Lower back pain

Background
  • Pain lasting >6wks is risk factor for more serious disease
  • Night pain and unrelenting pain are worrisome symptoms
  • Back pain in IV drug user is spinal infection until proven otherwise
  • 95% of herniated discs occur at L4-L5 or L5-S1 (for both pain extends below the knee)
  • Lumbago: acute, nonspecific back pain

Back Pain Risk factors and probability of Fracture or Malignancy[1]
Factor Post Test Probability (95%CI)
Older Age (>65yo)9% (3-25%)
Prolonged corticosteroid33% (10-67%)
Severe trauma11% (8-16%)
Presence of contusion or abrasion62% (49-74%)
Multiple red flags90% (34-99%)
History of malignancy33% (22-46%)

Clinical Features

Symptoms by Causes of Low back pain
Musculoskeletal pain Spinal stenosis Sciatica Cauda equina syndrome Rheumatologic
Radiation?NoPossible (can be bilateral)Yes (in the distribution of a lumbar or sacral nerve root)Possible?
Worsened by:Movement (e.g. twisting of torso)Walking (pseudo-claudication) and prolonged standingCoughing, Valsalva, sittingMorning stiffness >30minutes
Improved by:RestForward flexion, especially sittingLying in supine positionMovement throughout the day
Other symptoms:Urinary/bowel disturbances, perineal anaesthesiaOther rheum symptoms (e.g. ankylosing spondylitis, psoriatic arthropathy, IBD arthropathy, Reiter's disease)
Lumbar nerve root distribution

Waddell's Signs of Non-Organic Low back pain[2]

3 or more positives suggest non-organic or alternative organic source:

  • Over-reaction to the examination
  • Widespread superficial tenderness not corresponding to any anatomical distribution
  • Pain on axial loading of the skull or pain on rotation of the shoulders and pelvis together
  • Severely limited straight leg raising on formal testing in a patient who can sit forwards with the legs extended
  • Lower limb weakness or sensory loss not corresponding to a nerve root distribution

Differential Diagnosis
Differential diagnosis of back pain

Lower Back Pain

Evaluation

Exam
  • Straight leg raise testing
    • Screening exam for a herniated disk (Sn 68-80%)
    • Lifting leg causes radicular pain of affected leg radiating to BELOW the knee
    • Pain is worsened by ankle dorsiflexion
    • Pain may be relieved by pressing across biceps femoris and pes anserinus tendons behind knee ('bowstringing')
  • Crossed Straight leg raise testing (high Sp, low Sn)
    • Lifting the asymptomatic leg causes radicular pain down the affected leg
  • Nerve root compromise
  • Rectal exam, perineal sensation, palpable bladder?

Labs
  • Pregnancy test
  • Only necessary if concerned for infection, tumor, or rheumatologic cause
    • CBC, UA, ESR (90-98% Sn for infectious etiology)
  • Consider post void residual

Imaging

Management

Acute, Non-traumatic, Non-Radicular Back Pain
  • Instruct to continue daily activities using pain as limiting factor
  • Medications
    • Acetaminophen and/or NSAIDs
      • 1st line therapy
      • Consider gel/patch like diclofenac or ketoprofen (shown to be more effective than PO form and placebo in one study[3])
    • Lidocaine patch
    • Capsaicin or Cayenne
      • Skin desensitization upon repeated exposure
    • Muscle relaxants (limited evidence)
      • cyclobenzaprine 10 mg PO OR
      • methocarbamol 1500 mg PO
    • Opioids
      • Appropriate for moderate-severe pain but only for limited duration (<1 week)

Not Indicated

Acute, Radicular Back Pain (Sciatica)

80% of patients will ultimately improve without surgery

  • Treatment is mostly the same as for acute non-radicular back pain
  • Consider also gabapentin (titrate slowly) or TCAs (nortriptyline, amytriptyline)
    • Gabapentin Oral: Immediate release: 400mg-1200mg PO TID

Spinal stenosis
  • Treatment is the same as for musculoskeletal back pain

Cauda equina syndrome
  • Immediate spine surgery consultation for spinal decompression to avoid permanent bowel/bladder/neurologic injury

Disposition
  • Normally outpatient, as long as no signs of emergent pathology and able to ambulate

See Also
  • Back Pain (Red Flags)

Video

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References
  1. Downie A, et al. Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ. 2013; 347:f7095.
  2. Waddell G, et al. Non-organic physical signs in low-back pain. Spine. 1980; 5:117-125.
  3. Mazières B, Rouanet S, Velicy J, et al. Topical ketoprofen patch (100 mg) for the treatment of ankle sprain: a randomized, double-blind, placebo-controlled study. Am J Sports Med. 2005;33:515-523
  4. Friedman BW, et al. "Diazepam is no better than placebo when added to Naproxen for acute low back pain." Annals of EM. August 2017. 70(2):169-176
  5. Holve, RL, et al. Oral steroids in initial treatment of acute sciatica. J Am Board Fam Med. 2008; 21(5):469-474.
  6. Goldberg H, et al. Oral steroids for acute radiculopathy due to a herniated lumbar disk: a randomized clinical trial. JAMA. 2015 May 19;313(19):1915-23. PMID 25988461.
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