Surgery for thyrotoxicosis

Surgery for thyrotoxicosis

Preoperative preparation Traditional preparation aims to make the patient biochemi - cally euthyroid at operation. Preparation is as an outpatient and only rarely is admission to hospital necessary on account of severe symptoms at presentation, failure to control the hyperthyr oidism or non-compliance with medication. Care should be coordinated with endocrinology input. Carbimazole 30–40 /uni00A0 mg/day is the drug of choice for preparation. When euthyroid (after 8–12 weeks), the dose may be reduced to 5 /uni00A0 mg 8-hourly or a ‘block and replace’ regime used. In this case, the high dose of carbimaz ole is continued to inhibit T and T production and a maintenance dose of 3 4 0.1–0.15 /uni00A0 mg thyroxine is given daily . The last dose of carbi - mazole may be given on the evening before surgery . Iodides are not used alone because, if the patient needs preoperative trea tment, a more e ff ective drug should be given. An alternative method of preparation is to abolish the clinical manifestations of the toxic state, using β -adrenergic - blocking drugs. These act on the target organs and not on the gland itself. Propranolol also inhibits the peripheral conversion of T to T . The appropriate dosages are propranolol 40 /uni00A0 mg 4 3 three times daily . Clinical response to β -blockade is rapid and the patient may be rendered clinically euthyroid and operation arranged in a few days rather than weeks. The dose of β -adrenergic blocking drug is increased to achieve the required clinical response and quite often larger doses (propranolol 80 /uni00A0 mg three times daily or nadolol 320 /uni00A0 mg once daily) are necessary . of thyroid hormones, and hormone levels remain high during treatment and for some days after thyroidectomy . It is, there fore, important to continue treatment for 7 days postopera tively . Iodine may be given with carbimazole or a β -adrenergic blocking drug for 10 days before operation. Iodide alone pro duces a transient remission and may reduce vascularity , thereby marginally impro ving safety . The use of iodine preparations is not universal because of more e ff ective alternativ es. Iodine gives an additional measure of safety in case the early morning dose of β -adrenergic blocking drug is mistakenly omitted on the day of operation. The extent of the resection depends on the size of the gland, the age of the patient, the experience of the surgeon, the need to minimise the risk of recurrent toxicity and the wish to avoid postoperative thyroid r eplacement ( Table 55.5 Surgical technique of thyroidectomy The aim of thyroidectomy is to remove the entire thyroid lobe (bilaterally if total thyroidectomy), encompassing all disease and preserving the cervical strap muscles, external branches of the superior laryngeal nerve, the RLN, parathyroid glands and their blood supply in each case while minimising cosmetic impact. With the patient under general anaesthesia, supine, arms at their side, with their head on a ring and neck extended with a shoulder roll or the head of the table extended with the head of the bed raised (reverse Trendelenburg), the opera field is prepared from lower lip to upper chest. A nerve monitor endotracheal tube or electrode wrap can be used (see New technology in thyroidectomy ). The posi tion of the tube should be checked after positioning the patient as extending the neck can withdraw the tube and compromise the contact of the electrodes in the larynx. Either use a head drape or square o ff the surgical site. If head draping , include the nerve monitor leads in the head drape. Alter natively , squaring o ff the surgical site can giv ier access to the endotracheal tube if required. The skin incision is placed in a skin crease as close as possible to the cricoid at the superior edge of the thyroid isthmus, w hich is usually palpable. The length of the incision is determined by the size of the thyroid; however, there is little benefit in extending the incision much beyond the medial edge of the sternocleidomastoid muscle. Mark the incision before prepping and infiltrate with local anaesthetic and adrenaline (epinephrine). A scalpel is used for the skin incision. Incise through the dermis, making sure to use the full extent of the incision. Monopolar diathermy can be used to expose and divide the platysma. This plane is then used to raise a subplatysmal flap to the thyroid notch of the thyr oid cartilage superiorly and to the suprasternal notch inferiorly . Friedrich Trendelenburg , 1844–1924, successively Professor of Surgery at Rostock (1875–1882), Bonn (1822–1895) and Leipzig (1895–1911), Germany . The Trendelenburg position was first described in 1885. Bernhard Rudolf Konrad von Langenbeck , 1810–1887, Professor of Surgery , successively at Kiel and Berlin, Germany . riorly as, often, the sternohyoid muscles separate around the thyroid eminence. The sternohyoid muscles are raised with - toothed forceps and monopolar diather my is used to divide - the fascia, avoiding injury to the anterior jugular veins. A Lan - genbeck retractor helps dissect superior and inferior limits. The plane is developed to dissect between the muscle lay - - ers, elevating sternohyoid laterally until the ansa cervicalis is visualised. The sternothyroid muscle is then mobilised from the gland, taking great care with the delicate vasculature. If requir ed, the strap muscles may be divided superiorly to a ff ord greater exposure. There is usually an artery and a vein travel - ling between the two strap muscles superiolaterally; these can be injured if overly enthusiastic blunt dissection is used. Once the internal jugular vein is identified dissection medial and deep to this will allow identification of the common carotid artery , and between the vessels the vagus nerve. This should ). be stimulated to prove that the nerve monitor is functioning properly . If the latency reading on the nerve monitor is unex - pectedly short on the right side then consider a non-recurrent right laryngeal nerve. At this point the gland is exposed and ready for dissection. Minimal blood loss should have been encountered. The assistant now places Langenbeck retractors under ster nohyoid, one lateral to the upper pole and one medial. This displays the superior thyroid v ascular pedicle, which is controlled with ties or a bipolar energy device. T his not only mobilises the superior pole but also preserves the blood supply to the superior parathyroid gland. In addition, tive it minimises risk to the superior laryngeal nerve, which can often be seen passing medially towards the cricothyroid muscle. Gradually the superior pole is mobilised, taking care not to - dissect below the cricoid cartilage, at which point the RLN is at risk ( Figure 55.19 ) . Gentle traction on the fascia over the gland, immediately next to the superior plane, will show a plane to follow over the main thyroid. This is e eas - followed inferior ly , avoiding excessive lateral dissection to prevent inadvertent damage to the RLN. Blunt dissection will allow much of this fascia to be mobilised. Occasional vessels require bipolar cautery . Next, the trachea is identified in the midline below the isth - mus, staying on the cartilage and close to the gland in order to prevent damage to vessels that may contribute to arcades supplying the inferior para thyroid gland. At this point, the RLN is superior and lateral to the trachea and inferior to the plane developed superiorly . Depending on just how compliant the fascia is and how large the lobe is, much of the dissection may now be complete. A pledget may be used to brush fascia laterally . It is not uncommon that the RLN can be seen at this point. Assuming

