Observed patterns of cervical radiculopathy: how often do they differ from a standard, "Netter-diagram" distribution?

Key points

1. 01Only 54% of single-level ACDF patients had symptoms matching the standard Netter-diagram dermatomal pattern
2. 02Non-standard patterns differed from the expected distribution by an average of 1.6 dermatomal levels (p<0.01)
3. 03Ipsilateral neck pain was the most common symptom, present in 81% of all patients regardless of cervical level
4. 0419.2% of patients had only proximal neck, trapezial, or shoulder pain with no distal radiation, including 16.7% of C5-6 and 13.3% of C6-7 cases
5. 0540% of C3-4 patients had distal radicular symptoms, and 16.5% of C4-5 patients had symptoms below the elbow, contrary to expected patterns

How it was conducted

Design

Retrospective chart review

Setting

Academic medical center, 6 spine surgeons

Participants

239 adult patients with single-level cervical radiculopathy who underwent ACDF between March 2009 and March 2016

Inclusion criteria

Imaging-confirmed single-level root compression, refractory upper limb/neck symptoms, at least 75% symptom reduction by 6 months post-operatively

Comparison

Observed radicular symptom distribution versus the Keegan and Garrett dermatomal map (Netter standard)

Primary outcome

Proportion of patients presenting with standard versus non-standard radicular pattern

What they found

• Standard radicular pattern present in 130/239 (54%) patients; non-standard pattern in 109/239 (46%); no significant difference by cervical level (p=0.35)
• Non-standard patterns deviated by a mean of 1.68 dermatomal levels (SD 0.54) from the expected standard (p<0.01)
• At C5-6, non-standard presentation in 50.9%; at C6-7, non-standard in 44.7%
• Ipsilateral neck pain present in 81% of all patients; did not differ by cervical level (p=0.72)
• Shoulder pain present in 59.4% of all patients; did not differ by cervical level (p=0.21)
• Isolated neck/trapezial/shoulder pain with no distal radiation in 19.2% of all patients; most common at C3-4 (60%) (p=0.0001)
• 40% of C3-4 patients had distal radicular symptoms; 16.5% of C4-5 patients had symptoms below the elbow
• Right-sided symptoms in 51.2% of standard group versus 28.2% of non-standard group (p=0.0003)
• Binary logistic regression model was statistically significant overall (p=0.04) but no individual demographic variable significantly predicted non-standard presentation

Limitations

• Retrospective design relying on chart review and patient-derived pain diagrams, with no prospective standardization of symptom assessment
• MRI sequences were not standardized; scans came from multiple institutions, introducing potential variability in interpretation
• 75% symptom-improvement criterion confirms the operative level was relevant but does not exclude residual radiculopathy from other levels
• Some proximal symptoms (neck, shoulder) may partly reflect spondylosis rather than pure nerve root compression

Why it matters

For patients

If your neck or arm pain does not match the textbook description for your compressed nerve level, it does not mean your diagnosis is wrong, as non-standard patterns are common and surgery at the correct imaging-confirmed level typically still relieves symptoms.

For clinicians

Surgeons and clinicians should not rely solely on dermatomal distribution to confirm or exclude a causative cervical level, since nearly half of surgical patients present with non-standard patterns that can mimic adjacent levels by roughly 1.6 spinal segments.

For readers

This study challenges the teaching that cervical radiculopathy reliably follows textbook dermatomal maps, showing wide clinical variability that has direct implications for level-identification before surgery.