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Fig. 48.5 Identication of the RLN at the crico-tracheal joint
R. Simó et al.
Fig. 48.6 Identication of the RLN laterally at the level of the Tubercle of Zuckerkandl
the thyroid gland rst is systematically dissected, and its contour is followed down to the position of the superior parathyroid gland. Dissection is performed close to the cap­sule or pseudo-capsule to avoid unintentional removal of the glands. The thyroid gland is inspected before its nal removal to ensure that there are no parathyroid glands in the main specimen. In the event of an inadvertent removal, part of the gland is sent for frozen section, cut in small fragments and auto-transplanted in the ipsilateral sternocleidomastoid muscle pocket, which is then marked with ligaclips®. All total or completion thyroidectomies for ITGs should treated as high risk for hypocalcaemia and therefore should be given calcium as well as 1 alfa calcidol as prophylaxis (Fig.48.7).
48.7.1.8 Management ofBerry’s Ligament
Once the dissection reaches the Berry’s ligament, minimal traction is applied when holding the thyroid lobe to avoid traction injury to the nerve. The ligament is dissected from the nerve with ne instruments, usually with judicious usage of bipolar diathermy and ne scalpel dissection [17].
Closure
Wound Wash. Once the thyroidectomy is completed, the wound is washed with water or normal saline.
Haemostasis. Haemostasis is essential. To check for any bleeding points, the wound must be clean of clots. Once this has been completed, a Valsalva manoeuvre should be used at least twice to check.
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Fig. 48.7 Identication of the RLN inferiorly at the level of Beahr’s Triangle
Check that RLN’s and Parathyroid Glands. Once hae­mostasis is complete, the recurrent laryngeal nerves and the parathyroid glands should be checked to ensure that they are intact anatomically. If neuromonitoring is used, an EMG sig­nal should be obtained and recorded.
Drainage. Suction drains, particularly when a signicant dissection has resulted in a large dead space, or the patient uses anticoagulation are encouraged. The presence of a drain does not prevent hematoma, and an empty drain bottle is not evidence that there is no bleeding. The need for drains should be considered on an individual patient basis.
Subcutaneous Tissues and Skin Closure. The wound is closed in layers. The strap muscles should be approximated with an absorbable suture. The platysma should then be re­approximated using an absorbable suture. The skin should then be closed with meticulous attention to detail, as this should serve as the only evidence that these patients have undergone surgery. The technique is less important than the
Fig. 48.8 Clinical photograph demonstrating the T-cervico-thoracic incision and the subplatysmal aps in the neck
need to be precise and treat the skin edges with respect. The ideal closure will allow easy re-opening in the event of haematoma.
48.7.2.2 Cervical Stage
As per cervical approach.
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48.7.2 Extra-Cervical Approaches (ECA)
48.7.2.1 Combined Cervical andMidline
Sternotomy Approach
This approach was composed of three main stages
1. Cervical stage
2. Sternotomy and mediastinal stage
3. Thoracic inlet stage
48.7.2.3 Sternotomy andMediastinal Dissection
The chest is completely exposed and prepared from neck to umbilicus and areola mammae to areola mammae. A midline incision is made from the cervical wound to xiphisternum in T fashion (Fig.48.8). The subcutaneous fat is incised down to the periostieum with cautery or scalpel. At this point, the midline is identied superiorly at the sternal notch, inferiorly at the xiphisternum and at a midpoint by digital palpation of the rib spaces on each side. A linear incision in the sternal
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periosteum from top to bottom is then made with electrocau­thery precisely in the midline in preparation for the saw. The xiphisternum is cut with curved Mayo scissors and the supra­sternal ligament with electrocautery. Blunt dissection with a nger sweep retrosternally is then performed at the top and bottom to visualise the path of the saw and prepare a space for its path. The anaesthetist is instructed to stop ventilation while the sternum is split with the saw. Once the sternotomy is completed, ventilation is resumed and the bleeding from the periosteal edges controlled with electrocautery, and the Holmes-Sellars retractor is placed to expose the mediasti­num. The mediastinum is inspected to identify and clarify the extent and location of the goitre. The brachiocephalic or innominate vessels are identied and controlled with soft rubber vascular slings if necessary. Care is taken to minimise unnecessary pleural or pericardial breach especially if malig­nancy is suspected. In these cases, it is preferred to start the dissection as caudally as possible to clear out mediastinal fat containing lymph nodes. Once the goitre is identied and the mediastinal vessels controlled, the dissection is commenced in the extracapsular plane anteriorly to inferiorly ligating any extracapsular vessels that are encountered. The dissection proceeds posteriorly and laterally delivering the specimen in an upward direction until the thoracic inlet is reached (Fig.48.9). At this point, the cavity was inspected for haemo­stasis and to ensure that no mediastinal structures have inad­vertently injured [20].
of the RLN, which is carefully dissected from the reminding thyroid gland (Fig.48.10) [20].