Set-up. Exposure. Upper pole. Mobilising the rest of the gland. Identi /f_i cation of the recurrent laryngeal nerve.

it is not, dissection proceeds by gently mobilising the fascia around the gland, staying directly on the gland and not dividing anything that could be neural. The RLN will be close, often but not always behind the inferior thyroid artery (approximately 70%). By remaining vigilant, never dividing any structure that could remotely be neural and slowly dissecting fascia, the lobe can be delivered from above and below , mobilising in the direc tion of Berry’s ligament. Using this approach, the RLN will be identified and can be confirmed with the nerve stimulator. Once the nerve has been identified a number of approaches are possible. Ideally the nerve is largely lateral to the gland. T his allows dissection to progress until only Berry’s ligament remains. However, if the nerve lies medially , it may actually lie on the thyroid and require gentle dissection to free it from the thyroid surface. If this is the case, stay directly on the nerve and slowly dissect the nerve free of the surrounding tissue, endeav ouring not to injure the nerve by direct pressure. The nerve should be traced towards the cricothyroid joint as it enters the larynx. The pretracheal fascia condenses into Berry’s ligament at this point. Small vessels within the ligament retract if not controlled with bipolar cautery or ties, and the r esulting bleeding can disorientate the surgeon, placing the nerve at risk. In order to avoid this, pre-emptive diathermy to the ligament and careful layer-by-layer dissection allows final mobilisation of the thyroid lobe. Some surgeons prefer to iso late the ligament and apply a careful tie to achieve haemostasis. Whichever method is preferred, great care must be taken at this point. The exact anatomy her e will depend on how extensive the condensation of fascia (Berry’s ligament) is and how it rela tes to the RLN. This is are. In some the ligament is distant from the nerve. In others the nerve runs up to and even through the ligament. Keeping the nerv e in direct vision, minimal division of the ligament allows the RLN to move back and expose more of the liga - ment, allowing the process to continue, layer by layer, until the nerve is well lateral and the ligament has been divided. If, during this process, bleeding is encountered the use of targeted pressure and occasionally fine-tip suction to identify the specific bleeding point and careful use of bipolar cautery will achie ve haemostasis. This must be meticulous as re-exploration of this ar ea for bleeding puts the RLN at significant risk. Loose pretrachea fascia can now be opened with monopolar diathermy over the trachea to the midline and beyond to remove the isthmus, which is divided, encompassing any pyramidal lobe tissue . The residual isthmus is either oversewn or sealed with bipolar cautery . If a total thyroidectomy is required, the procedure is repeated on the other side. The operative field should be inspected. Irrigation with saline helps identification of small bleeding points. The anatomy should be confirmed, ideally with confirmation of neural integrity by stimulating the v agus (if previously located). Bipolar cautery is used carefully to avoid nerve or parathyroid injury . Most surgeons do not place a drain. Interrupted sutures are placed through the sternohyoid muscle to prevent adhesion betw een the trachea and skin. The aim is not to perform a watertight closure of the muscle in case this promotes pressure in the event of a haematoma. The platysma closure is followed by subcuticular skin clo - sure with an absorbable suture. - New technology in thyroidectomy The major immediate risk following thyroidectomy is haem - orrhage; conventionally , artery forceps, ligatures and sutures have been used to secure the meticulous haemostasis necessary to minimise the risk of this potentially life-threatening compli - cation. Ultrasonic shears , enhanced bipolar diathermy and harmonic vessel sealing devices are increasingly used in thyroid surgery and may be advantageous in complex procedures. - Monitoring of the RLN and v agus nerve has become available over the last few years. By placing electrodes on the endotracheal tube between the vocal cords, movements can be detected when the nerv e is stimulated. Such intermittent nerve monitoring is gaining in popularity . Advocates consider the monitor particularly useful in recurrent operations where scar tissue makes the nerve di ffi cult to identify . In addition, some find that operative time is reduced and that this is a valuable tool for training. There is also some support for the use of nerve - monitoring during bilateral thyroid surgery , as the information provided can aid in the identification of a unilateral palsy to prevent bilateral palsy that can require tracheostomy . Those who do not support the use of the nerve monitor highlight the lack of evidence that there is any real di ff erence in outcome associated with this practice. In addition, there is the expense of the base machine and the electrodes.

artery External branch superior laryngeal nerve Superior parathyroid gland Recurrent laryngeal nerve Inferior thyroid artery Inferior parathyroid gland Thyroid ima artery Figure 55.19 General anatomy of a thyroidectomy. Management of Berry’s ligament. Delivery of the gland. Closure.

