Shouguo Liu, Sha Zhou, Xiao Lu, Hongxing Wang, Jianan Li
Rehabilitation Department, The First Affiliated Hospital of Nanjing Medical University, China
DOI: 10.2340/16501977-2381

Objective: To explore the relationship between electrical current and nerve–needle distance for localization of target nerves in peripheral nerve block, and the effects of injection speed, concentration, and injectate volume on alcohol dispersion using an animal model.
Methods: Rabbit tibial nerves were selected for localization. Nerve–needle distance was ascertained using a manipulator. The minimum current eliciting motor responses was recorded at nerve–needle distances of 0, 1, 2, 3, 4 and 5 mm. Rabbit tibial nerves were assigned into 3 groups: speed group, concentration group, and volume group. Nerves were localized by a stimulator and neurolysed with alcohol/contrast medium. Helical computed tomography (CT) was performed to measure volume/dispersion patterns of injectate.
Results: A linear relationship was observed between nerve–needle distance (X) and minimal current (Y) (Y = 0. 13X + 0. 22; r2 = 0. 974; p<0. 05) for the localization of the target nerve. CT scan revealed that the injection speed and volume significantly influenced the dispersion of alcohol (p<0. 01), but concentration had no effect (p<0. 05).
Conclusion: This study found a positive linear relationship between nerve–needle distance and minimum electrical stimulation in tibial nerve blockade. In addition, the results suggest that a low volume of alcohol with a low injection speed can help to improve nerve block in clinical practice.

Spasticity can negatively influence rehabilitation training and activities of daily living. Nerve blockade with alcohol is a widely accepted method for reducing spasticity. Successful treatment requires accurate localization of the needle tip and understanding of the factors that influence alcohol dispersion. This study investigated the relationship between electrical stimulation and nerve–needle distance, as well as how injection speed, concentration and volume affect alcohol dispersion along the nerve trunk using an animal model. We conclude that there is linear relationship between nerve–needle distance and stimulation current for localization of the target nerve, and that the injection speed and volume influence the dispersion of alcohol, but that concentration has no effect.