What is radicular pain, how does it differ from axial or referred pain, and what are the diagnostic approach and stepwise management?

Radicular Pain: Definition, Differentiation, and Clinical Management

What is Radicular Pain?

Radicular pain is pain perceived in a limb distribution caused by irritation or compression of a spinal nerve root or dorsal root ganglion, characterized by sharp, shooting, or lancinating sensations that travel in a narrow band down the length of the extremity. 1

The pathophysiology involves more than simple mechanical compression—it results from a combination of compression sensitizing the nerve root to mechanical stimulation, stretching forces, and a chemically mediated non-cellular inflammatory reaction that generates ectopic nerve impulses perceived as pain in the axon's distribution. 1, 2

Key Distinctions from Other Pain Types

Radicular vs. Axial Pain

• Axial pain is localized to the spinal midline (neck or back) without distal radiation 3
• Radicular pain refers distally into the limb, typically following a dermatomal pattern, and is felt both superficially and deep 1

Radicular vs. Referred Pain

• Referred pain originates from deep spinal or paraspinal nociceptors and radiates in a diffuse, non-dermatomal pattern 2
• Radicular pain follows specific nerve root distributions with sharp, lancinating quality rather than dull, aching characteristics 1
• Radicular pain may coexist with somatic referred pain, complicating clinical presentation 1

Associated Radiculopathy

• Radicular pain may occur with or without radiculopathy (objective sensory/motor dysfunction from nerve conduction block) 1
• The presence of motor or sensory deficits indicates more severe nerve compromise requiring urgent evaluation 3, 4

Diagnostic Approach

Red Flags Requiring Immediate Action (Within 2 Weeks)

• Cauda equina syndrome: bladder/bowel dysfunction with saddle anesthesia demands immediate neurosurgical consultation 4
• Progressive neurological deficits: motor weakness or sensory loss in the affected territory 3, 4
• Severe disabling pain: prevents normal everyday tasks 3
• Suspected fracture, infection, or malignancy 4

Clinical Examination

• Spurling test (for cervical radicular pain): most common examination to identify nerve root compression 5
• Shoulder abduction test (for cervical radicular pain): relief with arm elevation suggests nerve root pathology 5
• Document specific dermatomal sensory changes and myotomal motor weakness 1

Imaging Strategy

• MRI without contrast is the gold standard imaging modality and should be obtained prior to any interventional treatments 5, 4
• Do not order MRI at primary care level for screening: MRI is too sensitive and not specific enough, leading to incidental findings that poorly correlate with symptoms 3
• Critical pitfall: Imaging abnormalities alone do not mandate treatment—disc abnormalities are common in asymptomatic patients, and MRI findings must correlate with clinical presentation 4
• Plain radiography or CT scanning may be appropriate in specific cases 5

Stepwise Management Algorithm

Initial Management (First 2 Weeks)

For all patients without red flags:

• Advise reactivation and explicitly avoid bed rest 3, 4
• Initiate NSAIDs as first-line medication (simple analgesics are ineffective for radicular pain) 4
• Consider neuropathic pain medications early (gabapentin, pregabalin, tricyclic antidepressants), though evidence is limited 5, 4
• Provide patient education and self-management resources 4
• Review within 2 weeks to assess improvement and screen for developing red flags 3, 4

Timing-Based Referral Thresholds

Urgent specialist referral (within 2 weeks):

• Disabling pain preventing normal activities 3
• Any motor or sensory deficits in the affected territory 3, 4

Routine specialist referral (no later than 3 months):

• Persistent symptoms despite conservative management 3
• Earlier referral if pain severity increases or functional disability worsens 4

Conservative Management Period (6 Weeks to 3 Months)

• Structured physical therapy focusing on reactivation 4
• Biopsychosocial assessment using tools like STarT Back to stratify risk 4
• Optimize pharmacological regimen with specialist input 4
• Strong opioids only with strict restrictions: lowest dose, shortest duration, close monitoring of efficacy and side effects 4

Natural history: More than 50% of cases settle with conservative measures 1

Interventional Procedures: Current Evidence

The 2025 BMJ guidelines issued strong recommendations AGAINST the following for chronic radicular spine pain (≥3 months):

• Dorsal root ganglion radiofrequency ablation with or without epidural injection 3
• Epidural injection of local anesthetic, steroids, or their combination 3

Important context from older guidelines:

• The 2013 British Pain Society guidelines suggested considering image-guided steroid injections for severe radicular pain 3
• However, the most recent 2025 BMJ guideline represents the highest quality evidence and supersedes previous recommendations 3

Critical caveat: These recommendations apply only to chronic radicular pain (≥3 months duration) and do not apply to acute radicular pain management 3

Surgical Referral Indications

Consider neurosurgical consultation after minimum 6 weeks (ideally 3 months) of conservative management for:

• Progressive neurological deficits 4
• Persistent functional disabilities despite comprehensive conservative treatments 4
• Severe radicular pain refractory to conservative measures 1
• Documented correlation between imaging findings and clinical symptoms 4

Post-surgical considerations:

• Spinal cord stimulation may be considered for persistent radicular pain after surgery 4

Common Pitfalls to Avoid

1. Delayed treatment for progressive neurological deficits associates with worse outcomes 4
2. Prescribing bed rest is contraindicated—staying active is superior for radicular pain 4
3. Treating radicular pain like non-specific low back pain—radicular pain requires different management strategies 4
4. Ordering MRI too early in primary care leads to incidental findings without clinical correlation 3
5. Assuming imaging abnormalities mandate intervention—disc pathology is common in asymptomatic individuals 4
6. Using epidural steroids for chronic radicular pain (≥3 months)—strong evidence recommends against this practice 3