identification of a damaged nerve, continuous nerve moni toring has now been developed. In theory , this provides the opportunity to identify a nerve when function is threatened (by excessive traction, for example). This technique, although theoretically advantageous, requires an electrode to be placed on the vagus nerve and has not gained widespread acceptance ( Figure 55.20 ). Alternative surgical techniques Over the past two decades, increasing experience has been gained in alternative approaches to thyroid surgery . Minimally invasive video-assisted techniques have been developed that allow surgeons to operate through an incision <2 /uni00A0 cm in length. With appropriately modified dissectors, experienced operators and advanced haemostatic electrosurgical devices, such procedures o ff er reduced scar length. However, they are only appropriate for small-volume disease and as such are not suitable for many thyroid cases. Remote access thyroid surgery is of increasing interest. A number of approaches have been developed via axillary or breast incisions and also through the oral cavity . These approaches can be used with laparoscopic or r obotic tech niques to allow a magnified view of the operative site. Such ‘maximally invasive’ techniques require extended dissection over the chest wall or neck and again are most suitable for small-volume disease. Experienced centres contin ue to expand the indications for these techniques. However, they are associ ated with increased and significant time, which currently limits their application to most thyroid surgical practice. P o s t o p e r a t i v e c o m p l i c a t i o n s Haemorrhage is the most frequent life-threatening complica tion of thyroidectomy . Around 1 in 50 patients will develop a haematoma, and in almost all cases this will develop in the first 24 hours. If an arterial bleed occurs, the tension in the central compartment pressure can rise until it exceeds venous pressure . V enous oedema of the larynx can then develop and cause airway obstruction, leading to death. Although improve ments in understanding of the blood supply to the larynx and technical developments in terms of haemostatic technologies - Although many surgeons worldwide practise da y case thyroid - ectomy , bleeding is the reason that, in the UK, thyroidectom y emains an inpatient procedure. r Intraoperative attention to detail in terms of haemostasis is critical. When closing the wound, avoiding a watertight closure of the strap muscles ma y allow a haematoma to escape into the subcutaneous tissues. Wound drains have not been shown to hav e a protective e ff ect. Close monitoring of the wound is advised postoperatively . If a haematoma develops, clinical sta ff should know to remove skin sutures in order to release some pressure and seek senior advice immediately . Endotra - cheal intubation should be used to secure the airway while the haematoma is evacuated and the bleeding point controlled. RLN paralysis and voice change RLN injury may be unila teral or bilateral, transient or permanent. Early routine postoperative laryngoscopy reveals a much higher incidence of transient cord paralysis than is detectable b y simple assess - ment of the integrity of the voice and cough. Such tempo - rary dysfunction is not clinically important, however, but voice and cord function should be assessed at first follow-up 4 weeks postoperatively . A British Association of Endocrine and Thyroid Surgeons audit re vealed an RLN palsy rate of 1.8% at 1 month, declining to 0.5% at 3 months for first-time operations. Permanent paralysis is rare if the nerve has been identified at operation. If an RLN is injured during surgery and the transected ends are identified, they should be reanastomosed. In the event that a length of nerve is excised (owing to invasion by malig - nancy , for e xample), anastomosis of the ansa cervicalis may be considered. This does not return mobility of the vocal cord but maintains neurological input to the muscles of the larynx. By avoiding denervation and rela ted muscle atrophy , the vocal quality is improved. Permanent vocal cord paralysis should be treated conservatively with speech therapy . If voice quality is unacceptable, medialisation procedures can be performed. Nerve grafting has shown promise but experience is limited. Injury to the external branch of the superior laryngeal nerve is more common because of its proximity to the superior - thyroid artery . This leads to loss of tension in the vocal cord with diminished power and range in the voice. P atients, particularly those who use their voice professionally , must be advised that any thyroid operation will result in change to the voice even in the absence of nerve trauma. Fortunately , for most patients - the changes are subtle and only demonstrable on formal voice assessment. Thyroxine replacement will be required following total thyroidectomy . Around one in three - patients who has a lobectomy will require supplementation; rates ar e higher in those with thyroid autoantibodies. Subtotal thyroidectomy was at one time performed with the aim of leaving su ffi cient tissue to maintain thyroid function. However, this is di ffi cult to judge and, over the years, the benign process that necessitated primary surgery may recur, requiring di ffi cult - revision procedures. For this reason, the practice of subtotal thyroidectomy has been more or less abandoned outside envi - ronments where exogenous thyroxine is not available.

Figure 55.20 Continuous monitoring of the vagus nerve (adapted from an image provided by Inomed UK Ltd). Thyroid insuf /f_i ciency.

