Muscle Spasm in Lumbar Radiculopathy
Yes, muscle spasm can occur in lumbar radiculopathy, though it is not a defining feature of the condition itself but rather a secondary phenomenon associated with spinal pathology and pain.
Primary Clinical Features of Lumbar Radiculopathy
Lumbar radiculopathy is fundamentally characterized by nerve root dysfunction, not muscle spasm 1, 2. The cardinal features include:
- Radicular pain that radiates down the leg below the knee in a dermatomal distribution (sciatica) 1, 2
- Sensory impairment including numbness or dysesthesia in the affected nerve root distribution 1, 2
- Motor weakness in muscles innervated by the compressed nerve root 1, 2
- Diminished deep tendon reflexes corresponding to the affected level 1, 2
- Sharp, shooting, or lancinating pain felt as a narrow band down the leg 3
Muscle Spasm as a Secondary Feature
While muscle spasm is not listed among the primary diagnostic criteria for radiculopathy, it can occur as a secondary response to spinal pathology:
- Paravertebral muscle spasm is recognized as a symptom that should prompt evaluation for spinal involvement when present alongside radicular symptoms 1
- Muscle spasm typically represents a protective response to underlying spinal pathology rather than direct nerve root compression 1
- The presence of paravertebral spasm, particularly when combined with axial pain and radiculopathy, warrants imaging evaluation 1
Clinical Distinction
The key distinction is that radiculopathy produces flaccid weakness and loss of reflexes, not spastic phenomena 1. The guidelines specifically describe complete plexopathy (and by extension radiculopathy) as causing "weakness, sensory loss, and flaccid loss of tendon reflexes" 1. This flaccid presentation contrasts with true muscle spasm.
Practical Clinical Implications
When evaluating a patient with suspected lumbar radiculopathy:
- Focus on dermatomal pain distribution below the knee as the primary symptom 1, 2
- Perform straight-leg-raise testing (positive between 30-70 degrees) to confirm nerve root tension 1, 2
- Document motor weakness, sensory changes, and reflex abnormalities in the affected nerve root distribution 1, 4
- Recognize that paravertebral muscle spasm, when present, suggests concurrent spinal pathology but is not diagnostic of radiculopathy itself 1
Common Pitfall
Do not confuse paravertebral muscle spasm (a nonspecific finding associated with various spinal conditions) with the neurological deficits that define radiculopathy 1. The diagnosis of radiculopathy requires evidence of nerve root dysfunction—not simply the presence of muscle spasm 1, 2.