Imaging in adults with acute low back pain

Unnecessary imaging causes harm, such as ionising radiation exposure, increased work absence and delay in starting appropriate treatment. Incidental findings can lead to a cascade of non-beneficial investigations, referrals, interventions and surgery, with their associated costs and harms. Incorrect interpretation of asymptomatic changes in the spine can leave the patient worried and concerned.^1,4

MRI within 30 days of symptom onset when there is no clear indication associated with higher rates of prolonged disability.³

Disease burden

• Acute low back pain, lasting four to six weeks, affects one in six Australians (16%),⁷ and is a frequent presentation in primary care.⁸

Clinical diagnosis

• Non-specific low back pain is a clinical diagnosis and no investigations are required. In approximately 90% of people presenting with acute low back pain, a clinical diagnosis of non-specific low back pain can be made after a history and physical examination.^1,2
• Five to 10 per cent of patients presenting with low back pain will have a clinical diagnosis of radicular syndrome. Indicators suggesting radicular syndrome include predominance of leg pain, progressive muscle weakness, neurogenic claudication, tingling or numbness or abnormal findings from a neurological examination of the lower limbs.²

Assessing for a serious underlying condition

• Serious causes are rare. Fewer than 1% of people presenting with acute low back pain will have a serious underlying condition such as spinal fracture, malignancy, infection or cauda equina syndrome.²
• Possible indications of a spinal fracture include older age, prolonged glucocorticosteroid use, significant trauma or the presence of a contusion or abrasion.^1,9
• Possible indications of a malignant cause include a history of malignancy or unintended weight loss.^1,9
• Possible indications of a spinal infection include fever or chills, immunocompromise, pain at rest or at night, intravenous drug use, a recent injury, or a recent dental or spine procedure.¹
• Possible indications of cauda equina syndrome include new dysfunction of the bowel or bladder, perineal numbness, altered saddle sensation, or persistent or progressive lower motor neuron changes.^1,10
• Possible indications of a severe neurological deficit include motor deficits at multiple levels or progressive lower limb weakness.¹ If a neurosurgical emergency is considered likely, refer the patient to an emergency department, instead of referring for imaging.

Diagnostic imaging

• Diagnostic imaging is not indicated in the vast majority of people with acute low back pain and may cause more harm than benefit.¹
• Imaging is only indicated if there is a strong clinical suspicion of a serious underlying cause.^1,4,5
• In radicular syndrome, imaging is not routinely indicated and should only be considered in the first six weeks if the symptoms are severe and not improving and surgery is being considered.^1,4,5
• If there is a strong clinical suspicion of a spinal fracture, consider a lumbar spine X-ray or a computed tomography (CT) scan.¹
• If there is a strong clinical suspicion of malignancy, infection, cauda equina syndrome or a severe neurological deficit, consider an MRI.^1,5 The clinical situation will determine the urgency. CT is an alternative if MRI is contraindicated or unavailable.⁵
• If imaging is undertaken, avoid giving the patient an unhelpful diagnostic label when discussing the results.¹

Prognosis

Most people, whether or not they have radiculopathy, experience substantial improvements in pain and function within four weeks.⁶

• Reassure the patient that, although their pain may be severe, non-specific low back pain is almost never caused by a serious condition and that their pain will almost certainly improve within four weeks.⁶
• Educate them about the importance of maintaining their usual activities, including work and physical activity.^4,11
• Advise them to not to rest in bed,⁴ as this can delay their recovery.
• Encourage them to return to work.¹¹
• Consider advising them to use superficial heat.⁴
• If analgesia is required, consider short-term non-steroidal anti-inflammatory drugs (NSAIDs).^4,11
• Although there is evidence that paracetamol is not effective in the management of non-specific low back pain, it can be offered if NSAIDs are not tolerated or are contraindicated.⁴
• Opioids have a very limited role in the management of acute low back pain, as there is no evidence of their efficacy, and they are associated with significant harms.^4,11
• Make a plan with the patient that you will reassess them if significant symptoms occur within the next four to six weeks.
• Reassess after four to six weeks.

• The RACGP, First do no harm: A guide to choosing wisely in general practice, Imaging in adults with acute low back pain patient resource
• The RACGP, Handbook of non-drug interventions (HANDI), Staying active for acute low back pain patient resource 
• The RACGP, Handbook of non-drug interventions (HANDI), Heat therapy for low back pain patient resource 
• The RACGP, Handbook of non-drug interventions (HANDI), Exercise for acute lower back pain 
• NSW Government and Agency for Clinical Innovation, Managing low back pain: Information for patients 
• NPS MedicineWise, Why tackle acute non-specific low back pain now?
• The Royal Australian and New Zealand College of Radiologists, Educational modules for appropriate imaging referrals for acute low back pain
• The Australian Commission on Safety and Quality in Health Care, Low back pain clinical care standard 

Tools to screen for risk of chronic disability in acute low back pain

• Keele University, Online STarTBacK calculator
• SA Health, Yellow flag screening in lumbar disorders 

Screening questionnaire for patients with workplace injuries and to assess risk of chronicity

• Neuroscience Research Australia
• NSW Government