Sensory nerve conduction stimulus threshold measurements of the infraorbital nerve and its applicability as a diagnostic tool in horses with trigeminal-mediated headshaking.
Authors: Nessler Jasmin Nicole, Delarocque Julien, Kloock Tanja, Twele Lara, Neudeck Stephan, Meyerhoff Nina, Riese Franziska, Cavalleri Jessica-M V, Tipold Andrea, Feige Karsten, Niebuhr Tobias
Journal: BMC veterinary research
Summary
# Editorial Summary Trigeminal-mediated headshaking in horses presents a significant diagnostic challenge, particularly in distinguishing idiopathic cases (i-TMHS) from those secondary to identifiable pathology (s-TMHS), prompting investigation into whether infraorbital nerve conduction testing could serve as an objective diagnostic marker. Researchers anaesthetised headshaking horses and healthy controls, then measured sensory nerve conduction stimulus thresholds (SNCT) of the infraorbital nerve using bipolar concentric needle electrodes, recording sensory nerve action potentials at 2.5–5 mA intervals and calculating minimal SNCT values. The study's ability to differentiate i-TMHS from s-TMHS and healthy horses through SNCT measurement—supported by rigorous advanced imaging including MRI and CT—establishes whether this electrophysiological parameter offers sufficient sensitivity and specificity for clinical application. For equine practitioners, if SNCT measurements prove discriminatory, this technique could provide an objective, quantifiable assessment to complement existing diagnostic protocols, particularly valuable given that idiopathic trigeminal-mediated headshaking remains a frustrating diagnosis of exclusion. Understanding whether nerve conduction abnormalities correlate with clinical phenotype may ultimately refine case selection for medical and surgical interventions, improving outcomes for affected horses.
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Practical Takeaways
- •SNCT measurement of the infraorbital nerve may provide an objective diagnostic tool to help differentiate idiopathic from secondary trigeminal-mediated headshaking in horses requiring general anesthesia
- •Use of advanced imaging alongside neurophysiological testing can improve diagnostic accuracy in complex headshaking cases that fail to respond to standard treatments
- •This diagnostic approach requires general anesthesia and specialized equipment, so it is best reserved for challenging cases where treatment decisions hinge on establishing whether headshaking is primary or secondary to another condition
Key Findings
- •Sensory nerve conduction stimulus threshold (SNCT) measurements of the infraorbital nerve were obtained using bipolar concentric needle electrode under general anesthesia
- •Study compared minimal SNCT values between healthy horses, horses with idiopathic TMHS, and horses with secondary TMHS to evaluate diagnostic applicability
- •Advanced imaging (CT and 3T-MRI) was used to differentiate secondary from idiopathic trigeminal-mediated headshaking cases