The use of magnetic motor evoked potentials in horses with cervical spinal cord disease.
Authors: Nollet H, Deprez P, Van Ham L, Verschooten F, Vanderstraeten G
Journal: Equine veterinary journal
Summary
# Editorial Summary: Magnetic Motor Evoked Potentials in Equine Cervical Spinal Cord Disease Transcranial magnetic stimulation offers a non-invasive neurophysiological tool for detecting motor tract dysfunction in horses presenting with cervical ataxia, a condition that can be diagnostically challenging when clinical signs are subtle or progression unclear. Nollet and colleagues compared motor evoked potentials (latency, amplitude, and waveform configuration) recorded from 12 ataxic horses against normal controls, finding significantly prolonged latencies, reduced amplitudes, and pathological polyphasic patterns in the affected group. Notably, whilst clinical improvement occurred in some ataxic horses during follow-up, their evoked potentials did not normalise, suggesting the technique may detect persistent neurophysiological abnormalities even when clinical signs resolve. The procedure's painless, safe application and high sensitivity for identifying lesions along the descending motor pathways make it a valuable adjunct to conventional imaging and clinical assessment—particularly useful for confirming spinal cord involvement in horses with equivocal lameness or incoordination where cervical pathology is suspected. For practitioners managing suspected cervical myelopathy, this technique could strengthen diagnostic confidence and potentially guide prognosis, though the persistent abnormalities despite clinical recovery warrant careful interpretation when counselling owners on long-term neurological status.
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Practical Takeaways
- •Magnetic motor evoked potentials provide a non-invasive, painless diagnostic tool to confirm cervical spinal cord lesions and assess motor pathway integrity in ataxic horses
- •This technique is sensitive enough to detect subclinical or subtle lesions that may not be apparent from clinical examination alone
- •Abnormal potentials may persist despite clinical improvement, so results should be interpreted alongside clinical progression rather than as a measure of recovery
Key Findings
- •Latency and peak-to-peak amplitude of magnetic motor evoked potentials were significantly different in 12 ataxic horses compared to normal horses
- •Abnormal potentials showed polyphasic configuration in affected horses
- •Magnetic transcranial stimulation detected lesions in horses with subtle clinical signs of incoordination
- •No normalization of evoked potentials occurred even after clinical improvement in any horse