Motor pathway evaluation by transcranial magnetic stimulation in Swedish horses with acquired equine polyneuropathy

Zitation: Pferdeklinik, LMU München, Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Gluck Equine Research Center, University of Kentucky, Neuropathologie, Zentrum für Klinische Tiermedizin, LMU München, Department of Animal Health and Antimicrobial Strategies, Swedish Veterinary Agency, May, Anna und Hanche-Olsen, Siv und Goehring, Lutz und Matiasek, Kaspar und Jäderlund, Karin Hultin und Zablotski, Yury und Gröndahl, Gittan: Motor pathway evaluation by transcranial magnetic stimulation in Swedish horses with acquired equine polyneuropathy. 3. April 2025. Open Data LMU. 10.5282/ubm/data.592

Be­schrei­bung

Abstract Background: Acquired Equine Polyneuropathy in Nordic horses (AEP) is the most prevalent equine polyneuropathy in Norway, Sweden and Finland. AEP is characterized by pelvic limb knuckling due to metatarsophalangeal extension dysfunction. Objectives: To evaluate function of descending motor pathways in AEP using transcranial magnetic stimulation (TMS). Study design: An analytical, observational cohort design Methods: Clinical findings and TMS results of 20 horses from an AEP outbreak in Sweden were evaluated at two timepoints with 5 months interval. Latency time (LT) in milliseconds (ms) between coil discharge and onset of muscle potential was recorded for thoracic and pelvic limbs. Results: Fourteen affected horses showed knuckling, and 6 horses were neurologically sound at first visit. Thirteen affected horses had improved clinically five months later, four no longer showed knuckling. Motor neurological dysfunction with increased LT was confirmed by TMS in all 14 affected horses at both visits. Mean difference in LT from normalized reference values (ΔLT) in pelvic limbs of affected horses was +12.95 ms (+38%) at first examination (1.9-29.6 ms; SD 1.23; n=14), and +8.1 ms (+24%) five months later (1.0-18.9 ms; SD 1.21; n=14), cutoff >0.8 ms. Eleven of 14 affected horses also presented delayed TMS responses in thoracic limbs, with up to 14% ΔLT increase. Neurologically sound, non-lame horses (n=8) showed mean ΔLT -0.5 ms ( -1.8 to 0.2 ms; SD=0.64) in pelvic, and -0.35 ms (range, -0.7 to 0 ms; SD=0.26; n=8) in thoracic limbs, cutoff >0.2 ms. Limitations: Examinations were only repeated once for organizational reasons. Conclusion: This study proved involvement of motor pathways in AEP. Findings add to previously established involvement of sensory nerve fibers. Sensory and motor involvement contribute to mismatch of ascending and descending nerve signals, which contributes to the clinical manifestations. TMS may be useful in evaluating clinical and subclinical cases of AEP.

Stichwörter

Knuckling, Schwannopathy, Polyneuropathy, Lower motor neuron, Latency time, Transcranial magnetic stimulation

Quellenangaben

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• Dokumententyp: Daten
• Name der Kontakt­person: May, Anna
• E-Mail der Kontaktperson: anna.may at lmu.de
• Fächer: Tiermedizin
• Dewey Dezimal­klassi­fikation: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Eingestellt von: Prof. Dr. Anna May