Parathyroid autotransplantation in extensive head and neck resections: case series report

Factors influencing the success of cryopreserved parathyroid autotransplantation: A systematic review

Permanent hypoparathyroidism is a postoperative complication of thyroid and parathyroid surgery and can be cured by cryopreserved parathyroid autotransplantation (CPAT). However, due to the lack of unified and standardized guidelines, the limited ability of the parathyroid tissue itself to withstand cryopreservation, and some yet-to-be-defined processes or technologies, the success rate of cryopreserved parathyroid autotransplantation varies between institutions; it is low for some institutions and high for others. Due to the sparsity of data, views vary on which factors most influence the success rate of cryopreserved parathyroid autotransplantation. In this review, we analyzed the following probable influencing factors: ischemic period before cryopreservation; processes of cryopreservation and thawing, including freezing medium; freezing and thawing methods; duration of cryopreservation; examination of the graft before transplantation; graft site; mass of transplanted tissue fragments; blood calcium level; and the evaluation criteria for cryopreserved parathyroid autotransplantation success. Although the effects of these factors are debatable, we hypothesized that examining them in the above-given order to determine whether they affect the success rate of cryopreserved parathyroid autotransplantation could be beneficial to maximizing the success rate. Our findings led us to conclude that cryopreserved parathyroid autotransplantation operations should be standardized. Standardized guidelines for cryopreserved parathyroid autotransplantation that include such factors as ischemic period time, freezing and thawing methods, and recipient status should be established based on a comprehensive analysis of these factors.

Development of Artificial Intelligence for Parathyroid Recognition During Endoscopic Thyroid Surgery

OBJECTIVE

We aimed to establish an artificial intelligence (AI) model to identify parathyroid glands during endoscopic approaches and compare it with senior and junior surgeons' visual estimation.

METHODS

A total of 1,700 images of parathyroid glands from 166 endoscopic thyroidectomy videos were labeled. Data from 20 additional full-length videos were used as an independent external cohort. The YOLO V3, Faster R-CNN, and Cascade algorithms were used for deep learning, and the optimal algorithm was selected for independent external cohort analysis. Finally, the identification rate, initial recognition time, and tracking periods of PTAIR (Artificial Intelligence model for Parathyroid gland Recognition), junior surgeons, and senior surgeons were compared.

RESULTS

The Faster R-CNN algorithm showed the best balance after optimizing the hyperparameters of each algorithm and was updated as PTAIR. The precision, recall rate, and F1 score of the PTAIR were 88.7%, 92.3%, and 90.5%, respectively. In the independent external cohort, the parathyroid identification rates of PTAIR, senior surgeons, and junior surgeons were 96.9%, 87.5%, and 71.9%, respectively. In addition, PTAIR recognized parathyroid glands 3.83 s ahead of the senior surgeons (p = 0.008), with a tracking period 62.82 s longer than the senior surgeons (p = 0.006).

CONCLUSIONS

PTAIR can achieve earlier identification and full-time tracing under a particular training strategy. The identification rate of PTAIR is higher than that of junior surgeons and similar to that of senior surgeons. Such systems may have utility in improving surgical outcomes and also in accelerating the education of junior surgeons.

LEVEL OF EVIDENCE

3 Laryngoscope, 2022.

Thyroid and Parathyroid Functions After Pharyngo-Laryngo-Esophagectomy for Cervical Esophageal Cancer

BACKGROUND

Cervical esophageal cancer (CEC) patients whose larynx function cannot be preserved often undergo chemoradiotherapy, whereas those with residual or recurrent lesions undergo a pharyngo-laryngo-esophagectomy (PLE); however, some need to undergo a pharyngolaryngectomy with total esophagectomy (PLTE) for synchronous or metachronous esophageal cancer. We retrospectively evaluated the relationship between preoperative irradiation (or the extent of esophageal resection) and postoperative endocrine complications in CEC, including hypothyroidism and hypoparathyroidism.

METHODS

The cancers of 35 (5.4%) of 678 esophageal cancer patients with esophagectomy treated in 2000-2017 were CECs. We also analyzed the 17 cases of CEC patients who underwent PLE with thyroid lobectomy-11 with irradiation before PLE and 6 without irradiation. Seven patients underwent a PLTE.

RESULTS

Hypothyroidism and hypoparathyroidism occurred in 14 and 12 patients, respectively. The hypothyroidism rate was significantly higher in patients with irradiation versus those without irradiation (100% vs. 50%; p = 0.010), and the hypoparathyroidism rate was significantly higher in the PLTE versus non-PLTE patients (100% vs. 50%; p = 0.026). The mean levothyroxine dosage was 1.60 μg/kg/day in the PLE patients post-irradiation.

