Location, number and morphology of parathyroid glands: results from a large anatomical series

Factors affecting the rates of incidental parathyroidectomy during thyroidectomy

BACKGROUND

The most important factors affecting the development of postoperative hypocalcaemia (PH) include intraoperative trauma to the parathyroid glands, incidental parathyroidectomy (IP), and the surgeon's experience. In this study, we aimed to determine the incidence of IP, evaluate its effect on postoperative calcium levels and investigate the effect of surgeon experience and volume on IP incidence and postoperative calcium levels.

METHODS

This retrospective study included 645 patients who underwent thyroid surgery at the Department of General Surgery, Kütahya Health Sciences University between September 2016 and March 2020. All patients underwent surgery at a single clinic by general surgeons experienced in thyroid surgery and their residents (3-5 years).

RESULTS

Normal parathyroid glands were reported in 58 (8.9%) of 645 patients. In 5 (8.6%) of 58 patients the parathyroid gland was detected in the intrathyroidal region. PH developed in ten patients (17.2%) with incidental removal of the parathyroid glands. A statistically significant difference was found between the number of incidentally removed parathyroid glands and the development of hypocalcaemia (p<0.05). Normal parathyroid glands were reported in the pathology of 37 (7.9%) patients operated on by general surgeons and 22 (12.6%) patients operated on by their residents. PH developed in 39 (8.2%) patients operated on by general surgeons and in 8 (4.5%) patients operated on by their residents.

CONCLUSIONS

We found that the complication rate during the resident training process was the same as that of experienced general surgeons. A thyroidectomy can be safely performed by senior residents during residential training.

The value of ultrasound in combination with 99mTc-MIBI imaging department of ultrasound medicine, for the diagnosis of ectopic parathyroid glands in the thyroid gland in patients with secondary hyperparathyroidism

To investigate the value of preoperative ultrasound combined with 99mTc-MIBI imaging for the diagnosis of ectopic intrathyroid parathyroid gland (ETPG) in patients with secondary hyperparathyroidism (SHPT). One hundred and eleven patients with SHPT who underwent total parathyroidectomy plus forearm transplantation from January 2015 to January 2022 in the Third Hospital of Hebei Medical University were selected. All patients underwent routine preoperative ultrasonography and 99mTc-MIBI imaging, and with pathological diagnosis as the gold standard, the clinical data of ETPG patients were selected, including clinical manifestations, laboratory tests, preoperative ultrasonography and 99mTc-MIBI imaging for localization and diagnosis, intraoperative exploration and postoperative pathology, and postoperative follow-up. To analyze the ultrasound manifestations of preoperative parathyroid hyperplasia and the results of 99mTc-MIBI imaging in patients with ETPG. Among 111 patients with SHPT, there were 5 patients with ETPG, 1 male and 4 females with a mean age of (45.00 ± 5.05) years, and 6 ectopic parathyroid glands were located in the thyroid gland. The incidence of ETPG was 4.5% (5/111), 4 were detected by ultrasound, 2 were not detected with a diagnostic accuracy of 66.7% (4/6), 3 were positive for 99mTc-MIBI imaging, 3 were negative with a diagnostic accuracy of 50.0% (3/6). Among them, one was not detected by ultrasound, but was positive for 99mTc-MIBI imaging, 2 with negative 99mTc-MIBI imaging, but all were detected by ultrasound, and one with negative 99mTc-MIBI imaging was detected by ultrasound but misdiagnosed as a thyroid nodule. A total of 5 ETPGs were detected by ultrasound combined with 99mTc-MIBI imaging, with a diagnostic accuracy of 83.3% (5/6). Patients' postoperative serum calcium and serum parathyroid hormone (PTH) levels were normalized or significantly decreased from preoperative levels. Ultrasound combined with 99mTc-MIBI imaging can achieve higher accuracy than either examination alone in the preoperative localization and diagnosis of ETPG in SHPT patients.

Outcomes of subtotal parathyroidectomy for renal hyperparathyroidism

BACKGROUND

Renal hyperparathyroidism due to end-stage kidney disease is associated with considerable morbidity, and when refractory is treated with parathyroidectomy. Recurrent renal hyperparathyroidism is a major surgical complication, yet initial target parathyroid remnant size and outcomes, including rates of recurrence are not well elucidated.

METHODS

This is a single-institution retrospective cohort study of patients who underwent initial subtotal parathyroidectomy for renal hyperparathyroidism on dialysis, from 1990-2022. The subtotal parathyroidectomy was defined as resection of 3 parathyroid glands ± partial resection of the fourth gland leaving a remnant of ∼75-100 mg, and postresection intraoperative parathyroid hormone goal was 150-250 pg/mL. Clinical data were examined for outcomes.

RESULTS

Among 204 patients who met inclusion criteria, 139 (68%) had follow-up data; 58% (80/139) were women and median age was 45 years. Surgical complications included 2 hematomas (1.4%), 1 recurrent laryngeal nerve injury (<1%), and no patient required readmission for intravenous calcium. Using a target remnant size of 75-100 mg, recurrent renal hyperparathyroidism was uncommon (14/139, 10%) and arose at a median interval of 58.6 months (range, 8-180). In cases of recurrence, the postresection intraoperative parathyroid hormone level was less likely to drop <250 pg/mL (40%, 4/10 vs nonrecurrence 65%, 80/123; P = .11) with a slightly lower median decrease (70% vs 81% in nonrecurrence, P = .8); however, neither were significant. Recurrence did not occur in the 19 patients who later received kidney transplantation (P = .2).

CONCLUSION

In subtotal parathyroidectomy for renal hyperparathyroidism, use of a target 75-100 mg remnant size results in low complication rates. Durable cure appears to be more likely with renal transplantation.

Low serum iPTH at the end of surgery is the earliest predictor of postoperative hypocalcemia after total thyroidectomy

BACKGROUND

The most frequent complication of total thyroidectomy remains hypocalcemia due to low postoperative levels of serum intact parathyroid hormone (iPTH). The purpose of this study was to investigate the role of decreased iPTH at the end of surgery in predicting hypocalcemia. In addition, we examined the percentage decrease of iPTH as potential indicator of hypocalcemia.

