Parathyroid Embryology Research Articles

Neonatal Severe Primary Hyperparathyroidism: A Series of Four Cases and their Long-term Management in India.

Context:Neonatal severe primary hyperparathyroidism (NSPHPT) is an extremely rare autosomal recessive disorder, requiring a high index of suspicion. Infants affected with this disorder present with severe life-threatening hypercalcemia early in life, requiring adequate preoperative medical management followed by surgery.Aims:We report four newborns with NSPHPT who were managed over 10 years.Subjects and Methods:Demography, clinical presentation, treatment, and follow-up data were retrospectively studied with descriptive analysis to highlight the utility of long-term medical management, surgery, and genetic testing reported in the literature.Statistical Analysis Used:Descriptive Analysis.Results:We had three males and one female infant with a mean age of diagnosis at 28.7 days, calcium 29.2+/-2.8 mg/dL, and parathormone (PTH) 1963+/-270.4 pg/mL. All four infants presented with failure to thrive, hypotonia, and respiratory distress. All infants were treated medically followed by total parathyroidectomy plus transcervical thymectomy, with an additional hemithyroidectomy in one of them. Imaging was negative in all four cases. Three babies became hypocalcemic while the fourth infant had a drop in PTH and is on the tab. cinacalcet 30 mg/day. CaSR mutation was positive in three infants.Conclusions:Diagnosing NSPHPT needs expert clinical acumen. It requires emergency medical management to control calcium levels. The crisis may present later, necessitating parathyroidectomy in these cases once the child is fit for surgery. Surgery offers a cure for this unusual lethal hypercalcemia while the role of cinacalcet needs a special mention. Sound knowledge in endocrinology with parathyroid embryology and morphology is of paramount importance. Our case series might add a few insights into managing this unusual genetic disorder.

Parathyroidectomy Without the Utilisation of iPTH: The Gold Standard is Still a Good Operation-How Understanding the Anatomy and a Simple US Can Help.

Parathyroid surgery is frequently performed after at least two preoperative localisation studies, in addition to the use of intraoperative ioPTH. The key to performing a successful parathyroidectomy is reliant on the surgeon having an outstanding knowledge of parathyroid embryology and anatomy. With this, it is possible to undertake surgery with a simple neck ultrasound and without more expensive pre- and intraoperative localisation studies.

Parathyroid Embryology, Anatomy, and Pathophysiology of Primary Hyperparathyroidism

Unregulated overproduction of parathyroid hormone (PTH) from an abnormal parathyroid gland is the origin of primary hyperparathyroidism (PHPT). Patients who have an elevated serum calcium concentration have a problem in one or more of their parathyroid glands. To understand this disease state adequately and provide appropriate treatment, a thorough understanding of parathyroid embryology, anatomy, physiology, and pathophysiology is essential. In this manuscript, we review our current understanding of parathyroid gland embryology, anatomy, histology, physiology, and pathophysiology.

Anatomy and embryology of the parathyroid gland

Experienced parathyroid surgeons recognize that the embryology of the parathyroid glands would guide them in their anatomic dissections to localize the abnormal glands. This becomes particularly important in circumstances when the glands are not in their “normal” locations. Surgeons must be familiar with the embryology that is so inherently linked with the final anatomic location of the glands. It is not uncommon for patients to have undergone failed surgical explorations secondary to parathyroid glands being in ectopic locations that were not appreciated. Parathyroid embryology knowledge can bridge that gap and direct the surgeon to those sites. In this article, variations in anatomic location, relation to critical structures including the recurrent laryngeal nerve, the number of glands, and even gland size and morphology would be explored and thereby provide the platform for parathyroid surgery.

Undescended parathyroid adenomas as cause of persistent hyperparathyroidism.

Undescended glands are a rare cause of primary and secondary hyperparathyroidism (HPT), but they are more common, however, among patients with recurrent HPT or those who have undergone a failed initial cervical exploration. The currently development of more precise noninvasive imaging techniques has improved the results of preoperative diagnosis of these ectopic lesions. The operative reports of patients undergoing parathyroidectomy at our institution were reviewed to identify patients with an undescended parathyroid gland adenomas. Demographic, clinical, imaging and surgical variables were recorded. Three patients were included: 2/598 parathyroidectomies performed for primary HPT and 1/93 performed for secondary HPT. One case is presented as jaw tumor syndrome (JTS). All the patients had undergone at least one operation before the definitive focused surgery and represented 6% of our parathyroid reoperations. No significant complications and no recurrences were observed in the long-term follow up. Accurate preoperative localization of these lesions was possible with noninvasive studies. High cure rate is possible through selective approach when accurate preoperative localization. Thorough knowledge of parathyroid embryology and meticulous surgical technique are essential, particularly in patients with previous unsuccessful explorations.