48.7.2.5 Closure
The cervical wound is closed as per the cervical approach. The same principles of wound washing and haemostasis are applied in the chest. Underwater size 28 drains are inserted, and these will drain the neck and mediastinum, and a second one is inserted if the pleura has been opened.
Titanium wires are used to close the sternum. The number of wires will be dependent on the weight and height of the patient. The subcutaneous tissues and skin are closed in a similar fashion than in the neck.
48.7.3 Combined Cervical andLateral
Thoracotomy Approach
This approach was indicated when the goitre had grown into the posterior mediastinum and reached the posterior pleura. In these cases, it was considered that a midline sternotomy would not offer enough space to dissect the goitre from its posterior position. This approach was performed in two main stages:
1. Cervical stage
2. Thoracotomy and intrathoracic and mediastinal stage
48.7.2.4 Thoracic Inlet Stage
Once the thyroid gland has been mobilised superiorly and inferiorly, then the dissection is commenced to mobilise the gland at the thoracic inlet. This is the narrowest part of the dissection and by doing this at the end allows superior mobil­isation of the gland. This also allows improved visualisation
48.7.3.1 Cervical Stage
The cervical stage follows the same approach as described above. The thyroid lobe was dissected from its cervical attachments (oesophagus and trachea) into the thoracic inlet as much as possible, and it was free from the upper medias-
Fig. 48.9 Mobilisation of the goitre inferiorly from its mediastinal bed
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Fig. 48.10 Mobilisation of the thyroid gland at the level of the thoracic inlet with the exposure of the RLN being checked with the IONM probe
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tinal attachments. At this point, the cervical portion of the thyroid lobe was amputated using harmonic scalpel, and the
This follows the same principles described above.
tissue between the recurrent nerve and the intrathoracic por­tion of the goitre was packed with two or three layers of Surgicel ®Fibrillar absorbable haemostat. This was done to facilitate the identication of the RLN and protect it during the nal stages of the thoracotomy approach.
48.7.3.4 Post-operative Care
Patients with transcervical approaches should be nursed and monitored in a dedicated surgical or head and neck ward.
Patients undergoing ECA should be nursed and moni­tored in the intensive care unit for 24h and then transferred
48.7.3.2 Thoracotomy andPosterior
to a dedicated surgical ward once stable.
Mediastinal Dissection Stage
The patient is re-positioned laterally but rolled back to allow access to the anterior neck simultaneously with the thoracotomy as needed. A high postero-lateral thoracot­omy is made, usually through the right chest, as from the left the aortic arch and its branches impede access. The latissimus dorsi is divided, the serratus anterior muscle preserved and the chest entered through the fourth inter­space. It is usually necessary to separate the goitre from the superior vena cava anteriorly, taking care not to injure the phrenic nerve, and from the trachea. Special care was taken not to injure the right RLN as is recurs around the great vessels at the thoracic inlet. By dividing Sibson’s fas­cia, it is possible to join the thoracic with the cervical planes of dissection. Lower down, the innominate vein was often stretched across the goitre, and in mobilising it, care should be taken not to tear this, or to avulse the feeding veins from the goitre. Mobilisation of the goitre was best achieved by blunt dissection within the capsule. Any bleeding from the vascularised surface of the goitre is con­trolled by gauze packing during the dissection. A surface cautery device such as the Aquamantys is used as a haemo­static adjunct [20].
Special consideration should be given to the
following
1. Post Extubation Airway Obstruction
In the case of bilateral surgery with both recurrent laryngeal nerves at risk, transient or permanent bilateral paralysis may cause life-threatening airway obstruction. This may not always be evident upon immediate extuba­tion, but should be suspected in a patient with stridor and respiratory compromise following total thyroidectomy, or a unilateral procedure on the background of co-existing contralateral RLN palsy. If the patient is stable enough for exible laryngoscopy, this will conrm the diagnosis. Management depends on the degree of respiratory com­promise and the level of condence in the nature of RLN paralysis, that is, transient versus permanent. This is where neuromonitoring is useful, as a nerve for which an intact monitoring circuit had been conrmed with pre and post dissection vagal stimulation should invariably recover function [21]. Depending on the situation, a decision may be made to closely monitor the patient with conservative airway measures (e.g. supplemental oxygen, adrenaline nebulisers) versus reintubation or tracheostomy.
