TY - JOUR

T1 - Surgical Preservation of Parathyroid Function During Total Thyroidectomy Can Be Improved by Intraoperative Imaging

AU - Feldt-Rasmussen, Ulla

AU - Lykke, Eva

AU - Christensen, Anders

AU - von Buchwald, Christian

PY - 2021

Y1 - 2021

N2 - BackgroundTotal thyroidectomy is a necessary surgical procedure in some cases of thyroid carcinomas (1) and an attractive method as alternative treatment of benign toxic and nontoxic multinodular goiters (2) and some cases of Graves’ disease (e.g., in young females of childbearing age with poorly controlled Graves’ disease or patients with Graves’ orbitopathy) (3,4). However, the risk of surgical complications is important, and the most serious ones in the long term, although rare, are permanent paralysis of the laryngeal nerve(s) and hypoparathyroidism (5,6). One important approach to preserve the function of parathyroid glands during thyroidectomy and to prevent postoperative hypocalcemia is assessment of parathyroid gland vascularity. Laser speckle contrast imaging (LSCI) has been shown to be accurate in detecting differences in parathyroid vascularity (7). The purpose of this surgeon-blinded prognostic study was to evaluate the relationship between intraoperative LSCI measurements and postoperative parathyroid outcomes of patients who undergo total thyroidectomy (8).MethodsA total of 72 patients were included (58 total thyroidectomy alone, 10 total thyroidectomy with lymph node dissection, 4 completion thyroidectomy). An LSCI device was used to image all identified parathyroid glands, and a speckle contrast value was calculated as an average value for each patient; the data were grouped according to whether the patient had normal or low concentrations of serum parathyroid hormone (PTH) on postoperative day 1 (POD1).The surgeon's visual assessment of each parathyroid gland was recorded into categories: well vascularized, compromised, and devascularized (subsequently autotransplanted). Parathyroid LSCIs were grouped according to these classifications and assessed by one-way analysis of variance. Patients with POD1 PTH below the accepted normal range were evaluated up to 6 months postoperatively to assess for recovery within that period.ResultsA speckle contrast limit of 0.186 separated the normal parathyroid and hypoparathyroid groups with 87.5% sensitivity and 84.4% specificity: 7 of 8 patients with low PTH concentration on POD1 had an average parathyroid speckle contrast above this limit, while 54 of 64 patients with a normal postoperative PTH concentration had an average parathyroid speckle contrast below this limit. Taking this value as the threshold for adequate parathyroid perfusion, it was determined that only one vascularized gland was needed for normal postoperative parathyroid function: 64 of 69 patients (92.8%) with at least one vascularized gland (determined by LSCI) had normal postoperative PTH values, while all 3 patients (100%) with no vascularized glands had low postoperative PTH values. Overall, the rates of temporary and permanent hypoparathyroidism in this study were 8.3% and 1.4%, respectively.ConclusionsLSCI is a promising technique for assessing parathyroid gland vascularity. It has the potential to help reduce the incidence of hypocalcemia after thyroidectomy by providing surgeons with additional information during surgery to aid in the preservation of parathyroid function.

AB - BackgroundTotal thyroidectomy is a necessary surgical procedure in some cases of thyroid carcinomas (1) and an attractive method as alternative treatment of benign toxic and nontoxic multinodular goiters (2) and some cases of Graves’ disease (e.g., in young females of childbearing age with poorly controlled Graves’ disease or patients with Graves’ orbitopathy) (3,4). However, the risk of surgical complications is important, and the most serious ones in the long term, although rare, are permanent paralysis of the laryngeal nerve(s) and hypoparathyroidism (5,6). One important approach to preserve the function of parathyroid glands during thyroidectomy and to prevent postoperative hypocalcemia is assessment of parathyroid gland vascularity. Laser speckle contrast imaging (LSCI) has been shown to be accurate in detecting differences in parathyroid vascularity (7). The purpose of this surgeon-blinded prognostic study was to evaluate the relationship between intraoperative LSCI measurements and postoperative parathyroid outcomes of patients who undergo total thyroidectomy (8).MethodsA total of 72 patients were included (58 total thyroidectomy alone, 10 total thyroidectomy with lymph node dissection, 4 completion thyroidectomy). An LSCI device was used to image all identified parathyroid glands, and a speckle contrast value was calculated as an average value for each patient; the data were grouped according to whether the patient had normal or low concentrations of serum parathyroid hormone (PTH) on postoperative day 1 (POD1).The surgeon's visual assessment of each parathyroid gland was recorded into categories: well vascularized, compromised, and devascularized (subsequently autotransplanted). Parathyroid LSCIs were grouped according to these classifications and assessed by one-way analysis of variance. Patients with POD1 PTH below the accepted normal range were evaluated up to 6 months postoperatively to assess for recovery within that period.ResultsA speckle contrast limit of 0.186 separated the normal parathyroid and hypoparathyroid groups with 87.5% sensitivity and 84.4% specificity: 7 of 8 patients with low PTH concentration on POD1 had an average parathyroid speckle contrast above this limit, while 54 of 64 patients with a normal postoperative PTH concentration had an average parathyroid speckle contrast below this limit. Taking this value as the threshold for adequate parathyroid perfusion, it was determined that only one vascularized gland was needed for normal postoperative parathyroid function: 64 of 69 patients (92.8%) with at least one vascularized gland (determined by LSCI) had normal postoperative PTH values, while all 3 patients (100%) with no vascularized glands had low postoperative PTH values. Overall, the rates of temporary and permanent hypoparathyroidism in this study were 8.3% and 1.4%, respectively.ConclusionsLSCI is a promising technique for assessing parathyroid gland vascularity. It has the potential to help reduce the incidence of hypocalcemia after thyroidectomy by providing surgeons with additional information during surgery to aid in the preservation of parathyroid function.

U2 - 10.1089/ct.2021;33.456-458

DO - 10.1089/ct.2021;33.456-458

M3 - Journal article

VL - 33

SP - 456

EP - 458

JO - Clinical Thyroidology

JF - Clinical Thyroidology

SN - 2329-9711

IS - 10

ER -