Effect of repetitive transcranial magnetic stimulation on trigeminal-mediated headshaking in 17 horses.

Abstract

BACKGROUND: Trigeminal-mediated headshaking is a neuropathic facial pain condition in horses. No treatment has been entirely successful. Repetitive transcranial magnetic stimulation (rTMS) is used in human medicine as a treatment for various neuropathic pain conditions, and good results have been achieved in cases of trigeminal neuralgia. OBJECTIVES: Apply rTMS to horses with trigeminal-mediated headshaking (TMHS) and to evaluate tolerability, application of the setting, and success rate. ANIMALS: Seventeen horses with nonseasonal signs of TMHS. METHODS: Other underlying causes of headshaking were ruled out. The rTMS was performed under standing sedation on 5 consecutive days applying 3 sets of 500 stimulations each, with a stimulation strength of 5&#x2009;Hz. Horses were evaluated on Day 1 (t0) and Day 5 (t1) of the treatment and 2 (t2) and 4&#x2009;weeks (t3) afterwards using a special scoring system. RESULTS: The rTMS was well tolerated. Headshaking signs during exercise were decreased by 70% (Day 5; t1). Four weeks after rTMS, signs were still decreased (mean reduction of 50%) during exercise. Improvement of mean resting and exercise scores was significant (P&#x2009;<&#x2009;.05) and effect sizes between pretreatment and all time points after treatment (t1, t2, t3) were large (>&#xb1;0.8). CONCLUSIONS AND CLINICAL IMPORTANCE: Repetitive transcranial magnetic stimulation may be a promising treatment for neuropathic pain and headshaking in affected horses. Pain-free periods after treatment differ individually, and repeated treatment may be necessary. More studies should be performed to determine ideal settings for horses.