Low Back Pain

Key Features

Essentials of Diagnosis

• May be categorized by pain on flexion versus pain on extension

• Nerve root impingement is suspected when pain is leg-dominant rather than back-dominant

• Alarming ("red flag") symptoms include unexplained weight loss, failure to improve with treatment, severe pain for more than 6 weeks, and night or rest pain

• The cauda equina syndrome often presents with bowel or bladder symptoms (or both) and is an emergency

General Considerations

• Cause is often multifactorial, although there are usually degenerative changes in the lumbar spine

• Alarming symptoms for back pain caused by cancer include

  • Unexplained weight loss

  • Failure to improve with treatment

  • Pain for more than 6 weeks

  • Pain at night or rest

  • Age > 50 years

  • History of cancer

• Alarming symptoms for infection include

  • Fever

  • Rest pain

  • Recent infection (urinary tract infection, cellulitis, pneumonia)

  • History of immunocompromise or injection drug use

• The cauda equina syndrome is suggested by

  • Urinary retention or incontinence

  • Saddle anesthesia

  • Decreased anal sphincter tone or fecal incontinence

  • Bilateral lower extremity weakness

  • Progressive neurologic deficits

• Risk factors for back pain due to vertebral fracture include

  • Use of corticosteroids

  • Age > 70 years

  • History of osteoporosis

  • Severe trauma

  • Presence of a contusion or abrasion

• Back pain may also be the presenting symptom in other serious medical problems including

  • Abdominal aortic aneurysm

  • Peptic ulcer disease

  • Kidney stones

  • Pancreatitis

Demographics

• Globally, number one cause of disability visits

• Second most common cause for primary care visits

• Annual prevalence is 15–45%

• Annual cost in the United States is over $87.6 billion

Clinical Findings

Physical Examination

• In the standing position

  • Observe the patient's posture

    • Commonly encountered spinal asymmetries include scoliosis, thoracic kyphosis, and lumbar hyperlordosis

  • Assess the active range of motion of the lumbar spine

  • Perform the one-leg standing extension test to assess for pain (the patient stands on one leg while extending the spine); a positive test can be caused by

    • Pars interarticularis fractures (spondylolysis or spondylolisthesis) or

    • Facet joint arthritis

• In the sitting position

  • Test motor strength, reflexes and sensation (eTable 41–1)

  • Assess the major muscles in the lower extremities for weakness by eliciting a resisted isometric contraction for approximately 5 seconds

  • Compare the strength bilaterally to detect subtle muscle weakness

  • Similarly, check sensory testing to light touch in specific dermatomes for corresponding nerve root function

  • Finally, check the knee (femoral nerve L2–4), ankle (deep peroneal nerve L4–L5), and Babinski (sciatic nerve L5–S1) reflexes can be checked

• In the supine position

  • Evaluate the hip for range of motion, focusing on internal rotation

  • Perform the straight leg raise test; it puts traction and compression forces on the lower lumbar nerve roots (Table 41–2)

• In the prone position

  • Carefully palpate each level of the spine ...