Bilateral cervical exploration has been considered the standard operation since its first description (Mandl, Vienna) in the 1930s. With appropriate expertise, the cure rate of the initial operation is over 95% with only minimal morbidity.
The therapeutic goal is the complete, long-term, and morbidity-free normalization of serum calcium through a single operation.
After exposing the thyroid gland, the first goal is to identify the recurrent laryngeal nerve and the inferior thyroid artery. The nerve is best identified caudal to the artery and is followed in its course up to its entry into the larynx. The nerve usually runs over the artery. Resection of a parathyroid gland before identifying the nerve is not permitted in bilateral cervical exploration.
The systematic search for the parathyroid glands should begin with the upper ones. The upper parathyroid gland is almost always found cranial to the inferior thyroid artery and dorsal to the recurrent laryngeal nerve. If that is not the case, it is dislocated dorsal next to the esophagus on the spine towards the posterior mediastinum. The lower parathyroid glands are more variable in their location. They lie caudal to the inferior thyroid artery and ventral to the recurrent laryngeal nerve.
If 4 parathyroid glands are identified, of which one is enlarged, the enlarged one is removed and the diagnosis is confirmed by frozen section examination. Only rarely is there a double adenoma (2-6 %). If 3 or more parathyroid glands are enlarged, a 3½ gland resection is recommended, provided that familial hyperparathyroidism and a MEN syndrome could be reliably excluded beforehand. The parathyroid remnant is marked with a clip.
Improved results of preoperative localization diagnostic procedures as well as the possibility of intraoperative determination of parathyroid hormone (Quick-Parathyroid Hormone Test) make minimally invasive procedures possible, although the significance of intraoperative Quick-PTH is not clearly proven and in studies only leads to an improvement in surgical success of 1 %.
Re-operations due to persistent or recurrent hyperparathyroidism are often extremely difficult, time-consuming and should in principle only be performed by surgeons who have experience in parathyroid surgery. To document the success of the operation, a determination of serum calcium should be carried out on the day following the operation, and in addition, the vocal cord function must be checked.
Parathyroid scintigraphy is primarily used in persistent hyperparathyroidism, in recurrent hyperparathyroidism, in suspicion of ectopia, and in planned minimally invasive surgical technique to further confirm the sonography findings.
MRI and CT show predominantly good results in a few studies, but are still classified as additive procedures for special cases.
Parathyroid adenomas can usually be localized by imaging procedures. Problems arise with the simultaneous presence of hypoechoic thyroid nodules, which are often indistinguishable from parathyroid adenomas. Conventional imaging procedures are also not always able to localize adenomas.
In such problem cases, parathyroid scintigraphy can be used to localize thyroid adenomas.
Here, a combination of thyroid scintigraphy with Tc pertechnetate and immediately before or after a scintigraphy with TL-chloride is used. By using an optimal SPECT technique, it is also possible to detect small parathyroid adenomas with a mass of 0.3 to 1 gram with a sensitivity of 95 %.
The standard operation for hyperparathyroidism involves bilateral cervical exploration and the identification of all four parathyroid glands and the removal of the pathologically altered parathyroid tissue. Through new localization methods such as TC Sestamibi scintigraphy, high-resolution ultrasound examination in conjunction with color duplex sonography, and intraoperative measurement of intact parathyroid hormone, targeted operative therapy without the need for exploration of all parathyroid glands has become possible.
Until the 1980s, open bilateral exploration with identification of all four parathyroid glands via a Kocher collar incision was the usual surgical method. For this procedure, cure rates of 92-99 %, surgery-related morbidity of 1-3 %, and a late recurrence rate of under 3 % were reported. Surgery-related deaths are only reported sporadically. Despite these excellent results, advances in preoperative localization diagnostics through high-resolution sonography and Tc Methoxy Isobutyl Isonitrile scintigraphy have led to efforts to minimize the procedure through targeted unilateral exploration via various access routes and thus further improve the results. Shortened operating times, shorter inpatient stays, and thus lower costs are arguments for targeted, possibly minimally invasive exploration.
However, since 10-20 % of patients have multi-gland disease due to 4-gland hyperplasia or double adenoma, which are only inadequately detected by preoperative localization diagnostics, targeted limited exploration requires optimized preoperative localization diagnostics and intraoperative functional success control. As preoperative diagnostics, high-resolution sonography and MIBI scintigraphy are usually performed. These procedures can correctly localize a solitary adenoma in 60 or 90 % of cases, respectively, but multi-gland disease is recognized as such in less than 20 % of cases. Through PTA monitoring, targeted unilateral exploration in primary hyperparathyroidism is possible with success rates identical to those for bilateral exploration and is the basis for a minimally invasive approach.