Selective laryngeal reinnervation: can rerouting of the thyrohyoid nerve simplify the procedure by avoiding the use of a nerve graft?

Purpose The objective of this study was to record the descriptive and metric anatomical characteristics of the thyrohyoid nerve with the aim of rerouting it in a selective laryngeal reinnervation procedure. Methods An anatomical study was performed on ten formalin-embalmed cadavers. The origin of the thyrohyoid nerve and the superior root of the ansa cervicalis , the location of the thyrohyoid nerve ending in the thyrohyoid muscle, and the recurrent laryngeal nerve were established. Then, a rerouting of the thyrohyoid nerve was performed. We measured the length of thyrohyoid nerve, the distance between the thyrohyoid nerve ending and the recurrent laryngeal nerve at the horizontal level of the cricothyroid joint before and after the rerouting, and the distance between the origin of the thyrohyoid nerve and the superior root of the ansa cervicalis . Results The thyrohyoid nerve was identified on both sides in all the cases. The average length of the thyrohyoid nerve was 27 mm. The end of the thyrohyoid nerve was found in 100% of the cases at the upper outer quarter of the thyrohyoid muscle. After the rerouting, an average reduction of 30% of the distance between the end of the thyroid nerve and the recurrent laryngeal nerve at the horizontal level of the cricothyroid joint was measured. Conclusion The rerouting of the thyrohyoid nerve provided a reduction in the length of the nerve graft in laryngeal reinnervation. Moreover, the constancy of the thyrohyoid nerve and its characteristics make it a valuable anatomical base for laryngeal reinnervation and laryngeal innervated allotransplantation.