Upper limb neurodynamic testing with radial and ulnar nerve biases: An analysis of cervical spinal nerve mechanics

Background: Clinical research supports a combination of upper limb neurodynamic testing (ULNT) strategies to rule out upper limb and cervical neurogenic pathology; however, knowledge of the biomechanical response of spinal nerves during ULNT is lacking for radial and ulnar nerve biases.

Objective: To assess whether radial and ulnar nerve biased strategies of ULNT elicit significant displacement and strain of cervical spinal nerves.

Study design: Cross-sectional.

Methods: Radiolucent markers were implanted into spinal nerves C5-C8 proximal and distal to the intervertebral foramen in nine unembalmed cadavers (six male; three female) age 80.1 ± 13.2 years. Fluoroscopic images were captured during ULNT with radial and ulnar nerve biases. Images at rest and maximum tension were digitized and displacement and strain were measured. All data were analyzed using one sample t-tests and a generalized linear mixed models approach.

Results: Upper limb neurodynamic testing with radial nerve bias resulted in displacement (2.44-3.04 mm) and strain (7.99-11.98%) and ULNT with ulnar nerve bias resulted in displacement (2.16-4.41 mm) and strain (7.12 and 12.95%). Significant extraforaminal displacement occurred during radial and ulnar nerve biases for all spinal nerves (all P < 0.05) whereas significant strain occurred during ulnar nerve biases for all spinal nerves but only in C6-C8 during radial nerve bias.

Conclusion: Upper limb neurodynamic testing using both radial and ulnar nerve biases resulted in cervical spinal nerve displacement and strain. Such techniques could be used to tension load or mobilize or cervical spinal nerves to evaluate for pathology.