What is the appropriate initial evaluation and management of a patient with back pain?

Examination of Patient with Back Pain

Conduct a focused history and physical examination to classify the patient into one of three categories: nonspecific low back pain (85% of cases), back pain with radiculopathy/spinal stenosis, or back pain with another specific spinal cause—this classification drives all subsequent management decisions. 1

History Components

Red Flags to Identify Immediately

Screen for serious underlying conditions that require urgent imaging or intervention 1:

• Cancer history or current unexplained weight loss (cancer prevalence ~0.7%) 1
• Fever or recent infection (spinal infection prevalence 0.01%) 1
• Significant trauma (compression fracture prevalence 4%) 1
• Severe or progressive neurologic deficits (cauda equina syndrome prevalence 0.04%) 1
• Osteoporosis or chronic steroid use (increases fracture risk) 1
• Age >50 years with new onset pain (higher cancer/fracture risk) 1

Neurologic Symptom Assessment

Determine if radiculopathy or spinal stenosis is present 1:

• Radicular leg pain (radiating below the knee in dermatomal pattern) 1
• Numbness or weakness in specific nerve distributions 1
• Bowel/bladder dysfunction (suggests cauda equina syndrome) 1

Psychosocial Risk Factors

Assess factors predicting chronic disability 1:

• Depression or passive coping strategies 1
• Job dissatisfaction or disputed compensation claims 1
• Higher baseline disability levels or somatization 1

Physical Examination Components

Neurologic Examination

Perform targeted testing based on symptom pattern 1, 2:

• Straight leg raise test (positive if reproduces radicular pain <70 degrees) 2
• Motor strength testing (L4: ankle dorsiflexion; L5: great toe extension; S1: ankle plantarflexion) 1
• Sensory examination (dermatomal distribution) 1
• Reflexes (knee jerk L4, ankle jerk S1) 1

Spinal Examination

Look for specific findings 2:

• Midline tenderness (suggests compression fracture or infection, especially with fever) 2
• Kyphosis or postural abnormalities (osteoporosis risk) 3
• Range of motion limitations 1

Imaging Decision Algorithm

Do NOT Image Routinely

Avoid imaging in nonspecific low back pain without red flags—routine imaging provides no clinical benefit and exposes patients to unnecessary radiation. 1

Image Immediately (MRI or CT)

Order urgent imaging when 1, 3:

• Severe or progressive neurologic deficits present 1
• Cauda equina syndrome suspected (saddle anesthesia, bowel/bladder dysfunction) 1
• Cancer history with new back pain (concern for metastasis/cord compression) 3
• Fever with back pain (concern for infection) 1

MRI is preferred over CT because it provides superior soft tissue, vertebral marrow, and spinal canal visualization without ionizing radiation 1, 3.

Consider Delayed Imaging

For patients without red flags 1, 2:

• Plain radiography after 4-6 weeks if symptoms persist despite conservative management 1, 2
• Plain radiography initially for suspected compression fracture in high-risk patients (osteoporosis, steroid use) 1

Alternative Screening Strategy

For patients with cancer risk factors but no neurologic deficits 1:

• ESR measurement (≥20 mm/h has 78% sensitivity, 67% specificity for cancer) 1
• Plain radiography first, then MRI if abnormal 1

Common Pitfalls to Avoid

• Never order routine imaging for acute nonspecific low back pain—this leads to identification of incidental findings (disc abnormalities present in 29-43% of asymptomatic patients) that may trigger unnecessary interventions 1
• Do not delay MRI when red flags are present—delayed diagnosis of cauda equina syndrome, infection, or cord compression worsens outcomes 1, 3
• Avoid recommending bed rest—maintaining activity within pain limits improves outcomes 2
• Do not miss psychosocial assessment—these factors strongly predict progression to chronic disabling pain 1

Reassessment Timing

Reevaluate patients with persistent unimproved symptoms after 1 month, as most acute low back pain improves substantially within the first month 1, 2. Earlier reassessment is appropriate for 1:

• Severe pain or functional deficits
• Older patients
• Signs of radiculopathy or spinal stenosis