What is the role of the Faber test in diagnosing radiculopathy and what are the treatment options for patients with a positive test result?

The FABER Test is Not a Diagnostic Tool for Radiculopathy

The FABER (Flexion, ABduction, External Rotation) test is designed to evaluate hip and sacroiliac joint pathology, not radiculopathy, and should not be used for diagnosing nerve root compression. The provided evidence does not support any role for the FABER test in radiculopathy diagnosis, as it assesses completely different anatomical structures and pathological processes.

Understanding the Distinction

What Radiculopathy Actually Is

• Radiculopathy is defined as pain or sensorimotor deficits in a dermatomal distribution with or without accompanying sensory or motor loss, reflecting spinal nerve root dysfunction 1
• Cervical radiculopathy presents as neck pain with arm pain accompanied by varying degrees of sensory or motor function loss in the affected nerve-root distribution 1
• Lumbar radiculopathy manifests as back pain with leg pain (sciatica) due to nerve root compression, typically from disc herniation or foraminal stenosis 2

Why Physical Examination Tests Have Limited Value

• A systematic review found limited evidence for correlation between physical examination findings and MRI evidence of cervical nerve root compression 1
• Most physical tests for radiculopathy (scoliosis, paresis, muscle weakness, muscle wasting, impaired reflexes, sensory deficits) show poor diagnostic performance when used in isolation 2
• Normal neurological examination results cannot eliminate abnormal electrodiagnostic test results, and vice versa 3

Appropriate Physical Examination Tests for Radiculopathy

For Cervical Radiculopathy

• The Spurling test (extension, lateral bending, and axial compression) is the most appropriate provocative maneuver for cervical radiculopathy 4
• This maneuver resulted in the highest pain scores and most distally elicited pain in patients with confirmed cervical radiculopathy 4
• Extension, rotation, and axial compression produced the highest paresthesia levels but was less tolerable 4

For Lumbar Radiculopathy

• The Straight Leg Raising (SLR) test shows high sensitivity (pooled estimate 0.92) in surgical populations with high prevalence of disc herniation 2
• The crossed SLR demonstrates high specificity (pooled estimate 0.90) but low sensitivity (0.28) 2
• The slump test had the highest sensitivity in detecting disc extrusion (0.78) and subarticular nerve compression (1.00), though specificity was low 5

Diagnostic Approach for Suspected Radiculopathy

Initial Clinical Assessment

• Diagnosis requires combination of clinical history, physical examination, and imaging—no single test is sufficient 1
• Look for dermatomal pain distribution, specific motor weakness patterns, sensory deficits in nerve root distributions, and diminished reflexes corresponding to specific nerve roots 1, 6
• Document whether symptoms are radicular (single nerve root) versus plexopathy (multiple nerve roots/plexus involvement) 1

When to Image

• In the absence of "red flags," imaging may not be required at initial presentation, as 75-90% of cervical radiculopathy cases resolve with conservative therapy 1
• For lumbar radiculopathy, MRI is indicated when radicular symptoms persist for at least 6 weeks despite conservative management and the patient is a surgical or epidural injection candidate 7
• Immediate MRI is warranted for severe or progressive neurological deficits, suspected cauda equina syndrome, or serious underlying conditions (cancer, infection) 7

Imaging Modality Selection

• MRI without contrast is the preferred initial imaging modality for suspected nerve root compression 7
• MRI provides superior soft-tissue contrast and visualization of disc herniations, nerve roots, and spinal canal compared to CT 1
• CT can be used when MRI is contraindicated or delayed, particularly for evaluating osseous structures like osteophytes and foraminal stenosis 1

Critical Pitfalls to Avoid

Overreliance on Physical Examination

• Physical examination tests alone have poor diagnostic accuracy for radiculopathy—they must be interpreted with imaging and electrodiagnostic studies 5, 2, 3
• Combining positive test results increases specificity, but few studies provide data on optimal test combinations 2

Misinterpreting MRI Findings

• MRI alone should not be used to diagnose symptomatic radiculopathy due to frequent false-positive and false-negative findings 1
• Up to 20-28% of asymptomatic individuals have disc herniations on MRI 7
• Spondylotic changes are commonly identified in patients >30 years of age and correlate poorly with neck pain presence 1

Premature Imaging

• Routine MRI for acute low back pain without radicular symptoms is not indicated and does not improve outcomes 7
• Most acute cervical and lumbar radiculopathy cases resolve spontaneously or with conservative treatment within 4-6 weeks 1, 7