EFFICACY OF PROSTHETIC LARYNGOPLASTY WITH AND WITHOUT BILATERAL VENTRICULOCORDECTOMY AS TREATMENTS FOR LARYNGEAL HEMIPLEGIA IN HORSES

Objective-To evaluate the efficacy of prosthetic laryngoplasty with an d without bilateral ventriculocordectomy for treatment of experimental ly induced left laryngeal hemiplegia (LLH). Animals-15 adult Standardb reds. Procedure-Horses were allotted to 3 equal groups, Sham operation (group 1), prosthetic laryngoplasty (group 2), or prosthetic laryngop lasty with bilateral ventriculocordectomy (group 3) was performed afte r induction of LLH. Upper airway function resting was performed prior to left recurrent laryngeal neurectomy (LRLN), 14 days after LRLN, and 60 and 180 days after surgical treatment. Measurements were obtained at rest and at treadmill speeds corresponding to 75 and 100% of maxima l heart rate. Videoendoscopy was performed at rest and during exercise in all horses prior to LRLN and 60 and 180 days after surgical treatm ent. Upper airway endoscopy was performed immediately after LRLN to do cument induction of grade-IV LLH. Also, horses in group 3 were endosco pically examined at 7, 14, 21, 28, and 120 days after surgical treatme nt to evaluate healing of the ventriculocordectomy sites. Results-When horses were at rest, significant differences were not apparent betwee n groups at any period or between periods for any measured variable. L RLN induced airway obstruction in all horses during exercise. In sham- operated horses, this obstruction was unaffected by time. In contrast, 60 and 180 days after surgical treatment, inspiratory flow limitation s induced by LRLN were reversed in horses of groups 2 and 3. There wer e no significant differences between the 2 treatment groups. Endoscopy revealed the left arytenoid cartilage abducted beyond the intermediat e position, but not touching the pharyngeal wall in all horses with a laryngeal prosthesis. After surgical treatment, 4 group-2 horses had f illing of both ventricles with air during exercise. There was moderate to marked swelling of the ventriculocordectomy sites immediately afte r surgery, and this swelling resolved by 7 days alter surgery. The ven triculocordectomy sites looked best at 14 and 180 days. Conclusions-60 and 180 days after prosthetic laryngoplasty, upper airway function re turned to pre-LRLN values in horses with experimentally induced LLH ex ercising a 100% of maximal heart rate. Combining ventriculocordectomy with prosthetic laryngoplasty does not further improve upper airway fu nction in these horses.