Contemporary parathyroidectomy: exploiting technology

A multi-institutional study evaluating and describing atypical parathyroid tumors discovered after parathyroidectomy

Objective

To describe common intraoperative and pathologic findings of atypical parathyroid tumors (APTs) and evaluate clinical outcomes in patients undergoing parathyroidectomy.

Methods

In this multi-institutional retrospective case series, data were collected from patients who underwent parathyroidectomy from 2000 to 2018 from three tertiary care institutions. APTs were defined according to the AJCC eighth edition guidelines and retrospective chart review was performed to evaluate the incidence of recurrent laryngeal nerve injury, recurrence of disease, and disease-specific mortality.

Results

Twenty-eight patients were identified with a histopathologic diagnosis of atypical tumor. Mean age was 56 years (range, 23-83) and 68% (19/28) were female. All patients had an initial diagnosis of primary hyperparathyroidism with 21% (6/28) exhibiting clinical loss of bone density and 32% (9/28) presenting with nephrolithiasis or renal dysfunction. Intraoperatively, 29% (8/28) required thyroid lobectomy, 29% (8/28) had gross adherence to adjacent structures and 46% (13/28) had RLN adherence. The most common pathologic finding was fibrosis 46% (13/28). Postoperative complications include RLN paresis/paralysis in 14% (4/28) and hungry bone syndrome in 7% (2/28). No patients with a diagnosis of atypical tumor developed recurrent disease, however there was one patient that had persistent disease and hypercalcemia that is being observed. There were 96% (27/28) patients alive at last follow-up, with one death unrelated to disease.

Conclusion

Despite the new AJCC categorization of atypical tumors staged as Tis, we observed no recurrence of disease after resection and no disease-specific mortality. However, patients with atypical tumors may be at increased risk for recurrent laryngeal nerve injury and incomplete resection.

Improving Intraoperative Parathyroid Hormone Lab Efficiency

BACKGROUND

Intraoperative parathyroid hormone (iPTH) testing is often used to confirm successful removal of hypersecreting parathyroid glands during parathyroidectomy. Unfortunately, the iPTH test can be a time-consuming and highly variable process that occurs while the patient is under anesthesia. We set out to improve iPTH lab efficiency and variability.

METHODS

We performed a retrospective review of 85 patients who underwent parathyroidectomy at our institution from October 2017 to October 2019. Each step of the iPTH lab reporting process was recorded and analyzed. Three simulations were performed of the entire process. We then established interventions to modify inefficiencies in the process and studied 21 patients who underwent parathyroidectomy at our institution from November 2019 to March 2020.

RESULTS

Twenty-five minutes of time inherent to the process were identified. Four critical steps were identified as modifiable steps in the process:1. Operating room (OR) blood draw ---> lab receipt.2. Lab receipt ---> placement on centrifuge.3. Removal from centrifuge ---> placement on PTH machine.4. PTH machine result ---> OR verbal report.We improved iPTH lab efficiency by 19%, decreasing the average lab result from 45 to 36 minutes (P = .001). We improved iPTH lab variability by 62%, decreasing the standard deviation from 21 to 8 minutes (P = .001).

DISCUSSION

Utilizing a team-based approach to identify and expedite critical steps in the iPTH lab process can make a significant improvement in iPTH lab efficiency, improving patient care by decreasing total anesthesia time.

Management protocol for primary hyperparathyroidism in a single institution: utility of surgeon performed ultrasound

Background

We aimed to: (I) discover preoperative diagnostic studies, intraoperative techniques, and patient factors most predictive of cure within a single hospital system; (II) establish practice guidelines for surgical treatment of primary hyperparathyroidism to maximize outcomes based on this hospital system's performance.

Methods

A retrospective chart review was undertaken of all parathyroid-related procedures from 01/01/02 to 7/31/15 at the Veteran's Administration Hospital.

Results

Seventy-one patients were eligible and charts available for analysis. Preoperative studies most predictive of cure were a combination of sestamibi parathyroid scan and surgeon performed ultrasound (S-US). When studies did not agree, S-US was most often correct. Intraoperative parathyroid hormone (PTH) rapid assay was helpful in predicting cure, but added an average of 33 minutes to operating room time. Patients who had two corroborating preoperative localizing studies, one of which was S-US, that agreed with intraoperative findings, and who did not undergo intraoperative PTH confirmation enjoyed equal cure rates and shorter operating room times. Successful achievement of normal calcium was high at 95.8%. Vitamin D deficiency was prevalent in this patient population, prompting more aggressive preoperative investigation and replacement.