thyroid glands or infarction through damage to the parathyroid end arteries; often both factors occur together. Vascular injury is probably far more important than inadvertent removal. The incidence of permanent hypopara thyroidism should be less than 1% and most cases present dramatically 2–5 days after operation; very rarely , the onset is delayed for 2–3 weeks or a patient with marked hypocalcaemia may be asymptomatic. The complication is limited to total thyroidectomy , as when lobectomy is performed the contralateral parathyroid glands are su ffi cient to maintain calcium levels. In particular, total thyroidectomy with central neck dissection places the parathy roid glands and their vascular supply at great risk and should only be performed when there is evidence of metastatic disease or high risk of occult disease in the regional lymph nodes. This is an acute exacerbation of hyperthyr oidism. It occurs if a thyrotoxic patient has been inadequately prepared for thyroidectom y and is now extremely rare. V ery rarely , a thyrotoxic patient presents in a crisis and this may follow an unrelated operation. Symptomatic and supportive treatment is for dehydration, hyperpyrexia and restlessness. This requires the administration of intravenous fluids, cooling the patient with ice packs, administration of oxygen, diuretics for cardiac failure, digoxin for uncontrolled atrial fibrillation, sedation and intravenous hydrocortisone. Specific treatment is by carbimazole 10–20 /uni00A0 mg 6-hourly , Lugol’s iodine 10 drops 8-hourly by mouth or sodium iodide 1 /uni00A0 g intravenously . Propranolol intravenously (1–2 /uni00A0 mg) or orally (40 /uni00A0 g 6-hourly) will block β -adrenergic e ff ects. Cellulitis requiring prescription of anti biotics, often by the general practitioner, is more common than most surgeons appreciate. A significant subcutaneous or deep cervical abscess is exceptionally rare and should be drained. This is more likely to form if the incision ov erlies the sternum and in dark-skinned individu als. Intradermal injections of corticosteroid should be given at once and repeated monthly if necessar y . Scar revision rarely results in significant long-term improvement. This may occur with or without sin formation and is seen after the use of non-absorbable, partic ularly silk, suture material. Absorbable ligatures and sutures should be used throughout thyr oid surgery . Postoperative care Following surgery , the patient should be returned to the recovery room and nursed overnight on the ward. Wound care should include vigilance for signs of a haematoma. Following total thyroidectomy , calcium levels should be checked postop eratively . Not all patients develop immediate hypocalcaemia and they should be educated about the signs (paraesthesia of the fingers and toes or around the mouth). Serial calcium monitoring should be recommended for those at highest risk. Jean Guillaume Auguste Lugol , 1786–1851, Physician, Hôpital Saint-Louis, Paris, France. replacement, which should start on day 1 postoperatively . On clinic review , in addition to checking the histology report, the wound should be inspected and the larynx e xamined for vocal cord function. Biochemical assessment of thyroid function and calcium, if required, should be arranged.

Thyrotoxic crisis (storm). Wound infection. Hypertrophic or keloid scar. Stitch granuloma.

