Reinnervation aspects of laryngeal transplantation.

Although restoration of laryngeal function after laryngeal transplantation depends on appropriate reinnervation, non-selective reinnervation procedures result in synkinesis and poor function restoration. This study was performed to test the feasibility of selective reinnervation procedures to restore laryngeal function. Three surgical reinnervation procedures were studied each in a group of ten cats: in group 1 a non-selective procedure in which the recurrent laryngeal nerve (RLN) was cut and reanastomosed; in group 2 selective abductor reinnervation was performed with the phrenic nerve; in group 3 selective abductor reinnervation with the phrenic nerve (PN) was combined with selective adductor reinnervation with the ansa cervicalis. Ten weeks after surgical reinnervation abductor and reflex adductor functions were evaluated with videolaryngoscopy and electromyography. Findings demonstrated that non-selective reinnervation not only gave poor abduction during inspiration but even resulted in paradoxical movement during reflex adduction. Selective abductor reinnervation resulted in good abductor function. Selective adductor reinnervation with the ansa cervicalis brought about muscle tonus in the animals studied but no restoration of reflex adduction. Enhanced activity during respiratory distress gave only slight compromise to the abductor function. In all, selective laryngeal reinnervation with the PN and ansa cervicalis produced good restoration of respiratory laryngeal function. However, deglutition following laryngeal motor and sensory reinnervation with protection of the respiratory tract is probably not sufficient, as in the present group of animals no reflex glottic closure was achieved. More research is required.