Back Pain - Non Sinister Causes

Back pain is an extremely common occurrence and is said to account for 5% of GP consultations.¹ It is important to distinguish simple or mechanical back pain from the less common but very important causes of sinister back pain. The latter may be due to more severe injury of the back resulting in prolapsed intervertebral disc or vertebral collapse or pathology outside the vertebral column such as carcinoma of pancreas or dissecting aortic aneurysm.

Warning features are often referred to as red flags if they suggest a sinister aetiology and yellow flags if they indicate a risk of the problem becoming chronic.

Certain terms are commonly used for the purpose of description:

• Low back pain is pain between the bottom of the ribs at the back and the top of the legs¹
• Simple low back pain is low back pain in which the cause of the pain cannot be attributed to any specific pathology. It is also commonly called non-specific, or uncomplicated, low back pain.
• Simple back pain is mechanical in that it varies with posture or activity, and it varies over time in response to altered activities or treatment.
• Nerve root pain (or radicular pain) is due to nerve root irritation. It may occur in conjunction with simple back pain.
• Sciatica is a lay term for pain and sensations of tingling from the buttocks down the back of the thigh, and possibly into the calf and heel. This is the distribution of the sciatic nerve and symptoms are caused by irritation. Pain can also be referred from the lumbar area to the distribution of the sciatic nerve.

Low back pain is classified as:

• Acute if it has lasted less than 6 weeks
• Sub-acute if it has lasted 6-12 weeks
• Chronic if it has lasted more than 12 weeks

This classification is important for research purposes but is of limited value to the clinician.

Low back pain often fluctuates over days, weeks, and months. It is thus not always possible to distinguish between a new acute event and an exacerbation of a chronic process.

Chronic pain and disability often seem to become dissociated from the original physical problem.

Incidence

• Back pain is so very common that most of us can expect to suffer from it at some time.
• Systematic enquiry in older people reveals that almost everyone has it but most regard it as a normal accompaniment of ageing and so do not complain. Pathological causes of back pain also become more frequent with advancing years.
• Between the ages of 25 and 64 the annual incidence is said to be 4.7% with a 59% chance of a lifetime occurrence.²

Prevalence

• At any given time the number of people affected by back pain will be between 4 and 33%.³
• The lifetime prevalence of low back pain is reported as over 70% in industrialized countries (one-year prevalence 15% to 45%, adult incidence 5% per year).
• Peak prevalence occurs between ages 35 and 55.⁴
• Men and women are equally effected.

In 1995, Bandolier⁵ estimated that there were 52 million days lost off work due to back pain, a figure that is rising over the decades. Costs to the NHS were £481 million, benefits cost £1.4 billion and lost production cost £3.8 billion.

Red flags have been described in sinister causes of back pain and assessment and management of low back pain and so they will not be repeated here.
Yellow flags represent psychosocial reasons for failure to recover and are worthy of mention and appropriate action may possibly prevent chronicity.

• Belief that activity that causes pain is harmful
• Sickness behaviours such as extended rest and taking to bed
• Social withdrawal
• Emotional problems such as low mood, depression, anxiety and stress
• Problems at work or dissatisfaction with work
• Problems with claims or compensation (compensation neurosis) problems with time off work
• Overprotective family or lack of support
• Inappropriate expectations of treatment, including not appreciating the need for active participation in treatment

There is a New Zealand screening questionnaire for psycho-social barriers to recovery.⁶ This is a useful tool for assessing yellow flags.

Risks for Developing Back Pain in Adults

• Heavy physical work
• Lifting and handling of loads, including patients
• Awkward postures and movements including bending, twisting, static postures and having to lift in an awkward way
• Whole body vibration as with driving a large driving vehicle

Risks for Developing Back Pain in Children

Although onset below 20 years of age is a red flag, back pain in children is not uncommon and the Clinical Knowledge Summaries guidelines examined some of the risk factors.

• There is no good evidence to link low back pain to height, growth, weight, or body mass index (BMI).
• Hypermobility may be a predisposing factor.
• There is no evidence that carrying heavy school bags causes low back pain.
• There is evidence that children with low back pain are more likely to have negative psychosocial experiences such as emotional and conduct problems, and they are more likely to have other somatic symptoms and musculoskeletal pain.
• There is some evidence to support the hypothesis that such negative experiences predict those at high risk of back pain in the future.
• Flexed posture was significantly associated with low back pain in a more recent cross-sectional study of 66 schoolchildren aged 11-16 years.

• Benign back pain is usually worse on arising in the morning and improves with activity. Failure to follow this pattern suggests a sinister cause.
• Benign back pain is usually in the lower lumbar region.
• Some people complain of pain in the hips but show the location of pain to be in the low back.
• About 70% of people with simple low back pain have pain referred to the buttocks and thighs. Referred pain is usually a dull, poorly localized pain, and can affect both legs.
• Nerve root pain is sharp and well localized, following a dermatome quite closely. People with nerve root pain often have a sensation of numbness, or tingling. Nerve root pain at the common L5 and S1 levels usually extends to the foot or toes.
• When nerve root pain is present it is usually the chief complaint.

Examination has been covered in back examination and so is not repeated here.

Differential diagnosis is covered in "sinister causes of back pain" - click here to link to that record.

There should be no investigation for simple back pain, only if sinister causes are suspected. A plain x-ray of the lumbar spine offers little information but gives 120 times the dose of radiation of a chest x-ray.

In 1994 the Clinical Standards Advisory Group published some revolutionary advice that did not seem to have a strong evidence base at the time and the advice was effectively a complete reversal of current policy.

