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Parathyroid identification during thyroid and parathyroid operations: A pilot study evaluating a novel low cost autofluorescence based device
Abstract
Background
The aim of this study was to develop a low-cost prototype near-infrared fluorescence device that enables contrast-free, real time, high-resolution intraoperative visualization of normal and pathological parathyroid glands (PG) by imaging their autofluorescence (AF).
Methods
A novel near-infrared parathyroid AF (NIR-PAF) imaging device with visible laser PG targeting was developed. The device was evaluated during parathyroid and thyroid operations in a pilot clinical study.
Results
Overall, of the 6 parathyroidectomies carried out in the study population a parathyroid adenoma was found to exhibit AF ex vivo in 6/6 (100%) of cases, and in vivo in 3/3 (100%) of these cases. Two of 4 thyroidectomies were evaluated in vivo and all PGs (6 PGs total) were identified by the NIR-PAF device. The NIRPAF device cost less than $1000 Canadian to build.
Conclusion
The inexpensive NIR-PAF device that we developed can successfully intraoperatively identify both normal and pathological PGs.
... Incidental excision of parathyroid glands is a common event during thyroid surgery [6]. Anyway, reduced parathyroid gland (PG) viability leads to decreased PG functional capacity, resulting in impaired PTH secretion, and leading to postoperative hypocalcemia [7]. Inadvertent damage to or excision of a healthy PG following a total thyroidectomy could result in transient hypocalcemia (< 6 months) in 5 -35% of cases or permanent hypocalcemia (> 6 months) in up to 7% of the patients [8][9][10][11]. ...
... The use of NIRAF for the identification can help too [29,30]. Recently a comprehensive review of novel techniques for intraoperative PG identification has been reported and found NIR-PAF to be among the most promising and reliable [7]. Also, if the parathyroid glands are damaged, auto-transplantation should be undertaken to preserve their function [23]. ...
Thyroid surgery, while generally safe, poses risks of parathyroid gland injury leading to postoperative hypocalcemia. Incidental excision during thyroidectomy is not uncommon, with reported rates as high as 22%. Identification challenges stem from the variable location of parathyroid glands, their small size, and shared blood supply with the thyroid. Factors like thyroiditis, radical neck dissection, and malignancy increase the risk. Preservation methods include meticulous dissection, real-time identification, and innovative techniques like Near-Infrared Autofluorescence (NIRAF) and Indocyanine Green (ICG) angiography. Recent studies suggest that NIRAF significantly reduces postoperative hypocalcemia rates. Additionally, ICG angiography proves reliable in parathyroid detection during surgery. Carbon nanoparticles (CNs) enhance lymph node visualization while sparing parathyroid glands. Understanding vasculature preservation principles is crucial, and methods like auto-transplantation can safeguard parathyroid function. Studies on pain experiences following thyroid and parathyroid surgery highlight the prevalence of sustained pain beyond the expected recovery period. Collaborative efforts between surgical and anesthetic teams are essential to tailor pain management strategies, incorporating regional anesthesia techniques and minimizing opioid use. A review of regional pain control strategies, such as cervical plexus blocks, underscores their potential benefits in optimizing postoperative pain relief. Lastly, insights from studies optimizing outpatient pain management reinforce the importance of tailored interventions and closer follow-up for patients experiencing prolonged pain. The culmination of these approaches ensures comprehensive care in thyroid surgery, minimizing pain and inadvertent parathyroid damage and associated complications.
... (c) Autofluorescence of parathyroids detected by infrared light or laser stimulation [27][28][29][30][31][32][33]. (d) Autofluorescence enhanced by injection of indocyanine green or 5-ALA [34,35]. ...
... Paras et al. were the first in 2011 to discover and describe [27] an autofluorescence of the parathyroids induced by stimulation with high-energy light sources of endogenous fluorophores that reacted by emitting low-energy light. The exploitation of this property, apparently easier to apply and with potentially more immediate advantages, has offered a new opportunity in the attempt to reduce post-surgical hypoparathyroidism [27][28][29][30][31][32][33]. ...
Background:
The diagnosis of thyroid cancer is continuously increasing and consequently the amount of thyroidectomy. Notwithstanding the actual surgical skill, postoperative hypoparathyroidism still represents its most frequent complication. The aims of the present study are to analyze the rate of postoperative hypoparathyroidism after thyroidectomy, performed for cancer by a single first operator, without any technological aid, and to compare the data to those obtained adopting the most recent technological adjuncts developed to reduce the postoperative hypoparathyroidism.