CONCLUSIONS

Irradiation appears to be a risk factor for hypothyroidism after PLE with thyroid lobectomy, while PLTE might have some effect on hypoparathyroidism. Due to vocal function loss, PLE patients may experience symptoms from endocrine complications. Levothyroxine treatment soon after PLE for post-irradiation patients and patients requiring as-needed calcium or vitamin D supplementation based on biochemical hypocalcemia for PLE (especially PLTE), may be effective in preventing symptomatic endocrine complications.

Preoperative vitamin D levels do not relate with the risk of hypocalcemia following total thyroidectomy. A cohort study

BACKGROUND

Hypocalcemia is the most common complication following total thyroidectomy. Few factors may relate with increased risk of postoperative hypocalcemia. Preoperative vitamin D values have been evaluated in few studies, but reports present conflicting data. Aim of our study is to evaluate the association of preoperative vitamin D values and hypocalcemia following total thyroidectomy.

METHODS

A retrospective analysis of patients undergoing total thyroidectomy in our department of endocrine surgery between November 2012 and November 2015 was performed.

RESULTS

Mean age of patients was 56.2 years (±14.0) and sex ratio (F:M) was 4.3:1. Sixty-four patients (17.4%) had preoperative vitamin D insufficiency (x<25 nmol/L), 138 patients (37.5%) vitamin D deficiency (25<x<50 nmol/L) and 166 patients (45.1%) vitamin D sufficiency (x>50 nmol/L). Following total thyroidectomy for both benign and malignant pathology, 66 patients (17.9%) had symptomatic hypocalcemia (x<2.0 mmol/L) requiring medical treatment (group 1), 64 patients (17.4%) biochemical hypocalcemia (2<x<2.1 mmol/L) not requiring treatment (group 2) and 238 patients (64.7%) had normal levels (x>2.1 mmol/L, group 3). Mean postoperative PTH value was 25.4 pg/ml (range 2-61). No statistical correlation between postoperative serum calcium and preoperative vitamin D values (R=-0.001, P=0.9849) was found nor associations were found regarding age, sex, type of thyroid disease or BMI.

CONCLUSIONS

In our cohort of patients, preoperative vitamin D levels were not associated with a higher risk of hypocalcemia following total thyroidectomy. Postoperative PTH appears to be the most sensible item to predict the risk of postoperative symptomatic hypocalcemia.

[Surgical treatment of secondary hyperparathyroidism: a systematic review of the literature]

Secondary hyperparathyroidism (HPT) has a high prevalence in renal patients. Secondary HPT results from disturbances in mineral homeostasis, particularly calcium, which stimulates the parathyroid glands, increasing the secretion of parathyroid hormone (PTH). Prolonged stimulation can lead to autonomy in parathyroid function. Initial treatment is clinical, but parathyroidectomy (PTx) may be required. PTx can be subtotal or total followed or not followed by parathyroid tissue autograft. We compared the indications and results of these strategies as shown in the literature through a systematic literature review on surgical treatment of secondary HPT presented in MedLine and LILACS from January 2008 to March 2014. The search terms were: hyperparathyroidism; secondary hyperparathyroidism; parathyroidectomy and parathyroid glands, restricted to research only in humans, articles available in electronic media, published in Portuguese, Spanish, English or French. We selected 49 articles. Subtotal and total PTx followed by parathyroid tissue autograft were the most used techniques, without consensus on the most effective surgical procedure, although there was a preference for the latter. The choice depends on surgeon's experience. There was consensus on the need to identify all parathyroid glands and cryopreservation of parathyroid tissue whenever possible to graft if hypoparathyroidism arise. Imaging studies may be useful, especially in recurrences. Alternative treatments of secondary HPT, both interventional and conservative, require further study.

Perioperative indicators of hypocalcemia in total thyroidectomy: the role of vitamin D and parathyroid hormone

BACKGROUND

Hypocalcemia is a common complication of thyroidectomy. The aim of this study was to identify risk factors for this problem.

METHODS

This prospective analysis included 111 patients undergoing total or completion thyroidectomy. Preoperative vitamin D levels and postoperative day 1 parathyroid hormone levels were analyzed for their predictive effects on postoperative hypocalcemia.

RESULTS

Patients with ionized calcium <4.4 mg/dL had significantly lower mean parathyroid hormone levels than normocalcemic patients (13.0 vs 28.4 pg/mL, P < .001). Parathyroid hormone levels were also significantly lower in symptomatic patients (11.0 vs 28.4 pg/mL, P < .001). Preoperative vitamin D level, body mass index, gender, and pathologic findings were not associated with low calcium levels or symptoms of hypocalcemia.

CONCLUSIONS

Younger age and low postoperative parathyroid hormone levels are predictive of symptomatic hypocalcemia. A parathyroid hormone level outside of the reference range may indicate a need for more aggressive postoperative calcium supplementation and treatment with activated vitamin D. Older patients with normal postoperative parathyroid hormone levels may be safely discharged with appropriate calcium supplementation.