Invisible scar endoscopic thyroidectomy by the dorsal approach: experimental development of a new technique with human cadavers and preliminary clinical results

A unilateral gasless single-surgeon videoendoscopic thyroidectomy procedure using a dorsal cephalic approach from the scalp with the option for a bilateral approach was developed with human cadavers and a porcine model for access training. The final preclinical trials and the first three clinical cases are described in detail.

Preclinical evaluation and training for the procedure were conducted with fresh human cadavers. The procedure was defined precisely by a sequence of nodal points initiating surgical steps. A quality score was developed by issuing each important anatomic structure a specific organ value and a factor for positive identification, inability to identify a given anatomic structure, spare it (meaning omit causing a lesion) or injure the structure. The quality of each operation was expressed as a single number or quality score value, calculated by summing the points achieved for the individual anatomic structures. The results of the procedures were controlled by prospective video documentation and autopsy. After conclusion of the preclinical training, the operation was performed for patients. The reported patients are part of a feasibility study approved by the institutional review board of the University of Munich.

Nodal points were helpful in preparation for the operation by mental training. During the procedure, they helped to guide the preparation in the neck, where the working space must first be created on the way to the target organ. The surgical quality score improved over the first three cases and reached the maximum score, which was reproducible every time after that. It showed that the dorsal approach from the scalp to the thyroid gland is easily achievable without complications. The technical challenge is exposure of the recurrent laryngeal nerve (RLN) and the parathyroid glands. There was no difference between the results achieved by the resident and the senior surgeon. Preclinical training was good preparation for hemithyroidectomy in patients. All cases could be managed without postoperative hemorrhage or impairment of the parathyroid or the RLN.