Poster Design & Printing by Genigraphics ® - 800.790.4001 DESIGN: A prospective evaluation of the relationship of the recurrent laryngeal nerve (RLN) to the superior parathyroid gland (SPG) during consecutive thyroidectomies. When one structure was noted, careful dissection was performed to locate the other structure, to preserve the natural anatomic relationship between them. PATIENTS: 103 consecutive thyroid lobectomies were performed on 73 different patients. Pathology included benign and malignant thyroid nodules, a parathyroid cyst and an exploration for a stab wound to the neck. The distance from the SPG to the ipsilateral RLN was measured. RESULTS: In 88 (88.9%) of these cases the gland was identified within 5 mm of the RLN, and in 62 (62.3%) cases the RLN was within 1 mm of the SPG. Two secondary measures proved statistically significant. Height of the thyroid lobe was positively associated with distance between the structures (p=0.0011). The incidence of cancer was also positively associated with distance (p=0.033). The incidence of RLN paresis was <4%. CONCLUSIONS: In the majority of cases, the nerve was found in close proximity to the SPG. In a thyroid gland with a large height, or in a cancerous lobe, this relationship is less reliable. RELATIONSHIP OF THE RECURRENT LARYNGEAL NERVE TO THE SUPERIOR PARATHYROID GLAND DURING THYROIDECTOMY David Myssiorek, M.D.; Michael Persky, M.D.; Yixin Fang, Ph.D. Department of Otolaryngology-Head and Neck Surgery New York University School of Medicine Langone Medical Center It is important to identify the recurrent laryngeal nerve during thyroid surgery so as to avoid the significant morbidity of nerve paralysis or paresis. It has been shown that permanent injury to the nerve in expert hands can occur in up to 1.4% of thyroidectomies, with temporary paralysis in up to 5.4% 5 . However, it has been shown that proper identification of the nerve during surgery decreases the rate of RLN injury 6 . There are many methods of finding the RLN during thyroid surgery, but there is little in the literature quantitatively documenting the relationship of the superior parathyroid gland to the RLN. A consistent relationship exists between the RLN and the superior parathyroid gland, bilaterally, as our results show that the majority (89% in our study) of patients undergoing thyroid surgery will have a RLN that lies between 0-5mm from the superior parathyroid. This is without regard to gender, age, thyroid weight, width or depth. Interestingly, the data show that the distance between the structures does significantly differ with regard to thyroid height and pathology; in longer lobes (in the superior-inferior dimension) and cancerous lobes the distance between the nerve and the SPT is likely to be farther than average. So, the preoperative assessment of lobe size and pathology can factor in to the surgeon’s determination if this approach to RLN identification is appropriate. It is important for a surgeon to have knowledge of common and uncommon surgical techniques in order to provide the best care with the least amount of morbidity possible. A statistically significant relationship of the RLN to the superior parathyroid has been demonstrated. Using this technique for a thyroidectomy allows identification of the RLN during the routine performance of parathyroid gland sparing. Thus, it does not add time or morbidity to the operation. This documentation of the proximity of the superior parathyroid gland to the RLN will reinforce this anatomic relationship for surgeons performing parathyroid surgery as well, thereby resulting in a safer procedure. This method can also be used for endoscopic approaches to the thyroid gland. Of course, unlike other approaches, this requires the identification of the superior parathyroid, which can be difficult. Thus, identification of the RLN using the superior parathyroid should only be used when the patient has an intact superior parathyroid. It should be noted that the authors did not observe aberrant anatomy during data collection, and so cannot comment of the anatomical relationship between the two structures in patients with anatomical anomalies such as a poorly migrated parathyroid or nonrecurrent laryngeal nerve. Conversely, during explorations for parathyroid glands (i.e. four gland parathyroid exploration), the recurrent laryngeal nerve can be used to identify the normal superior parathyroid gland. 103 consecutive thyroid lobectomies were performed by one surgeon at NYU Langone Medical Center, Bellevue Hospital in New York City. Each patient underwent either a thyroid lobectomy, total thyroidectomy, or a lobectomy that was converted to a total thyroidectomy intraoperatively. The patients ranged in age from 22 to 81 years, with approximately 17 percent of the lobes residing in men and 83 percent in women. The thyroid pathology was both benign and malignant. Thyroid weight and dimensions were recorded from the pathological specimen report. In cases of total thyroidectomy where there was no individual weight per lobe, the total weight was divided in half. Postoperative vocal fold function was assessed as a measure of nerve damage. Various methods of identifying the recurrent laryngeal nerve were utilized, including those described in the introduction. If the RLN was identified prior to the superior parathyroid, it was subsequently dissected to the nerve’s closest relationship to the parathyroid. If the superior parathyroid was identified first, careful attempts were made to expose the nerve in its vicinity. Blood supply was preserved to the parathyroid gland by grasping its capsule and dissecting it bluntly on its medial surface. The nerve, when identified, was always deep and slightly lateral to the parathyroid gland. The moment the nerve was positively identified, dissection was halted and care was taken to preserve the natural distance between the RLN and superior parathyroid. The distance of the recurrent laryngeal nerve from the superior parathyroid was measured in millimeters with a ruler and recorded. Of note, none of these operations were performed endoscopically. The recorded distance between the nerve and superior parathyroid was put into one of three categories: 0-5mm (Group A); 6-10mm (Group B); >11mm (Group C). If the nerve was not identified it was assumed to be greater than 11mm from the superior parathyroid and included in Group C. There were no patients excluded from this study. The data analysis was based on 73 patients, 43 of whom had only one lobe removed. 