METHODS

We retrospectively collected the data of patients who underwent total thyroidectomy for benign and malignant diseases at our institution between 2010 and 2022. The iPTH level was measured before and at the end of surgery, and serum calcium levels on the first postoperative day. Demographic, clinical, and biochemical characteristics of patients with low iPTH were compared with patients with normal iPTH levels using ANOVA for continuous variables and χ2-tests for categorical variables. Multivariable logistic regression analysis evaluated the association of iPTH at the end of surgery and the relative reduction of iPTH with postoperative hypocalcemia.

RESULTS

The mean age of the 607 patients in this study was 55.6 years, and the female-to-male ratio was 5:1. Goiter was the most common indication for surgery (N = 382, 62.9%), followed by Graves' disease (N = 135, 22.2%). The mean preoperative iPTH was 49.0 pg/ml, while the mean postoperative iPTH was 29.3 pg/ml. A total of 197 patients (32.5%) had an iPTH level below normal, 77 patients (39%), had iPTH levels of 10-15.0 pg/ml and 120 patients (61%) of < 10.0 pg/ml at the end of surgery. Among all patients, 124 (20.4%) developed hypocalcemia on the first postoperative day. The mean percentage of decrease of iPTH was highest among patients with iPTH < 10 pg/ml (76.9%, p < 0.01); this group of patients had also the highest rate of postoperative hypocalcemia on day one (45.0% vs. 26.0% vs 12.2%, p < 0.01).

CONCLUSIONS

Measurement of iPTH at the end of total thyroidectomy predicts patients who are at risk for postoperative hypocalcemia. The combination of low serum iPTH with a decrease in iPTH level of ≥ 50% may improve prediction of hypocalcemia compared to iPTH levels alone allowing for early calcium substitution in these patients at high risk of developing postoperative hypocalcemia.

Efficacy of parathyroid autotransplantation in endoscopic total thyroidectomy with CLND

Purpose

To evaluate the safety and efficacy of autologous parathyroid transplantation in laparoscopic total thyroidectomy combined with central lymph node dissection (CLND).

Methods

Retrospective analysis of clinical data of 152 patients admitted to the General Surgery Department of Gansu Provincial People's Hospital who underwent endoscopic total thyroidectomy combined with CLND from June 2018 to December 2021. The intraoperative parathyroid glands were divided into the orthotopic preservation group (non-transplantation group) and the immediate active autologous transplantation group (transplantation group) according to the different treatment management of parathyroid glands during operation. The levels of Ca2+ in parathyroid blood and the incidence of hypoparathyroidism were compared between the two groups before operation and 1 day, 3 day, 1 week, 1 month, 3 months and 6 months after operation.

Results

There was no significant difference in PTH between the preoperative transplantation group compared and the non-transplantation group (P>0.05); The PTH in the transplantation group was lower than that of the non-transplantation group 1 and 3 d after surgery, and the difference was statistically significant (P<0.05); No statistically significant difference in PTH between patients in the transplantation group compared with those in the non-transplantation group at 1 week postoperatively (P>0.05); PTH was significantly higher in the transplant group than in the non-transplant group at 1, 3 and 6 months after surgery, with statistically significant differences (P<0.05); there was no statistically differences (P>0.05) in serum Ca2+ between the preoperative, 1d, 3d and 1 week postoperative transplantation group and the non-transplantation group; Blood Ca2+ was significantly higher in the transplant group than in the non-transplant group at 1, 3 and 6 months after surgery, with statistically significant differences (P<0.05); The rate of temporary hypoparathyroidism in the transplantion group was higher than that in the non-transplantion group, and the rate of permanent hypoparathyroidism was lower than that in the non-transplantion group (P=0.044); There was no significant difference in the concentration of PTH in the cephalic vein of the elbow between the transplanted side and the non-transplanted side at 1 day and 3 days postoperatively (P>0.05); the concentration of PTH in cephalic vein of the elbow was significantly higher than that in non-transplanted side at 1 week, 1 month, 3 months and 6 months postoperatively (P<0.001); the number central area dissection and metastasis dissection in the transplantation group were significantly higher than those in the non-transplantation group (P<0.05).

Conclusions

Most autologous parathyroid glands, having functional parathyroid autograft, is helpful to the occurrence of hypoparathyroidism after endoscopic total thyroidectomy with CLND, and it is an effective strategy to prevent permanent hypoparathyroidism, and more thorough area dissection is beneficial to the disease prognosis.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Comparative Effectiveness of MRI, 4D-CT and Ultrasonography in Patients with Secondary Hyperparathyroidism

Objective

Accurate preoperative localization of abnormal parathyroid glands is crucial for successful surgical management of secondary hyperparathyroidism (SHPT). This study was conducted to compare the effectiveness of preoperative MRI, 4D-CT, and ultrasonography (US) in localizing parathyroid lesions in patients with SHPT.

Methods

We performed a retrospective review of prospectively collected data from a tertiary-care hospital and identified 52 patients who received preoperative MRI and/or 4D-CT and/or US and/or ^99mTc-MIBI and subsequently underwent surgery for SHPT between May 2013 and March 2020. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of each imaging modality to accurately detect enlarged parathyroid glands were determined using histopathology as the criterion standard with confirmation using the postoperative biochemical response.

Results

A total of 198 lesions were identified intraoperatively among the 52 patients included in this investigation. MRI outperformed 4D-CT and US in terms of sensitivity (P < 0.01), specificity (P = 0.455), PPV (P = 0.753), and NPV (P = 0.185). The sensitivity and specificity for MRI, 4D-CT, and US were 90.91%, 88.95%, and 66.23% and 58.33%, 63.64%, and 50.00%, respectively. The PPV of combined MRI and 4D-CT (96.52%) was the highest among the combined 2 modalities. The smallest diameter of the parathyroid gland precisely localized by MRI was 8×3 mm, 5×5 mm by 4D-CT, and 5×3 mm by US.

Conclusion

MRI has superior diagnostic performance compared with other modalities as a first-line imaging study for patients undergoing renal hyperparathyroidism, especially for ectopic or small parathyroid lesions. We suggest performing US first for diagnosis and then MRI to make a precise localization, and MRI proved to be very helpful in achieving a high success rate in the surgical treatment of renal hyperparathyroidism in our own experience.

