Selective laryngeal abductor reinnervation in cats using a phrenic nerve transfer and ORG 2766

Reinnervation of the recurrent laryngeal nerve following nerve injury often leads to laryngeal synkinesis. Selective reinnervation of adductor and abductor muscles might be able to avoid synkinesis. This study presents the results of selective abductor reinnervation in cats, using a phrenic nerve transfer to the recurrent laryngeal nerve and directing all reinnervating axons toward the abductor muscle. Simultaneously, a blind, placebo-controlled, pilot study was performed to evaluate the capacity of ORG 2766, administered subcutaneously (25 micrograms/kg per 48 hours), to facilitate reinnervation by stimulation of axon sprouting. Reinnervation surgery was performed in 10 cats. Postoperative evaluation included videolaryngoscopy, electromyography, histological examination, and quantification of reinnervating axons. Nine cats could be evaluated, of which eight demonstrated electromyographic and laryngoscopic activity as soon as 6 weeks following surgery. The one cat showing no abduction was found to have an inadequate nerve anastomosis and was marked as a surgical failure. After 10 weeks, near-normal or more than normal abduction was seen in the eight cats, and histological proof of reinnervation was obtained in seven of them; one cat could not be evaluated histologically owing to unsuccessful fixation. Although no conclusive evidence was obtained concerning the effect of ORG 2766, the tendencies found warrant further experiments with this compound on laryngeal reinnervation.