Veyseller B, Aksoy F, Y YS, Karataş A, Özturan O. Effect of Recurrent Laryngeal Nerve Identification Technique in Thyroidectomy on Recurrent Laryngeal Nerve Paralysis and Hypoparathyroidism. Arch Otolaryngol Head Neck Surg. 2011;137(9):897-900. doi:10.1001/archoto.2011.134
Author Affiliations: Departments of Otorhinolaryngology–Head and Neck Surgery, Bezmialem Vakif University, Istanbul, Turkey (Drs Veyseller, Aksoy, and Özturan); Elbistan State Hospital, Kahramanmaraş, Turkey (Dr YIldIrIm); and Haseki Research and Training Hospital, Istanbul (Dr Karataş).
Objective To investigate whether the recurrent laryngeal nerve (RLN) identification technique used in thyroidectomy affects RLN paralysis and hypoparathyroidism.
Design Patients were allocated into 2 groups according to the thyroidectomy technique used to identify the RLN: (1) superior-inferior direction, exploring the nerve where it enters the larynx, followed by superior pedicle ligation; and (2) inferior-superior direction, following the inferior pedicle ligation and identifying the nerve in the tracheoesophageal groove. The first and second groups included 67 and 128 patients, respectively. In the first group, 19 patients underwent lobo-isthmectomy, and 48 underwent total thyroidectomy. In the second group, 42 patients underwent lobo-isthmectomy, and 86 underwent total thyroidectomy. We performed 115 and 214 RLN dissections in the first and second groups, respectively.
Setting Academic tertiary hospital.
Patients The study included 195 consecutive patients, 161 female (82.5%), and 34 male (17.5%), who underwent thyroidectomy for goiter between January 2006 and August 2009. Their mean age was 44.7 years (range, 14-79 years). The mean follow-up was 26 months (range, 12-42 months).
Interventions Unilateral or bilateral total thyroidectomies performed using extracapsular dissection with 2 different RLN identification techniques.
Main Outcome Measures Incidence of hypocalcemia, vocal cord paralysis, hemorrhage, and wound infection.
Results No RLN paralysis was observed in the first group. In the second group, unilateral RLN paralysis was seen in 2 of 128 patients (1.5%). Groups 1 and 2 included 48 and 86 total thyroidectomies, respectively. Temporary hypoparathyroidism was observed in 4 patients in the first group (8.3%). In the second group, permanent hypoparathyroidism was observed only in 4 patients (4.6%), and temporary hypoparathyroidism was observed in 14 patients (16.2%).
Conclusions Comparing the 2 groups based on the frequencies of RLN paralysis and hypoparathyroidism, we found that complications were significantly lower in the first group (P < .05) in terms of hypoparathyroidism. The rate of hypoparathyroidism was significantly lower in the thyroidectomies that located the RLN using the superior-inferior approach. In our hands, the superior-inferior approach was a safer technique, in terms of avoiding complications.
Thyroidectomy is one of the most common operations, particularly in countries where iodine deficiency is a common condition.1- 4 The preferred type of surgery in multinodular goiter has been controversial, but today, total thyroidectomy is becoming the main surgical option.2,3 Total thyroidectomy seems to be appropriate when both thyroid lobes are involved and when the risk of recurrence is high.2,3 The most serious postoperative complications are recurrent laryngeal nerve (RLN) paralysis and hypoparathyroidism.
The RLN should definitely be identified in total thyroidectomies performed using an extracapsular approach. However, excessive dissection of the tracheoesophageal groove during the search for the RLN may devascularize the parathyroid, leading to temporary or permanent hypoparathyroidism. Following thyroid surgery, hypoparathyroidism may develop owing to the faulty dissection leading to destruction or total removal of the parathyroid glands, deterioration of blood flow, or necrosis secondary to hematoma.5
The reported frequency of hypoparathyroidism varies, and the frequency of potential postoperative hypoparathyroidism is affected by the thyroid pathologic characteristics, type of surgery performed, dexterity and experience of the surgeon, and his/her knowledge of parathyroid anatomy.3- 6
Thyroid nodules may involve all of the thyroid tissue, particularly in patients with multinodular goiter, sometimes leaving no healthy thyroid tissue. Korun et al7 reported that thyroid nodules were located in the dorsal part of the thyroid in 40% of patients with goiter, and these nodules generally remained following subtotal resection.
