Is the Outcome of Diagnostic Nerve Block Related to Spastic Muscle Echo Intensity? A Retrospective Observational Study on Patients with Spastic Equinovarus Foot.

Objective: To investigate the relationship between spastic calf muscles echo intensity and the outcome of tibial nerve motor branches selective block in patients with spastic equinovarus foot.

Methods: Retrospective observational study. Methods: Forty-eight patients with spastic equinovarus foot. Methods: Each patient was given selective diagnostic nerve block (lidocaine 2% perineural injection) of the tibial nerve motor branches. All patients were evaluated before and after block. Outcomes were: spastic calf muscles echo intensity measured with the Heckmatt scale; affected ankle dorsiflexion passive range of motion; calf muscles spasticity measured with the modified Ashworth scale and the Tardieu scale (grade and angle).

Results: Regarding the outcome of tibial nerve selective diagnostic block (difference between pre- and post-block condition), Spearman's correlation showed a significant inverse association of the spastic calf muscles echo intensity with the affected ankle dorsiflexion passive range of motion (p = 0.045; ρ = 00-0.269), modified Ashworth scale score (p = 0.014; ρ = -0.327), Tardieu grade (p = 0.008; ρ = -0.352) and Tardieu angle (p = 0.043; ρ = -0.306).

Conclusions: These findings support the hypothesis that patients with spastic equinovarus foot with higher spastic calf muscles echo intensity have a poor response to selective nerve block of the tibial nerve motor branches.