Methods:
During the period 1997-2020 at the Endocrine Surgery Unit of the Department of Clinical and Experimental Medicine of the University of Florence, 1648 consecutive extracapsular thyroidectomies for cancer (401 with central compartment node dissection) were performed. The percentage of hypoparathyroidism, temporary or permanent, was recorded both in the first period (Group A) and in the second, most recent period (Group B). Total thyroidectomies were compared either with those with central compartment dissection and lobectomies. Minimally invasive procedures (MIT, MIVAT, some transoral) were also compared with conventional. Fisher's exact and Chi-square tests were used for comparison of categorical variables. p < 0.01 was considered statistically significant. Furthermore, a literature research from PubMed® has been performed, considering the most available tools to better identify parathyroid glands during thyroidectomy, in order to reduce the postoperative hypoparathyroidism. We grouped and analyzed them by technological affinity.
Results:
On the 1648 thyroidectomies enrolled for the study, the histotype was differentiated in 93.93 % of cases, medullary in 4% and poorly differentiated in the remaining 2.06%. Total extracapsular thyroidectomy and lobectomy were performed respectively in 95.45% and 4.55%. We recorded a total of 318 (19.29%) cases of hypocalcemia, with permanent hypoparathyroidism in 11 (0.66%). In regard to the literature, four categories of tools to facilitate the identification of the parathyroids were identified: (a) vital dye; (b) optical devices; (c) autofluorescence of parathyroids; and (d) autofluorescence enhanced by contrast media. Postoperative hypoparathyroidism had a variable range in the different groups.
Conclusions:
Our data confirm that the incidence of post-surgical hypoparathyroidism is extremely low in the high volume centers. Its potential reduction adopting technological adjuncts is difficult to estimate, and their cost, together with complexity of application, do not allow immediate routine use. The trend towards increasingly unilateral surgery in thyroid carcinoma, as confirmed by our results in case of lobectomy, is expected to really contribute to a further reduction of postsurgical hypoparathyroidism.
Introduction:
Hypocalcemia is commonly reported after thyroidectomy and has multiple possible etiologies including: parathyroid devascularization, reactive hypoparathyroidism from relative hypercalcemia in thyrotoxicosis, and abrupt reversal of thyrotoxic osteodystrophy. In patients that are actively hyperthyroid and undergoing thyroidectomy, it is not known how many experience hypocalcemia from nonhypoparathyroidism etiologies. Therefore, our aim was to examine the relationship among thyrotoxicosis, hypocalcemia, and hypoparathyroidism.
Methods:
A retrospective review was performed of prospectively-collected data from all patients undergoing thyroidectomy for hyperthyroidism by 4 surgeons from 2016 to 2020. All patients carried a diagnosis of Graves' disease or toxic multinodular goiter. Patient demographics, preoperative medications, laboratory reports, and postoperative medications were reviewed. Hypocalcemia within the first month of surgery despite a normal parathyroid hormone (PTH) level was the primary outcome of interest and was compared between patients with and without thyrotoxicosis. Secondary outcomes were duration of postoperative calcium use and the relationship between preoperative calcium supplementation and postoperative calcium supplementation. Descriptive statistics, Wilcoxon rank-sum, and chi-square tests were used for bivariate analysis, as appropriate.
Results:
A total of 191 patients were identified, with mean age of 40.5 y (range 6-86). Most patients were female (80%) and had Graves' disease (80%). At the time of surgery, 116 (61%) had uncontrolled hyperthyroidism (thyrotoxic group, Free Thyroxine >1.64 ng/dL or Free Triiodothyronine > 4.4 ng/dL), with the remaining 75 (39%) considered euthyroid. Postoperative hypocalcemia (calcium < 8.4 mg/dL) developed in 27 (14%), while hypoparathyroidism (PTH < 12 pg/mL) was observed in 39 (26%). Thyrotoxic patients comprised a majority of those with hypocalcemia (n = 22, 81%, P = 0.01) and hypoparathyroidism immediately following surgery (n = 14, 77%, P = 0.04). However, a majority of initially hypocalcemic, thyrotoxic patients had normal PTH values within the first month after surgery (n = 17, 85%), pointing to a potential nonparathyroid etiology. On bivariate analysis, no significant relationship was found for thyrotoxic patients with initial postoperative hypocalcemia (18%) and hypoparathyroidism <1-month after surgery (29%, P = 0.29) or between 1 and 6 mo after surgery (2%, P = 0.24). Of the 19 patients in the nonhypoparathyroidism group, 17 (89%) were off all calcium supplements by 6 mo postop.
