First-in-Human Demonstration of High-Frequency Electrical Motor Nerve Block: Case Report.

Abstract: This feasibility study tested the capability of high-frequency stimulation to block muscle contractions elicited by electrical stimulation of the same nerve proximally. During a tendon lengthening surgery in the forearm, the anterior interosseous nerve was exposed. A specialized nerve cuff electrode was placed around the nerve, and a stimulating probe held on the nerve 1 cm proximal to the cuff electrode delivered pulses of current causing the pronator quadratus muscle to contract. Through the cuff electrode, 20-kHz high-frequency stimulation was delivered to the nerve for 10 secs during proximal stimulation. High-frequency stimulation amplitudes between 5 and 10 mA peak-to-peak were tested to determine which produced complete and partial block of the electrically induced contractions. The minimum high-frequency stimulation amplitude that produced complete block was 8 mA, with lower amplitudes producing partial block. In all trials, muscle contractions resumed immediately after high-frequency stimulation was turned off. This demonstration of high-frequency electrical nerve block is a milestone in the road to clinical implementation of high-frequency stimulation mediated motor block for spasticity.