Correlation between preoperative calcium and parathormone levels with parathyroid gland volume

Objective. Hyperparathyroidism is a prevalent disease with parathyroid adenomas being the most common cause. Surgical excision remains the standard treatment for parathyroid adenoma. Successful preoperative localization of the parathyroid adenoma could facilitate the decision regarding the extent of surgical exploration. The aim of the current study was to assess the correlation between the preoperative values of parathyroid hormone and ionized calcium with the adenoma weight and volume in patient with primary hyperparathyroidism caused by single-gland adenoma. Patients and Methods. We did this retrospective review for all patients who were diagnosed with primary hyperparathyroidism due to a solitary parathyroid adenoma in our general surgery department over 4 years. SPSS software was used to get the correlation coefficient between the peak preoperative levels of calcium and parathyroid hormone with the parathyroid adenoma weight and volume. Results. Ninety-nine patients were included into the study. The average age at surgery was 62.65±12.00 years. The correlation coefficient between the adenoma volume and weight with the preoperative ionized calcium level was weakly positive (r=0.329, p<0.01) and (r=0.281, p=0.019), respectively, while the correlation with the preoperative parathyroid hormone level was stronger (r=0.708, p<0.01) and (r=0.650, p<0.01), respectively. Conclusions. The strong positive relationship between the preoperative parathyroid hormone and calcium levels with the parathyroid adenoma size and weight can help the surgeon to predict the volume of the involved gland and avoid an unnecessary dissection.

A case of normocalcemic primary hyperparathyroidism presenting with a mass in the oral cavity and accompanying incidental papillary thyroid carcinoma

Hyperparathyroidism (HPT) is an endocrine disorder characterized by high secretion of parathyroid hormone. Brown tumor is one of the skeletal manifestations of HPT. Its overall prevalence is low (about 0.1%). Involvement of facial bones is extremely rare. The mandible is involved in 4.5% of cases. Primary HPT (PHPT)with vitamin D deficiency worsens the clinical course. Parathyroid adenoma is detected in ectopic places with a rate of 8.5%. 0.2% is intrathyroidal, 2% is located in different neck regions, 4.1% is in the upper mediastinum, and 2.2% is in the lower mediastinum. The prevalence of papillary thyroid cancer (PTC) in PHPT patients has been reported to range from 2% to 15%. In the literature, incidentally detected papillary thyroid cancer in patients with hyperparathyroidism was detected in patients who underwent total thyroidectomy associated with intrathyroidal parathyroid adenoma. In this article, we present a case of incidental papillary thyroid carcinoma with ectopic parathyroid adenoma accompanied by severe vitamin D, and diagnosed during accompanying surgery following a brown tumor was considered after primary hyperparathyroidism was detected. However, the patient was admitted with a mass in the oral cavity, diagnosed before as a pyogenic granuloma with a delayed diagnosis without considering brown tumor because it was normocalcemic. It is the first case in the literature of papillary thyroid carcinoma detected incidentally with ectopic parathyroid adenoma in the thyrothymic region.

Diagnosis of Ectopic Intrathyroidal Parathyroid Adenoma with Nodular Goiter by 18F Fluorocholine: A Case Report

The occurrence of ectopic intrathyroidal parathyroid adenoma (EPTA) is very rare, which causes some difficulties in diagnosis and complicates treatment. In addition, the occurrence of EPTA with nodular goiter (NG) is rare, which makes diagnosis difficult and requires the assistance of clinical evidence, imaging data, and cytological examination results. Therefore, we present a patient with a final diagnosis of ETPA with NG.

Variation in parathyroid adenoma size in patients with sporadic, primary hyperparathyroidism: small gland size does not preclude single gland disease

PURPOSE

Small, abnormal parathyroid glands are usually associated with multigland hyperplasia in patients with primary hyperparathyroidism (pHPT). The purpose of this study was to determine the association between parathyroid adenoma size and biochemical cure rates in patients undergoing single gland parathyroidectomy.

METHODS

The study included patients with sporadic pHPT who underwent initial parathyroidectomy and met intraoperative PTH criteria for cure after resection of a single adenoma (SGD). Patients were divided into quartiles (Q1 = smallest) based on gland weight and maximum dimension; cure rates were compared across groups.

RESULTS

A single parathyroid adenoma was removed in 517 patients, with a median gland weight of 500 mg (range 50-11890). Median maximum gland dimension was 15 mm (range 5-55). With median follow-up of 28 months (range 6-81), the biochemical cure rate was 97.1%. There was no difference in cure rate by gland weight (Q1 94.6%, Q2 96.9%, Q3 98.4%, Q4 98.5%, p = 0.217) or maximum gland dimension (Q1 95.6%, Q2 97.6%, Q3 97.1%, Q4 98.2%, p = 0.641). When Q1 patients (by gland weight) were divided by quartile, there was no difference in cure rates (93.1% [50-140 mg]; 95.2% [150-190 mg]; 97.1% [200-230 mg]; 93.3% [240-280 mg]; p = 0.665).

CONCLUSION

For patients with pHPT who underwent single gland parathyroidectomy, there was no difference in cure rates by gland weight or maximum dimension. These data suggest that the removal of parathyroid adenomas as small as 50 mg with an appropriate decline in ioPTH likely represent single gland disease and additional exploration may not be necessary.

Dynamic 18F-fluorocholine PET/CT for parathyroid imaging in patients with primary hyperparathyroidism

OBJECTIVE

In the past few years, F-fluorocholine PET/CT has been established as a promising imaging technique for preoperative localization of parathyroid adenomas, but the optimal time point to start PET/CT acquisition after tracer injection is yet unknown. The aim of the present study was to assess the optimal time frame to acquire the PET/CT images and to evaluate the ability of dynamic imaging to differentiate parathyroid adenomas from active lymph nodes, a common cause for false-positive scan results.

