Practice Patterns in Parathyroid Surgery: A Survey of Asia-Pacific Parathyroid Surgeons

Nerve monitoring in endocrine surgery: Practice patterns differ among surgeons for parathyroidectomy and thyroidectomy

BACKGROUND

It is unknown whether intraoperative nerve monitoring is associated with reduced vocal cord dysfunction after parathyroidectomy. We aimed to investigate intraoperative nerve monitoring use among Collaborative Endocrine Surgery Quality Improvement Program surgeons and factors associated with vocal cord dysfunction after parathyroidectomy.

METHODS

Patients who underwent parathyroidectomy included in the Collaborative Endocrine Surgery Quality Improvement Program (2014-2022) were identified. The annual percent change in parathyroidectomies performed with intraoperative nerve monitoring was calculated using joinpoint regression. Multivariable logistic regression was used to compare outcomes between patients undergoing parathyroidectomy with/without intraoperative nerve monitoring. To compare surgeon-specific trends, Collaborative Endocrine Surgery Quality Improvement Program thyroidectomy and parathyroidectomy datasets (2014-2021) were combined. Parathyroidectomies performed by surgeons who used intraoperative nerve monitoring consistently in thyroidectomy were identified. Factors associated with intraoperative nerve monitoring were examined using multivariable logistic regression.

RESULTS

A total of 9,813 patients underwent parathyroidectomy. Intraoperative nerve monitoring was used in 49% of cases (n = 4,818). There was an increase in parathyroidectomies with intraoperative nerve monitoring from 2014 to 2018 (annual percent change 22.2, P = .01), followed by a plateau (2018-2022 annual percent change -0.66, P = .85). Few patients (0.44%, n = 43) developed vocal cord dysfunction. Vocal cord dysfunction was not associated with intraoperative nerve monitoring (adjusted odds ratio 0.92, P = .75). Whereas 41% (n = 56/138) of surgeons used intraoperative nerve monitoring routinely in parathyroidectomy, 65% (n = 90/138) used it routinely in thyroidectomy. Among surgeons who used intraoperative nerve monitoring routinely in thyroidectomy, only 57% used it routinely in parathyroidectomy; factors associated with intraoperative nerve monitoring during parathyroidectomy included reoperation (adjusted odds ratio 2.51, P < .01), secondary/tertiary hyperparathyroidism (adjusted odds ratio 1.42, P = .02), multiglandular disease (adjusted odds ratio 1.76, P < .001), and non-localized disease (adjusted odds ratio 1.65, P < .001).

CONCLUSION

Endocrine surgeons use intraoperative nerve monitoring selectively. Surgeons who routinely use intraoperative nerve monitoring during thyroidectomy are more likely to use it during parathyroidectomy. Future studies should determine who may benefit most from intraoperative nerve monitoring in parathyroidectomy.

Utility of intraoperative digital scintigraphy in radioguided parathyroidectomy

BACKGROUND

Intraoperative scintigraphy (IoS) has been proposed as a tool for real-time intraoperative decision-making regarding parathyroid adenoma localization and confirmation of excision.

METHODS

Retrospective review of patients who underwent minimally invasive parathyroidectomies with scintigraphy performed intraoperatively. Preoperative neck ultrasound, 4D computed tomography, as well as intraoperative parathyroid hormone (IOPTH) and gamma probe measurements were conducted per standard practice. IoS images were obtained prior to and following parathyroid excision. Cases were reviewed to determine accuracy of IoS for localizing parathyroid pathology and confirming successful excision.

RESULTS

Fifty-six cases met the inclusion criteria. Twenty-nine patients (51.8%) showed confirmation of excision of an abnormal gland on post-excision IoS. There were no significant differences in IOPTH reduction and postoperative laboratory values between patients with IoS-identified resolution and those without IoS-identified resolution.

CONCLUSIONS

With low accuracy in correctly localizing abnormal glands and confirming their excision, there is no appreciable benefit of IoS at this time.

Three-phase four-dimensional computed tomography as a first-line investigation in primary hyperparathyroidism

INTRODUCTION

Parathyroid computed tomography using multiple phases (four-dimensional computed tomography (4DCT) for parathyroid localization was first described in 2006. Since its inception, there has been variable uptake of this technique due to inconsistency of results between institutions and perceived higher radiation dose than technetium-99 sestamibi scans (MIBI). 4DCT has been the primary imaging modality for parathyroid localization at our institution since 2013.

METHODS

A retrospective study of surgically managed patients with primary hyperparathyroidism who had preoperative localization with 4DCT from 2013-2018 was performed.

RESULTS

A total of 353 patients were included for analysis. The positive predictive value (PPV) of our three-phase 4DCT protocol was 93.3%, sensitivity (localized) 85.2% with a 5.8% false-positive rate and 13.9% false-negative (non-localizing) rate when reported by a head and neck radiologist (HNR). Calculated effective dose varied from 4.5 to 8.9mSV. On multivariable logistic regression, reporting by an experienced HNR (P < 0.001) and gland weight > 200 mg (P = 0.002) were significant for higher accuracy, lower false positives and false negatives.

CONCLUSION

A first-line three-phase 4DCT protocol for primary hyperparathyroidism is an accurate technique providing precise anatomical localization of abnormal parathyroid glands, particularly when performed by a specialist HNR. In our practise, it provides the best rate of detection and superior anatomical localization needed for minimally invasive parathyroid surgery, compared to other commonly used localization techniques. It also avoids the need for four gland exploration in the majority of patients with primary hyperparathyroidism.

