Evaluation of sciatic nerve function after ultrasonic and electrocautery muscle dissection: an electromyographic study.

BACKGROUND Minimally invasive surgery has been developed with various innovative surgical tools. Ultrasonic (US) blades have been introduced as an alternative to conventional electrocautery (EC) monopolar device. The purpose of the present study was to evaluate the effects of surgical devices used for muscle dissection close to peripheral nerves on motor nerve function using electromyographic (EMG) recordings. MATERIALS AND METHODS A total of 24 rats were used in this study. The rats were assigned to the following three groups: Control (n = 8), EC (n = 8), and US (n = 8). A stimulus electrode was placed under the sciatic nerve at a sciatic notch. A pair of recording electrodes was implanted into the midbelly regions of the gastrocnemius muscle. To evoke compound muscle action potentials (CMAPs), 3-V stimuli with 0.3-ms duration were applied to the sciatic nerve at a frequency of 1 Hz. After the recording of the baseline, a monopolar surgical device (EC or US) was applied to cut the muscle 10 mm in length and 2 mm away on both sides of the sciatic nerve. Amplitude and latency of the evoked CMAPs were measured. CMAPs were monitored until 3 hours after the device application. RESULTS The EC device caused a marked drop in the amplitude of CMAP with no recovery at the end of the experiment. In the US group, the amplitude of CMAP was stable and constant CMAP over 3 hours, similar to the control group could be measured. In all three groups, the latency of CMAP showed no significant changes through the experiment. CONCLUSION The study showed that the EC device resulted in injury to several motor units in the sciatic nerve. The US device may be a safe tool for muscle dissection around peripheral nerves.