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2. Bleeding Post-operative bleeding may manifest as increased
drain output (e.g. over 100 mL in <1h) or an expanding neck haematoma without any obvious increase in drain output. Both situations require immediate neck re­exploration and arrest of haemorrhage to avoid both air­way and cardiovascular compromise.
3. Calcium Management Calcium levels and post-operative hypoparathyroid-
ism need to be avoided in order to prevent cardiovascular and neurological complications from hypocalcaemia. After total thyroidectomy, the calcium and PTH levels should be checked and the postoperative hypocalcaemia protocol applied accordingly.
4. Post-operative Vocal Cord Function Voice changes are common following thyroid surgery.
These are often caused by oedema of the larynx due to the placement of the endotracheal tube during surgery, post­surgical venous congestion of the larynx and not neces­sarily by injury to the RLN.
The main reason for postoperative evaluation as
already stated is accurate visualisation of the vocal cords and their function and therefore provides the measure­ment of one of the main outcomes of the surgery. Post­operative evaluation also provides functional information that allows accurate correlation with the interpretation of the EMG during neuromonitoring of the RLN. Finally, recurrent laryngeal nerve palsy has implications for safety of swallowing and of future contralateral surgery.
Recent reliable guidance suggests a more proactive
approach recommending pre- and post-operative evalua­tion of RLN function in all thyroid and parathyroid sur­gery procedures [22].
5. Thyroid Function Following total or completion thyroidectomy, post-
operative thyroid hormone replacement is required. This is usually in the form of oral levothyroxine, with doses adjusted over a 2–8 weeks in order to achieve optimum levels of serum thyroxine for individual patients. Following hemithy­roidectomy, there is a 12–35% risk of hypothyroidism [23,
24]; hence, patients should have their thyroid function
assessed within 6–8weeks post surgery. Risk factors predic­tive of hypothyroidism following unilateral thyroid lobec­tomy include high normal serum TSH levels, lower free thyroxine levels and Hashimoto’s thyroiditis [25, 26].
References
1. White ML, Doherty GM, Gauger PG.Evidence-based surgical man­agement of substernal goiter. World J Surg. 2008;32(7):1285–300.
2. Randolph GW, Shin JJ, Grillo HC, etal. The surgical management of goitre: part II. Surgical treatment and results. Laryngoscope. 2011;121(1):68–76.
3. Nixon IJ, Simo R. The neoplastic goitre. Curr Opin Otolaryngol Head Neck Surg. 2013;21(2):143–9.
4. Landerholm K, Jarhult J.Should asymptomatic retrosternal goitre be left untreated? A prospective single-centre study. Scand J Surg. 2015;104(2):92–5.
5. Dempsey GA, Snell JA, Coathup R, Jones TM.Anaesthesia for massive retrosternal thyroidectomy in a tertiary referral centre. Br J Anaesth. 2013;111(4):594–9.
6. Chiang FY, Lu IC, Chen HC, etal. Intraoperative neuromonitoring for early localization and identication of recurrent laryngeal nerve during thyroid surgery. Kaohsiung J Med Sci. 2010;26(12):633–9.
7. Findlay JM, Sadler GP, Bridge H, Mihai R. Post-thyroidectomy tracheomalacia: minimal risk despite signicant tracheal compres­sion. Br J Anaesth. 2011;106(6):903–6.
8. Randolph GW, Kobler JB, Wilkins J. Recurrent laryngeal nerve identication and assessment during thyroid surgery: laryngeal pal­pation. World J Surg. 2004;28(8):755–60.
9. Lorente-Poch L, Sancho JJ, Ruiz S, Sitges-Serra A.Importance of in situ preservation of parathyroid glands during total thyroidec­tomy. Br J Surg. 2015;102(4):359–67.
10. Huins CT, Georgalas C, Mehrzad H, Tolley NS.A new classica­tion system for retrosternal goitre based on a systematic review of its complications and management. Int J Surg. 2008;6(1):71–6.
