What does radiculopathy indicate in a patient with lumbar disc degeneration at L4‑5 with loss of disc height?

Radiculopathy in Lumbar Disc Degeneration: Clinical Significance

Radiculopathy in a patient with L4-5 disc degeneration and loss of disc height indicates nerve root compression or irritation from the degenerative disc, manifesting as radiating leg pain, numbness, weakness, and sensory deficits in the distribution of the affected nerve root. 1

Pathophysiological Meaning

When radiculopathy accompanies lumbar disc degeneration at L4-5, it signifies that the degenerative process has progressed beyond simple disc height loss to cause:

• Direct nerve root compression from disc herniation, bulging, or protrusion at the affected level 2
• Foraminal or lateral recess stenosis from the combination of disc collapse, osteophyte formation, and facet joint hypertrophy 2
• Inflammatory irritation of the nerve root even without direct mechanical compression 3

The L4-5 level is the most commonly affected site for both disc degeneration and radiculopathy, with symptoms typically following the L5 nerve root distribution (lateral leg, dorsum of foot, great toe weakness) 2, 4

Clinical Presentation Specifics

Look for these specific findings that distinguish radiculopathy from simple axial back pain:

• Dermatomal sensory loss along the anterolateral calf and dorsum of the foot for L5 radiculopathy 2
• Myotomal weakness including foot dorsiflexion weakness (foot drop), ankle inversion weakness, or hip abduction weakness 2
• Radiating pain that extends below the knee into the leg and foot, not just buttock or upper thigh pain 1, 2
• Positive nerve tension signs on examination 3

Management Implications

The presence of radiculopathy fundamentally changes the treatment approach:

Initial Conservative Management (First 6-12 Weeks)

Conservative treatment remains first-line even with radiculopathy, as this is typically a self-limited condition. 1

• Patient education, physical therapy, and pain management without routine imaging for acute presentations (<4 weeks) 1
• Imaging is warranted only after 4-6 weeks of failed conservative management or if red flags are present 1
• Epidural steroid injections show moderate evidence (Level B) for effectiveness 3
• McKenzie method, mobilization, exercise therapy, and neural mobilization all have moderate evidence supporting their use 3

Surgical Considerations

Lumbar fusion is NOT recommended as routine treatment for isolated disc herniation with radiculopathy. 1

Surgical intervention becomes appropriate when:

• Conservative management fails after 6-12 weeks AND advanced imaging (MRI) shows nerve root compression corresponding to clinical findings 1, 5
• Simple discectomy alone is the appropriate surgical procedure for isolated radiculopathy from disc herniation 1

Fusion should only be considered if additional factors are present:

• Significant chronic axial back pain (not just radicular pain) 1
• Documented segmental instability 1
• Severe degenerative changes beyond simple disc herniation 1
• Recurrent disc herniation with instability 1

Critical Pitfalls to Avoid

• Do not order imaging in acute radiculopathy (<4 weeks) without red flags, as 84% of imaging abnormalities remain unchanged or improve even after symptoms develop 1
• Do not assume imaging findings correlate with symptoms, as disc protrusions occur in 29-43% of asymptomatic patients depending on age 1
• Do not routinely add fusion to discectomy for isolated radiculopathy, as this increases complexity and complications without proven benefit (Level III-IV evidence shows no improvement in outcomes) 1
• Recognize that most disc herniations show reabsorption by 8 weeks, making early surgical intervention often unnecessary 1

Red Flags Requiring Urgent Evaluation

Immediate imaging and specialist referral are warranted if radiculopathy is accompanied by:

• Cauda equina syndrome symptoms (bowel/bladder dysfunction, saddle anesthesia) 1
• Progressive neurological deficits 5
• Suspicion for malignancy, fracture, or infection 1