Neural tension patterns during cervical spine rotation: diagnostic implications from a cadaveric study.

Abstract

Background: Cervical neural tension reflects the biomechanical and physiological responses of spinal nerves to positional changes. Although clinical tests exist for the lower cervical spinal nerve, tension patterns in the upper and mid-cervical nerves remain underexplored, limiting the diagnostic accuracy for conditions such as occipital neuralgia.

Methods: This cadaveric study quantified tensile load changes at the cervical spinal nerve level (C1-C5) during passive cervical spine rotation in five formalin-embalmed cadavers. Tension was measured on the cervical spinal nerves (C1-C5) using force gauges attached proximal to the division between the dorsal and ventral rami. C1 measurements were obtained from a single specimen. Two movement conditions were used: cervical flexion-rotation for C1-C3 and neutral-plane rotation for C4-C5.

Results: Ipsilateral increases in neural tension were observed in C1-C3 during flexion-rotation movements. By contrast, C4-C5 exhibited a consistent pattern of contralateral load increase during rotation in the neutral plane. Statistically significant variations in the tensile load were observed at the C5 level under different rotation conditions, specifically at C5 left (p = 0.003) and C5 right (p = 0.006). Post-hoc analyses of C5 measurements during neutral-plane rotation revealed significant differences between right and left rotation (p = 0.018) and between left rotation and neutral rotation (p = 0.018) on the left side, as well as between right rotation and left rotation and neutral rotation (p = 0.026, p = 0.024) on the right side. Intraclass correlation coefficients (ICC) indicated good-to-excellent reliability (ICC > 0.75), particularly at C2-C5.

Conclusions: Cervical rotation influenced neural tension, with distinct patterns observed between the upper cervical segments (tested under flexion-rotation) and the middle cervical segments (tested under neutral plane rotation). These exploratory findings suggest that replacing lateral neck flexion with rotation in the upper-limb tension test may represent a promising direction for future research. Additionally, the flexion-rotation test may provide a basis for clinical validation as a potential indicator of greater occipital nerve tension. These results lay the groundwork for refining neurodynamic assessments and warrant further in vivo investigation.