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Efficacy of transcranial motor evoked potentials, mechanically elicited electromyography, and evoked electromyography to assess nerve root function during sustained compression in a porcine model.
Spine (Phila Pa 1976). 2014 Aug 01; 39(17):E989-93.S

Abstract

STUDY DESIGN

This is an animal experiment using transcranial motor evoked potentials (TcMEPs), mechanically elicited electromyographic (EMG) responses, and evoked EMG responses during nerve root compression in a pig model.

OBJECTIVE

To compare these 3 electrophysiological measures for compression applied to a lumbar nerve root.

SUMMARY OF BACKGROUND DATA

Lumbar nerve root injury may result in motor weakness in up to 30% of spinal deformity cases. Compressive injury may occur during the surgical approach, decompression, and manipulation of the spine. Using an established porcine model, we examined the changes to TcMEPs, mechanically elicited EMG responses, and evoked EMG responses during varied compressive forces.

METHODS

TcMEPs, mechanically elicited EMG responses, and evoked EMG responses were recorded for the tibialis anterior muscle in 16 experiments. Precompression TcMEP and nerve root stimulation threshold (NRT) were obtained. The dominant root was compressed at 1 N (n = 8) or 2 N (n = 8) for 10 minutes. TcMEP was recorded every minute during compression, and TcMEP and NRT were recorded after both compression and 10 minutes of recovery.

RESULTS

After 10 minutes of 1-N compression, TcMEP amplitude of the tibialis anterior muscle decreased to 69% ± 13% of baseline (P < 0.02 vs. baseline). The mean NRT increased to 645% ± 433% (P < 0.02 vs. baseline NRT). After the recovery period, TcMEP in the 1-N group returned to 98% ± 11% of baseline (P = 0.36 vs. baseline). After 10 minutes of 2-N compression, TcMEPs from the tibialis anterior muscle decreased to 27% ± 15% of baseline (P < 0.02 vs. baseline). After the recovery period, TcMEP in the 2-N group returned to 30% ± 10% of baseline (P < 0.02 vs. baseline). Tonic EMG activity was observed in 3 nerve roots compressed at 2 N.

CONCLUSION

Compression at 1 and 2 N produced consistent changes in TcMEPs and EMG responses. TcMEP monitoring is sensitive to an increase in compressive force. TcMEP amplitude change was correlated to the force applied and the ability of the nerve root to recover. Mechanically elicited EMG responses were not sensitive to nerve root compression.

LEVEL OF EVIDENCE

N/A.

Authors+Show Affiliations

*Department of Orthopaedic Surgery, University of California, San Francisco †Division of Operating Rooms, Department of Clinical Neurophysiology, University of California, San Francisco; and ‡Department of Anesthesia and Perioperative Care, University of California, San Francisco.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

24875956

Citation

Valone, Frank, et al. "Efficacy of Transcranial Motor Evoked Potentials, Mechanically Elicited Electromyography, and Evoked Electromyography to Assess Nerve Root Function During Sustained Compression in a Porcine Model." Spine, vol. 39, no. 17, 2014, pp. E989-93.
Valone F, Lyon R, Lieberman J, et al. Efficacy of transcranial motor evoked potentials, mechanically elicited electromyography, and evoked electromyography to assess nerve root function during sustained compression in a porcine model. Spine. 2014;39(17):E989-93.
Valone, F., Lyon, R., Lieberman, J., & Burch, S. (2014). Efficacy of transcranial motor evoked potentials, mechanically elicited electromyography, and evoked electromyography to assess nerve root function during sustained compression in a porcine model. Spine, 39(17), E989-93. https://doi.org/10.1097/BRS.0000000000000442
Valone F, et al. Efficacy of Transcranial Motor Evoked Potentials, Mechanically Elicited Electromyography, and Evoked Electromyography to Assess Nerve Root Function During Sustained Compression in a Porcine Model. Spine. 2014 Aug 1;39(17):E989-93. PubMed PMID: 24875956.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Efficacy of transcranial motor evoked potentials, mechanically elicited electromyography, and evoked electromyography to assess nerve root function during sustained compression in a porcine model. AU - Valone,Frank,3rd AU - Lyon,Russ, AU - Lieberman,Jeremy, AU - Burch,Shane, PY - 2014/5/31/entrez PY - 2014/5/31/pubmed PY - 2015/5/30/medline SP - E989 EP - 93 JF - Spine JO - Spine VL - 39 IS - 17 N2 - STUDY DESIGN: This is an animal experiment using transcranial motor evoked potentials (TcMEPs), mechanically elicited electromyographic (EMG) responses, and evoked EMG responses during nerve root compression in a pig model. OBJECTIVE: To compare these 3 electrophysiological measures for compression applied to a lumbar nerve root. SUMMARY OF BACKGROUND DATA: Lumbar nerve root injury may result in motor weakness in up to 30% of spinal deformity cases. Compressive injury may occur during the surgical approach, decompression, and manipulation of the spine. Using an established porcine model, we examined the changes to TcMEPs, mechanically elicited EMG responses, and evoked EMG responses during varied compressive forces. METHODS: TcMEPs, mechanically elicited EMG responses, and evoked EMG responses were recorded for the tibialis anterior muscle in 16 experiments. Precompression TcMEP and nerve root stimulation threshold (NRT) were obtained. The dominant root was compressed at 1 N (n = 8) or 2 N (n = 8) for 10 minutes. TcMEP was recorded every minute during compression, and TcMEP and NRT were recorded after both compression and 10 minutes of recovery. RESULTS: After 10 minutes of 1-N compression, TcMEP amplitude of the tibialis anterior muscle decreased to 69% ± 13% of baseline (P < 0.02 vs. baseline). The mean NRT increased to 645% ± 433% (P < 0.02 vs. baseline NRT). After the recovery period, TcMEP in the 1-N group returned to 98% ± 11% of baseline (P = 0.36 vs. baseline). After 10 minutes of 2-N compression, TcMEPs from the tibialis anterior muscle decreased to 27% ± 15% of baseline (P < 0.02 vs. baseline). After the recovery period, TcMEP in the 2-N group returned to 30% ± 10% of baseline (P < 0.02 vs. baseline). Tonic EMG activity was observed in 3 nerve roots compressed at 2 N. CONCLUSION: Compression at 1 and 2 N produced consistent changes in TcMEPs and EMG responses. TcMEP monitoring is sensitive to an increase in compressive force. TcMEP amplitude change was correlated to the force applied and the ability of the nerve root to recover. Mechanically elicited EMG responses were not sensitive to nerve root compression. LEVEL OF EVIDENCE: N/A. SN - 1528-1159 UR - https://www.unboundmedicine.com/medline/citation/24875956/Efficacy_of_transcranial_motor_evoked_potentials_mechanically_elicited_electromyography_and_evoked_electromyography_to_assess_nerve_root_function_during_sustained_compression_in_a_porcine_model_ L2 - http://dx.doi.org/10.1097/BRS.0000000000000442 DB - PRIME DP - Unbound Medicine ER -