Conclusions:
In patients with hyperthyroidism, those in active thyrotoxicosis at time of surgery have a higher rate of postoperative hypocalcemia compared to euthyroid patients. When hypocalcemia lasts >1 mo postoperatively, data from this study suggest that hypoparathyroidism may not be the primary etiology in many of these patients, who typically require calcium supplementation no more than 6 mo postoperatively.
Background:
Primary hyperparathyroidism is characterized by hypercalcemia with inappropriately normal or elevated parathyroid hormone. However, the absolute parathyroid hormone value that is defined as inappropriately normal is unclear. We reviewed our experience with parathyroidectomy in patients with hypercalcemia and parathyroid hormone of ≤50.0 pg/mL (normal range 12.0-88.0 pg/mL).
Methods:
A total of 2,349 patients underwent parathyroidectomy for primary hyperparathyroidism between 2000 and 2021. Of these, 149 patients had preoperative parathyroid hormone ≤50.0 pg/mL (parathyroid hormone ≤50). The biology and outcomes were compared to patients with parathyroid hormone >50.0 pg/mL (parathyroid hormone >50).
Results:
Of the parathyroid hormone ≤50 patients, the median parathyroid hormone was 40.0 pg/mL (range 11.6-50.0 pg/mL). All patients were found to have abnormal hypercellular parathyroid glands with a cure rate of 96.7%. When compared to the parathyroid hormone >50 group, the parathyroid hormone ≤50 group was younger (56 ± 15 vs 60 ± 14 years, P < .001) with a lower body mass index (28.7 ± 7.0 kg/m2 vs 31.2 ± 7.9 kg/m2, P < .001), higher rate of fatigue (73.2% vs 63.0%, P = .033), and higher rate of multiglandular disease (58.9% vs 31.9%, P < .001). There was no difference between the groups with respect to patient demographics, rate of previous parathyroidectomy, surgical cure, or postoperative complications (persistent or recurrent hyperparathyroidism and hypocalcemia).
Conclusion:
Patients with hypercalcemia and parathyroid hormone ≤50 pg/mL have a similar clinical presentation and rate of surgical cure to other primary hyperparathyroidism patients and should be considered for parathyroidectomy. Most of these patients have multiglandular disease and thus should be considered for bilateral parathyroid exploration.
Introduction
Total thyroidectomy (TT) has been shown to be a safe and effective treatment for Graves’ disease. However, the time course for improvement of symptoms has not been defined.
Methods
With an institutional review board approval, we prospectively gathered survey data of all patients (n = 79) undergoing TT for Graves’ disease at a single institution from 2019 to 2021. After informed consent was obtained, patients completed surveys preoperatively and at 2 wk followed by monthly postoperative visits/phone calls. Patient demographics and survey results were collected and analyzed. Symptom recovery time was evaluated using Kaplan–Meier analysis.
Results
A total of 50 patients completed the survey on postoperative follow-up (response rate 63%). Average age was 38 y (range 12-80 y) and 88% of patients were female. The most common preoperative symptoms were fatigue (90%) and heat/cold intolerance (88%). Tremor (median time to resolution: 1 wk; interquartile range [IQR] 1-3), diarrhea (median 1 wk [IQR 1-3]), and palpitations (median 1 wk [IQR 1-3]) resolved the most rapidly followed by eye symptoms (median 3 wk [IQR 1-6]), heat/cold intolerance (median 3 wk [IQR 3-30]), memory deficits (median 3 wk [IQR 1-undefined]), and fatigue (median: 3 wk [IQR 1-14]). There were no significant differences in time to resolution of symptoms by gender or age (less than versus 40 y and older). Those with uncontrolled Graves' had more severe symptoms but no difference in time to resolution from the euthyroid Graves’ patients.
Conclusions
Many Graves’ disease symptoms improve rapidly following TT, with a median time to improvement of less than 1 mo.