Surgery for thyrotoxicosis

Preoperative preparation Traditional preparation aims to make the patient biochemi - cally euthyroid at operation. Preparation is as an outpatient and only rarely is admission to hospital necessary on account of severe symptoms at presentation, failure to control the hyperthyr oidism or non-compliance with medication. Care should be coordinated with endocrinology input. Carbimazole 30–40 /uni00A0 mg/day is the drug of choice for preparation. When euthyroid (after 8–12 weeks), the dose may be reduced to 5 /uni00A0 mg 8-hourly or a ‘block and replace’ regime used. In this case, the high dose of carbimaz ole is continued to inhibit T and T production and a maintenance dose of 3 4 0.1–0.15 /uni00A0 mg thyroxine is given daily . The last dose of carbi - mazole may be given on the evening before surgery . Iodides are not used alone because, if the patient needs preoperative trea tment, a more e ff ective drug should be given. An alternative method of preparation is to abolish the clinical manifestations of the toxic state, using β -adrenergic - blocking drugs. These act on the target organs and not on the gland itself. Propranolol also inhibits the peripheral conversion of T to T . The appropriate dosages are propranolol 40 /uni00A0 mg 4 3 three times daily . Clinical response to β -blockade is rapid and the patient may be rendered clinically euthyroid and operation arranged in a few days rather than weeks. The dose of β -adrenergic blocking drug is increased to achieve the required clinical response and quite often larger doses (propranolol 80 /uni00A0 mg three times daily or nadolol 320 /uni00A0 mg once daily) are necessary . of thyroid hormones, and hormone levels remain high during treatment and for some days after thyroidectomy . It is, there fore, important to continue treatment for 7 days postopera tively . Iodine may be given with carbimazole or a β -adrenergic blocking drug for 10 days before operation. Iodide alone pro duces a transient remission and may reduce vascularity , thereby marginally impro ving safety . The use of iodine preparations is not universal because of more e ff ective alternativ es. Iodine gives an additional measure of safety in case the early morning dose of β -adrenergic blocking drug is mistakenly omitted on the day of operation. The extent of the resection depends on the size of the gland, the age of the patient, the experience of the surgeon, the need to minimise the risk of recurrent toxicity and the wish to avoid postoperative thyroid r eplacement ( Table 55.5 Surgical technique of thyroidectomy The aim of thyroidectomy is to remove the entire thyroid lobe (bilaterally if total thyroidectomy), encompassing all disease and preserving the cervical strap muscles, external branches of the superior laryngeal nerve, the RLN, parathyroid glands and their blood supply in each case while minimising cosmetic impact. With the patient under general anaesthesia, supine, arms at their side, with their head on a ring and neck extended with a shoulder roll or the head of the table extended with the head of the bed raised (reverse Trendelenburg), the opera field is prepared from lower lip to upper chest. A nerve monitor endotracheal tube or electrode wrap can be used (see New technology in thyroidectomy ). The posi tion of the tube should be checked after positioning the patient as extending the neck can withdraw the tube and compromise the contact of the electrodes in the larynx. Either use a head drape or square o ff the surgical site. If head draping , include the nerve monitor leads in the head drape. Alter natively , squaring o ff the surgical site can giv ier access to the endotracheal tube if required. The skin incision is placed in a skin crease as close as possible to the cricoid at the superior edge of the thyroid isthmus, w hich is usually palpable. The length of the incision is determined by the size