Dual laryngeal reinnervation in bilateral vocal fold paralysis: anatomical pitfalls.

Background: Bilateral laryngeal reinnervation can be a promising procedure for reanimation of laryngeal muscles, but currently not yet standardized. Besides patient conditions some intraoperative anatomical pitfalls need to be solved.

Methods: Twelve human head and neck specimens (24 sides) have been studied using microdissection and histological serial sections of the nerves. The surgical anatomy of the dual reinnervation procedure according to JP Marie was investigated notably the branching pattern of the phrenic nerve (PN), the Ansa cervicalis (AC) and the recurrent laryngeal nerve (RLN).

Results: Despite variations of the AC, a prominent inferior common trunk for sterno-hyoid and sterno-thyroid muscles can be used in more than 90% of the specimens. If the AC is missing because of previous surgery, the tiny nerve of the thyro-hyoid muscle can be used preferred. The PN display a double roots pattern from C3 to C4 cervical plexus in 50% of the specimens. A single root pattern can be found and an end-to-lateral neurorraphy can be used. Intra-laryngeal nerves pattern of the RLN display tiny collaterals which cannot be selected for abduction-adduction activity. Direct implantation of the Y-shape great auricular nerve within the posterior crico-arytenoid muscles can be a reliable method leading to challenging mechanical and functional conditions.

Conclusion: Several anatomical pitfalls, including intra-operative choices and variants of the donor nerves, but also the challenging intra-laryngeal dissection of the inferior laryngeal nerve need to be solved. A successful laryngeal reinnervation still needs further studies for a simplified procedure.