Electrical artifact during intraoperative electromyographic neuromonitoring
Ronald C Pearlman1, Michael R Isley, Jason C Ganley
1Department of Communication Sciences and Disorders, Howard University, Washington, DC, USA.
American Journal of Electroneurodiagnostic Technology
|August 7, 2008
Summary
The "crossed swords" effect, an artifact in acoustic electromyography (EMG), occurs when surgical instruments touch in fluid. This metal-to-metal contact artifact mimics nerve irritation signals but is distinct from genuine EMG responses.
Area of Science:
- Neurosurgery
- Neuromonitoring
- Bioacoustics
Background:
- Acoustic electromyography (EMG) is crucial for nerve protection during surgery.
- A
- crossed swords
- artifact from metal instrument contact can mimic neural irritation.
- This artifact's characteristics are not well-defined.
Purpose of the Study:
- To investigate the properties of the
- crossed swords
- artifact.
- To determine the conditions required for artifact generation.
- To differentiate the artifact from true EMG signals.
Main Methods:
- Simulated metal-to-metal and metal-to-nonmetal instrument contact in fluid media.
- Tested artifact detection in surgical and control channels.
- Analyzed artifact morphology and acoustic properties.
- Measured electrical discharge potential.
Main Results:
- The artifact occurred only with metal-to-metal contact in a fluid medium.
- Metal-to-nonmetal contact did not produce the artifact.
- Artifacts were not detected on control channels or in SSEP background activity.
- Artifacts exhibited unique acoustic and morphological features compared to true EMG.
Conclusions:
- The
- crossed swords
- artifact is likely a galvanic couple discharge between metals.
- It can be distinguished from true neural signals during neuromonitoring.
- Understanding this artifact improves surgical nerve protection accuracy.
