Atlas of Parathyroid Surgery

© Springer Nature Switzerland AG 2020

A. Shifrin (ed.)Atlas of Parathyroid Surgeryhttps://doi.org/10.1007/978-3-030-40756-8_1

1. Bilateral Exploration for Hyperparathyroidism

Janice L. Pasieka¹ and Steven Craig²  

(1)

Department of Surgery, Foothills Medical Centre, Calgary, AB, Canada

(2)

Department of Surgery, Illawarra Shoalhaven Local Health District, NSW, Australia

Steven Craig

Email: [email protected]

Keywords

HyperparathyroidismBilateral neck explorationOperative technique

Introduction

A bilateral neck exploration (BNE) is a fundamental skill for any surgeon involved in the treatment of parathyroid disease, and it remains the gold standard procedure for the management of hyperparathyroidism (HPT). In experienced hands, it is a safe and highly effective procedure. Furthermore, it is a cost-effective operation that can be performed anywhere in the world, without need for sophisticated preoperative imaging modalities or intra-operative surgical adjuncts. This chapter describes the morphological information and technical steps that facilitate performing this operation in a safe and efficient manner.

Preoperative Considerations for Confirmed Hyperparathyroidism

Indications

Non-visualization of parathyroid adenoma on preoperative imaging studies

Discordant results on preoperative imaging studies

Limited or no access to preoperative imaging and/or surgical adjuncts such as intra-operative parathyroid hormone (iPTH) monitoring

Familial causes of HPT, including multiple endocrine neoplasia (MEN) type 1 or 2, familial isolated HPT, and HPT-jaw tumor syndrome

Four-gland parathyroid hyperplasia, including progressive secondary and tertiary HPT

Conversion from a unilateral approach, due to failure to identify one normal and one abnormal gland

Conversion from a focused, image-directed approach, due to failure of intra-operative parathyroid hormone iPTH measurements to fall in accordance to defined criteria

Advantages of Bilateral Approach

Allows for morphological examination of all parathyroid glands to distinguish single-gland disease (SGD) from multi-gland disease (MGD), which can remain occult on preoperative localization studies and iPTH criteria

Cost-effective effective surgical strategy as it does not depend on preoperative imaging or surgical adjuncts

Lower rate of long-term recurrence compared to focused approaches [1, 2]

Disadvantages of Bilateral Approach

Typically requires a general anesthesia.

Exposure of all parathyroid glands and both recurrent laryngeal nerves (RLN) increases the risk of RLN injury and post-operative hypocalcemia.

Preoperative Assessment

Confirmation of Diagnosis

Diagnosis of HPT is biochemical; imaging modalities aid in surgical planning only, not in diagnosis.

Initial assessment should include serum calcium, phosphate, PTH, 25-hydroxyvitamin D, 24-hour urine calcium and creatinine, serum creatinine levels.

Genetic counselling should also be considered in young patients (<40 years), especially those with MGD and/or a significant family history of hyperparathyroidism or hereditary endocrine syndrome [3].

Assessment of Symptoms and End-Organ Effects

Objective manifestation: nephrolithiasis, fragility fractures, osteoporosis/osteopenia (on BMD measurement), hypercalcemic crisis, pancreatitis, confusion

Subjective symptoms: musculoskeletal, gastrointestinal, cognitive, and neuropsychiatric complaints

Preoperative Imaging

Imaging should be used to exclude concomitant thyroid pathology and to help plan the optimal surgical approach. It has no utility in confirming or excluding the diagnosis of HPT. Negative imaging results do not exclude a patient from consideration for surgery.

Ultrasound provides information on parathyroid localization and anatomical relationships, as well as characterization of concomitant thyroid pathology that may need to be investigated and treated prior to, or in conjunction with, HPT.

Sestamibi scan and 4D CT scan are not essential in patients planned for a BNE. However, if discordant imaging results occur, there is a higher risk of MGD, and as such a BNE would be indicated.

Informed Consent

General and anesthetic risks: DVT/PE, pneumonia, MI etc.

Postoperative bleeding and infection: <1% [4–6]

Injury to RLN: 1–2% [5, 7]

Hypoparathyroidism: <1% for SGD, 1–3.5% for MGD [5, 8, 9]

Recurrence <2% [1, 2, 10]

Instruments Required

General anesthetic.

General instruments including scalpel with no. 15 blade, skin hooks, army-navy retractors, Crile forceps, Metzenbaum scissors, and toothed and nontoothed forceps.

Self-retaining retractor.

Monopolar and bipolar cautery.

Energy-based vessel sealing devices (e.g., Harmonic or LigaSure systems) are NOT required to safely perform a BNE.

Access to a pathology service for frozen section examination is desirable, though again not essential for BNE.

Surgical loupes greatly improve the appreciation of the subtle morphological clues for identifying parathyroid glands, but are also not essential for the operation.

Intra-operative PTH:

Though not needed in a BNE, iPTH may be a useful surgical adjunct to help guide the extent of dissection and amount of parathyroid tissue removed in multi-gland disease.

