Trapezius Motor Evoked Potentials From Transcranial Electrical Stimulation and Transcranial Magnetic Stimulation: Reference Data, Characteristic Differences and Intradural Motor Velocities in Horses.
Abstract: So far, only transcranial motor evoked potentials (MEP) of the extensor carpi radialis and tibialis cranialis have been documented for diagnostic evaluation in horses. These allow for differentiating whether lesions are located in either the thoraco-lumbar region or in the cervical myelum and/or brain. Transcranial trapezius MEPs further enable to distinguish between spinal and supraspinal located lesions. No normative data are available. It is unclear whether transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) are interchangeable modalities. Unassigned: To provide normative data for trapezius MEP parameters in horses for TES and TMS and to discern direct and indirect conduction routes by neurophysiological models that use anatomical geometric characteristics to relate latency times with peripheral (PCV) and central conduction velocities (CCV). Unassigned: Transcranial electrical stimulation-induced trapezius MEPs were obtained from twelve horses. TES and TMS-MEPs (subgroup 5 horses) were compared intra-individually. Trapezius MEPs were measured bilaterally twice at 5 intensity steps. Motoneurons were localized using nerve conduction models of the cervical and spinal accessory nerves (SAN). Predicted CCVs were verified by multifidus MEP data from two horses referred for neurophysiological assessment. Unassigned: Mean MEP latencies revealed for TES: 13.5 (11.1-16.0)ms and TMS: 19.7 (12-29.5)ms, comprising ∼100% direct routes and for TMS mixed direct/indirect routes of L:23/50; R:14/50. Left/right latency decreases over 10 > 50 V for TES were: -1.4/-1.8 ms and over 10 > 50% for TMS: -1.7/-3.5 ms. Direct route TMS-TES latency differences were 1.88-4.30 ms. 95% MEP amplitudes ranges for TES were: L:0.26-22 mV; R:0.5-15 mV and TMS: L:0.9 - 9.1 mV; R:1.1-7.9 mV. Unassigned: This is the first study to report normative data characterizing TES and TMS induced- trapezius MEPs in horses. The complex trapezius innervation leaves TES as the only reliable stimulation modality. Differences in latency times along the SAN route permit for estimation of the location of active motoneurons, which is of importance for clinical diagnostic purpose. SAN route lengths and latency times are governed by anatomical locations of motoneurons across C2-C5 segments. TES intensity-dependent reductions of trapezius MEP latencies are similar to limb muscles while MEP amplitudes between sides and between TES and TMS are not different. CCVs may reach 180 m/s.
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The research article discusses a study conducted to establish normative data for trapezius motor evoked potentials (MEPs) in horses. The study compared the results of transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS), analyzed conduction routes, and related latency times with peripheral and central conduction velocities.
Objective of the Study
The study was conducted to provide normative data for parameters of transcranial electrical and magnetic stimulation-induced trapezius motor evoked potentials in horses.
It sought to discern direct and indirect conduction routes using neurophysiological models that use anatomical geometric characteristics to understand latency times with peripheral and central conduction velocities.
Methodology
The researchers obtained transcranial electrical stimulation-induced trapezius MEPs from twelve horses.
Intra-individual comparisons were done between transcranial electric stimulation and transcranial magnetic stimulation MEPs in a subgroup of five horses.
The trapezius MEPs were measured bilaterally twice at five intensity steps.
To localize motoneurons, nerve conduction models of the cervical and spinal accessory nerves were used.
The predicted central conduction velocities were verified using multifidus MEP data obtained from two horses referred for neurophysiological evaluations.
Results
TES provided mean MEP latencies of 13.5ms (range of 11.1-16.0ms), and TMS provided 19.7ms (range of 12-29.5ms).
Both TES and TMS roughly provided 100% direct routes, with TMS comprising a mix of direct and indirect routes.
The latency decreases over 10 > 50 V for TES were calculated to be -1.4/-1.8 ms, whereas, for TMS, it was -1.7/-3.5 ms.
The direct route TMS-TES latency differences ranged between 1.88-4.30 ms.
95% of MEP amplitude ranges for TES were: Left: 0.26-22mV; Right: 0.5-15mV and TMS: Left: 0.9 – 9.1mV; Right: 1.1-7.9mV.
Conclusions
The research successfully provided the first set of normative data characterizing TES and TMS-induced trapezius MEPs in horses.
The complex innervation of the trapezius leaves TES as the only reliable stimulation modality.
The differences in latency times along the spinal accessory nerve route allow for the estimation of active motoneuron locations, serving important clinical diagnostic purposes.
TES intensity-dependent reductions of trapezius MEP latencies are similar to limb muscles, while MEP amplitudes between sides and between TES and TMS are not different.
The central conduction velocities can reach up to 180 m/s.
Cite This Article
APA
Journée SL, Journée HL, Berends HI, Reed SM, Bergmann W, de Bruijn CM, Delesalle CJG.
(2022).
Trapezius Motor Evoked Potentials From Transcranial Electrical Stimulation and Transcranial Magnetic Stimulation: Reference Data, Characteristic Differences and Intradural Motor Velocities in Horses.
Front Neurosci, 16, 851463.
https://doi.org/10.3389/fnins.2022.851463
Research Group of Comparative Physiology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Journée, Henricus Louis
Department of Neurosurgery, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.
Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands.
Department of Orthopedics, Amsterdam University Medical Center, Amsterdam, Netherlands.
Berends, Hanneke Irene
Department of Orthopedics, Amsterdam University Medical Center, Amsterdam, Netherlands.
Reed, Steven Michael
Rood and Riddle Equine Hospital, Lexington, KY, United States.
Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, United States.
Bergmann, Wilhelmina
Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
de Bruijn, Cornelis Marinus
Wolvega Equine Clinic, Oldeholtpade, Netherlands.
Delesalle, Cathérine John Ghislaine
Research Group of Comparative Physiology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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