11. McKenzie GA, Rook W.Is it possible to predict the need for ster­notomy in patients undergoing thyroidectomy with retrosternal extension? Interact Cardiovasc Thorac Surg. 2014;19(1):139–43.
12. Grainger J, Saravanappa N, D'Souza A, Wilcock D, Wilson PS.The surgical approach to retrosternal goitres: the role of computerized tomography. Otolaryngol Head Neck Surg. 2005;132(6):849–51.
13. Rios A, Sitges-Serra A.Surgical treatment of intrathoracic goitre. Cirugia Esp. 2012;90(7):421–8.
14. Coskun A, Yildirim M, Erkan N.Substernal goitre: when is a ster­notomy required? Int Surg. 2014;99(4):419–25.
15. Randolph G. Surgery of the thyroid and parathyroid glands. Amsterdam: Elsevier; 2013.
16. Simo R, Nixon I, Tysome J, Balfour A, Jeannon JP. Modied extended Kocher incision for total thyroidectomy with lateral com­partment neck dissection—a critical appraisal of surgical access and cosmesis in 31 patients. Clin Otolaryngol. 2012;37:395.
17. Bliss RD, Gauger PG, Delbridge LW. Surgeon’s approach to the thyroid gland: surgical anatomy and the importance of technique. World J Surg. 2000;24(8):891–7.
18. Darr EA, Randolph GW.Management of laryngeal nerves and para­thyroid glands at thyroidectomy. Oral Oncol. 2013;49(7):665–70.
19. Hisham AN, Lukman MR. Recurrent laryngeal nerve in thyroid surgery: a critical appraisal. ANZ J Surg. 2002;72(12):887–9.
20. Simo RNI, Ofo E. Surgery for intrathoracic goitre (retrosternal) goitres. In: Fagan J, editor. Open access atlas of otolaryngology, head and neck operative surgery. Cape Town: University of Cape Town; 2015.
21. Randolph GW, Dralle H, Abdullah H, et al. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and para­thyroid surgery: international standards guideline statement. Laryngoscope. 2011;121(Suppl 1):S1–16.
22. Chandrasekhar SS, Randolph GW, Seidman MD, etal. Clinical practice guideline: improving voice outcomes after thyroid surgery. Otolaryngol Head Neck Surg. 2013;148(6 Suppl):S1–37.
23. Piper HG, Bugis SP, Wilkins GE, Walker BA, Wiseman S, Baliski CR. Detecting and dening hypothyroidism after hemithyroidec­tomy. Am J Surg. 2005;189(5):587–91.
24. McHenry CR, Slusarczyk SJ.Hypothyroidisim following hemithy­roidectomy: incidence, risk factors, and management. Surgery. 2000;128(6):994–8.
25. Stoll SJ, Pitt SC, Liu J, Schaefer S, Sippel RS, Chen H.Thyroid hormone replacement after thyroid lobectomy. Surgery. 2009;146(4):554–8.
26. De Carlucci D Jr, Tavares MR, Obara MT, Martins LA, Hojaij FC, Cernea CR.Thyroid function after unilateral total lobectomy: risk factors for postoperative hypothyroidism. Arch Otolaryngol Head Neck Surg. 2008;134(10):1076–9.
Part XIX
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Parathyroid Surgery
Bilateral Exploration
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Parathyroidectomy
F.FaustoPalazzo andAntonioSitges-Serra
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49.1 Introduction
Despite improved localisation studies that have led to focused parathyroid surgery, there is still a role for bilateral neck exploration parathyroid surgery. This is required when mul­tiple gland disease is highly probable either due to a genetic predisposition, the presence of known secondary or tertiary disease or when there is no clear localisation of the diseased gland or glands. The objective is the visualisation of all four parathyroid glands and removal of only those that are diseased.
The objective of parathyroid surgery for primary hyper­parathyroidism is to achieve long-term normocalcaemia and normalisation of the patient’s serum parathyroid hormone (PTH) level. In renal dialysis and in post-renal transplant patients with severe secondary or tertiary hyperparathyroid­ism, the role of parathyroidectomy is to reduce the signi­cant serum PTH excess to an extent that is tailored to the patient’s situation. Whatever the goals in parathyroid sur­gery, they should be achieved with minimal morbidity. Successful parathyroid surgery requires the surgeon to be aware of the numerous guises and distribution of normal and pathological parathyroid glands and to have acquired the technical skills required to safely remove abnormal glands and preserve normal parathyroid glands and their function. Nowhere is this more true than in modern open parathyroid surgery. This chapter describes the standard bilateral explo­ration parathyroidectomy (BEP) for non-localised adenomas or for suspected or conrmed multiglandular disease.