Background:
Intra-operative identification of parathyroid glands is often a challenge for surgeons performing parathyroid or thyroid surgery. Parathyroid glands stimulated by near-infrared light emit autofluorescence, which allows their discrimination from all other tissues in the region, and this may be of value during thyroid and parathyroid surgery. In this study, we present the results of the utilization of a low-cost device developed for the identification of parathyroid glands in surgery for primary hyperparathyroidism.
Case presentation:
In 5 patients operated in our hospital with the diagnosis of primary hyperparathyroidism and non-concordant ultrasonography and Sestamibi scan, we used a 780 nm Light Emitting Diode (LED) to stimulate the cervical area. The resulting autofluorescence was visualized with night vision goggles with a 832 nm filter assembled. In all the five patients, an easily distinguishable nodule was identified and excised, and confirmed as parathyroid adenoma by histological exam. Intra-operative PTH assay showed significant decrease compared with basal values, fulfilling the Miami Criteria for surgical success in use in our institution.
Conclusion:
The utilization of autofluorescence for intra-operative identification of parathyroid glands may have a clinical application in surgery for primary hyperparathyroidism, being of special utility when ultrasonography and Sestamibi Scan are non concordant.
We created an auto-para viewer, an autofluorescence imaging device, to localize the parathyroid glands during thyroidectomy using an inexpensive Raspberry Pi. A special emission filter in the auto-para viewer was designed to pass 1/100 of visible light and nearly all infrared light longer than 808 nm. With this emission filter, we simultaneously acquired an autofluorescence image of the parathyroid and a visible light image of the surrounding surgical field. The auto-para viewer displayed four times brighter autofluorescence of the parathyroid glands compared to the background tissues without operating room light. Additionally, it showed two times brighter autofluorescence than the background tissues simultaneously showing the surgical field illuminated by the visible light from the operating room light. The NOIR camera, using the auto-para viewer, could reduce the camera's exposure time so the parathyroid glands to be viewed in real-time, which is expected to prevent unintentional damage to the parathyroid gland during thyroidectomy.
Native fluorescence, or autofluorescence (AF), consists in the emission of light in the UV-visible, near-IR spectral range when biological substrates are excited with light at suitable wavelength. This is a well-known phenomenon, and the strict relationship of many endogenous fluorophores with morphofunctional properties of the living systems, influencing their AF emission features, offers an extremely powerful resource for directly monitoring the biological substrate condition. Starting from the last century, the technological progresses in microscopy and spectrofluorometry were convoying attention of the scientific community to this phenomenon. In the future, the interest in the autofluorescence will certainly continue. Current instrumentation and analytical procedures will likely be overcome by the unceasing progress in new devices for AF detection and data interpretation, while a progress is expected in the search and characterization of endogenous fluorophores and their roles as intrinsic biomarkers.
Introduction
The parathyroid glands (PGs) are critical for calcium regulation and homeostasis. The preservation of PGs during neck surgery is crucial to avoid postoperative hypoparathyroidism. There are no existing guidelines for intraoperative PG identification, and the current approach relies heavily on the experience of the operating surgeon. A technique that accurately and rapidly identifies PGs would represent a useful intraoperative adjunct.
Areas covered
This review aims to assess common dye and fluorescence-based PG imaging techniques and examine their utility for intraoperative PG identification. A literature search of published data on methylene blue (MB), indocyanine green (ICG) angiography, near-infrared autofluorescence (NIRAF), and the PGs between 1971 and 2020 was conducted on PubMed.
Expert opinion
NIRAF and near-infrared (NIR) parathyroid angiography have emerged as promising and reliable techniques for intraoperative PG identification. NIRAF may aid with real-time identification of both normal and diseased PGs and reduce the risk of postoperative complications such as hypocalcemia. Further large prospective multicenter studies should be conducted in thyroid and parathyroid surgical patient populations to confirm the clinical efficacy of these intraoperative NIR-based PG detection techniques.
