Back pain – Assessment

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BackPain
Introduction

  • This section refers to lumbar back pain rather than thoracic back pain
  • Is a common primary care and emergency department presentation.
  • The majority of causes are benign but there are some key red flags (see below) to be wary of that suggest serious or even life or limb-threatening disease.
  • A good history, MSK and neuro exam is a minimal requirement.
  • There is  a tendency to over-image musculoskeletal cause of back pain even though there are clear internationally accepted guidelines that guide this.  This should only be done if fractures, infection or malignancy are considered
  • Pejorative labels can be prematurely given to patient with long but intermittent history of pain even though by and large most of these patients are usually functional and  not opiate dependent (cf chronic pain syndrome)
  • Analgesia early  in assessment facilitates back examination and neurological examination
  • If patient is shocked then an intra-abdominal catastrophe should be considered such as ruptured abdominal aortic aneurysm.  Early IV access, surgical opinion should be sought
  • Consider non-MSK causes of back pain.  Some important cause include abdominal aortic aneurysm, acute pancreatitis, pyelonephritis and ureteric calculi

Assessment

  •  It is always helpful to follow the Principles of a Systematic Assessment
  • The chronology of the pain is important to establish as well as any antecedent precipitants.  This gives a clue to the likely pathology,  Abrupt or acute onset of pain without a clear history of changes in activity point away from the possibility of MSK pain.
  • A MSK exam of the back is essential.  This may have to occur after strong analgesia is administered to facilitate examination.   If the MSK exam is unconvincing, an alternative cause for  non-MSK causes of back pain should be sought
  • Other clues to non-MSK causes of back pain are abdominal tenderness, unilateral loin/flank tenderness, urinary symptoms,  prominent GIT symptoms
  • A neuro exam including the sacral functions and looking for radiculopathy

Red flags

  • A normal MSK back examination suggests retroperitoneal pathology
  • Signs of infection – focal bone tenderness or inflammation, fever, elevated inflammatory markers, post-procedural, intravenous drug use is also a risk factor
  • Suspicion of malignancy – night pain, history of cancer, constitutional symptoms such as weight loss, unrelenting pain > 4 weeks not responding to physical therapy
  • Evidence of cord/conus/cauda compression – bilateral leg weakness or sensory change, loss of sacral function

Investigations 
Usually not required

  • WCC/CRP – if suspicion of infection
  • Calcium, Phosphate, ALP – If suspicion of malignancy or known systemic bone disease

Indications for Urgent CT or MRI

  • Paraplegia or signs of loss of sacral function
  • Localising tenderness with fever or raised inflammatory markers

Management of Mechanical Back Pain

  • It is a acceptable to initially provide a short course of strong analgesia to enable the patient to mobilise
  • Light activity should be encouraged
  • Gentle physical therapy can be introduced as the patient becomes more comfortable
  • The purpose of analgesia is to progressively introduce higher levels of activity, in itself it does not alter the natural history
  • Strict bed rest, inactivity, rigid sleeping surfaces and back braces should be discouraged
  • After the convalescent period, core strengthening exercise should be made routine
  • Advice about correct lifting technique should be provided e.g. lifting with bent knees, avoiding twisting movement when lifting loads
  • The majority of patient will resolve within 4 weeks including those with sciatica.  Failure is due non-compliance, inadequate physical therapy or a sinister cause.
  • A different approach should be made for chronic, unresponsive back pain which has been extensively investigated.

DISPOSITION

Urgent Neurosurgical Consultation

  • Acute paralysis or loss of sacral function due to a suspected or confirmed compressive lesion or pathological fracture (on imaging)

Neurological consultation

  • Acute paralysis or loss of sacral function without compressive lesion or pathological fracture (on imaging)

Radiation Oncology consultation

  • Acute paralysis or loss of sacral function due to a compressive neoplastic compressive lesion (on imaging)

Discharge Criteria

  • Obvious MSK cause
  • No evidence of infection
  • Mobilising adequately after analgesia
  • No bilateral leg symptoms
  • Intact sacral function

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