Association between intraoperative nerve monitoring and the duration of thyroid surgery: A tertiary care center experience

Hani Z Marzouki; Ammar Ali Alasmari; Fahad Saad Alsallum; Mohammad Alzahrani; Majed Alharbi; Faisal Zawawi; Amani Alhozali; Mazin Merdad; Shaza Samargandy

doi:10.4103/sjoh.sjoh_5_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 24 | Issue : 1 | Page : 40-43

Association between intraoperative nerve monitoring and the duration of thyroid surgery: A tertiary care center experience

Hani Z Marzouki¹, Ammar Ali Alasmari², Fahad Saad Alsallum¹, Mohammad Alzahrani¹, Majed Alharbi¹, Faisal Zawawi¹, Amani Alhozali², Mazin Merdad¹, Shaza Samargandy²
¹ Department of Otolaryngology-Head and Neck Surgery, Endocrine unit, King Abdulaziz University, Jeddah, Saudi Arabia
² Department of Medicine, Endocrine unit, King Abdulaziz University, Jeddah, Saudi Arabia

Date of Submission	23-Jan-2022
Date of Decision	17-Feb-2022
Date of Acceptance	19-Feb-2022
Date of Web Publication	30-Mar-2022

Correspondence Address:
Dr. Shaza Samargandy
Department of Internal Medicine and Endocrinology, King Abdulaziz University, Jeddah
Saudi Arabia

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sjoh.sjoh_5_22

Abstract

Background: Recurrent laryngeal nerve (RLN) injury is one of the serious complications of thyroid surgeries, which has been a topic of medicolegal concern. Although the course of the nerve can vary between patients, RLN visualization has been the gold standard method for identifying the nerve intraoperatively. However, over recent years, intraoperative nerve monitoring (IONM) has gained more acceptance and has been standardized and utilized, in addition to visual nerve identification, in many thyroids and parathyroid surgery centers. In this study, we aim to determine the association between the use of nerve integrity monitoring systems and the duration of thyroid surgery. Materials and Methods: This is a retrospective chart review, conducted at hospital in Jeddah, Saudi Arabia. We included all patients who underwent thyroid surgery during the period between 2014 and 2019, with no exclusion criteria. We studied variables including duration of surgery, preoperative assessment, diagnosis, surgical procedure, use of IONM, and comorbidities. Results: A total of 236 patients were included, of which 69 (29.2%) cases used IONM. The mean duration of all surgeries was 179.95 ± 96.9 min, whereas the mean duration of surgeries using IONM only was 214.39 min, compared to 165.72 min of surgeries without IONM, which reveals a statistically significant association between the use of nerve monitoring and an increase in the duration of surgery (P ≤0.002). Conclusion: IONM utilization in thyroid surgeries was associated with a longer duration of surgery. However, more studies are required to support this result.

Keywords: Duration of surgery, intraoperative nerve monitoring, thyroid surgery

How to cite this article:
Marzouki HZ, Alasmari AA, Alsallum FS, Alzahrani M, Alharbi M, Zawawi F, Alhozali A, Merdad M, Samargandy S. Association between intraoperative nerve monitoring and the duration of thyroid surgery: A tertiary care center experience. Saudi J Otorhinolaryngol Head Neck Surg 2022;24:40-3

How to cite this URL:
Marzouki HZ, Alasmari AA, Alsallum FS, Alzahrani M, Alharbi M, Zawawi F, Alhozali A, Merdad M, Samargandy S. Association between intraoperative nerve monitoring and the duration of thyroid surgery: A tertiary care center experience. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2022 [cited 2022 May 16];24:40-3. Available from: https://www.sjohns.org/text.asp?2022/24/1/40/341365

Introduction

Thyroidectomy is a total or partial removal of the thyroid gland tissue and can have serious complications, one of which is recurrent laryngeal nerve (RLN) injury. The RLN supplies the vocal cords to create sound through the process of phonation.^[1],[2],[3] Unilateral RLN paresis can seriously affect the quality of life, causing partial or total one-sided vocal cord paralysis, which results in noticeable voice changes and subsequent limitations in occupational, emotional, and social functioning abilities. Bilateral RLN injury, on the other hand, can result in a life-threatening total vocal cord paralysis, compromising airways.^[4] Therefore, careful dissection and identification of the nerve during neck surgery is vital to avoid such complications. Globally, permanent postoperative RLN damage is reported in nearly 3–30/1000 cases, and transient palsy in 30–80/1000 patients.^[5],[6],[7] The incidence reached as much as 14% in Switzerland, and approximately 4% in Saudi Arabia and Iraq.^[8],[9]

Although the course of the RLN can vary among patients, RLN visualization, based on surgeon experience and anatomical knowledge, has been the gold standard method for identifying the nerve intraoperatively.^{[9],[10],[11]} However, in recent years, the intraoperative nerve monitoring (IONM) system has gained more acceptance and has been standardized and utilized in many thyroids and parathyroid surgery centers, alongside visual nerve identification. IONM is an electrical stimulation technique that allows real-time identification and functional assessment of the RLN in the operative field.^[12],[13] Nevertheless, the use of this technology and its effectiveness in minimizing RLN injury and reducing surgery time has been a very controversial topic. Many studies have concluded that IONM technology in thyroid surgeries was unsuccessful in reducing the rate of RLN palsy. In one of the large prospective studies, it was found that IONM is more beneficial in revision surgeries, but it was not superior to intraoperative nerve visualization alone in protecting the nerve during primary thyroid surgery.^[14] Our aim in this study is to test the hypothesis that the use of IONM is useful in reducing operating times in thyroid surgeries.