Contrast-free autofluorescence (AF) of the parathyroid glands (PTGs) and thyroid tissue occurs in the near-infrared (NIR) spectrum on excitation by light in the upper range of the visible spectrum or lower NIR spectrum. In vivo, PTGs autofluoresce more brightly than thyroid (by a factor of 2-20 times) and appear as a bright spot against surrounding thyroid, muscle or fat on a processed image which is generated in real-time. NIR-AF of PTGs was first described in 2009 although NIR-AF had previously been used in several other clinical applications. Since then there has been a great amount of interest in the use of NIR-AF in thyroid and parathyroid surgery with over 25 published reports of the utilisation of both self-built and proprietary NIR-AF devices in neck endocrine surgery. All of these reports have confirmed the feasibility of NIR-AF intraoperatively and its ability to detect PTGs, although the reported accuracy varies from 90-100%. Reports of the effect of NIR-AF on relevant clinical endpoints i.e., post-operative hypoparathyroidism in thyroidectomy and persistent disease in parathyroidectomy are however scant. There has been one multicentre clinical trial of NIR-AF in thyroidectomy but this did not report clinical outcomes and two single-centre, non-randomised studies which did report post-operative hypoparathyroidism but with differing results: one showing no benefit in 106 NIR-AF vs. 163 controls and one, a reduction of early hypocalcaemia from 20% to 5% in 93 NIR-AF patients vs. 420 controls. There were only 2 cases of permanent hypoparathyroidism across both studies and therefore no significant observable difference in this key outcome variable. In parathyroidectomy, possible variability of the AF signal due to composition of a PTG adenoma, secondary/tertiary disease and MEN1 as well as depth-penetration preventing detection of sub-surface PTGs would imply that NIR-AF in its current form is not well-placed to improve cure-rates in hyperparathyroidism, which may already be as high as 98%. Thus far, no study has addressed this. Despite the promising results of NIR-AF, the absence of data demonstrating an improvement in outcomes and the cost of its use currently limit its use in routine clinical practice, especially in a publicly funded healthcare system with budgetary constraints. However, it can be utilised in research settings and this should be undertaken within the context of well-designed and conducted randomised, multi-centre, appropriately powered studies, which will assist in establishing its role in neck endocrine surgery.
Objective:
With the recent approval of 2 NIRAF-based devices for label-free identification of PG by the Food and Drug Administration, it becomes crucial to educate the surgical community on the realistic scope of this emerging technology. Here, we have compiled a review of studies that utilize NIRAF and present a critical appraisal of this technique for intraoperative PG detection.
Background:
Failure to visualize PGs could lead to accidental damage/excision of healthy PGs or inability to localize diseased PGs, resulting in postsurgical complications. The discovery that PGs have NIRAF led to new avenues for intraoperatively identifying PGs with high accuracy in real-time.
Methods:
Using the following key terms: "parathyroid, near infrared, autofluorescence" in various search engines such as PubMed and Google Scholar, we identified various publications relevant to this review of NIRAF as a technique for PG identification. Articles were excluded if they focused solely on contrast agents, served as commentaries/overviews on NIRAF or were not written in English.
Results:
To date, studies have investigated the potential of NIRAF detection for (i) identifying PG tissues intraoperatively, (ii) locating PGs before or after dissection, (iii) distinguishing healthy from diseased PGs, and (iv) minimizing postoperative hypocalcemia after total thyroidectomy.
Conclusions:
Because NIRAF-based identification of PG is noninvasive and label-free, the popularity of this approach has considerably surged. As the present limitations of various technologies capable of NIRAF detection are identified, we anticipate that newer device iterations will continue to be developed enhancing the current merits of these modalities to aid surgeons in identifying and preserving PGs. However, more concrete and long-term outcome studies with these modalities are essential to determine the impact of this technique on patient outcome and actual cost-benefits.
Preservation of the parathyroid gland (PTG) in neck endocrine surgery is an important for regulating the amount of calcium in the blood and within the bones. Localization of the PTG has been attempted using various methods such as ultrasound, sestamibi, CT, MRI, and ICG fluorescence imaging. These methods cannot be used during surgery, have high sensitivity, or have PTG specificity. However, autofluorescence technique has shown high sensitivity and does not require exogenous contrast. In this study, a new optical system was designed and developed into a clinical system. The system enabled easier and faster focusing on the surgical area and high‐resolution video imaging while maintaining a clear image. The system was located above the head of the surgeon. The surgeon was able to see the real‐time autofluorescent image on the monitor next to the operating table at any time to locate the PTG. The PTG buried in the adipose tissue and connective tissue was located easily and accurately. The clinical trial conducted in this study consisted of 56 parathyroid cases in 26 patients. For the statistical results, the sensitivity and accuracy in this redesigned autofluorescent imaging system were 98.1% and 96.4%, respectively. This article is protected by copyright. All rights reserved.