Development of a Rapid Intraoperative Point-of-Care Method Using Tissue Suspension to Differentiate Parathyroid Tissue: A Possible Substitute for Frozen Sections

BACKGROUND

We reported that aspartate aminotransferase (AST)/lactate dehydrogenase (LDH) ratio of a tissue suspension can precisely differentiate normal and hyperfunctioning parathyroid tissue (PT) from other tissues. However, in these studies, LDH and AST were measured using the standard method for blood samples, with a turnaround time of approximately 1 h, hampering clinical application. Here, we developed a rapid and robust method to differentiate PT instead of using frozen sections.

METHODS

Excised specimens from 28 patients (n = 69) who underwent thyroid or parathyroid surgery between October 2019 and April 2020 were analyzed. AST and LDH were measured in suspensions of PT or other tissues, using both the standard method in the in-facility laboratory and a point-of-care testing device (NX500, Fujifilm, Japan).

RESULTS AND CONCLUSIONS

A good correlation was found between the standard method and NX500 for AST and LDH levels >10 IU/L. In the analyses using 52 specimens with ≥ 10 IU/L of both AST and LDH measured using the NX500, PT was distinguished with 100% sensitivity and specificity using an optimal cutoff AST/LDH ratio of 0.48. The turnaround time was estimated to be less than 10 min. This method could be a cost- and labor-effective alternative to frozen sections to reduce the incidence of postoperative hypoparathyroidism and improve the outcome of primary hyperparathyroidism in low-resource areas.

Measurement of the AST to LD Ratio in Parathyroid Tissue Suspension Can Precisely Differentiate a Hyperfunctioning Parathyroid

BACKGROUND

Frozen section of excised tissue is used to confirm removal of the etiology of primary hyperparathyroidism in the current era of intraoperative parathyroid hormone measurement and provides safeguards for surgeons. We recently reported that the aspartate aminotransferase (AST)/lactate dehydrogenase (LD) ratio in tissue suspension can accurately distinguish normal parathyroid tissue from other tissues. Therefore, we hypothesized that this ratio may also be applied to distinguish hyperfunctioning parathyroid tissue (HPT) from other tissues.

METHODS

We prospectively analyzed 22 patients who underwent parathyroidectomy for primary hyperparathyroidism (benign, 21; malignant, 1) from July 2018 to October 2019. In total, 27 specimens were examined. Approximately 1 mm3 of minced HPT as confirmed by frozen sections was suspended in 1 mL of normal saline and AST and LD levels were measured. The AST/LD ratios of other tissues (normal parathyroid tissue, thyroid gland, adipose tissue, and others; n = 94) were obtained from our previous report.

RESULTS

The AST/LD ratio of benign HPT was consistently higher than that of other tissues (P < 0.001). The optimal cut-off value was 0.36 according to the receiver operating characteristic curve, with 100% sensitivity and specificity. The AST/LD ratio in malignant HPT was also markedly lower than that in benign HPT.

CONCLUSION

This method might be a new adjunct for intraoperative differentiation of HPT with an accuracy and turnaround time comparable with those of frozen sections, minimal cost, and no need for dedicated pathological staff. Additionally, this method might increase the treatment success rate in settings with limited medical resources.

Main Surgical Principles and Methods in Surgical Treatment of Primary Hyperparathyroidism

The only curative treatment for primary hyperparathyroidism (pHPT) is surgery. The most important factors that increase the success rate of a parathyroidectomy are the establishment of the correct diagnosis and the surgeon's good knowledge of anatomy and embryology. The lower parathyroid glands develop from the dorsal portion of the third pharyngeal pouch, and the upper parathyroid glands from the fourth pharyngeal pouch. Humans typically have 4 parathyroid glands; however, more than 4 and fewer than 4 have been observed. Typically, the upper parathyroid glands are located in the cricothyroid junction area on the posterolateral portion of the middle and upper third of the thyroid, while the lower parathyroids are located in an area 1 cm in diameter located posterior, lateral, or anterolateral to the lower thyroid pole. Ectopic locations of parathyroid glands outside the normal anatomical regions due to the abnormal migration during embryological development or acquired ectopy due to migration of enlarged parathyroids are not uncommon. There are various surgical techniques to treat HPT; however, 2 main surgical options are used: bilateral neck exploration (BNE) and minimally invasive parathyroidectomy (MIP). While there are open, endoscopic, and video-assisted MIP (MIVAP) approaches, most often an open lateral MIP technique is used. In addition, endoscopic or robotic parathyroidectomy methods performed from remote regions outside the neck have been reported. Although currently MIP is the standard treatment option in selected patients with positive imaging, BNE remains the gold standard procedure in parathyroid surgery. In 80% to 90% of patients with pHPT, a pathological parathyroid gland can be detected with preoperative imaging methods and MIP can be applied. However, the pathological gland may not be found during a MIP procedure as a result of false positive results. The parathyroid surgeon must also know the BNE technique and be able to switch to BNE and change the surgical strategy if necessary. If the intended gland is not found in its normal anatomical site, possible embryological and acquired ectopic locations should be investigated. It should be kept in mind that MIP and BNE are not alternatives to each other, but rather complementary techniques for successful treatment in parathyroid surgery.