Materials and Methods

With the approval of the Institutional Review Board, this retrospective chart review took place in June–July 2019. The operative data of all patients who underwent thyroid surgery during the period from 2014 to 2019 were collected and analyzed. To evaluate the effectiveness of the RLN monitoring system, we included the following variables in our analysis: Duration of surgery, preoperative assessment, diagnosis, surgical procedure, use of IONM, and comorbidities. All of which were obtained from the hospital information system. Given that the surgeries were performed in an academic center, all of them were performed by senior trainees alongside the attending consultant. These data were entered into Google Forms and statistically analyzed by IBM SPSS Statistics for Windows (Version 21.0). For descriptive statistics, continuous variables were summarized using means and associated standard deviations and compared using Student's t-test. While categorical variables were presented using numbers and associated frequencies. They were compared utilizing Chi-square test. P < 0.05 was deemed significant.

This study protocol was reviewed and approved by the ethics committee, approval number.

Results

Demographics

We reviewed the medical records of 236 patients: 82.2% were females, the mean patient age was 42.15 ± 12.9 years. Among the patients reviewed, 42.4% were diagnosed with malignant neoplasms, 21.2% had benign neoplasms, and 17.8% had a multinodular goiter. Intraoperative nerve monitoring was used in 69 surgeries, 49 total thyroidectomies, 12 hemithyroidectomies, and 8 revision surgeries.

Primary results

The mean duration of operations without IONM was 165.72 ± 86.5 min, while with IONM used alone was 214.39 ± 111.72 min, revealing a statistically significant association between using the nerve monitoring technique and an increase (P ≤ 0.002), rather than a decrease, in the mean duration of surgery [Table 1].

Table 1: Baseline characteristics of the study sample and association between using the nerve monitoring technique and the mean duration of surgery

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Secondary results

In terms of diagnosis, most cases in which IONM was used were thyroid malignant (42.4%) (P ≤ 0.025). Moreover, the diagnosis had a considerable impact on operative duration (P ≤ 0.013). In addition, among all types of surgical interventions, nerve integrity assessment was used more in revision surgeries (P ≤ 0.009). In preoperative assessment, neck enlargement (57.2%) was the most frequent clinical manifestation (P ≤ 0.01), followed by compressive symptoms (19.9%) and preexisting voice changes (5.9%), with P > 0.05. As for coexisting morbidities, hypertension (12.7%) and diabetes (11.4%) were insignificantly associated with the use of nerve stimulation in thyroid surgeries. However, alongside other chronic disorders such as renal and bone diseases, they contribute to longer surgical durations (P ≤ 0.034). As for the length of hospitalization (P >.05) and size of foci (P > 0.05), both showed no significant correlation with the use of the neural monitoring device [Table 2].

Table 2: Association between operative duration and the underlying diagnosis

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Discussion

In this study, we found a significant increase in the duration of surgery when using nerve stimulating technology. This is similar to a randomized controlled trial (RCT) by Barczyński et al., which showed comparable results, whereas a study conducted in Los Angeles, USA, showed no significant relation with duration.^[15] We believe the reason for the prolonged operating times is that the IONM system is more frequently used in complicated and challenging cases rather than usual ones, such as thyroid cancer cases, which may well affect the time spent on preoperative preparation and postoperative wound closure. The presence of debilitating morbidities should also be noted as they could extend the surgical duration, even though their observed effects in this study were statistically insignificant.

Regarding diagnosis, malignant neoplasms were linked strongly with the use of nerve integrity monitoring systems. Contrary to our results, in the abovementioned RCT, nontoxic nodular goiter was the diagnosis most significantly associated with IONM, probably because the study had a larger sample size than ours.^[15] Furthermore, revision surgeries have a greater association with the use of nerve stimulation than total and hemithyroidectomies. That finding is consistent with a study conducted at Massachusetts Eye and Ear Infirmary, USA. In contrast, a couple of studies highlighted a marked connection between total thyroidectomy and the nerve stimulation system.^{[15],[16],[17]} We assume that this outcome might be influenced by our hospitals' cost-effective policy, which prefers that nerve stimulation technology be used in complex rather than simple situations.

Unexpectedly, we found no differences in the number of hospitalization days between IONM-assisted and non-IONM-assisted groups. This was contrary to what we anticipated; that is, the more complicated the case, the more likely the hospital stay to be longer. Moreover, the size of thyroid foci showed no correlation with the nerve monitoring system. We did not find any relevant studies discussing these correlations.

In terms of preoperative assessment, neck mass was the most common documented manifestation, and it was strongly correlated with the utilization of nerve integrity monitoring, followed by compressive symptoms and preexisting voice changes. These findings are comparable with a study done in the University of Halle-Wittenberg, Germany, which revealed dyspnea and cervical compression, then hoarseness as the most reported clinical presentations.^[18] Our results could be explained by the fact that patients mostly appear late to our tertiary care center and do not receive early assessment before the development of symptoms, also because they do not undergo routine checkups. In addition, chronic diseases, such as hypertension or diabetes, revealed insignificant associations with the use of IONM. On the other hand, patients without comorbidities had a similar association with the use of IONM; however, they had significantly shorter surgery durations. These findings are consistent with data documented in an article from China, which noted that chronic comorbidities are utterly irrelevant to nerve monitoring utility.^[19] A possible explanation for this might be that thyroid surgeries are not considered urgent and critical procedures, and therefore, chronic diseases should have no uncontainable effect. Our limitations included the limited number of cases using the IONM instrument due to its recent introduction into our hospital.

Conclusion

Our main results showed that operating times increase when surgeons use nerve stimulation technology to identify the RLN compared to relying on visual recognition only. However, more studies regarding neural integrity systems are required to support this result. We suggest more studies with larger sample sizes and longer study periods, preferably with a prospective design.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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