Conclusions

A management protocol was developed based on the findings of this study: (I) obtain two preoperative localization studies, one of which is surgeon-performed ultrasound; (II) obtain preoperative vitamin D levels and supplement as indicated; and (III) in select patients who have two strongly corroborating preoperative localization studies, one of which is surgeon performed ultrasound, and intraoperative findings are consistent with the localizing studies, intraoperative PTH (IOPTH) may not be necessary.

Preoperative 4D CT Localization of Nonlocalizing Parathyroid Adenomas by Ultrasound and SPECT-CT

Objective

To evaluate 4-dimensional (4D) computed tomography (CT) for the localization of parathyroid adenomas previously considered nonlocalizing on ultrasound and single-photon emission CT with CT scanning (SPECT-CT). To measure radiation exposure associated with 4D-CT and compared it with SPECT-CT.

Study Design

Case series with chart review.

Setting

University tertiary hospital.

Subjects and Methods

Nineteen adults with primary hyperparathyroidism who underwent preoperative 4D CT from November 2013 through July 2014 after nonlocalizing preoperative ultrasound and technetium-99m SPECT-CT scans. Sensitivity, specificity, predictive values, and accuracy of 4D CT were evaluated.

Results

Nineteen patients (16 women and 3 men) were included with a mean age of 66 years (range, 39-80 years). Mean preoperative parathyroid hormone level was 108.5 pg/mL (range, 59.3-220.9 pg/mL), and mean weight of the excised gland was 350 mg (range, 83-797 mg). 4D CT sensitivity and specificity for localization to the patient’s correct side of the neck were 84.2% and 81.8%, respectively; accuracy was 82.9%. The sensitivity for localizing adenomas to the correct quadrant was 76.5% and 91.5%, respectively; accuracy was 88.2%. 4D CT radiation exposure was significantly less than the radiation associated with SPECT-CT (13.8 vs 18.4 mSv, P = 0.04).

Conclusion

4D CT localizes parathyroid adenomas with relatively high sensitivity and specificity and allows for the localization of some adenomas not observed on other sestamibi-based scans. 4D CT was also associated with less radiation exposure when compared with SPECT-CT based on our study protocol. 4D CT may be considered as first- or second-line imaging for localizing parathyroid adenomas in the setting of primary hyperparathyroidism.

Surgical management of primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a common endocrine disorder in which the inappropriate elevation in serum parathyroid hormone level results in hypercalcemia. Most cases are caused by a single adenomatous parathyroid gland and less than 15% are caused by multiglandular disease. The incidence of PHPT appears to be increasing. More patients are being identified earlier and often before symptoms develop. Parathyroidectomy is the only definitive management; with it, the patient can achieve biochemical homeostasis and symptom relief, and sequelae are prevented. Even for asymptomatic patients with PHPT, there is a growing trend to recommend early surgical intervention. Controversy continues regarding the role of and reliance on various technologies, such as preoperative localization imaging, intraoperative parathyroid hormone level measurements, and minimally invasive surgery. Although both traditional bilateral 4-gland exploration and targeted approaches are accepted surgical techniques, there is a growing trend in unilateral targeted operations often using these technologies. Regardless of surgical approach, the expected success rate is greater than 95%. This article provides an overview of the contemporary surgical management of PHPT.

Parathyroidectomies Using Intraoperative Parathormone Monitoring: When Should We Stop Measuring Intraoperative Parathormone Levels?

Intraoperative parathyroid hormone monitoring (IOPM), in use for the last 15 years, has facilitated focused parathyroidectomy. We undertook this study to determine if a drop in IOPT hormone levels below 50 per cent of baseline were sufficient to terminate the procedure. We conducted a retrospective chart review (January 2007 to September 2010) of 104 patients who underwent initial parathyroidectomies with IOPM by general surgeons for primary hyperparathyroidism. Patients were followed up for serum calcium levels (range, 6 to 48 months). The number of specimens excised was significantly decreased when IOPT hormone levels dropped to greater than 50 per cent and came within the normal range earlier. Moreover, for single-gland parathyroid adenomas, once the parathyroid hormone values dropped to less than 50 per cent in the 5-minute sample, they continued to decrease in the subsequent samples. In 23 cases requiring further exploration, the parathyroid hormone values had already decreased to greater than 50 per cent in 14 cases but had not normalized (reference range, 8 to 74), leading to additional exploration. However, subsequent pathologic analysis showed that the initial gland removed was the adenoma in all these cases. A drop in the initial 5-minute parathyroid hormone value to less than 50 per cent of the baseline should serve as sufficient evidence to terminate the procedure. This would translate into significant laboratory and personnel cost savings over time. However, this should be carefully correlated with preoperative ultrasound/sestamibi findings.

