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

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 Hz. Horses were evaluated on Day 1 (t0) and Day 5 (t1) of the treatment and 2 (t2) and 4 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 < .05) and effect sizes between pretreatment and all time points after treatment (t1, t2, t3) were large (>±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.