PATIENTS AND METHODS

Patients with primary hyperparathyroidism who had undergone a dynamic F-fluorocholine PET/CT positive for parathyroid disease and who subsequently underwent successful parathyroidectomy were retrospectively included in this study. On the 20 minutes dynamic images, standardized uptake value measurements were acquired per 1 minute frame for the parathyroid adenoma, the thyroid gland, blood pool activity, and, if present, lymph node activity.

RESULTS

A total of 101 patients were included in this study. Time-activity curves showed a decrease of activity in parathyroid and thyroid glands, with faster wash-out from the thyroid gland and on average a stable, lower activity in lymph nodes. Blood pool activity was particularly present in the first 2 minutes. Differentiation of a parathyroid adenoma from active lymph nodes was best before 5 minutes, but no definitive cutoff value could be determined. Differentiation of a parathyroid adenoma from the thyroid gland was best after 10 minutes.

CONCLUSION

Dynamic imaging starting at the early time point of 2 minutes after injection of F-fluorocholine is useful for characterization of hyperfunctioning parathyroid glands.

Synchronous intrathyroidal parathyroid carcinoma and thyroid carcinoma: case report and review of the literature

BACKGROUND

Parathyroid carcinoma is a rare endocrine malignancy, rarer when synchronous with a non medullary well differentiated thyroid carcinoma. Parathyroid carcinoma accounts of 0.005% of all malignant tumors and it is responsible for less than 1% of primary hyperparathyroidism. The intrathyroidal localization of a parathyroid gland is not frequent with a reported prevalence of 0.2%. Carcinoma of parathyroids with intrathyroidal localization represents an even rarer finding, reported in only 16 cases described in literature. The rare constellation of synchronous parathyroid and thyroid carcinomas has prompted us to report our experience and perform literature review.

CASE PRESENTATION

We herein report a case of a 63-years-old man with multinodular goiter and biochemical diagnosis of hyperparathyroidism. Total thyroidectomy with radio-guide technique using gamma probe after intraoperative sesta-MIBI administration and intraoperative PTH level was performed. The high radiation levels in the posterior thyroid lobe discovered an intrathyroidal parathyroid. Microscopic examination revealed a parathyroid main cell carcinoma at the posterior thyroidal left basal lobe, a classic papillary carcinoma at the same lobe and follicular variant of papillary carcinoma at the thyroidal right lobe. To the best of our knowledge, this is the first case documenting a synchronous multicentric non medullary thyroid carcinomas and intrathyroidal parathyroid carcinoma.

CONCLUSIONS

Our experience was reported and literature review underlining challenging difficulties in diagnostic workup and surgical management was carried out.

Application of carbon nanoparticles combined with intraoperative neuromonitoring in papillary thyroid microcarcinoma surgery

PURPOSES

To improve the lymph node dissection as well as protect parathyroid gland and recurrent laryngeal nerve, the carbon nanoparticles and intraoperative neuromonitoring were applied in papillary thyroid microcarcinoma surgery.

METHODS

Carbon nanoparticles and intraoperative neuromonitoring were used in the experimental group, whereas the control group were not. Routine pathological examination was performed.

RESULTS

The lymph nodes dissected was significantly higher in the experimental group, but the metastatic lymph nodes were not. The number of mistakenly dissected parathyroid gland and postoperative hypoparathyroidism were 3 and 13 in the experimental group respectively, significantly less than 10 and 25 in the control group. The incidences of overall, transient and persistent recurrent laryngeal nerve palsy in the experimental group were 5.5%, 5.5% and 0% respectively, whereas in the control group were 8.6%, 6.9% and 1.7%.

CONCLUSIONS

Carbon nanoparticles can improve lymph node dissection in papillary thyroid microcarcinoma surgery, and the combination of carbon nanoparticles with intraoperative neuromonitoring can reduce surgical complications and improve patient quality of life.

Plasma Cell Proliferation Is Reduced in Myeloma-Induced Hypercalcemia and in Co-Culture with Normal Healthy BM-MSCs

OBJECTIVE

In multiple myeloma (MM), stimulation of osteoclasts and bone marrow (BM) lesions lead to hypercalcemia, renal failure, and anemia. Co-culture of the myeloma cells in both hypocalcemia and hypercalcemia concentrations with bone marrow-mesenchymal stem cells were evaluated.

MATERIALS AND METHODS

Viability and survival of myeloma cells were assessed by microculture tetrazolium test and flow cytometric assays. Mesenchymal stem cells (MSCs) were extracted from normal and myeloma patients and were co-cultured with myeloma cells.

RESULTS

Myeloma cells showed less survival in both hypocalcaemia and hypercalcemia conditions (P <.01). The paracrine and juxtacrine conditions of demineralized bone matrix-induced hypercalcemia increased the proliferation and survival of the cells (P <.05). Unlike myeloma MSCs, normal MSCs reduced the survival of and induced apoptosis in myeloma cells (P <.1).

CONCLUSION

Normal healthy-MSCs do not protect myeloma cells, but inhibit them. However, increasing the ratio of myeloma cells to MSCs reduces their inhibitory effects of MSCs and leads to their myelomatous transformation.

Near-infrared auto-fluorescence spectroscopy combining with Fisher's linear discriminant analysis improves intraoperative real-time identification of normal parathyroid in thyroidectomy

BACKGROUND

To evaluate the efficacy of a sensitive, real-time tool for identification and protection for parathyroid glands during thyroidectomy.

METHODS

Near-infrared (NIR) auto-fluorescence was measured intraoperatively from 20 patients undergoing thyroidectomy. Spectra were measured from suspicious parathyroid glands and surrounding neck tissues during the operation with a NIR fluorescence system. Fast frozen sections were performed on the suspicious parathyroid glands. Accuracy was evaluated by comparison with histology and NIR identification. Data were attracted for Fisher's linear discriminant analysis.

RESULTS

The auto-fluorescence intensity of parathyroid was significantly higher than that of thyroid, fat and lymph node. The peak intensity of auto-fluorescence from parathyroid was 5.55 times of that from thyroid at the corresponding wave number. Of the 20 patients, the parathyroid was accurately detected and identified in 19 patients by NIR system, compared with their histologic results. One suspicious parathyroid did not exhibit typical spectra, and was proved to be fat tissue by histology. The NIR auto-fluorescence method had a 100% sensitivity of parathyroid glands identification and a high accuracy of 95%. The positive predictive value was 95%. The parathyroid gland have specific auto-fluorescence spectrum and can be separated from the other three samples through the Fisher's linear discriminant analysis.