Total thyroidectomy is a favored treatment for patients with thyroid cancer. However, the preference for total thyroidectomy to treat benign multinodular goiter is disputed because of the frequent complications related to this surgery.8,9
Secondary thyroidectomies performed for recurrent disease are the reason for the most frequently reported complications: hypoparathyroidism and the RLN paralysis.6 Recent research suggests that total thyroidectomies can be performed with a complication rate as low as that observed in subtotal thyroidectomy.1
In our clinic, the minimum surgery is the unilateral lobectomy and isthmectomy, and total thyroidectomy is preferred with extracapsular dissection only if bilateral disease is present. Two different RLN identification methods are used during thyroidectomy. The first identifies the nerve where it penetrates the larynx, following superior pedicle ligation, and the other traces the nerve in the superior direction after locating it in the tracheoesophageal groove.
In thyroid surgery, several studies have examined the association between the type of surgery (total, subtotal, or near-total) and prevention of severe complications such as RLN damage and hypoparathyroidism, according to whether the nerve is identified and whether nerve monitoring is used. However, to our knowledge, no prospective study has compared RLN identification techniques.
In this study, RLN damage and hypoparathyroidism complications were compared in thyroidectomies that were performed using 2 different technical paths of RLN identification.
The study was performed prospectively at the Haseki Training and Research Hospital, Otorhinolaryngology–Head and Neck Surgery Clinic. The study included 195 consecutive patients (161 female [82.5%] and 34 male [17.5%]) who underwent thyroidectomy for goiter between January 2006 and August 2009. Their mean age was 44.7 years (range, 14-79 years). The mean follow-up period was 26 months (range, 12-42 months). The study was approved by the Haseki Training and Research Hospital ethics committee and was conducted in accordance with the Declaration of Helsinki. Patients were informed about the surgery, and written consent was obtained. Patients with benign multinodular goiter, uninodular goiter, thyroid cancer, thyroiditis, Grave disease, and recurrent goiter were included in the study.
Before surgery, all patients underwent thyroid ultrasonography, thyroid hormone evaluations (free triiodothyronine, free thyroxine, and thyrotropin), calcium level assessments, and vocal cord examinations. An ultrasonographically guided fine-needle aspiration biopsy was performed for dominant nodules.
The preoperative clinical diagnosis was multinodular goiter in 154 cases, uninodular goiter in 34, and diffuse goiter in 7 cases. Sixty-one lobo-isthmectomies and 134 total thyroidectomies were performed. Twelve cases had been referred to our clinic owing to relapsed goiter.
Our study was designed as a prospective study. Unilateral or bilateral total thyroidectomy was performed by a specialist or by fourth- or fifth-year residents under the supervision of 2 specialists. The method of identifying the RLN was based on the preference of the attending surgeon. All thyroidectomies were performed using the extracapsular technique with RLN identification.
The patients were separated into 2 groups according to the RLN identification technique. The first group included thyroidectomies performed in a superior-inferior direction by fixing the nerve where it enters into the larynx, followed by superior pedicle ligation. The second group included thyroidectomies performed in an inferior-superior direction, following inferior pedicle ligation and determination of the nerve in the tracheoesophageal groove.
The first and second groups included 67 and 128 patients, respectively. In the first group, 19 patients underwent lobo-isthmectomy, and 48 underwent total thyroidectomy. In the second group, 42 patients underwent lobo-isthmectomy, and 86 patients underwent total thyroidectomy. We performed 115 and 214 RLN dissections in the first and second groups, respectively.
All parathyroid glands were identified and kept intact, whenever possible. The RLN was identified using of the 2 different approaches. A complementary thyroidectomy was performed in 5 patients who underwent lobo-isthmectomy following the first week of thyroid cancer diagnosis. Postoperatively, levothyroxine was administered with the dose adjusted according to the free triiodothyronine, free thyroxine, and thyrotropin levels.