Until that time, the advice for back pain had been rest. Patients would be told to rest in bed with a firm mattress or a board under the mattress and to stay there for perhaps a week, 10 days or even a fortnight. The new advice said that bed rest should be avoided if possible and if permitted, it should be for no more than 48 hours. Analgesia should be given and the patient told to work through the pain.

Despite this being such a very common problem, good RCTs of management are comparatively few. A review from 2002⁷ concluded that exercise may have a positive effect while bed rest is ineffective and may be harmful, simple analgesics and NSAIDs have short-term benefits, and spinal manipulation may be effective in the first four weeks. No evidence was found for traction or back schools. Further research is also needed on how to prevent acute back pain from becoming chronic.

Not only does activity seem to lead to more rapid recovery from simple back pain but the old treatment may be associated with considerable morbidity. If a fit and healthy person is put on bed rest for a week or more, there is significant loss of muscle and bone and with it hypercalciuria, there is loss of power and proprioception, the ability of the circulation to adapt to changes in posture is impaired, there is loss of diurnal rhythm and there may even be overt depression too.

Drugs

The best form of analgesia is a NSAID because of the adverse effects of codeine and related compounds but some people are unable to tolerate these substances and they may have problems with COX-2 inhibitors too. Paracetamol is often not strong enough and the Oxford League Table for Analgesics⁸ may give some guidance. The new COX-2 inhibitors seem very well placed.

Where muscle spasm is a great problem, diazepam may help but it must be used short term only and sedation may make it more appropriate for use only at night. In chronic back pain, antidepressants may be of value.⁹

Physiotherapy

There is very limited evidence for the value of physiotherapy for back pain. This is partly because more than one modality is often employed at once. A Cochrane review was unimpressed by traction for back pain, with or without sciatica.¹⁰ Segmental stabilizing exercises for acute, subacute and chronic low back pain seem to be better than usual GP treatment but not better than other physiotherapy techniques.¹¹

Manipulation

Manipulation, usually by chiropractors or osteopaths, has long been used for back pain. Many other people also do some manipulation, including some physiotherapists and GPs.There have been a number of reviews. Adverse events associated with such treatments are very few. A Cochrane review in 2003 concluded that there is no evidence that spinal manipulative therapy is superior to other standard treatments for patients with acute or chronic low back pain although it is superior to sham therapies and those known to be ineffectual or harmful.¹² Finally, from Exeter, came a systematic review of systematic reviews and it concluded that spinal manipulation was not a useful technique.¹³

Placebo control in studies of manipulation is difficult. Usually sham manipulation is used but this may have some effect. Attempts to "manipulate the wrong level" may be fallacious as spinal reflexes often mean that the precise segmental level of the diagnosis is wrong and manipulation is not so specific that it is possible to manipulate a specific level without also manipulating nearby levels too.

How manipulation works is not understood. The concept that the joint is slightly subluxed and manipulation "puts it back" is untenable. The most likely mechanism is an over-stretching of the pain fibres within the joint, thereby blocking the gate-pathway for pain. This may be similar to the mechanism for traction.

Acupuncture

A Cochrane review of acupuncture for low back pain concluded that it may be of value in chronic pain but not in acute back pain.¹⁴

Massage

Massage may be of value in acute back pain.¹⁴

Although pain from the thoracic spine is a red flag, it may well be simple back pain. Such an injury is often acquired by lifting something heavy and rotating with it.

The neck is the highest part of the back and like the lumbar spine, needs active management. Injury is common, especially whiplash injury after a road traffic accident. The recommendations of the CSAG were readily taken up after 1994 but it took many more years before the message came through that an active approach to whiplash injuries was also needed. The Quebec Task Force published its work on whiplash injury in 1995 but that had little impact for years. Soft collars should be discarded, analgesics prescribed and exercises encouraged to get the neck moving again. Massage may be valuable for the relief of spasm.

After acute trauma the neck must still be treated with the utmost caution until it is proved safe to move to active rehabilitation. An evidence based patient information booklet for whiplash patients has been developed¹⁵ but it has no yet been shown to change outcome.

Probably the most important complication of non-sinister back pain, is the ability of it to become chronic and this may be because of failure of active management and behaviour by the patient that predisposes to chronicity rather than cure. The yellow flag features have been well described but there is, as yet, little good evidence as to how to manage them. It would seem that such people must be encouraged or cajoled into taking part in an active process of rehabilitation.

If chronicity can be prevented, then recovery should be full but in a variable time. Back pain in old age probably is, as many assume, simply a feature of advancing years. Analgesics may help but the most important aspect is to stay active.

According to the Clinical Knowledge Summaries guidelines, about 75% of people who are off work are able to return within 4 weeks. The risk of recurrence is about 25% within 3 months and about 75% with 12 months. They recommend that if there is not a good response to management within 4 to 6 weeks that referral for further investigation and treatment should be undertaken.

Over the past 40 years there have been far fewer jobs that involve heavy manual labour. Mechanical lifting devices are more often used. Almost anyone whose job involves lifting has an induction programme to teach safe lifting and the Health and Safety Executive¹⁶ has advice on the subject. Hence it is surprising that the figures from Bandolier⁵ should show a rise rather than a fall in the incidence of back pain. They suggest that the change is due to changing attitudes and expectations rather than to pathology.

To a considerable extent, back pain is a preventable condition and safe practice with regard to lifting should be able to prevent much. There are European Guidelines for the prevention of low back pain.