CONCLUSIONS

NIR auto-fluorescence spectroscopy can accurately identify normal parathyroid gland during thyroidectomy. The Fisher's linear discriminant analysis demonstrated the specificity of the NIR auto-fluorescence of parathyroid tissue and its efficacy in parathyroid discrimination.

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.

Ultrasonography of Extrathyroidal Diseases Mimicking Intrinsic Thyroid Lesions

Some localized or multisystem diseases as well as congenital anomalies occasionally involve thyroid and unusual findings will be identified during thyroid ultrasonography. Recognition of these entities will minimize unnecessary complementary examination and lead to appropriate management for patients. Therefore, we aim to review sonographic features of these extrathyroidal diseases that affect thyroid in adults. Our review derives from cases diagnosed in our hospital and published literature, with pictures accessible using as illustration. These disorders included intrathyroidal parathyroid adenoma, intrathyroidal cystic findings of nonthyroid origin, metastases to the thyroid, esophageal diverticulum, paratracheal air cysts, and ossification of anterior longitudinal ligament.

[Ectopic tissue of the thyroid gland and the parathyroid glands]

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.

Rare concurrence of ectopic intrathyroidal parathyroid gland and papillary thyroid carcinoma within a thyroid lobe: A care-compliant case report

RATIONALE

The inferior parathyroid glands derive from the third branchial pouch and seldom ectopically migrate to thyroid grand, mediastinum, thymus. Ectopic intrathyroidal parathyroid grand (ETPG) is rare and it cannot be consistently detected by any imaging examinations. The unusual ETPG is easily resected during thyroidectomy, which might cause postoperative hypoparathyroidism. Auto-transplantation of even a parathyroid gland can restore parathyroid function to some extent. Until now, there are not any guidelines on the management of ETPG.

PATIENT CONCERNS

Without any symptoms, a 27-year-old female patient was admitted to our hospital for a thyroid nodule. Thyroid ultrasonography demonstrated a hypoechoic nodule, measuring 0.6 cm × 0.6 cm × 0.7 cm, with multiple punctate micro-calcifications within the right thyroid lobe. Thyroid function tests were normal. The invasive fine needle aspiration cytology for the thyroid nodule was rejected by patient.

DIAGNOSES

The patient was firstly diagnosed as right thyroid hypoechoic nodule, which was pathologically proved to be papillary thyroid carcinoma (PTC) finally.

INTERVENTIONS

The patient underwent right thyroidectomy, central compartment neck dissection, parathyroid exploration, and auto-transplantation of the normal ETPG.

OUTCOMES

The right thyroid hypoechoic nodule was diagnosed as PTC by pathological examination. The inferior parathyroid gland could not found in normal locations. On the cut surface of excised thyroid lobe, a yellow and soft nodule was discovered and it was pathologically diagnosed as a normal parathyroid grand. In the end, auto-transplantation of the normal ETPG was conducted. Postoperative follow-ups found both serum calcium and parathyroid hormone tests were normal.

LESSONS

ETPG in a patient with PTC is easily overlooked and unexpectedly excised for its rarity. ETPG brings about a failed parathyroid exploration. However, within the thyroid parenchyma, it might be occasionally discovered by cutting a thyroid lobe into slices. Auto-transplantation of normal ETPG is necessary.

The prevalence and anatomy of parathyroid glands: a meta-analysis with implications for parathyroid surgery

Purpose

The anatomy of parathyroid glands (PTG) is highly variable in the population. The aim of this study was to conduct a systematic analysis on the prevalence and location of PTG in healthy and hyperparathyroidism (HPT) patients.

Methods

An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the number of PTG per patient and location of PTG. The data was extracted from the eligible studies and pooled into a meta-analysis.

Results

The overall analysis of 26 studies (n = 7005 patients; n = 23,519 PTG) on the number of PTG showed that 81.4% (95% CI 65.4–85.8) of patients have four PTG. A total of 15.9% of PTG are present in ectopic locations, with 11.6% (95% CI 5.1–19.1) in the neck and 4.3% (95% CI 0.7–9.9) in mediastinum. The subgroup analysis of ectopic PTG showed that 51.7% of ectopic PTG in the neck are localized in retroesophageal/paraesophageal space or in the thyroid gland. No significant differences were observed between the healthy and HPT patients and cadaveric and intraoperative studies.

Conclusions

Knowledge regarding the prevalence, location, and anatomy of PTG is essential for surgeons planning for and carrying out parathyroidectomies, as any unidentified PTG, either supernumerary or in ectopic location, can result in unsuccessful treatment and need for reoperation.

Electronic supplementary material

The online version of this article (10.1007/s00423-019-01751-8) contains supplementary material, which is available to authorized users.

Diagnostic pitfalls in a cystic ectopic intrathyroidal parathyroid adenoma mimicking a nodular goiter: A care-compliant case report

RATIONALE

Cystic parathyroid adenomas are rare and seldom arise in ectopically located glands which may be found within the carotid sheath, mediastinum, thymus, or thyroid grand. They cannot be detected consistently by any imaging methods. Unusual symptoms may bring about certain pitfalls and difficulties for the diagnosis of primary hyperparathyroidism (PHPT) caused by cystic parathyroid adenomas. Until now, there are no specific guidelines on the management of cystic ectopic intrathyroidal parathyroid adenoma (ETPA).

PATIENT CONCERNS

An 82-year-old male musician presented abrupt thyroid enlargement, hoarseness, and trachea compression when he was playing the clarinet. Thyroid and renal function tests were normal. Serum-free calcium and parathyroid hormone (PTH) were in high concentration. Thyroid ultrasonography (US) detected a giant and cystic nodule within right thyroid lobe, which is the very image of cystic nodular goiter. Parathyroid US was negative. The cystic nodule had a decreasing radioactive uptake of Technetium-99m-methoxyisobutylisonitrile (Tc-MIBI). At patient's request, the invasive fine-needle aspiration (FNA) was not conducted.

