Complication Risk in Secondary Thyroid Surgery

Factors Associated With Injury to Recurrent Laryngeal Nerve in Patients Undergoing Surgery for Thyroid Cancer: A Single-centre Study Using Translaryngeal Ultrasound

AIMS

Intraoperative injury to the recurrent laryngeal nerve (RLN) is a serious complication occurring more frequently in patients with thyroid cancer than in those with benign thyroid diseases. However, data on the risk factors for RLN injury among patients with thyroid cancer are scarce. Currently, RLN injury is diagnosed by laryngoscopy, but translaryngealultrasonography (TLUS), which is less invasive, appears to have a similar accuracy. Herein, we analysed risk factors ofintraoperative RLN injury in patients with thyroid cancer and assessed the diagnostic performance of TLUS.

PATIENTS AND METHODS

In this prospective study, we enrolled patients undergoing surgery for thyroid cancer from October 2020 to October 2021. Medical and surgical variables were analysed as risk factors of RLN injury. TLUS was compared with laryngoscopy in diagnosing RLN injury.

RESULTS

There were 185 patients who underwent 196 surgeries. Of all surgeries, 23 (11.7%) caused RLN injury ascertained on laryngoscopy. Compared with laryngoscopy, TLUS displayed high sensitivity (97.7%; 95%CI: 94.3%-99.4%) and specificity (100%; 95% CI: 82.4%-100%). Before surgery, medical and surgical characteristics did not differ significantly between patients with or without RLN injury, but RLN entrapment by tumour was more frequent in those with the injury (P < 0.001). The risk of RLN injury was increased in patients undergoing thyroidectomy with lateral neck dissection (OR = 4.53; 95% CI: 1.29-14.32) and in those with lymph node metastases (OR = 2.76; 95% CI: 1.03-7.01).

CONCLUSION

Intraoperative RLN injury in patients with thyroid cancer is more common after operations requiringgreater resections and with lymph node involvement. TLUS could be used to diagnose RLN injury.

Effects of Central Neck Dissection on Complications in Differentiated Thyroid Cancer

Objective

It is still controversial whether performing central neck dissection (CND) in addition to total thyroidectomy (TT) increases the risk of complications. In the present study, we aimed to evaluate the effect of CND on the development of complications in differentiated thyroid cancer (DTC) compared to TT.

Material and Methods

The data of 186 patients (136 females and 50 males) with a mean age of 48.73±14.78 (range, 17-82) whom were operated for DTC were evaluated retrospectively. The patients were divided into two groups; TT (Group 1) and CND±TT/Completion thyroidectomy±lateral neck dissection (Group 2).

Results

There were 117 (91 F, 26 M) patients in Group 1 and 69 (45 F, 24 M) patients in Group 2. Parathyroid auto transplantation (PA) was significantly higher in Group 2 compared to Group 1 (42% vs. 6%) (p=0.000). Total (58% vs. 21.4%, respectively; p=0.000) and transient hypoparathyroidism (52.2% vs. 20.5%, respectively; p=0.000) were significantly higher in Group 2 than in Group 1, but permanent hypoparathyroidism rates were statistically not significant (5.8% vs. 0.9%, respectively; p=0.064). In the multinomial logistic regression analysis, CND alone was determined as an independent risk factor for increased both total and transient hypoparathyroidism. The relative risk (RR) of CND for total hypoparathyroidism was 5.2 times increased (odds ratio [OR]: 0.192) (p=0.007), while the RR for transient hypoparathyroidism was 3.5 times increased (OR: 0.285) (p=0.036). According to the number of nerves at risk, CND was performed in 119 neck side and only thyroidectomy was performed in 253 neck side. Total vocal cord paralysis (VCP) rate (9 [7.6%] vs. 6 [2.4%], respectively) (p=0.017) and transient VCP rate (7 [6%] vs. 4 [1.6%], respectively) (p=0.021) in patients who underwent CND were significantly higher compared to those who underwent only thyroidectomy. In multinomial logistic regression analysis performing only CND was an independent risk factor for total VCP, and increased the total VCP RR approximately 5.34 times (OR:0.184; p=0.007).

Conclusion

Although CND can be applied without increasing the rates of permanent hypoparathyroidism and VCP compared to TT, it increases the risk of total and transient hypoparathyroidism, total, and transient VCP. Patients undergoing CND should be followed carefully in terms of transient hypoparathyroidism.