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Intraoperative lateral rectus electromyographic recordings optimized by deep intraorbital needle electrodes
Tatsuya Oishi1, Jamie J Van Gompel2, Michael J Link2
1Department of Neurology, Mayo Clinic, 200 First St SW, Rochester, MN 55902, USA.
Summary
Longer needle electrodes placed in the lateral rectus muscle provide superior electromyography (EMG) monitoring during intracranial surgery. This method offers improved signal amplitude and nerve discrimination, with a favorable safety profile for abducens nerve monitoring.
Area of Science:
- Neurosurgery
- Neurology
- Biomedical Engineering
Background:
- Intracranial surgeries require precise monitoring of cranial nerves.
- Lateral rectus electromyography (EMG) is crucial for abducens nerve monitoring.
- Standard-length subdermal electrodes may have limitations in signal quality and specificity.
Purpose of the Study:
- To compare the efficacy and safety of long intraorbital needle electrodes versus standard-length subdermal electrodes for lateral rectus EMG recording.
- To evaluate the reliability of long electrodes for abducens nerve monitoring during intracranial procedures.
Main Methods:
- A comparative study involving 10 intracranial surgeries.
- Placement of insulated 25 mm and uninsulated 13 mm needle electrodes targeting the lateral rectus muscle.
- Recording of spontaneous and stimulation-induced EMG activities, with review of postoperative complications in 36 additional patients.
Main Results:
- 25 mm electrodes yielded 6- to 26-fold greater EMG waveform amplitude compared to 13 mm electrodes.
- 13 mm electrodes showed significant volume conduction interference from facial nerve stimulation.
- No significant clinical or radiographic complications were observed in patients with long electrode placement.
Conclusions:
- Long intraorbital needle electrodes offer more reliable lateral rectus EMG monitoring than shorter electrodes.
- This technique provides excellent discrimination between abducens and facial nerve stimulations.
- Long needle electrode placement is a practical, safe, and reliable method for abducens nerve monitoring in neurosurgery.
