LAUSR

Recurrent laryngeal nerve (RLN) palsy, subjective voice complaints, and iatrogenic hypoparathyroidism are the main risk factors of thyroid surgery [1, 2]. The rate of unintentional transient RLN injury after total thyroidectomy has been reported in up to 30% of patients, and permanent paralysis ranges between 1 and 5.7% [3, 4]. In patients undergoing concomitant central and/or lateral node dissection, the reported incidence is even greater [5]. Patients with a RLN injury typically experience dysphonia for 10–12 weeks, with ~8–10% having a permanent vocal dysfunction. Even in the absence of overt nerve paralysis, voice alterations can be seen in 46–84% of postthyroidectomy patients [6, 7]. Attempts to decrease the risk of nerve injury have been limited to accurate visualization and meticulous technique, performance of less extensive surgery and/or the use of nerve monitoring devices despite that their usage has never been shown to decrease RLN injury rates [8–10]. The current study aimed at reducing the incidence of intra-operative laryngeal nerve damage with application of a protective allogeneic shield derived from human amnion and chorion membrane of the amniotic sac. The human amniotic membrane is comprised of two distinct tissues, the amnion and the chorion. Grafts derived from the amnion and chorion membrane have been used medically for over a century. Such allografts have been approved for medical uses by the FDA and with the emergence of new preservation techniques and advancements in research, they have become frequently used in various treatments [11]. Since, the human amnion/chorion membrane (HACM) allograft contains growth factors, stem cells, and antiinflammatory properties, it was hypothesized that its application may reduce RLN injury rates and negative voice outcomes. Over a 4-month period, 58 consecutive patients (106 RLNs at risk) undergoing thyroid surgery by T.C. at YaleNew Haven Hospital were enrolled. A group of 58 consecutive patients who were operated on in the preceding months by the same surgeon having identical thyroidectomy procedures served as the historical control group (Table 1). The indication for surgery was malignancy in 52 of 116 (44.8%) of the cases, and concomitant central and modified radical neck dissections were performed in 43 and 13 cases, respectively. Seven patients also had primary hyperparathyroidism and thus underwent simultaneous parathyroidectomy. There was no variation in the anesthesia technique, and nerve monitoring devices were not used. The surgical technique was standardized and involved protecting all branches of the superior and recurrent or non-recurrent laryngeal nerves. The RLN is most commonly identified at its insertion into the cricothyroid muscle first and then followed caudally (tobogganing technique). However, if not detected within 10 s, it is identified in the tracheoesophageal groove and followed cephalad. For patients receiving HACM, surgery was identical except for HACM being placed upon the dissected nerve as soon as possible during the operation to serve as a protective barrier from any surgical trauma and was left in place and not removed during wound closure. HACM was produced and provided by MedRex (Atlanta, GA). The allograft is shaped to cover the delicate recurrently laryngeal nerve, which has a gently curve in its upper aspect and branches in its most superior aspect. The graft was cut to length based upon the dissected nerve’s length of exposure. HACM was applied with amniotic membrane orientation placed immediately upon the dissected nerve. The thyroid cartilage was digitally pulled cephalad and to the contralateral side to expose the greatest surface area of the nerve. The voice outcome (VO) was determined based on * Tobias Carling [email protected]