What steps should be considered in the patient who has had a negative cervical exploration for primary hyperparathyroidism?

The key to cure of the patient with persistent primary hyperparathyroidism is a clear understanding of the investigations, operative procedure and pathology related to the initial procedure. Reinvestigation and subsequent surgery should be performed in a specialist unit. A logical pathway of increasingly sophisticated localization studies (MIBI, ultrasound, CT/MRI, selective venous catheterization for PTH) will usually guide the surgeon to the missing parathyroid gland/s. Improved preoperative localization can facilitate the use of a minimally invasive small incision approach. The surgeon must have a detailed knowledge of the nuances of parathyroid embryology and a meticulous surgical technique, not only to identify and safely remove the retained gland/s but also do so without causing unnecessary morbidity. Results of re-operation (84-98% cure) from centres of excellence are highly commendable, yet the use of 'new' technology (that includes intra-operative PTH) has not translated into improved outcomes in all cases. Some parathyroid glands are extremely difficult to find! Re-operative parathyroid surgery is a challenge, sometimes easy, and on other occasions extremely difficult.

Reoperative parathyroid surgery

Reoperative parathyroid surgery can be technically challenging and exposes the patient to a higher risk of complications than initial parathyroidectomy. Initial surgical failure can be avoided by thorough, bilateral exploration by an experienced parathyroid surgeon or by the use of intraoperative parathyroid hormone (PTH) monitoring if a limited exploration is planned. Before undertaking a reoperation for hyperparathyroidism the patient must be fully reevaluated including a reassessment of the need for surgery, a review of all previous surgical and pathology reports, and the performance of imaging studies to identify the location of the missing gland. An understanding of parathyroid embryology and anatomy helps identify possible locations of missing glands. The specific surgical approach is dictated by the anticipated location of the abnormal gland. Intraoperative PTH monitoring can limit the extent of reoperative surgery. Recurrent laryngeal nerve monitoring can help decrease the risk of complications.

Parathyroid imaging with Tc-99m sestamibi planar and SPECT scintigraphy.

Technetium-99m sestamibi planar and single-photon-emission computed tomographic scintigraphy is useful in the diagnosis of parathyroid gland disease. To understand the various patterns of parathyroid disease, it is important to understand parathyroid embryology and anatomy. The spectrum of parathyroid disease demonstrated with Tc-99m sestamibi scintigraphy includes eutopic disease, ectopic disease, solitary adenoma, double or multiple adenomas, cystic adenoma, lipoadenoma, multiple endocrine neoplasia, hyperfunctioning parathyroid transplant, entities with atypical washout, and nonparathyroid entities that take up Tc-99m sestamibi. The diagnosis of parathyroid tumors with Tc-99m sestamibi scintigraphy is based on the difference in clearance rates between the thyroid and diseased parathyroid glands, and any condition that interferes with radiotracer clearance will limit the effectiveness of the study. The technique is most clearly indicated for the preoperative evaluation of recurrent or persistent hyperparathyroidism, but it is increasingly being used before the initial surgical exploration as well. Subtraction Tc-99m sestamibi and iodine-123 scintigraphy may be helpful in difficult cases. Parathyroid hyperplasia, multisite parathyroid disease, and concomitant thyroid and parathyroid disease remain potential hurdles for this scintigraphic technique, and optimal handling of these problems still relies heavily on the skill and experience of the endocrine surgeon.

Surgical Embryology and Anatomy of the Thyroid and Parathyroid Glands

A thorough knowledge of parathyroid embryology and anatomy is essential for maximum success in restoration of calcium homeostasis in those patients who have a form of hyperparathyroidism. In fact, an initial meticulous neck dissection by a competent parathyroid surgeon who is well versed in the embryology and anatomy of the neck is the current "hi tech" method of choice for parathyroid gland localization.