Invisible scar endoscopic thyroid surgery by the dorsal approach: importance of the spinal accessory nerve.

Purpose: With about 100,000 surgeries per year in Germany, thyroid operations count among the most common procedures performed in general and endocrine visceral surgery. Twentieth century technological development gives the opportunity to perform thyroid surgery without leaving visible scar like conventional approaches do. This study is part of the work on the videoendoscopic retro-auricular access to the thyroid gland using the EndoCATS method by Schardey and Schopf. To avoid possible complications with the spinal accessory nerve (SAN), like irritation or injury of the nerve as happened during a feasibility study, a systematic study of the surgical anatomy at the nerve's entry to the posterior cervical triangle is performed especially in relation to the EndoCATS operation method.

Methods: Sixty-one neck regions in fifty-three specimens were examined at the anatomical institute of Munich to investigate the course of the SAN relative to the anatomic landmarks tip of mastoid bone, sternal notch, and posterior border of the sternocleidomastoid muscle together with the SAN's course variants at its entry to the posterior cervical triangle. The results were then statistically analyzed.

Results: From this analysis, we derived a simple method to predict the course of the SAN preoperatively and offer a new approach to protect the SAN during EndoCATS surgery. Additionally, we found a significant difference of the SAN's course between male and female specimens.

Conclusion: The EndoCATS method can be a safe alternative to conventional thyroid surgery, but the SAN is at risk during the surgery procedure. Here we give feasible solutions to eliminate the SAN-problem performing EndoCATS thyroid surgery.