Background:
Hypoparathyroidism (hypoPT) is the most common complication after bilateral thyroid operations. Thyroid surgeons must employ strategies for minimizing and preventing post-thyroidectomy hypoPT. The objective of this American Thyroid Association Surgical Affairs Committee Statement is to provide an overview of its diagnosis, prevention and treatment.
Summary:
HypoPT occurs when a low intact parathyroid hormone (PTH) level is accompanied by hypocalcemia. Risk factors for post-thyroidectomy hypoPT include bilateral thyroid operations, autoimmune thyroid disease, central neck dissection, substernal goiter, surgeon inexperience, and malabsorptive conditions. Medical and surgical strategies to minimize perioperative hypoPT include optimizing vitamin D levels, preserving parathyroid blood supply, and autotransplanting ischemic parathyroid glands. Measurement of intraoperative or early postoperative intact PTH levels following thyroidectomy can help guide patient management. In general, a postoperative PTH level <15 pg/mL indicates increased risk for acute hypoPT. Effective management of mild to moderate potential or actual postoperative hypoPT can be achieved by administering either empiric/prophylactic oral calcium and vitamin D, selective oral calcium and vitamin D based on rapid postoperative PTH level(s), or serial serum calcium levels as a guide. Monitoring for rebound hypercalcemia is necessary to avoid metabolic and renal complications. For more severe hypocalcemia, inpatient management may be necessary. Permanent hypoPT has long term consequences for both objective and subjective well-being, and should be prevented whenever possible.
The thyroid and parathyroid chapter of the Head and Neck book gives a broad overview from the most frequent to the rarest diseases of these endocrine glands. Considerations on epidemiology, etiopathogenesis, morphology, and resumed clinical management are provided for each disease, as well as some of the most up-to-date information on molecular markers. Exhaustive photographic documentation is provided for each disease, including macroscopic and microscopic images, as well as recent bibliographic references to guide further readings.
Identification of the parathyroid glands during thyroid surgery may prevent their inadvertent surgical removal and thus provide a better postoperative quality of life. Nevertheless, the most common "technique" for intraoperative evaluation of perfusion of parathyroid gland tissues during thyroid surgery is visual inspection of the physical condition of tissues, e.g., their color and bleeding edges. Another technique is measurement of intact parathyroid hormone. Recently, indocyanine green-enhanced fluorescence has been used in various surgical techniques, particularly laparoscopic surgery, to improve visualization and to provide detailed anatomical information. Fluorescent optical guidance helps surgeons to avoid inadvertent tissue injury while enhancing procedural efficiency. This technique has potential use for evaluating perfusion of the parathyroid gland in real-time intraoperative angiography.
BID = bis in die DSPTC = diffuse sclerosing papillary thyroid cancer FNA = fine-needle aspiration HT = Hashimoto thyroiditis iPTH = intact parathyroid hormone 25OHD = 25-hydroxy vitamin D PTH = parathyroid hormone TPO = thyroid peroxidase US = ultrasonography.
Hypocalcaemia is common after thyroidectomy. Accurate prediction and appropriate management may help reduce morbidity and hospital stay. The aim of this study was to perform a systematic literature review and meta-analysis of predictors of post-thyroidectomy hypocalcaemia.
A systematic search of PubMed, EMBASE and the Cochrane Library databases was undertaken, and the quality of manuscripts assessed using a modified Newcastle-Ottawa Scale.
Some 115 observational studies were included. The median (i.q.r.) incidence of transient and permanent hypocalcaemia was 27 (19-38) and 1 (0-3) per cent respectively. Independent predictors of transient hypocalcaemia included levels of preoperative calcium, perioperative parathyroid hormone (PTH), preoperative 25-hydroxyvitamin D and postoperative magnesium. Clinical predictors included surgery for recurrent goitre and reoperation for bleeding. A calcium level lower than 1·88 mmol/l at 24 h after surgery, identification of fewer than two parathyroid glands (PTGs) at surgery, reoperation for bleeding, Graves' disease and heavier thyroid specimens were identified as independent predictors of permanent hypocalcaemia in multivariable analysis. Factors associated with transient hypocalcaemia in meta-analyses were inadvertent PTG excision (odds ratio (OR) 1·90, 95 per cent confidence interval 1·31 to 2·74), PTG autotransplantation (OR 2·03, 1·44 to 2·86), Graves' disease (OR 1·75, 1·34 to 2·28) and female sex (OR 2·28, 1·53 to 3·40).