DIAGNOSES

The patient was initially diagnosed as cystic nodular goiter and inconclusive PHPT.

INTERVENTIONS

Enucleation of solitary cystic intrathyroidal nodule was conducted.

OUTCOMES

The cystic nodule strongly resembled a nodular goiter grossly, but it was proved cystic ETPA by histopathology. Postoperative follow-ups found that serum-free calcium and PTH decreased sharply into normal range, and hoarseness and trachea displacement were obviously improved.

LESSONS

The diagnosis of cystic ETPA is easily overlooked for its rarity. Diagnostic pitfalls, including atypical symptoms, inconclusive imaging manifestation, and unidentified gross specimen, are highlighted. They make the diagnosis of PHPT caused by cystic ETPA challenging. Patients would rather choose surgical excision directly than invasive FNA. Acute hemorrhage of the preexisting ETPA may account for the cystic degeneration.

Coexistence of a large functioning parathyroid cyst with papillary thyroid carcinoma: A case report and review of the literature

Parathyroid cysts constitute a rare cause of primary hyperparathyroidism (PHPT). PHPT may also rarely coexist with non-medullary thyroid carcinoma (NMTC). We describe a case of a 70-year-old woman who was diagnosed with PHPT, on the occasion of nephrolithiasis (corrected calcium and PTH levels: 10.8 mg/dl and 187 pg/ml, respectively). Ultrasonographic and scintigraphic investigation confirmed the diagnosis of a large parathyroid cyst attached to the lower pole of the right thyroid lobe and, consequently, the patient underwent parathyroidectomy. Due to the coexistence of multinodular goitre, with some nodules characterized as suspicious of malignancy, a total thyroidectomy was also performed. A histological diagnosis of cystic parathyroid adenoma was made. A unifocal papillary thyroid carcinoma of follicular subtype, 6 mm in diameter, was also detected. The patient's post-surgical course was uneventful and she remained normocalcaemic two years later. PHPT may rarely coexist with papillary thyroid carcinoma (PTC). The pathogenetic mechanisms linking these two endocrine entities are currently unknown.

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Parathyroid cysts constitute a rare cause of primary hyperparathyroidism (PHPT).

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Primary hyperparathyroidism may also rarely coexist with non-medullary thyroid carcinoma.

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The pathogenetic mechanisms linking these two endocrine entities are currently unknown.

AHNS Series: Do you know your guidelines? Optimizing outcomes in reoperative parathyroid surgery: Definitive multidisciplinary joint consensus guidelines of the American Head and Neck Society and the British Association of Endocrine and Thyroid Surgeons

BACKGROUND

Revision parathyroid is challenging due to possible diagnostic uncertainty as well as the technical challenges it can present.

METHODS

A multidisciplinary panel of distinguished experts from the American Head and Neck Society (AHNS) Endocrine Section, the British Association of Endocrine and Thyroid Surgeons (BAETS), and other invited experts have reviewed this topic with the purpose of making recommendations based on current best evidence. The literature was also reviewed on May 12, 2017. PubMed (1946-2017), Cochrane SR (2005-2017), CT databases (1997-2017), and Web of Science (1945-2017) were searched with the following strategy: revision and reoperative parathyroidectomy to ensure completeness.

RESULTS

Guideline recommendations were made in 3 domains: preoperative evaluation, surgical management, and alternatives to surgery. Eleven guideline recommendations are proposed.

CONCLUSION

Reoperative parathyroid surgery is best avoided if possible. Our literature search and subsequent recommendations found that these cases are best managed by experienced surgeons using precision preoperative localization, intraoperative parathyroid hormone (PTH), and the team approach.

In Situ Preservation Fraction of Parathyroid Gland in Thyroidectomy: A Cohort Retrospective Study

BACKGROUND AND OBJECTIVES

Parathyroid failure is the most common symptom after thyroidectomy. To prevent it, a gland was preserved in situ or an ischemic one was autotransplanted. This study explored the relationship between in situ preservation of the parathyroid gland and gland failure.

METHODS

Consecutive patients who underwent initial total thyroidectomy were enrolled retrospectively in a prospectively maintained database. Patients were divided into groups by parathyroid gland remaining in situ fraction (PGRIF) (PGRIF = number of in situ glands/(total number of identified glands - number of glands in specimen). Patients were graded by tertiles and followed at least one year after surgery.

RESULTS

559 patients were included. PGRIF is significantly inversely associated with transient hypoparathyroidism, protracted hypoparathyroidism, and postoperative hypocalcemia. PGRIF was identified as an independent risk factor for transient hypoparathyroidism, protracted hypoparathyroidism, and postoperative hypocalcemia (OR = 0.177, 0.190, and 0.330, resp.). Autotransplantation of parathyroid gland would not affect the calcium level in the long term.

CONCLUSION

In situ preservation of parathyroid gland is crucial for parathyroid function. Less preserved is the independent risk factor for postoperative hypoparathyroidism and hypocalcemia, resulting in a worse function of parathyroid gland in the long term.

Reoperation for persistent or recurrent secondary hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism is a common acquired disorder seen in chronic renal failure. Its pathophysiology is mainly due to hyperphosphatemia and vitamin D deficiency and resistance. When medical treatment fails, subtotal and total parathyroidectomy with autotransplantation are the standard procedures, although both are associated with high recurrence rates.

METHODS AND RESULTS

4 patients experienced persistence and 9 relapse. The first 4 were subjected to reoperation after 6 months for the persistence of symptoms due to the finding of a supernumerary adenomatous gland while the remaining patients at the reoperation showed in 5 cases 2 more glands in over thymic position, and 4 an hyperplasia of the residual glandular tissue. A classic cervicotomy was sufficient to remove the residual parathyroid in patients with persistent hyperparathyroidism. For cases of recurrent hyperparathyroidism it was enough a medial approach and sometimes lateral for the complete excision of the hyperplastic tissue. The advent of the intraoperative technique of parathyroid hormone dosage allowed a better performance of the surgical technique for the last 3 patients undergoing reoperation. After reoperation all patients had immediate regression of clinical symptoms with normalization of serum calcium and PTH levels.