On the first postoperative day, blood calcium levels were measured and vocal cord function evaluated using a flexible laryngoscopy in all patients. Data on the incidence of wound infection and hemorrhage was also collected. Postoperative hypocalcemia was defined as calcium levels lower than 8.0 mg/dL in 2 subsequent blood samples. These patients were monitored by the endocrinology clinic every 3 months until their calcium levels improved. Hypocalcemia or RLN paralysis was considered permanent if it did not improve within 1 year. This study compared the complication rates with the 2 different surgical techniques. The postoperative histopathologic diagnoses are listed in Table 1, and a comparison of characteristic between the 2 groups is provided in Table 2.
Postoperative RLN paralysis was observed in 2 of our patients. Two early postoperative hemorrhages occurred, and 1 late abscess formed in the thyroid lobe associated with a silk reaction. The complications are listed in Table 3.
The frequency of postoperative complications was evaluated by following up with the patients for 12 to 42 months. Five patients in group 1 and 23 patients in group 2 experienced complications. Recurrent laryngeal nerve paralysis was not observed in group 1, whereas 2 patients in group 2 developed permanent RLN paralysis. One of the patients with RLN paralysis had been admitted with recurrent disease. Hypoparathyroidism developed in 4 group 1 patients and 14 group 2 patients. Permanent hypoparathyroidism was observed in only 4 group 2 patients. The frequency of complications was significantly (P < .05) lower in group 1 when the frequencies of RLN paralysis and hypoparathyroidism were compared.
Thyroidectomy is one of the most common operations, particularly in regions where iodine deficiency is common.1- 4 The main objectives of the surgical treatment of thyroid disease are to eliminate the disease while causing as few complications as possible and to minimize the reoperation rate in multinodular goiter compared with incidental thyroid cancer.
The RLN is the motor nerve supplying all of the intrinsic laryngeal muscles except the cricothyroid muscle. It runs in the tracheoesophageal groove to the larynx after exiting from the superior mediastinum, and its path has a very close anatomical relation to the thyroid gland, parathyroid glands, and inferior thyroid artery trunk. The nerve passes near the Berry ligament and enters the larynx. Owing to its anatomical relationship, the inferior laryngeal nerve is quite unprotected during surgical manipulation in the area of the Berry ligament, the tubercle of Zuckerkandl, and the tracheoesophageal groove and dissection of the sixth cervical vertebra area. Therefore, special attention should be exercised in these areas during thyroid surgery. Furthermore, the RLN may have variants, such as nonrecurrence or extralaryngeal branching.
In recent years, the main discussion with respect to thyroid surgery has been the extent of surgery.2 Continuing controversy over the surgical treatment of benign thyroid nodules exists. Several surgical techniques can be used to treat multinodular goiter, including unilateral or bilateral subtotal thyroidectomy, hemithyroidectomy, bilateral total thyroidectomy, and near-total thyroidectomy. Those advocating limited resection suggest that serious complications, such as RLN paralysis and hypoparathyroidism, are more common in total thyroidectomy.10 Conversely, it is also suggested that complications in thyroidectomy may be minimal with the use of an appropriate surgical technique (extracapsular dissection).11
In the current literature, the reported frequency of RLN paralysis is between 0.3% and 1.7%, and that of permanent hypoparathyroidism is between 0.7% and 3.0% among total thyroidectomies.1- 3,10- 12 The frequency of RLN complications in nontotal thyroidectomies performed for multinodular goiter ranges from 12% to 20%.13 Revision surgery is required in approximately half of the patients who have recurrence of a benign goiter, and the risk of developing permanent complications is reported to be much higher.1 Owing to the risks of incomplete resection and the safety of total thyroidectomy with appropriate surgical techniques, total thyroidectomy is frequently used for benign disease.1,3
In 1% to 2% of cases, nerve paralysis due to accidental injury of the RLN is reported, even by the most experienced surgeons.1,2,10- 12 The reported frequency of hypoparathyroidism varies from 1.6% to 50.0% in several studies.1,2,10- 14
