Does recurrent laryngeal nerve anatomy condition the choice of the side for approaching the anterior cervical spine?

Aim. The anterior cervical presternocleidomastoid approach is a safe and standardized procedure. Nevertheless, in all the largest series presented in literature, a certain risk of injury to the recurrent laryngeal nerves (RLNs) is reported and the choice of the side of the approach seems to influence such risk. Our aim was to study the surgical anatomy of the RLNs and to understand whether the side of the approach can be a risk factor for their surgical damage. Methods. We performed an anatomical dissection of 6 fresh cadavers, studying the origin and the course of both the RLNs, to assess their vulnerability in the anterior presternocleidomastoid approach to the cervical spine. Results. The origin of the right RLN was at C7 in 2 cases and at T1 in 4 cases. In all cases it arose where vagus nerve crossed the subclavian artery and it was directed superiorly and transversely to the esophagotracheal groove. Conclusions. The right and left RLNs have different origin and course. Although the discussion about the best side for the anterior cervical approach is debated, in our opinion, both anatomical and surgical considerations, concerning RLNs, lead to the evidences that the left side approach, when possible, should be preferred below the level of C4.