Equine veterinary journal2015; 47 Suppl 48; 14; doi: 10.1111/evj.12486_31

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

Vanschandevijl, K
·
Nollet, H
·
Vercauteren, G
·
Ducatelle, R
·
Deprez, P

Abstract: Transcranial magnetic stimulation (TMS) is an electrophysiological technique used to elicit motor evoked potentials (MMEPs) to evaluate the functional integrity of the descending motor fibres in the spinal cord. Successful application of the technique was reported in horses with spinal cord compression. However, limited data are available on the correlation of TMS with histopathological changes. Objective: To determine sensitivity of TMS for assessing the integrity of the spinal cord in horses with compressive lesions of the spinal cord. Methods: Case series. Methods: The study was conducted on 6 horses with spinal ataxia grade III-V/V admitted to the Faculty of Veterinary Medicine, Ghent University. The horses underwent TMS, radiography of the cervical or thoracolumbar vertebral column, and myelography (4/6). All horses were subjected to euthanasia and the spinal cord examined histopathologically. Results: In 5/6 horses MMEPs with abnormal onset latencies in both extensor carpi radialis muscles and cranial tibialis muscles were recorded, suggesting a cervical spinal cord lesion. Radiography revealed cervical vertebral malformation (4/5) with cervical vertebral canal stenosis (3/5) and tumour/osteomyelitis (1/5). In 1/6 horse MMEPs with normal onset latencies in extensor carpi radialis muscles and prolonged onset latencies in tibialis cranialis muscles were recorded, suggesting a thoracolumbar spinal cord lesion. Radiography revealed deformation of the 7th and 8th thoracic vertebrae. Myelography showed reduction in dural diameter and dorsal contrast column (4/4). Histopathological examination of the spinal cord confirmed compressive type lesions in all 6 horses with degenerative changes in the white matter of all funiculi, ballooning of myelin sheets, swollen axons, loss of axons and astroglial activation. Conclusions: In this case series abnormal function of descending motor pathways as registered by TMS showed 100% sensitivity with the histopathological characteristics of compressive lesions in the spinal cord, but the number of horses is limited and further research is warranted. Ethical animal research: Research ethics committee oversight not currently required by this conference: the study was performed on material collected during clinical procedures. Explicit owner informed consent for participation in this study was not stated. Background: Not applicable. Competing interests: None declared.

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Publication Date: 2015-09-17 PubMed ID: 26375301DOI: 10.1111/evj.12486_31Google Scholar: Lookup

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The study explores the effectiveness of Transcranial Magnetic Stimulation (TMS) in evaluating the functional status of descending motor fibers in horses with spinal cord compression. The findings suggest TMS’s high sensitivity in detecting functional aberrations corresponding to histopathological changes due to cervical and thoracolumbar spinal cord lesions.

Objective and Methods of Research

The primary aim of the study was to determine if TMS could accurately assess the integrity of the spinal cord in horses with compressive lesions.
The study involved six horses with third to fifth grade spinal ataxia admitted to the Ghent University’s Faculty of Veterinary Medicine.
The techniques used were TMS, radiography of the cervical or thoracolumbar vertebral column, and in some instances, myelography.
After these tests, the horses were euthanized for histopathological examination of the spinal cord.

Results of the Study

In five out of six horses, TMS detected anomalies in two specific muscles, suggesting cervical spinal cord lesions. These findings were confirmed by radiography, which showed cervical vertebral malformations in four of these five horses.
Abnormalities found in one horse pointed towards a thoracolumbar spinal cord lesion, with radiography revealing deformations in the 7th and 8th thoracic vertebrae.
Myelographic studies showed reduction in dural diameter and dorsal contrast column in all four cases where it was applied.
The histopathological examinations revealed compressive type lesions in all six horses accompanied by degenerative changes in the white matter, ballooning of myelin sheets, swelling and loss of axons, and activation of star-shaped glial cells.

Conclusions and Further Research

The research findings highlighted that abnormal function of descending motor pathways registered by TMS showed complete sensitivity to the histopathological characteristics of the compressive lesions in the spinal cord.
This suggests that TMS effectively picks up on functional anomalies that correspond to underlying pathological changes.
However, as the number of horses studied was limited, the researchers advocated for additional research on a larger scale for comprehensive evaluation.

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APA

Vanschandevijl K, Nollet H, Vercauteren G, Ducatelle R, Deprez P. (2015). Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015. Equine Vet J, 47 Suppl 48, 14. https://doi.org/10.1111/evj.12486_31