title: Neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminal-mediated headshaking: A safe procedure resulting in medium-term remission in five of seven horses.
abstract: BACKGROUND
  There are no consistently safe and effective methods for the treatment of trigeminal-mediated headshaking in horses. In affected horses, the trigeminal nerve is sensitised, appearing to result in neuropathic pain. Percutaneous electrical nerve stimulation (PENS) therapy is a minimally invasive neuromodulatory treatment used in people to manage neuropathic pain.
  
  
  OBJECTIVE
  To determine whether PENS therapy is safe, tolerated and effective for the management of trigeminal-mediated headshaking in horses.
  
  
  METHODS
  Descriptive case series.
  
  
  METHODS
  Seven horses diagnosed with trigeminal-mediated headshaking and currently showing clinical signs were studied. All procedures were carried out in sedated horses with a needle-prick sized area of skin desensitised with local anaesthetic to facilitate probe insertion. A disposable PENS probe was advanced subcutaneously adjacent to the nerve, rostral to the infraorbital foramen under ultrasonographic guidance. The nerve was stimulated for 25 min following a protocol of alternating frequencies and a perception threshold based on human clinical data. The probe was removed and the procedure repeated on the contralateral side. The protocol used comprised a series of 3 or 4 treatments, with treatments being repeated when signs of headshaking recurred.
  
  
  RESULTS
  All horses tolerated the procedure well. Three horses developed a haematoma at the site on one occasion and 2 had increased clinical signs for up to 3 days following first treatment. Six horses demonstrated a positive response to their first treatment, returning to ridden work at the same level as prior to onset of headshaking, with 5 continuing to respond. Median remission time for first treatment was 3.8 days (range 0-8 days, n = 7), second treatment 2.5 weeks (0-8 weeks, n = 7), third treatment 15.5 weeks (0-24 weeks, n = 5) and fourth treatment 20 weeks (12-28 weeks ongoing, n = 2).
  
  
  CONCLUSIONS
  Percutaneous electrical nerve stimulation therapy is a safe, well tolerated, minimally invasive, repeatable management option for trigeminal-mediated headshaking, with encouraging efficacy for amelioration of clinical signs in the short- to medium term.
authors.affiliation: School of Veterinary Sciences, University of Bristol, Somerset, UK.
authors.forename: V L H
authors.initials: VL
authors.lastname: Roberts
authors.affiliation: Institute of Neurosciences, Southmead Hospital, Bristol, UK.
authors.forename: N K
authors.initials: NK
authors.lastname: Patel
authors.affiliation: School of Veterinary Sciences, University of Bristol, Somerset, UK.
authors.forename: W H
authors.initials: WH
authors.lastname: Tremaine
mesh_terms: D000818:Animals; D006257:Head; D019416:Head Movements / Q000502:physiology*; D006734:Horse Diseases / Q000628:therapy*; D006736:Horses; D004561:Transcutaneous Electric Nerve Stimulation; D014276:Trigeminal Nerve / Q000502:physiology*
keywords: headshaking; horse; neuromodulation; percutaneous electrical nerve stimulation PENS; trigeminal-mediated