Abstract
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.
Keywords
ultrasonic surgical device - nerve injury - compound muscle action potential - surgical
invasion - motor unit