Patient Positioning and Theater Setup

Patient should be positioned supine on the operating table with the head extended. This is achieved by placing a soft roll transversely beneath the shoulders and a foam head ring below the cranium. Care should be taken to ensure the head is not hanging in the extended position but is properly supported by the head ring.

Both arms are appropriately tucked by the sides with pressure point padding.

The bed is positioned in slight reverse Trendelenburg to reduce venous pressure in the neck.

Endotracheal tube and ventilator tubing are directed off the table in the midline.

Recurrent laryngeal nerve monitoring is NOT required to safely perform a BNE.

Operative Steps and Technique

Incision and Exposure

A transverse skin incision is marked on the anterior neck approximately 2 cm above the sternal notch.

A 15-blade scalpel is used to incise the skin, subcutaneous tissue, and platysma.

The superior platysmal flap is raised to the level of the thyroid cartilage notch. The inferior platysmal flap is raised to the level of the suprasternal notch.

Mobilization of Strap Muscles

The sternohyoid muscles are separated along the median raphe in the midline using electrocautery and Crile forceps, and the dissection continues through the loose areolar tissue to expose the anterior surface of the thyroid gland.

Lateral Mobilization of Thyroid Gland and Identification and Ligation of Middle Thyroid Vein

A Crile is used to help dissect the fibroareolar tissue lateral to the thyroid down to the anterior surface of the carotid artery.

The anterior surface of the carotid artery is a safe dissection plane; the only structure passing anterior to the surface of carotid is the middle thyroid vein, which should be carefully ligated between two Criles with 3–0 silk.

Identification of Parathyroid Glands

The next step of the procedure is to identify the key landmarks and morphologic features that can help to locate the parathyroid glands using a combination of visual inspection, manual palpation, and careful blunt dissection.

Pearls for Identification of Parathyroid Glands

Aside from the classic description of normal parathyroid glands being London tan in color and about the size of a grain of rice, there are a number of other subtle and less frequently described morphological features that aid in their identification:

Bloodless field: A bloodless surgical field is of high importance when attempting to identify parathyroid glands, as any bloodstaining impairs the ability to identify and assess the morphological features of the gland.

Parathyroid glands are not palpable unless abnormal: A normal parathyroid gland is soft and quite compressible on digital palpation. This important feature can help to differentiate a normal gland from a small lymph node, which is normally rubbery and palpable.

Fat pads (Fig. 1.1): The parathyroid glands are often encased in a fat pad located in a region where the thymus points to the inferior pole of the thyroid gland (inferior gland), and cranial to the ITA and generally posterior to the RLN (superior gland).

Vascular pedicle: A small vascular pedicle can often be seen entering the parathyroid gland.

Cope’s sign (Fig. 1.2): Bruising of the parathyroid gland that can occur with mobilization or dissection.

Kissing glands (Fig. 1.3): This term is used to describe two parathyroid glands that are so close in position that they appear to a single, bilobed gland. Although uncommon, this possible configuration should be borne in mind when searching for a missing gland. Kissing glands can be differentiated from a true bilobar gland by identifying a cleavage plane between the capsules of the two glands.

Slides under fascia: The parathyroid glands are usually found within the thyroids pretracheal fascial capsule, but not adherent to it. This feature allows the gland to be gently slid or rolled under the fascia by a fine instrument such as a Crile.

Fig. 1.1

Fat pads. Visual inspection can yield many clues to aid in the identification of the parathyroid glands. Inspection should begin by looking for a fat pad located where the thymus points to the inferior pole of the thyroid gland for the inferior gland, and 1–2 cm cranial to the inferior thyroid artery on the posterior surface of the thyroid gland and anterior to the recurrent laryngeal nerve (as shown)

Fig. 1.2

Cope’s sign. Mobilization in the area of the parathyroid gland can cause bruising and discoloration of the parathyroid gland. This sign is often subtle, but it can be an important visual cue to direct further dissection. This image shows a red-purple discoloration at the top of the thymus in the region of the inferior parathyroid gland. Further dissection allowed morphologic identification of a normal inferior gland

Fig. 1.3

Kissing left upper and lower parathyroid glands. Parathyroid tissue was identified in a fat pad at the level of the inferior thyroid artery, which initially appeared to be a single, bilobed gland. Closer inspection revealed a cleavage plane between the lobes, which was carefully dissected, and separate upper and lower glands were able to be morphologically identified

Identification of Superior Parathyroid Gland

Exposure of the Prevertebral Fascia

The first step in identifying the superior gland is to locate the inferior thyroid artery (ITA).

The ITA is a crucial reference point for the location of the superior parathyroid gland; the superior parathyroid gland is usually found in an area 1 cm cranial to the ITA.

Once the ITA has been identified, blunt dissection cranial to the artery and directly posterior is performed down to the shiny prevertebral fascia.

The prevertebral fascia defines the posterior extent of the dissection, and the most posterior location possible for a superior