Lumbar Radiculopathy and Sciatica

Definitions and Relationship

The American College of Physicians defines sciatica as the most common symptom of lumbar radiculopathy, describing pain radiating down the leg below the knee in the distribution of the sciatic nerve, suggesting nerve root compromise due to mechanical pressure or inflammation 1
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, with sciatica being a symptom of this condition 1

Radiculopathy is a pathophysiological diagnosis that includes objective findings such as motor weakness, sensory deficits, and reflex changes in addition to pain 1

A patient can have sciatica without meeting full criteria for radiculopathy if they have radiating leg pain but lack objective neurological findings, such as weakness, sensory loss, or reflex changes 1
Conversely, radiculopathy always involves nerve root dysfunction with demonstrable neurological deficits, not just pain 1

The diagnosis of radiculopathy requires a comprehensive neurological examination, including assessments of knee strength and reflexes for L4 nerve root, great toe and foot dorsiflexion strength for L5 nerve root, foot plantarflexion and ankle reflexes for S1 nerve root, and dermatomal sensory distribution testing 2
The combination of radicular pain pattern, dermatomal sensory changes, and motor weakness in a nerve root distribution establishes the diagnosis of radiculopathy even without a positive straight leg raise test 2
The straight leg raise test has high sensitivity (91%) but poor specificity (26%) for disc herniation, meaning many positive tests are false positives 2