Imaging techniques in parathyroid surgery for primary hyperparathyroidism

As more patients present with the incidental diagnosis of primary hyperparathyroidism due to biochemical screening, treatment guidelines have been developed for the treatment of hyperparathyroidism. Management of primary hyperparathyroidism has evolved in recent years, with considerable interest in minimally invasive approaches. Successful localization of the diseased gland(s) by nuclear imaging and anatomical studies, along with rapid intraoperative parathyroid hormone assay, has allowed for focused and minimally invasive surgical approaches. Patients in whom the localization studies have identified single-gland adenoma or unilateral disease are candidates for such focused approaches instead of the traditional approach of bilateral exploration. These imaging techniques have also been critical in the successful management of patients with persistent or recurrent disease.

Point-of-care rapid intraoperative parathyroid hormone assay of needle aspirates from parathyroid tissue: a substitute for frozen sections

BACKGROUND

The intraoperative parathyroid hormone (IOPTH) assay is an important tool that facilitates targeted parathyroidectomy and may increase surgical cure rates. We sought to evaluate the utility of a point-of-care assay to distinguish parathyroid adenomas from nonparathyroid tissues, which can sometimes pose a challenge during parathyroidectomy and is commonly achieved with the use of frozen sections. We hypothesized that point-of-care rapid IOPTH assays of needle aspirates from suspected adenomas would be faster and equal in accuracy to frozen sections.

METHODS

Parathyroid and nonparathyroid lesions were excised, and the tissues were needle aspirated, diluted in saline, and submitted to a rapid IOPTH assay located in the operating room. Frozen sections were simultaneously sent for analysis. The time intervals to result availability were tracked and compared using a paired t test.

RESULTS

Point-of-care IOPTH assays of needle aspirates were available in a mean (±SD) of 11.6 ± 1.5 minutes compared to 18.7 ± 4.0 minutes for frozen sections (P = .005). The findings were concordant 100% of the time for both parathyroid (mean parathyroid hormone [PTH] > 3338.9 pg/mL) and parathyroid tissues (mean PTH = 8.7 pg/mL).

CONCLUSION

Point-of-care IOPTH assay of needle aspirates is an accurate method of distinguishing parathyroid from nonparathyroid tissues. It is suggested that this would be particularly useful in instances where use of IOPTH is planned for assessment of a drop in serum PTH.

Restoring Point-of-Care Testing during Parathyroidectomy with a Newer Parathyroid Hormone Assay

Objective. Intraoperative parathyroid hormone (IOPTH) monitoring has emerged as a useful adjunct in parathyroidectomy. Originally performed within the operating room, removal of the Nichols assay from the market forced many surgeons to rely on testing done in central laboratories, reducing convenience and prolonging operative times. The authors hypothesized that PTH assessment with a newer point-of-care (POC) assay would reduce results reporting time compared with central-laboratory PTH assays.

Study Design. Cross-sectional study with planned data collection.

Setting. Academic medical center.

Subjects and Methods. Patients underwent parathyroidectomy for primary or recurrent hyperparathyroidism. Intraoperative monitoring of serum PTH levels was used to confirm biochemical cure following adenoma excision. Samples were run in duplicate using both a POC PTH assay (Future Diagnostics) located within the operating room and a laboratory-based assay (Turbo PTH). Samples were taken at incision and at 5-, 10-, and 15-minute intervals following removal of suspected parathyroid adenomas. Results reporting time was recorded and compared by nonparametric Wilcoxon rank sum test.

Results. Sixty-six serum samples were assayed. There was excellent correlation between POC and central-laboratory IOPTH results ( r = 0.880, P < .001). The POC IOPTH results were available faster than corresponding central-laboratory results, with a mean of 14.4 minutes compared with 30.7 minutes, respectively ( P < .001). All patients (100%) demonstrated a biochemical cure by the end of the procedure.

Conclusion. Use of a rapid POC IOPTH assay results in a significant decrease in the amount of time for laboratory results to be communicated to the surgical team. This reduces operative times for parathyroidectomy and improves patient care.

Intraoperative adjuncts for parathyroid surgery

In recent years, parathyroid surgery has evolved from traditional bilateral neck exploration to minimal invasive parathyroidectomy. This trend became possible due to preoperative localization imaging that guides the surgeon in the search for a parathyroid adenoma. Intraoperative adjuncts are complementary to preoperative localization and assist in localizing parathyroid glands, confirming parathyroid tissue and establishing a cure. Institutions and surgeons utilize different intraoperative adjuncts in different protocols with varying results. The purpose of this article is to review the available intraoperative adjuncts to parathyroid surgery and critically evaluate their utility, accuracy and their added value to the surgeon.

