Technical Advances in Upper Airway Surgeries (in the Horse)

Laryngeal hemiplegia (RLN)

Treatment of abnormal upper respiratory noise: The bilateral ventriculocordectomy procedure has been shown experimentally to be the most effective treatment, but acceptable results are seen with ipsilateral laserassisted ventriculocordectomy (VC).1 Therefore, a unilateral laser-assisted ventriculocordectomy or bilateral ventriculocordectomy is the preferred treatment for use in sport and draft horses where abnormal respiratory noise is the main complaint.

Technical update: The VC procedure is more commonly done under videoendoscopic control with the laser in three steps: 1) transection of the ventral aspect of the vocal fold; 2) transection of the caudal aspect of the fold; 3) and eversion of the ventricle. The procedure can be performed standing under sedation or under general anesthesia using nitrox or compressed to lower the inspired oxygen (target 21%). Horses under anesthesia do not do well on 21% inspired oxygen because of venous admixture. The anesthetist needs to monitor SpO2 continuously and take blood gases intermittently. So the surgeon has to be quick! As soon as the laser stage of surgery is over the air should be flushed from the system with oxygen. A suction device is needed to remove the fumes.

Treatment of poor performance
To treat poor performance associated with airflow limitation, the following options are available: ventriculocordectomy, partial arytenoidectomy, laryngoplasty, and laryngeal reinnervation. For treatment of early laryngeal hemiparesis or a minimally debilitating obstruction, ipsilateral ventriculocordectomy alone is a real option. For horses experiencing full arytenoid collapse at exercise, laryngoplasty is still the gold treatment. Partial arytenoidectomy should be recognized as an effective alternative to laryngoplasty.

Technical updates: 
Laryngoplasty: In recent years, an attempt at fusion of the crico-arytenoid (CA) joint is used as part of the laryngoplasty procedure. Three techniques are used:
• Transection of the tendon of both compartments of the crico-arytenoid dorsalis and moterising burr (Parente’s technique).
• Transection of the tendon of both compartments of the crico-arytenoid dorsalis and lasering of joint (Hawkin’s technique).
• Application of PMMA into a slit made in the CA joint. [...]