The effects of neurodynamic mobilization on fluid dispersion within the tibial nerve at the ankle: an unembalmed cadaveric study

Objective: To evaluate the effects of neurodynamic mobilization on the fluid dynamics of the tibial nerve in cadavers. Background: Evidence showing patients benefit from neural mobilization is limited. Mechanisms responsible for changes in patient symptoms are unclear. Methods: Bilateral lower limbs of six unembalmed cadavers (n=12) were randomized into matched pairs and dissected to expose the tibial nerve proximal to the ankle. Dye composed of Toulidine blue and plasma was injected into the nerve. The longitudinal dye spread was measured pre- and post-mobilization. The experimental group received the intervention consisting of 30 repetitions of passive ankle range of motion over the course of 1 minute. The matched control limb received no mobilization. Data were analysed using a 262 repeated measures ANOVA with subsequent t-tests for pairwise comparisons. Results: Mean dye spread was 23.8 +/- 10.2 mm, a change of 5.4 +/- 4.7% in the experimental limb as compared to 20.7 +/- 6.0 mm, a change of -1.5 +/- 3.9% in the control limb. The ANOVA was significant (P <= 0.02) for interaction between group (experimental/control) and time (pre-mobilization/post-mobilization). t-test results were significant between pre- and post-mobilization of the experimental leg (P=0.01), and between control and experimental limbs post-mobilization (P <= 0.02). Conclusion: Passive neural mobilization induces dispersion of intraneural fluid. This may be clinically significant in the presence of intraneural edema found in pathological nerves such as those found in compression syndromes.