What is the recommended workup for lumbar radiculopathy?

Workup of Lumbar Radiculopathy

Initial Clinical Assessment

Begin with a focused history and neurological examination to identify red flags and determine the need for imaging. 1

Key History Elements to Obtain:

• Duration and character of symptoms: Assess for radiating leg pain (typically worse than back pain), numbness, tingling, or weakness in a dermatomal distribution 2
• Red flag symptoms requiring urgent evaluation: 1
  • Bowel or bladder dysfunction (cauda equina syndrome)
  • Progressive or severe motor weakness
  • Saddle anesthesia
  • History of cancer, recent infection, fever, or unexplained weight loss
  • History of significant trauma, osteoporosis, or chronic steroid use

Essential Physical Examination Components:

• Motor strength testing: Evaluate specific muscle groups corresponding to nerve root levels (L3: knee extension; L4: ankle dorsiflexion; L5: great toe extension; S1: ankle plantarflexion) 2
• Deep tendon reflexes: Check patellar (L4) and Achilles (S1) reflexes 2
• Sensory examination: Test dermatomal distribution 2
• Provocative testing: Perform straight leg raise test (high sensitivity for nerve root tension, particularly for L5-S1 radiculopathy) 3, 4
• Gait assessment: Observe for antalgic gait or foot drop 3

Imaging Strategy

When NOT to Image:

Do not routinely obtain imaging in patients with radicular symptoms without red flags or neurological deficits. 1 The natural history of lumbar disc herniation with radiculopathy shows improvement within the first 4 weeks with conservative management in most patients 1, 5.

When to Image:

Obtain MRI (preferred) or CT immediately if: 1

• Severe or progressive neurological deficits are present
• Red flag symptoms suggest serious underlying conditions (cauda equina syndrome, vertebral infection, cancer with impending spinal cord compression)
• Delayed diagnosis in these scenarios is associated with poorer outcomes

Obtain MRI (preferred) or CT for persistent symptoms if: 1, 5

• Radicular symptoms persist beyond 4-6 weeks despite conservative therapy AND
• The patient is a potential candidate for surgery or epidural steroid injection
• There is no compelling evidence that routine imaging affects treatment decisions or improves outcomes in patients not being considered for invasive interventions 1

Why MRI is Preferred:

• MRI provides superior visualization of soft tissue, vertebral marrow, and the spinal canal compared to CT 1, 5
• Avoids ionizing radiation exposure 1
• Better identifies nerve root compression, disc herniation characteristics, and foraminal stenosis 5

Important Caveat:

MRI findings must be correlated with clinical symptoms and neurological deficits. 3 Many radiographic abnormalities are poorly correlated with symptoms and could lead to unnecessary interventions 1. Findings on imaging are often nonspecific without clinical correlation 5.

Role of Electrodiagnostic Testing

Electromyography (EMG) and nerve conduction studies are not routinely recommended for initial evaluation of lumbar radiculopathy 1. However, EMG may be useful when: 2, 6

• The diagnosis remains unclear after history, examination, and imaging
• Multiple nerve root levels are potentially involved
• Differentiating radiculopathy from peripheral neuropathy or other neuromuscular conditions

Additional Testing Considerations

Plain radiography may be reasonable for: 1

• Initial evaluation of suspected vertebral compression fracture in high-risk patients (history of osteoporosis, chronic steroid use)
• Persistent symptoms beyond 1-2 months without clear radiculopathy when advanced imaging is not immediately available

Do not obtain: 1

• Routine plain radiographs for nonspecific low back pain with radicular symptoms (exposes patients to unnecessary radiation without improving outcomes)
• Thermography (not recommended for evaluation)

Clinical Pitfalls to Avoid

• Do not delay imaging in patients with progressive neurological deficits - this is associated with significantly poorer outcomes 5
• Avoid ordering MRI in all patients with radicular pain - most improve with conservative management within 4 weeks, and early imaging does not change outcomes 1, 5
• Do not assume positive imaging findings are clinically significant - correlation with examination findings is essential, as many asymptomatic individuals have disc abnormalities on MRI 1, 3
• Recognize that clinical tests have limitations: The straight leg raise has high sensitivity but low specificity; neurodynamic tests generally lack diagnostic accuracy for specific MRI findings 4