Additionally, Testini et al. Therefore, despite the strong correlation between autotransplantation and transient hypocalcaemia, these results may be partially confounded by the indication for autotransplantation being parathyroid devascularization. Two studies have demonstrated a statistically significant decrease in permanent hypoparathyroidism after parathyroid autotransplantation. Ahmed et al. The patients in this study were initially randomly assorted but favorable results in the autotransplantation group led to a policy of routine autotransplantation, this demonstrates a bias towards the use of parathyroid grafting.
Wei et al. They found that permanent hypoparathyroidism was lower after parathyroid autotransplantation compared with preservation in situ, 0. The authors also note that autotransplantation may allow a more comprehensive central neck dissection. This may illustrate that parathyroid autotransplantation is more effective in cases where central neck dissection is required as these have been demonstrated to have an increased risk of post-operative hypocalcaemia However, no significant difference was found between patients undergoing parathyroid transplantation or controls.
Overall parathyroid autotransplantation is associated with transient hypoparathyroidism but a reduction in rates of permanent hypoparathyroidism. Although the number of patients benefitted will be low, as only one functioning gland in situ may be enough for prevention, the morbidity related to permanent hypocalcaemia is so significant that this small potential benefit is more advantageous than leaving devascularized or jeopardized glands in place where their ongoing function is unpredictable.
Despite a lack of clear empirical evidence, parathyroid autotransplantation is an effective procedure that can safeguard against permanent hypoparathyroidism Table 2. Cryopreservation is another method, again pioneered by Wells 61 , to avoid permanent hypoparathyroidism following parathyroid or thyroid surgery 9 , Cryopreservation involves the freezing and storage of parathyroid tissue in case permanent hypoparathyroidism occurs It has been advocated in patients undergoing surgery for persistent or recurrent hyperparathyroidism and patients requiring subtotal or total parathyroidectomy but also in thyroid and central neck dissection due to the risk of failure of immediately transplanted autografts Although its most obvious indication remains primary multi-glandular hyperparathyroidism when it is unclear if post-operative patients will go on to develop further hyperparathyroidism but remain at considerable risk of developing permanent hypoparathyroidism postoperatively Agarwal et al.
However, 2 of the patients remained on high dose calcium at the conclusion of their study. They did not offer parathyroid gland cryopreservation for routine thyroidectomy patients. On the other hand, a large multicenter trial in France cryopreserved 1, parathyroid tissue samples. Cryopreservation is a useful and potentially beneficial procedure in only a very small number of selected cases of permanent hypocalcaemia.
Most studies continue to focus on prevention of parathyroid dysfunction by careful preservation in situ and utilizing selective parathyroid autotransplantation when necessary.
Yet the disease burden of post-operative hypocalcaemia remains high with many studies reporting a low level of permanent hypocalcaemia despite utilizing autotransplantation. Considering the relative success of parathyroid autotransplantation and the innate characteristic of parathyroid tissue to be transplanted 67 it is worth considering allotransplantation in the treatment of chronic hypoparathyroidism.
Unfortunately, to date, allotransplantation has had variable results usually due to rejection by alloimmunization or inflammatory responses causing fibrosis compromising graft survival 68 , The risks involved in immunosuppression both from medication side effects and risk of infection are generally not considered to outweigh the benefit in terms of long term treatment for hypoparathyroidism.
Yet Agha et al. Alternatively, Nawrot et al. They found that of 85 allotransplants, 65 cellular allografts retained endocrine function for two months with a mean overall graft survival of 6. Graft function was considered present when overall PTH level increased compared to pre-operatively, the was an evident PTH gradient between ipsilateral and contralateral arms and patients no longer required vitamin D and only minimal calcium supplementation.
Case reports have also demonstrated increased survival through the use of microencapsulated parathyroid tissue. Alternatively, new stem cell research has yielded promising results regarding the generation of parathyroid-like cells. Ignotski et al. They note that parathyroid cells are optimal for cellular replacement as each cell contains that complete function of the organ, no architectural structure is needed for parathyroid cells to resume function and autotransplantation has been demonstrated to reconstitute normal parathyroid function.
Therefore, more research is required before stem cells differentiated to produce parathyroid hormone are useful in the treatment of post thyroidectomy hypoparathyroidism. Hypocalcemia can cause tremors, stiffness and muscle pain, as well as confusion and memory problems in some cases. When is parathyroid gland reimplantation performed? Parathyroid gland reimplantation or autotransplantation can be performed to reduce the risk of hypoparathyroidism if the parathyroid glands are accidentally removed during a thyroidectomy thyroid gland removal , for example in the case of thyroid cancer.
