Red flag symptoms: Back pain

This red flags article explains the signs and symptoms of potentially serious pathology in patients presenting with back pain.

Red flag symptoms

  • Signs and symptoms of cauda equina or cord compression
  • Immunosuppression
  • Trauma
  • History of cancer
  • Nocturnal pain
  • Systemic upset – weight loss, fevers, night sweats
  • Thoracic pain
  • Abnormal gait

Back pain is common, but it is crucial to be aware of signs and symptoms which could herald a more serious underlying pathology or where the cause is more complex than simple mechanical pain.

History

It is vital not to miss cauda equina or spinal cord compression. The former is rare but with devastating consequences for the patient if missed. It can present with bladder, bowel or sexual disturbances.

There can be reduced sensation of the urinary system, lack of desire to void or poor stream or even new onset of faecal incontinence (due to loss of sensation of a full rectum). There may be sensory changes in the perianal or saddle region with saddle anaesthesia or paraesthesia. Sensory changes and weakness can occur in the lower limbs so examination is crucial.

The age and sex of the patient should alert the clinician to other possible causes, such as ankylosing spondylitis in a young man. Elderly patients (and those with osteoporosis) fracture more easily, even from minor trauma.

Back pain can sometimes be the symptom of malignant spread (lung, prostate, breast, thyroid or kidney), or myeloma. Often, the pain here remains on lying down, aching night time pain which disturbs sleep, and thoracic pain (which can also be a sign of other causes like aortic aneurysm).

Consider early investigation of patients who are generally unwell, with associated unexplained fevers, night sweats and weight loss; also, if they are immunocompromised, for example with HIV, diabetes or due to long-term steroid use.

Location is important. Thoracic pain should alert to other causes, such as intra-abdominal or thoracic conditions (pancreatitis or aortic dissection, for example).

Consider excluding inflammatory causes of pain if the patient is relatively young (less than 45 years), has pain which is improved with mobilising and has insidious onset with a chronic course.

It’s also worth establishing if there are any signs or symptoms of sciatica (or lumbar radiculopathy). This usually presents with unilateral leg pain that radiates below the knee to the foot or toes (but not always). Usually in these cases the leg pain is much worse than the back or sometimes the back pain is minimal or absent.

Examination

Abnormal gait as the patient walks in could suggest a serious pathology. Expose and inspect the back: do not miss shingles or psoriasis (indicating inflammatory arthritis).

Look for kyphosis, scoliosis or the 'question mark' appearance of ankylosing spondylitis.

Consider checking BP in both arms. Check movements of the spine, and consider straight leg raise or Schober's test if clinically indicated.

Lower limb neurological examination is vital. Tone and reflexes can be increased and brisk or reduced and absent, depending on the site of the lesion. Any severe or progressive neurological deficit in the lower limbs in the context of back pain should be considered for immediate referral. Check power (look for foot drop) and plantar reflexes. Note the distribution of any sensory changes.

Consider checking perianal sensation and anal tone (reduced or "lax") if cauda equina or cord compression is a possibility (offer a chaperone).

Consider lumbar radiculopathy if there are signs of nerve root compression (neurological disturbances in a nerve root pattern).

Investigations

History and examination remain the keystones, but if serious pathology is suspected, FBC, bone profile (abnormal in malignant spread or Paget's disease ), ESR, CRP (raised in malignancy, inflammatory or infective causes but often non-specifically raised so interpret results with caution), PSA (if there is a risk of prostatic malignancy, but counselling the patient about the false positive and negative rates of the test), or myeloma screen may be useful.

An X-ray may show fracture or infection (although evidence supporting x-ray use in non-specific back pain is limited), while an MRI, if indicated, may reveal spinal cord compression or other serious pathology more accurately if needed.

A word of caution, however. The CKS from NICE (updated April 2015) suggest that overall evidence for the use of red flags which may indicate serious spinal pathology in the primary care setting is not strongly established. The review suggests suspicion of spinal fracture or malignancy should not be made on the presence of a single red flag feature alone.

Differential diagnoses
  • Muscular/postural problems
  • Trauma/fracture
  • Inflammatory arthritis
  • Degenerative
  • Prolapsed disc
  • Paget's disease
  • Malignancy
  • Referred pain
  • Infective cause
  • Dr Adel Baluch is a Portfolio GP in London
  • This is an updated version of an article that was first published in November 2012.

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