Multipulse transcranial electrical stimulation (TES): normative data for motor evoked potentials in healthy horses.
Authors: Journée Sanne Lotte, Journée Henricus Louis, de Bruijn Cornelis Marinus, Delesalle Cathérine John Ghislaine
Journal: BMC veterinary research
Summary
# Editorial Summary: Transcranial Electrical Stimulation in Horses Transcranial electrical stimulation (TES) offers a promising alternative to magnetic stimulation for evaluating motor pathway integrity in horses, yet clinicians have lacked standardised reference values to interpret results. This prospective study established normative motor evoked potential (MEP) data from 12 healthy horses, measuring motor latency times (MLT), amplitude and waveform characteristics bilaterally from the extensor carpi radialis and tibialis cranialis muscles. Motor latency times proved highly reproducible within individual horses (coefficients of variation 1.4–8.2%), with reference intervals of 16.1–22.6 ms for forelimb and 31.9–41.1 ms for hindlimb muscles, whilst MLTs showed a voltage-dependent decrease and positive correlation with withers height, though no significant left–right asymmetry. These normative parameters now enable farriers, veterinarians and physiotherapists to identify abnormal motor conduction patterns in horses with suspected spinal cord or neuromuscular disease, whilst the technique's ease of application and excellent reproducibility make it suitable for monitoring neurological recovery or progression in clinical cases.
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Practical Takeaways
- •Transcranial electrical stimulation (TES) is a reliable and reproducible diagnostic tool for assessing spinal motor function in horses, with high intra-individual consistency suitable for clinical baseline establishment
- •These normative values provide reference ranges for comparing motor function in suspected spinal cord disease cases, though further validation studies comparing TES to transcranial magnetic stimulation are needed
- •Stimulation voltage must be standardised during TES testing as it significantly affects motor latency measurements
Key Findings
- •Motor latency times (MLT) for extensor carpi radialis were 16.1-22.6 ms and for tibialis cranialis were 31.9-41.1 ms in healthy horses
- •Intra-individual coefficient of variation for MLTs was 2.2-8.2% (ECR) and 1.4-6.3% (TC), demonstrating high reproducibility
- •Motor latency times showed significant voltage-dependent decreases (p<0.05) with slope coefficients of -0.049 to -0.089 ms/V across muscles
- •Positive correlation found between height at withers and MLTs in all 4 muscle groups