The procedure can also be carried out as part of a parathyroidectomy or removal of the parathyroid glands, related to an overfunction of the parathyroid glands, called hyperparathyroidism. How does the parathyroid gland reimplantation procedure work?
Parathyroid gland reimplantation can be done immediately during surgery or after cryopreservation of the glands cooling at very low temperature. Fragments of the parathyroid glands are injected with a syringe into the sternocleidomastoid muscle of the neck or in the forearm, under the skin.
Is parathyroid gland reimplantation effective? Introduction: Parathyroid autotransplantation plays an important role in preventing hypoparathyroidism following thyroidectomy. The preferred reimplantation site is still the sternocleidomastoid muscle, but this approach does not permit to check graft vitality postoperatively. The authors report the first prospective evaluation of normal parathyroid gland reimplantation in forearm subcutaneous tissue using the same technique proposed during parathyroidectomy for hyperplasia in case of devascularized or inadvertently removed glands during thyroid surgery.
The muscle pockets were closed using small metallic clips or silk sutures. Blood samples were drawn from both forearms at the antecubital fossae within 24 hours of surgery day 1 and again at 3, 14 2 weeks , 28 1 month , 56 2 months , and 84 3 months days after surgery.
Prolonged use of a tourniquet was avoided before blood sampling. Three milliliters of venous blood were collected in plain bottles, which were immediately spun in a refrigerated centrifuge to separate serum from cells. In addition, serum calcium levels were measured every 12 to 24 hours. Replacement therapy with oral calcium supplements calcium carbonate, g daily or vitamin D analog calcitriol, 0.
The 7 patients are described in Table 1. They had a median age of 48 years range, years. The right and left forearms were used for PTX in 1 and 6 patients, respectively.
The number of parathyroid glands seen during surgery ranged from 2 to 4. Three patients developed symptomatic hypocalcemia requiring replacement therapy to maintain normocalcemia before hospital discharge. Use of the supplements was gradually discontinued 2 to 4 months after surgery, accompanied by normalization of PTH levels. The serum calcium level remained normal 2 weeks after discontinuation of calcium supplementation. The PTH measurements and gradients between the grafted and nongrafted arm venous samples for all patients are summarized in Table 2.
Figure 1 shows the PTH values of grafted and nongrafted forearm samples in individual patients with documented grafted function at 3 months. Biochemical graft function, as seen by a 1. All patients had normal PTH levels in venous samples obtained from nongrafted forearms 3 months after surgery.
The PTH measurements sampled from nongrafted arms were within the reference range in all patients during follow-up. Within the time scheduled for venous sampling during follow-up, PTH progressively recovered in venous samples from grafted and nongrafted forearms Figure 3 , and the overall maximal PTH hormone gradient was reached 2 months after surgery Figure 4. In , Murray 12 proposed several criteria to evaluate successful endocrine transplantations, including 1 documented hormone deficiency before transplantation, 2 evidence of correction of hormonal deficiency after grafting, 3 microscopic evidence of graft survival, 4 return of hormonal deficiency after removal of the graft, and 5 postmortem evaluation of ectopic endocrine tissue.
With reference to PTX, it is difficult to apply these unequivocal morphological and functional criteria to human studies. However, functional assessment of parathyroid autografts has included maintenance of normocalcemia without calcium supplementation, elevated PTH concentration in blood draining from the grafted site compared with systemic blood, increase in PTH level after transplantation, and graft uptake of radioisotopes.
Wells et al 1 demonstrated successful PTX clinically and biochemically in a large series of patients who underwent surgery for hyperparathyroidism. In autotransplantation of parathyroid tissue during persistent primary, secondary, or tertiary hyperparathyroidism, forearm autotransplantation is usually performed to avoid reoperation on the neck and for easy monitoring of abnormal graft function.
Parathyroid autotransplantation has been performed in humans during partial thyroidectomy in an attempt to preserve parathyroid function.
Despite being a procedure with a long tradition, biochemical graft function and the success of PTX during thyroid surgery cannot be easily documented. In fact, primary hyperparathyroidism may develop, albeit rarely, after autotransplantation of histologically normal parathyroid tissue during thyroid surgery. Several studies on PTX during thyroidectomy determined graft function mainly based on biochemical analysis of the serum calcium concentration 11 , 16 , 17 or infrequently on PTH measurement in peripheral circulation.
Funahashi et al 18 documented the recovery patterns of the PTH level from undetectable to the preoperative level 2 weeks after autotransplantation of 2 to 4 parathyroid glands in 17 patients.
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