The most common indication for BEP is negative or dis­cordant preoperative imaging studies. Negative parathyroid
F. F. Palazzo (*) Department of Thyroid and Endocrine Surgery, Hammersmith Hospital and Imperial College London, London, UK e-mail: f.palazzo@imperial.ac.uk
A. Sitges-Serra Department of Surgery, Hospital del Mar, Barcelona, Spain e-mail: asitges@parcdesalutmar.cat; asitges@hospitaldelmar.cat
Tc-mibi scintigraphy and/or negative neck ultrasound may occur in the presence of small adenomas, a deep posteriorly placed parathyroid gland (particularly in superior glands), and in the presence of concomitant thyroid nodular disease [13].
Candidate multigland disease syndromes include second­ary hyperparathyroidism in patients on haemodialysis, hyperparathyroidism after renal transplantation, lithium­induced hyperparathyroidism and the hereditary forms of hyperparathyroidism, mainly familial isolated hyperparathy­roidism and the MEN 1 and 2 syndromes [4].
Given that at least 5–10% of primary hyperparathyroid­ism cases are caused by multigland disease and localisation is frequently negative because of the increasingly mild dis­ease at diagnosis, the need for BEP is not uncommon and likely to become more common in time. Furthermore, the pendulum may have swung slightly away from low- threshold selective parathyroid surgery because BEP can be performed quickly through small incisions and may have a marginally lower rate of persistence and recurrence [5].
49.2 Preoperative Checklist,
Considerations andAnaesthesia
Parathyroid surgery should be preceded by informed con­sent. It is important that the surgeon quanties the surgical risks based on his or her own practice data. The failure to cure the patient of hyperparathyroidism is likely to be the most common adverse effect of surgery, which even in expert hands will occur in 2–5% of cases. Other risks include voice change, bleeding, infection, hypoparathyroidism and the possible need for an associated thyroidectomy. Same-day discharge may be discussed with those patients who meet the criteria for major ambulatory surgery.
Co-existent thyroid nodular disease, usually benign, is common in some countries where goitre is highly prevalent, and partial or total thyroidectomy may need to be performed
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at the time of parathyroidectomy [6]. This possibility should be assessed in the preoperative thyroid/parathyroid ultra­sound and discussed with the patient. Eventually, full work­ up for thyroid disease (e.g. FNA, calcitonin, autoantibodies) may be necessary.
BEP is usually performed under general anaesthesia but also can be performed with local anaesthetic and sedation and bilateral supercial cervical plexus anaesthesia, although care is required due to the risk of bilateral phrenic nerve paralysis. Antibiotic prophylaxis is not usually required unless the patient has increased risk factors for post- operative infection, such as immune suppression, renal failure, diabe­tes or particular constitutional frailty. Compression stock­ings are sufcient prophylaxis against deep venous thrombosis in patients at risk, as the operation is usually brief and early post-operative mobilisation is the norm. The patient is supine or in Fowler’s position, with a mild degree of neck extension. The skin incision can be marked to ensure the placement of a symmetrical skin crease incision.
All imaging performed should be available for review prior to surgery. Intraoperative PTH monitoring is not essen­tial in BEP, since the aim to identify all parathyroid glands.
49.3 Indications
Regardless of the approach adopted, parathyroid surgery requires an incontrovertible diagnosis of primary or tertiary hyperparathyroidism. The clinical indications for BEP in pri­mary hyperparathyroidism, either sporadic or familial, are identical to those of targeted surgery and can be grossly sum­marised as patients of any age with symptoms or evidence of end organ damage (osteoporosis, nephrolithiasis, hypercal­caemic syndrome, decreasing renal function), all patients under the age of 50years regardless of symptoms, and prob­ably most asymptomatic patients older than 50years who are t for surgery, since there is no satisfactory alternative long­term medical treatment. Delaying surgery in asymptomatic young patients with MEN1 may be advisable, owing to the relatively high risk of recurrence even after appropriate ini­tial surgical treatment (subtotal parathyroidectomy plus tran­scervical thymectomy being the preferred approach).