CONCLUSIONS

On the basis of these considerations, diagnostic imaging has a not negligible role because during the first intervention helps to have an idea of the possible location of the glands and thus to avoid the risk of recurrence and relapse due to ectopic or supernumerary tissue.

Persistent and recurrent hyperparathyroidism

Despite remarkable progress in imaging modalities and surgical management, persistence or recurrence of primary hyperparathyroidism (PHPT) still occurs in 2.5-5% of cases of PHPT. The aim of this review is to expose the management of persistent and recurrent hyperparathyroidism. A literature search was performed on MEDLINE using the search terms "recurrent" or "persistent" and "hyperparathyroidism" within the past 10 years. We also searched the reference lists of articles identified by this search strategy and selected those we judged relevant. Before considering reoperation, the surgeon must confirm the diagnosis of PHPT. Then, the patient must be evaluated with new imaging modalities. A single adenoma is found in 68% of cases, multiglandular disease in 28%, and parathyroid carcinoma in 3%. Others causes (<1%) include parathyromatosis and graft recurrence. The surgeon must balance the benefits against the risks of a reoperation (permanent hypocalcemia and recurrent laryngeal nerve palsy). If surgery is necessary, a focused approach can be considered in cases of significant imaging foci, but in the case of multiglandular disease, a bilateral neck exploration could be necessary. Patients with multiple endocrine neoplasia syndromes are at high risk of recurrence and should be managed regarding their hereditary pathology. The cure rate of persistent-PHPT or recurrent-PHPT in expert centers is estimated from 93 to 97%. After confirming the diagnosis of PHPT, patients with persistent-PHPT and recurrent-PHPT should be managed in an expert center with all dedicated competencies.

INCIDENTAL PARATHYROIDECTOMY DURING THYROID SURGERY - RISK, PREVENTION AND CONTROVERSIES; AN EVIDENCE-BASED REVIEW

Background

Postoperative hypocalcemia after thyroid surgery has a high prevalence ( 16-55% in different series). Incidental parathyroidectomy (IP) is a less discussed complication of thyroidectomy with consequences not properly defined. The aim of our study was to find incidence, risk factors and how to prevent IP.

Methods

Extensive search of English literature publications via PubMed was performed and 73 papers from 1980 to 2017 were analysed using the GRADE system/classification, quality of evidence was classified as "strong" when the result is highly unlikely to change existing recommendation and "weak" when opposite.

Results

Incidence of IP is 3.7-24.9%, while prevalence of permanent hypoparathyroidism is less frequent 6-12%. Direct relation between IP and hypoparathyroidism/hypocalcemia remains controversial. Female patients, ectopic parathyroids, small thyroids, Graves', malignancy, redo surgeries and total thyroidectomy favour IP. Routine visualization of parathyroids, new hemostatic devices, magnifying instruments and fluorescence can prevent incidental removal of parathyroids. Incidence of IP during videoassisted or robotic thyroidectomies was similar to open procedures. High volume, experienced and younger surgeons have lower complication rates (including hypoparathyroidism).

Conclusions

Incidental parathyroidectomy is more frequent than we might have expected. It should be avoided and parathyroid glands should be kept in situ. Majority of studies are retrospective (low degree of evidence according to previous mentioned GRADE classification) and further meta-analysis or randomized control studies are welcome in order to define the impact of incidental removal of parathyroids on postoperative outcome.

Incidental Parathyroidectomy during Total Thyroidectomy: Risk Factors and Consequences

Objective. To evaluate the incidence of accidental parathyroidectomy in our series of total thyroidectomies, to investigate its clinical and biochemical consequences, and to identify potential risk factors. Methods. Patients who underwent total thyroidectomy between January 2006 and December 2015 were retrospectively analyzed. Pathology reports were reviewed to identify those cases who had an incidental parathyroidectomy and these were compared to patients with no parathyroidectomy, in terms of clinical (age, sex, and symptoms of hypocalcemia), pathological (thyroid specimen weight, Hashimoto thyroiditis, and malignancy), and biochemical (serum calcium and phosphate levels) factors. Results. 281 patients underwent total thyroidectomy during the study period. Incidental parathyroidectomy was noticed in 24.9% of cases, with 44.3% of parathyroid glands found in an intrathyroidal location. Evidence of postoperative biochemical hypocalcemia was noticed in 28.6% of patients with parathyroidectomy, compared with 13.3% in the no-parathyroidectomy group (p = 0.003). Symptomatic hypocalcemia was observed in 5.7% and 3.8%, respectively (p = 0.49). Age, sex, thyroid specimen weight, Hashimoto thyroiditis, and malignancy did not differ significantly between the two groups. Conclusions. Our study found an association of incidental parathyroidectomy with transient postoperative biochemical hypocalcemia, but not with clinically symptomatic disease. Age, sex, thyroid gland weight, Hashimoto thyroiditis, and malignancy were not identified as risk factors.

Electrical Impedance Spectroscopy to Aid Parathyroid Identification and Preservation in Central Compartment Neck Surgery: A Proof of Concept in a Rabbit Model

BACKGROUND

Accurate identification of parathyroid glands during thyroid surgery is crucial to avoid postthyroidectomy hypocalcemia. Electrical impedance spectroscopy has the potential to differentiate between tissues of different morphology. The aim of this study was to determine the electrical impedance patterns of the thyroid, parathyroid, and other soft tissue structures in the rabbit neck.

METHODS

The central compartments were exposed in 9 freshly culled New Zealand White rabbits. In situ and ex vivo electrical impedance was measured from thyroid lobes, external parathyroid glands, adipose tissue, and strap muscle using the APX100 device. Specimens of all identified glands were sent for histopathology examination.

RESULTS

Histology confirmed correct identification of all excised thyroid and parathyroid glands. The impedance was higher for thyroid tissue at lower frequencies and for parathyroid tissue at higher frequencies. Ex vivo electrical impedance spectra were significantly higher compared with the in situ spectra across all frequencies for thyroid and parathyroid tissues (P < .001). The ratio of low to high frequency in situ impedance of thyroid, parathyroid, and muscle was significantly different (P < .001), allowing for differentiation between these tissues.