Factors affecting hypoparathyroidism are operative damage to the parathyroid glands, the extent of surgery, experience of the surgeon, and number of parathyroid glands left after surgery.15
Although the total rate of complications is low, once RLN paralysis occurs, it remains a lifelong problem. Paralysis of the RLN is more frequent in thyroid cancer, Grave disease, extensive resections, and reoperation cases.2,13- 15 The frequency of postoperative RLN paralysis is lower in thyroidectomy when the nerve is identified at surgery.16
Searching for the RLN in the tracheoesophageal groove and following it where it enters the larynx requires more dissection and can lead to parathyroid devascularization, which can cause ischemia and necrosis and lead to hypoparathyroidism. The superior-inferior approach to the RLN allows the surgeon reach to the region directly and involves less dissection and less parathyroid damage. Total thyroidectomy increases the risk to all of the parathyroid glands. Following thyroid surgery, hypoparathyroidism may develop because of the total resection and reimplantation of the parathyroid glands, infarction of parathyroid glands with manipulation, or vessel damage.6,15,17
Some surgeons believe that parathyroid- and RLN-related complications are less frequent in thyroidectomy if some thyroid tissue is left at the laryngeal nerve intersection. During hemostasis of the remaining thyroid tissue in subtotal or near-total thyroidectomy, the risk of damage may increase.14
Given the lower complication rates, subtotal thyroidectomy is considered the standard approach for multinodular goiter. However, subtotal thyroidectomy does not completely eliminate the risk of complications.18 Following subtotal thyroidectomy, the goiter recurs in over 23% of the patients.18 Leaving residual thyroid tissue puts the patient at risk of recurrent disease and a repeated operation.18,19 After partial resection, hormone suppression therapy does not prevent the remaining tissue from growing.18 The reported recurrence rates in subtotal thyroidectomies are 14.5% with suppression therapy and 43.0% without it.20 In addition, suppression therapy has adverse effects. Because RLN paralysis and hypoparathyroidism are most frequent after secondary surgery, it is unwise to leave any thyroid tissue behind in the surgery where total removal is indicated.21
During the surgery, nerve monitoring is a useful tool for identifying the RLN, and its major advantage is that it can demonstrate whether the nerve is intact postoperatively. Nevertheless, owing to the expense of nerve monitoring, it is not recommended in all cases. Nerve monitoring is recommended in revision surgery, thyroid cancer, patients with retrosternal extension or a giant goiter, and those who previously received radiotherapy.22,23
Meticulous hemostasis and a delicate technique are required to prevent nerve and parathyroid gland injury. The knowledge of the anatomic variation of the parathyroid glands is of utmost value to the surgeon to avoid their inadvertent avulsion or devascularization. The possible intrathyroidal location of the parathyroid glands should be remembered. Systematic dissection of the RLN reduces RLN paralysis but increases hypoparathyroidism, mainly by devascularizing the parathyroid glands.24 Rimple et al25 demonstrated that postoperative hypocalcemia was caused by extensive thyroid resection and parathyroid gland manipulation. As a result, significantly lower rates of RLN paralysis and hypoparathyroidism were observed in thyroidectomies using a superior-inferior approach. In conclusion, the superior-inferior approach is a safer technique in terms of avoiding complications. These results should be corroborated with larger case series.
Correspondence: Yavuz Selim YIldIrIm, MD, Elbistan Devlet Hastanesi Kulak Burun Boğaz Kliniği, 46300, Karaelbistan, Kahramanmaraş, Turkey (firstname.lastname@example.org).
Submitted for Publication: October 10, 2010; final revision received May 26, 2011; accepted May 30, 2011.
Published Online: August 15, 2011. doi:10.1001/archoto.2011.134
Author Contributions: Dr Veyseller had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Veyseller, Karataş, and Özturan. Acquisition of data: Aksoy and YIldIrIm. Analysis and interpretation of data: YIldIrIm. Drafting of the manuscript: Aksoy and Karataş. Critical revision of the manuscript for important intellectual content: Veyseller, YIldIrIm, and Özturan. Study supervision: Veyseller, Aksoy, YIldIrIm, Karataş, and Özturan.
Financial Disclosure: None reported.