Perioperative PTH, preoperative vitamin D and postoperative changes in calcium are biochemical predictors of post-thyroidectomy hypocalcaemia. Clinical predictors include female sex, Graves' disease, need for parathyroid autotransplantation and inadvertent excision of PTGs.
A major challenge in endocrine surgery is the intraoperative detection of parathyroid glands during both thyroidectomies and parathyroidectomies. Current localization techniques such as ultrasound and sestamibi scan are mostly preoperative and rely on an abnormal parathyroid for its detection. In this paper, we present near-infrared (NIR) autofluorescence as a nonintrusive, real-time, automated in vivo method for the detection of the parathyroid gland. A pilot in vivo study was conducted to assess the ability of NIR fluorescence to identify parathyroid glands during thyroid and parathyroidectomies. Fluorescence measurements at 785 nm excitation were obtained intra-operatively from the different tissues exposed in the neck region in 21 patients undergoing endocrine surgery. The fluorescence intensity of the parathyroid gland was found to be consistently greater than that of the thyroid and all other tissues in the neck of all patients. In particular, parathyroid fluorescence was two to eleven times higher than that of the thyroid tissues with peak fluorescence occurring at 820 to 830 nm. These results indicate that NIR fluorescence has the potential to be an excellent optical tool to locate parathyroid tissue during surgery.
Permanent hypoparathyroidism is a recognized complication of thyroidectomy. Apart from preservation of parathyroid glands in situ by meticulous dissection, parathyroid autotransplantation (PTHAT) has been performed increasingly to avoid permanent hypoparathyroidism.
From January 1995 to October 1997, PTHAT was performed routinely for devascularized or inadvertently removed glands in 98 (36%) of 271 patients undergoing thyroidectomy. Potential risk factors and the impact of PTHAT on postoperative hypocalcemia were studied.
Postoperative hypocalcemia occurred in 40 patients (14.8%), whereas 5 patients (1.8%) had permanent hypocalcemia during a median follow-up of 9 months. The incidence of transient hypocalcemia (n = 35) was higher in patients who underwent PTHAT (21.4%) than in patients who did not undergo PTHAT (8.1%) (P < .01). Permanent hypocalcemia occurred only in patients who did not undergo PTHAT. None of the 21 patients who had postoperative hypocalemia after PTHAT had permanent hypoparathyroidism compared with 26% (5/19) of patients who did not undergo PTHAT (P = .018). When the resected thyroid gland was examined for parathyroid tissue, the incidence of positive identification was higher in patients who did not undergo PTHAT (13%) than in patients who did undergo PTHAT (4%) (P = .015).
Patients with postoperative hypocalcemia after PTHAT have virtually no risk of having permanent hypoparathyroidism. A more careful examination of the resected thyroid tissue can help to identify inadvertently removed parathyroid glands for autotransplantation.
Primary hyperparathyroidism (HPT) in 80% of patients is due to a solitary parathyroid adenoma, while in 20% multigland pathology exists, usually hyperplasia [Scott-Coombes, Surgery, 21(12):309-312, 2003]. Despite recent advances in minimally invasive parathyroidectomy, better preoperative localisation techniques and intraoperative parathyroid hormone (PTH) monitoring, a 4% failure rate [Grant CS, Thompson G, Farley D, Arch Surg, 140:47-479, 2005] persists making accurate differentiation between adenomas and hyperplasia of prime importance. We investigated the ability of Raman spectroscopy to accurately differentiate between parathyroid adenomas and hyperplasia. Raman spectra were measured at defined points on the parathyroid tissue sections using a bench-top microscopy system. Multivariate analysis of the spectra was carried out to construct a diagnostic algorithm correlating spectral results with the histopathological diagnosis. A total of 698 spectra were analysed. Principal-component (PCA)-fed linear discriminant analysis (LDA) used to construct a diagnostic algorithm. Detection sensitivity for parathyroid adenomas was 95% and hyperplasia was 93%. These preliminary results indicate that Raman spectroscopy is potentially an excellent tool to differentiate between parathyroid adenomas and hyperplasia.
Thyroid and parathyroid glands
- Wiseman