MRI Diagnosis of Nerve Root Compression
Diagnostic Performance
- MRI correctly predicts nerve root compression in 88% of surgically confirmed cases, significantly outperforming CT (50%), conventional myelography (57%), and CT myelography (81%) in the cervical spine 1, 2, 4
- MRI has become the preferred method for evaluating cervical nerve root impingement due to its superior soft-tissue contrast and high spatial resolution 3, 4
- MRI demonstrates nerve root compression in patients with radiculopathy or clinical signs of spinal stenosis, with accurate depiction of disc disease and neural compression in the lumbar spine 5, 6, 7
- In symptomatic patients, 57% with low back pain and 65% with radiculopathy show disc herniation on MRI, compared to only 20-28% in asymptomatic individuals 5, 6, 7
Important Limitations and Caveats
- MRI demonstrates frequent false-positive and false-negative findings in cervical radiculopathy, with abnormal MRI levels not always corresponding to clinical examination findings 2, 3
- Degenerative findings are commonly observed in asymptomatic patients, so imaging must be correlated with clinical presentation 1, 4
Clinical Application Algorithm
- Patients with radiculopathy who have failed 6 weeks of conservative therapy and are surgical or interventional candidates should undergo MRI 5, 6, 7
- Urgent MRI is indicated for suspected cauda equina syndrome due to its ability to accurately depict soft-tissue pathology and assess spinal canal patency 5, 6, 7
- New or progressive neurologic deficits with clinical signs of nerve root irritation are indications for MRI 5, 6
Contrast Enhancement
- MRI without IV contrast is the appropriate initial study for evaluating nerve root compression 2, 3, 5, 6, 7
- Contrast is reserved for postoperative patients to distinguish recurrent/residual disc from fibrosis/scar, or when noncontrast MRI is nondiagnostic 5, 6, 7, 9, 10