49.4 Surgical Strategy andTechnique
The key objective in a BEP is the visualisation of all four parathyroid glands; doing so remains the most likely guar­antee to a long-term cure of hyperparathyroidism. The sur­gery can be achieved via a 3- to 4-cm transverse cervicotomy in all but patients with the highest body mass index or those with a concomitant goitre. A thorough anatomical and
embryological understanding of the parathyroid glands, which forms the basis of the surgical exploration, is essen­tial [7].
• A standard transverse cervicotomy incision is placed 1–2cm below the cricoid cartilage, and the platysma is divided with a blade or electrocautery. The avascular sub­platysmal aps are raised supercial to the anterior jugu­lar veins. The infrahyoidal muscles are separated on the bloodless midline. Occasionally, some small vessels may cross the midline, especially at and above the thyroid car­tilage; these must be controlled.
• The rst step of BEP is not to look for the abnormal para­thyroid gland, but rather to identify the key landmarks in a bloodless eld. The sternohyoid and sternothyroid muscles are mobilised off the underlying thyroid gland. Division of the sternothyroid muscle’s upper insertion may be required to properly mobilise the upper pole of the thyroid lobe in patients with a short neck. The thyroid lobe is then rotated medially off the major vessels (Fig.49.1). This requires division of the middle thyroid vein (which can be absent, small or multiple) to allow full lateral mobilisation from the superior pole of the thy­roid to the thyrothymic ligament’s lateral margin inferi­orly. Care should be taken to isolate the thyrothymic ligament anterolaterally from the sternohyoid muscle and posteriorly from the level VI nodal compartment (Fig.49.2). This step is key to not missing the inferior parathyroid glands. The prevertebral fascia, the inferior thyroid artery and the recurrent laryngeal nerve should all be clearly identied. At this point, most parathyroid glands are in view—especially those that are pathologi­cal (Fig.49.3).
• If the parathyroid glands are not immediately visible at this point, then a systematic approach to each parathyroid gland is required, following a predetermined plan that may be modied according to the surgeon’s preference. (The following is the authors’ preference.)
• Look for the superior parathyroid gland rst; it is more constant in position and is the most rapidly identiable. If this gland is normal, it provides the surgeon with the blue­print for how the normal parathyroid glands are likely to look in this particular patient. Most superior parathyroid glands are within a 1-cm radius of the cricothyroid joint and close to the crossing of the inferior thyroid artery and the recurrent laryngeal nerve. The superior parathyroid glands are usually posterior to the recurrent laryngeal nerve. The most common cause of non-visualisation of a normal or an abnormal upper gland is a posterior para/ retroesophageal position. An uncommon intercricothyroi­dal gland may require division of the upper pole vessels for proper identication (Fig.49.4a).
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Fig. 49.1 After retracting the infrahyoid muscles, the whole length of the external border of the thyroid lobe is freed to allow elevation and expo­sure of its dorsal surface
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Fig. 49.2 A left lower thymic parathyroid adenoma. Notice the clean separation between the medial border of the sternohyoid muscle and the thyrothymic ligament
• The inferior parathyroid gland is typically situated caudal to the inferior thyroid artery, anterior to the recurrent laryngeal nerve and lateral to the midline. The most com­mon causes of non-identication of an inferior gland are a thyroid subcapsular at position or a low descent within the thyrothymic ligament (Figs.49.2 and 49.4b).
• If all four glands are positively identied, the one or more that are abnormal may be removed, leaving the normal, well-vascularised and minimally disturbed glands in situ. If all four are abnormal, a physiologically sized remnant is fashioned rst prior to removing the other three glands. The option of marking the remnant with a long, nonab-
sorbable suture may be considered in order to facilitate reoperation in case of remnant hyperplasia, a potential cause of recurrence in renal and MEN1 patients.
• When a standard exploration does not nd the pathologi­cal parathyroid gland(s), a dedicated search is now required. Several sites require specic assessment:
– Para/retroesophageal descended superior gland in
close vicinity to the recurrent laryngeal nerve (Fig.49.5)
– Medial to the superior thyroid pole (intercricothyroidal
position)
– Low thymic inferior gland
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Fig. 49.3 Exposure of the dorsal surface of the left thyroid lobe and identication of key anatomical landmarks to approach an upper parathyroid adenoma
F. F. Palazzo and A. Sitges-Serra
a
b
Fig. 49.4 (a, b) A right lower parathyroid adenoma lying within neatly dissected thyrothymic ligament