.
Dr Kevin McCarroll is a consultant physician in geriatric medicine in St James’ Hospital, Dublin.