Low Back Pain

Key Features

Essentials of Diagnosis

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

• Alarming symptoms include unexplained weight loss, failure to improve with treatment, severe pain for > 6 weeks, and night or rest pain

• Cauda equina syndrome is an emergency; often presents with bowel or bladder symptoms (or both)

General Considerations

• Low back pain is the condition associated with the highest years lived with disability

• Cause is often multifactorial, making the exact cause difficult to diagnose

• There are usually degenerative changes in the lumbar spine involving the disks, facet joints, and vertebral endplates (Modic changes)

• The sacroiliac joint, muscles, and tendons also can cause pain

• Aggravating factors of flexion and prolonged sitting suggests anterior spine disk problems

• Aggravating factors of extension suggests facet joint, stenosis, or sacroiliac joint problems

• Alarming symptoms for back pain caused by cancer include

  • Unexplained weight loss

  • Failure to improve with treatment

  • Pain for > 6 weeks

  • Pain at night or rest

  • History of cancer and age > 50 years

• Alarming symptoms for infection include

  • Fever

  • Rest pain

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

  • History of immunocompromise or injection drug use

• 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, and presence of a contusion or abrasion

Demographics

• Remains the number one cause of disability globally

• Is the second most common cause for primary care visits

• Annual prevalence is 15–45%

• Annual health care spending for low back and neck pain is estimated to be $87.6 billion

Clinical Findings

• The majority of patients with persistent low back pain have co-occurring areas of pain, especially

  • Axial pain (18–58%)

  • Extremity pain (6–50%)

  • Multi-site musculoskeletal pain (10–89%)

• In the standing position,

  • The patient's posture can be observed for spinal asymmetries such as scoliosis, thoracic kyphosis, and lumbar hyperlordosis

  • The active range of motion of the lumbar spine can be assessed; common directions include flexion, extension, rotation, and lateral bending

  • The one-leg standing extension test can be used to assess for pain

    • A positive test can be caused by pars interarticularis fractures (spondylolysis or spondylolisthesis) or facet joint arthritis, although sensitivity and specificity of the test is limited

• With the patient sitting,

  • Motor strength, reflexes, and sensation can be tested (Table 41–2)

  • Major muscles in the lower extremities are assessed for weakness by eliciting a resisted isometric contraction for about 5 seconds

  • Comparing the strength bilaterally to detect subtle muscle weakness is important

  • Similarly, sensory testing to light touch can be checked in specific dermatomes for corresponding nerve root ...