Current concepts in the management of primary hyperparathyroidism

Primary hyperparathyroidism is the commonest cause of hypercalcemia in the ambulatory setting. Widespread use of routine laboratory screening has resulted in a large number of patients presenting with subclinical disease. In truly asymptomatic patients, consensus guidelines have been developed to determine which patients need definitive treatment. The most common pathologic finding is parathyroid adenoma, followed by hyperplasia, double adenomas and parathyroid carcinoma. The mainstay of treatment is surgery. While there is still an important role for four gland exploration and evaluation, there is now considerable interest in a more focused surgical approach. This paradigm shift is based on localizing studies that combine sestamibi scanning with anatomic imaging, most commonly ultrasound scanning. A range of minimally invasive approaches have been developed to treat parathyroid adenomas, including unilateral and single gland explorations as well as a number of different endoscopic techniques. Intra-operative rapid parathormone assay has replaced histologic examination as a more effective method to confirm the adequacy of surgery in most cases. Functional localization and exploration using a gamma probe has also been described. The management of patients with persistent or recurrent hyperparathyroidism is difficult and requires a multidisciplinary approach.

Endoscopic parathyroidectomy in primary hyperparathyroidism

During the past decade, endoscopic video-assisted parathyroidectomy (EP) for primary hyper parathyroidism (PHPT) has gained wider acceptance. The endoscopic gasless procedure described by P. Miccoli (1997-1998) offers an attractive technique. A routine preoperative localization study was performed with both ultrasonography and 99m TC-Sestamibi scintigraphy for each patient with sporadic PHPT. The criteria to select patients eligible for EP included absence of significant nodular goiter, a previous neck surgery, a need for concomitant thyroidectomy, a significant obesity, and multiple enlarged parathyroid glands. The surgical outcome and the use of preoperative localization together with the operative strategy were evaluated. From 2005 to 2009, 59 out of 75 patients (78%) were potentially candidates for this approach. An enlarged parathyroid gland was located by both types of imaging for 34 patients (57%) and by 99 m Tc-Sestamibi scintigraphy for 46 patients (77%). Conversion was required in 11 cases (18%). Nine patients had a negative preoperative imaging study and five underwent a successful EP. The operating time ranged from 35 to 120 min (median 45 min). Usually patients were discharged home at 48 h. There were no cases of permanent hypocalcemia or recurrent laryngeal nerve palsy. Postoperative review showed that all calcium and parathyroid hormone levels remained normal at 3 months except for 1 patient with a double adenoma. EP is a quick, safe, and effective procedure in a selected group of patients. Our results show that this technique can be easily introduced into a general head and neck practice.

Pre-operative parathyroid localisation: surgical review of sesta-methoxyisobutylisonitrile images is important

OBJECTIVE

To highlight the importance of pre-operative review of sesta-methoxyisobutylisonitrile imaging before parathyroid surgery.

CASE REPORT

Technetium-99 m sesta-methoxyisobutylisonitrile scanning is a well established imaging modality undertaken to locate the parathyroid glands prior to parathyroidectomy. Because of the relative lack of detail in the images obtained, the radiological report is normally the most important piece of information used by the surgeon for surgical planning. We report a case that illustrates the importance of surgical image review prior to revision parathyroid surgery. We also present a review of literature highlighting the need for surgical review of such imaging.

CONCLUSION

We propose that surgeons routinely review sesta-methoxyisobutylisonitrile images pre-operatively.

Nuclear imaging and minimally invasive surgery in the management of hyperparathyroidism

Primary hyperparathyroidism is the most common cause of hypercalcemia, and the treatment is primarily surgical. Because of biochemical screening, more patients now present with asymptomatic primary hyperparathyroidism, and consensus guidelines have been developed for the treatment of these patients. There is now considerable interest in minimally invasive approaches to the treatment of hyperparathyroidism. Sestamibi scanning as a localizing study, used in combination with anatomic imaging and intraoperative rapid parathyroid hormone assays, has enabled focused surgical approaches. Patients with localizing studies that indicate a single parathyroid adenoma are candidates for such approaches, including unilateral neck exploration, minimally invasive single-gland exploration, or endoscopic exploration instead of the traditional approach of bilateral neck exploration. Nuclear imaging is also critical to the successful management of patients with persistent or recurrent hyperparathyroidism.