5 of the 30 patients with both thyroid lobes removed underwent separate operations for each lobe. There were 55 left thyroid lobes removed and 48 right. INTRODUCTION METHODS AND MATERIALS 1. Jatzko GR, Lisborg PH, Müller MG, Wette VM. Recurrent nerve palsy after thyroid operations--principal nerve identification and a literature review. Surgery 1994;115(2):139-44. 2. Abadin SS, Kaplan EL, Angelos P. Malpractice litigation after thyroid surgery: the role of recurrent laryngeal nerve injuries, 1989-2009. Surgery 2010;148(4):718-22. 3. Richer SL, Randolph GW. Management of the recurrent laryngeal nerve in thyroid surgery. Operative Techniques in Otolaryngology 2009; 20:29-34. 4. Shindo ML, Wu JC, Park EE. Surgical anatomy of the recurrent laryngeal nerve revisited. Otolaryngol Head Neck Surg 2005; 133(4):514-9. 5. Lo CY, Kwok KF, Yuen PW. A prospective evaluation of recurrent laryngeal nerve paralysis during thyroidectomy. Arch Surg 2000; 135 (2):204-207. 6. Zakaria HM, Al Awad NA, Al Kreedes AS. Recurrent laryngeal nerve injury in thyroid surgery. Oman Med J 2011; 26(1): 34-38. DISCUSSION RESULTS REFERENCES Figure 1. View of the spatial relationship between the RLN and the superior parathyroid gland. Yellow arrow = left superior parathyroid gland. White arrow = left recurrent laryngeal nerve Table 1. Frequency of distance between the RLN and superior parathyroid gland ABSTRACT David Myssiorek, MD Department of Otolaryngology – Head and Neck Surgery, New York University School of Medicine Email: david.myssiorek@nyumc.org Phone: 212 731-6085 CONTACT The recurrent laryngeal nerve was identified during 99 of the 103 thyroid lobes removed (96%). In 88.9% of thyroid lobectomies the recurrent laryngeal nerve was identified within 5 mm from the superior parathyroid, and 62.6% of the time it was found within 1 mm from the SPT. This relationship was consistent on the right and the left. The nerve was found between 6 and 10mm from the SPT (Group B) 7.8% of the time. The nerve was 11mm or greater from the SPT, or not identified, (Group C) 5.8% of the time. Two secondary measures proved significant by fitting a linear regression model with distance as the response variable. It was found that, on average, when a thyroid lobe was cancerous the distance between the nerve and the SPT was increased (p=0.033). Also, the larger the height of the thyroid, the farther the structures were from each other, on average (p=0.001). There was no correlation found when comparing the relationship between the structures to sex, age, thyroid weight, width, or depth. Furthermore, we did not take into account the cancerous nodule’s size or location. Four patients developed RLN paresis postoperatively. One of these patient’s superior parathyroid gland was avulsed prior to identification of the nerve. Of the remaining patients with postoperative paresis, two were in group A and one was in group B. Identification of the recurrent laryngeal nerve should be paramount in any surgery where the nerve is at risk, the most common of which is thyroid surgery. Proper identification and preservation of the nerve reduces the incidence of postoperative paresis of the ipsilateral vocal fold, keeping the airway unobstructed and voice quality intact 1 . Furthermore, glottic closure will remain unhindered, keeping the risk of aspiration low. Injury to the nerve is a main cause of malpractice associated with thyroid surgery 2 ; thus, improved identification and preservation should lead to decreased malpractice suits, a practical concern for any surgeon. Currently, there are many documented approaches to identify the recurrent laryngeal nerve. The three main methods of identification during thyroid surgery were described by Richer and Randolf in 2009: The lateral approach, where the nerve is identified at the thyroid midpole level by medial retraction of the thyroid and lateral retraction of the strap muscles; the inferior approach, where the nerve is found at the point it crosses the inferior thyroid artery; and finally, the superior approach, where the nerve is found at its laryngeal entry point, after dissection of the superior pole of the thyroid 3 . Some literature also indicates the cricothyroid joint (or inferior cornu of the thyroid cartilage) as a superior landmark 4 . In our review of the literature, we found very few descriptions of primarily identifying the superior parathyroid gland, which is relatively constant in location as compared to the inferior parathyroid gland, in order to subsequently localize the recurrent laryngeal nerve, often just millimeters away. To this end, we studied the relationship of the recurrent laryngeal nerve to the superior parathyroid gland. Distance Distance Frequency Percent Cumulative Frequency Cumulative Percent 0 49 49.49 49 49.49 1 13 13.13 62 62.63 2 7 7.07 69 69.70 3 9 9.09 78 78.79 4 7 7.07 85 85.86 5 3 3.03 88 88.89 6 4 4.04 92 92.93 7 1 1.01 93 93.94 10 3 3.03 96 96.97 11 2 2.02 98 98.99 15 1 1.01 99 100.00 Thyroid gland