Can low back pain cause radiculopathy and how is it managed?

Low Back Pain and Radiculopathy: Mechanisms and Management

Low back pain itself does not cause radiculopathy, but underlying conditions that cause low back pain, such as herniated discs or spinal stenosis, can lead to radiculopathy through nerve root compression and inflammation. 1, 2

Understanding Radiculopathy

Radiculopathy is defined as dysfunction of a nerve root associated with pain, sensory impairment, weakness, or diminished deep tendon reflexes in a nerve root distribution. 1

• Radiculopathy differs from non-specific low back pain by presenting with sharp, shooting or lancinating pain that radiates down the leg in a narrow band, often with associated neurological deficits 3, 2
• The most common symptom of lumbar radiculopathy is sciatica, which is pain radiating down the leg below the knee in the distribution of the sciatic nerve 1
• The pathophysiology involves more than just mechanical compression - it includes a combination of:
  • Nerve root compression sensitizing the nerve to mechanical stimulation 2
  • Stretching of the nerve root 2
  • Chemical inflammation from a non-cellular inflammatory reaction 2, 4

Mechanisms of Radiculopathy Development

Radiculopathy develops when specific spinal conditions affect nerve roots:

• Herniated disc: Herniation of the nucleus pulposus through its fibrous covering can compress adjacent nerve roots 1, 5
• Spinal stenosis: Narrowing of the spinal canal causing bony constriction of the cauda equina and emerging nerve roots 1
• Inflammatory mediators: Substances like phospholipase A2, prostaglandins, leukotrienes, and pro-inflammatory cytokines can cause direct neural injury and inflammation 4
• Mechanical compression: Physical pressure on nerve roots from structural abnormalities 2, 5

Clinical Evaluation

Proper assessment helps differentiate radiculopathy from non-specific low back pain:

• Focused history and physical examination to determine likelihood of specific underlying conditions 1
• Assessment for neurological deficits, including motor deficits at multiple levels, sensory changes, or reflex abnormalities 1, 3
• Straight-leg-raise test: Reproduction of the patient's sciatica when the leg is raised between 30-70 degrees suggests nerve root tension 1
• Evaluation for "red flags" such as cauda equina syndrome (urinary retention, bilateral motor weakness, saddle anesthesia) 1

Diagnostic Approach

• Diagnostic triage into three categories guides management: non-specific low back pain, back pain with radiculopathy/spinal stenosis, or back pain associated with another specific cause 1
• MRI is the preferred imaging modality for persistent radiculopathy in patients who are candidates for invasive interventions 3
• Electrodiagnostic testing (EMG, nerve conduction studies) can help confirm radiculopathy and rule out other neurological conditions 6, 5
• Avoid routine imaging for non-specific low back pain as it provides no clinical benefit and may lead to unnecessary interventions 3

Management of Radiculopathy

Conservative Management

• Maintain activity rather than bed rest - staying active is more effective for patients with radicular pain 3
• Pain management with appropriate medications, though radicular pain often responds poorly to simple analgesics 3
• Direction-sensitive exercises based on positions that decompress the affected nerve root 5

Interventional Approaches

• Image-guided epidural steroid injections are recommended for persistent radicular symptoms despite conservative therapy 3, 2
• Transforaminal epidural steroid injections can provide significant and lasting pain relief 2

Surgical Considerations

• Surgical referral should be considered for patients with progressive neurological deficits 3
• Discectomy may be appropriate for persistent radicular symptoms due to lumbar disc herniation 3, 7
• Spinal cord stimulation can be considered for persistent radicular pain after surgery 3

Referral Timing

• Early referral (within 2 weeks) is recommended for severe radicular pain or patients with neurological deficits 3
• For less severe radicular pain, referral to specialized services should occur by 3 months if symptoms persist 3
• Surgical consultation may be appropriate after failed conservative measures for at least 1 year 1

Common Pitfalls to Avoid

• Delaying treatment for patients with progressive neurological deficits, which can lead to worse outcomes 3
• Over-reliance on imaging findings without clinical correlation, as MRI findings are often non-specific 3
• Using non-image-guided injections, which compromise safety and efficacy 3
• Prolonged use of strong opioids, which should be restricted to the lowest possible dose for the shortest time 3