CONCLUSION

The electrical impedance spectra of rabbit thyroid and parathyroid glands are distinct and different from each other and from skeletal muscle. If these results are replicated in human tissue, they have the potential to improve patient outcomes by achieving early identification and preservation of parathyroid glands.

Value of Prophylactic Cervical Thymectomy in Parathyroid Hyperplasia

BACKGROUND

In parathyroid hyperplasia (HPT), parathyroid glands within the cervical thymus are a cause for recurrence. As a result of differences in pathophysiology, variable practice patterns exist regarding performing bilateral cervical thymectomy (BCT) in primary hyperplasia versus hyperplasia from renal failure or familial disease. The objective of this study was to capture patients where thymic tissue was found with subtotal parathyroidectomy (PTX) and intended BCT, identify number of thymic supernumerary glands (SNGs), and determine overall cure rate.

METHODS

Retrospective review of patients with four-gland exploration and intended BCT for HPT from 2000 to 2013 was performed. Identification of thymic tissue and SNGs were determined by operative/pathology reports. Univariate analysis identified differences in cure rate for patients undergoing subtotal PTX with or without BCT.

RESULTS

Thymic tissue was found in 52 % of 328 primary HPT (19 % unilateral, 33 % bilateral), 77 % of 128 renal HPT (28 % unilateral, 49 % bilateral), and 100 % of familial HPT (24 % unilateral, 76 % bilateral) patients. Nine percent of primary, 18 % of renal, and 10 % of familial HPT patients had SNGs within thymectomy specimens. Cure rates of primary HPT patients with BCT were 99 % compared to 94 % in subtotal PTX alone. Renal HPT cure rates were 94 % with BCT compared to 89 % without BCT.

CONCLUSIONS

Renal HPT patients benefited most in cure when thymectomy was performed. Although the rate of SNGs found in primary HPT was lower than renal HPT, the cure rate mimicked the pattern in renal disease. Furthermore, the incidences of SNGs in primary and familial HPT were similar. On the basis of these data, we advocate that BCT be considered in primary HPT when thymic tissue is readily identified.

Comparison of 4D CT, ultrasonography, and 99mTc sestamibi SPECT/CT in localizing single-gland primary hyperparathyroidism

OBJECTIVE

The present study was designed to evaluate 4D computerized tomography (CT) as a means of localizing abnormal parathyroid glands in primary hyperparathyroidism (HPT).

STUDY DESIGN

Case series with expertized image review.

SETTING

Tertiary care hospital.

SUBJECTS AND METHODS

A total of 38 patients were recruited for study, all of whom had undergone focused parathyroidectomy for single-lesion primary HPT between June 2011 and September 2013. In each patient, 3 imaging procedures were performed: cervical ultrasonography (US), 99mTc-sestamibi SPECT/CT (SeS), and 4D CT. Collective imaging data were blindly reviewed and compared.

RESULTS

4D CT outperformed US and SeS in terms of sensitivity (P=.27), specificity (P=.01), positive predictive value (PPV) (P<.01), negative predictive value (NPV) (P=.19), and accuracy (P<.01). In 7.9% (3/38) of patients, 4D CT provided specific anatomic information that was unaffordable by US and SeS. Localization by 4D CT correlated with tissue parathyroid hormone level (P=.02), maximum diameter (P=.01), and volume (P<.01) of abnormal parathyroid glands.

CONCLUSION

4D CT proved helpful in localizing target parathyroid glands of primary HPT that were missed by traditional imaging.

Relationship between hypoparathyroidism and the number of parathyroid glands preserved during thyroidectomy

Background

The relationship between the number of parathyroid glands preserved and hypoparathyroidism is not well understood. We sought to determine the number of parathyroid glands that need to be preserved to prevent hypoparathyroidism.

Methods

We analyzed 454 patients who underwent total thyroidectomy for papillary thyroid carcinoma. We analyzed the frequency of hypoparathyroidism according to the number of parathyroid glands preserved.

Results

Incidental parathyroidectomy occurred in 19.8% of the patients; one parathyroid gland in 17.6%, two in 1.5%, and three in 0.7%. Transient hypoparathyroidism was increased when incidental parathyroidectomy occurred (odds ratio 1.83, 95% confidence interval 1.04 to 3.23, P = 0.036) on multivariate regression analysis, but was not influenced by the actual number of parathyroid glands removed. There was no relationship between the number of parathyroid glands preserved and permanent hypoparathyroidism (P = 0.147).

Conclusions

Preservation of all parathyroid glands decreases transient hypoparathyroidism compared with when three or fewer glands are preserved, but does not affect permanent hypoparathyroidism. During total thyroidectomy, preserving at least one parathyroid gland with an intact blood supply appears to be sufficient to prevent permanent hypoparathyroidism when autotransplantation is not performed.

Identification of parathyroid glands: anatomical study and surgical implications

While performing thyroid surgery, the unintentional lesion of parathyroid glands and laryngeal nerves results in a profound alteration in patient's quality of life. To minimize thyroid surgery morbidity, the surgeon must have an in-depth knowledge of the thyroid gland morphology and its anatomical relations in the anterior compartment of the neck. This work intended to simulate total thyroidectomies using cadaver parts and isolate fragments that may correspond to parathyroid glands. The thyroid glands and "eventual" parathyroid glands were then submitted to histological study. Ninety-two cadaver parts were used for macroscopic dissection. A total of 242 fragments were isolated, 154 of which were confirmed through histological study to be parathyroid glands. In 36 cases, all "eventual" parathyroid glands isolated during dissection were confirmed through histological verification. In 40 cases, some glands were confirmed. In 16 cases, none of the "eventual" parathyroid glands was confirmed. The 92 thyroid glands isolated during dissection were also submitted to histological study. In 21 thyroid glands, 16 parathyroid glands were identified in the histological cuts: 8 sub-capsular, 8 extra-capsular, 6 intra-thyroidal. There was no statistical difference between the dimensions of the parathyroid glands. Parathyroid gland identification and preservation are sometimes a challenge during thyroid surgery, difficulty that has been demonstrated during dissection of cadaver parts.