Facilitation of motor evoked potentials after tetanic peripheral nerve stimulation

• Published in: Clinical neurophysiology Vol. 162; pp. 2 - 8
• Main Authors: Wehab, Zaman, Lutz, Michael W., Bell, Emily P., Johnson, Holly E., AlGaeed, Mohanad, Husain, Aatif M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2024
• Subjects: Adolescent; Adult; Aged; Child; Electric Stimulation - methods; Enhancement; Evoked Potentials, Motor - physiology; Female; Humans; Male; Middle Aged; Motor evoked potentials; Myelopathy; Neurology; Neuropathy; Peripheral Nerves - physiology; Peripheral Nerves - physiopathology; Peripheral Nervous System Diseases - physiopathology; Peripheral Nervous System Diseases - therapy; Tetanic stimulation; Transcranial Direct Current Stimulation - methods; Young Adult; Myelopathy; Tetanic stimulation; Motor evoked potentials; Neuropathy; Enhancement; neuropathy; enhancement; tetanic stimulation; myelopathy
• ISSN: 1388-2457; 1872-8952; 1872-8952
• DOI: 10.1016/j.clinph.2024.03.011

•Motor evoked potential amplitudes may be small and difficult to monitor during surgery in some patients.•Tetanic stimulation of peripheral nerves improves motor evoked potential amplitudes.•Tetanic stimulation can also be used in patient with myelopathy and peripheral neuropathy, with some cautions. Tetanic stimulation of a peripheral nerve prior to transcranial electrical stimulation (TES) may enhance motor evoked potential (MEP) amplitudes. The purpose of this study was to investigate the post-tetanic MEP (p-MEP) technique in improving MEP amplitudes. Conventional TES MEPs (c-MEP) and p-MEPs with left upper limb stimulation (p-MEPUL) or left lower limb stimulation (p-MEPLL) were performed in 26 patients. Bilateral hand and foot MEP amplitudes obtained with each protocol were compared. Subgroup comparisons were performed for myelopathy and peripheral neuropathy patients. Within-subject amplitude differences between c-MEP and each p-MEP technique were compared using a Wilcoxon test. The mean age of the patients was 52.7 years (range, 12–79 years). Overall, p-MEPUL resulted in MEP improvement in 25 of 26 (96%) patients, and p-MEPLL improved MEPs in 19 of 26 (73%) patients. The increase in MEP amplitudes were statistically significant in all muscle groups except left foot. Similar improvements were seen in the myelopathy group; in the neuropathy group, p-MEPUL produced similar results, but p-MEPLL did not. The p-MEP technique can improve MEP amplitudes, including in patients with myelopathy. In patients with peripheral neuropathy, the results were mixed. Tetanic stimulation can enhance intraoperative MEP amplitudes.