of the thyroid; however, there is little benefit in extending the incision much beyond the medial edge of the sternocleidomastoid muscle. Mark the incision before prepping and infiltrate with local anaesthetic and adrenaline (epinephrine). A scalpel is used for the skin incision. Incise through the dermis, making sure to use the full extent of the incision. Monopolar diathermy can be used to expose and divide the platysma. This plane is then used to raise a subplatysmal flap to the thyroid notch of the thyr oid cartilage superiorly and to the suprasternal notch inferiorly . Friedrich Trendelenburg , 1844–1924, successively Professor of Surgery at Rostock (1875–1882), Bonn (1822–1895) and Leipzig (1895–1911), Germany . The Trendelenburg position was first described in 1885. Bernhard Rudolf Konrad von Langenbeck , 1810–1887, Professor of Surgery , successively at Kiel and Berlin, Germany . riorly as, often, the sternohyoid muscles separate around the thyroid eminence. The sternohyoid muscles are raised with - toothed forceps and monopolar diather my is used to divide - the fascia, avoiding injury to the anterior jugular veins. A Lan - genbeck retractor helps dissect superior and inferior limits. The plane is developed to dissect between the muscle lay - - ers, elevating sternohyoid laterally until the ansa cervicalis is visualised. The sternothyroid muscle is then mobilised from the gland, taking great care with the delicate vasculature. If requir ed, the strap muscles may be divided superiorly to a ff ord greater exposure. There is usually an artery and a vein travel - ling between the two strap muscles superiolaterally; these can be injured if overly enthusiastic blunt dissection is used. Once the internal jugular vein is identified dissection medial and deep to this will allow identification of the common carotid artery , and between the vessels the vagus nerve. This should ). be stimulated to prove that the nerve monitor is functioning properly . If the latency reading on the nerve monitor is unex - pectedly short on the right side then consider a non-recurrent right laryngeal nerve. At this point the gland is exposed and ready for dissection. Minimal blood loss should have been encountered. The assistant now places Langenbeck retractors under ster nohyoid, one lateral to the upper pole and one medial. This displays the superior thyroid v ascular pedicle, which is controlled with ties or a bipolar energy device. T his not only mobilises the superior pole but also preserves the blood supply to the superior parathyroid gland. In addition, tive it minimises risk to the superior laryngeal nerve, which can often be seen passing medially towards the cricothyroid muscle. Gradually the superior pole is mobilised, taking care not to - dissect below the cricoid cartilage, at which point the RLN is at risk ( Figure 55.19 ) . Gentle traction on the fascia over the gland, immediately next to the superior plane, will show a plane to follow over the main thyroid. This is e eas - followed inferior ly , avoiding excessive lateral dissection to prevent inadvertent damage to the RLN. Blunt dissection will allow much of this fascia to be mobilised. Occasional vessels require bipolar cautery . Next, the trachea is identified in the midline below the isth - mus, staying on the cartilage and close to the gland in order to prevent damage to vessels that may contribute to arcades supplying the inferior para thyroid gland. At this point, the RLN is superior and lateral to the trachea and inferior to the plane developed superiorly . Depending on just how compliant the fascia is and how large the lobe is, much of the dissection may now be complete. A pledget may be used to brush fascia laterally . It is not uncommon that the RLN can be seen at this point. Assuming

Set-up. Exposure. Upper pole. Mobilising the rest of the gland. Identi /f_i cation of the recurrent laryngeal nerve.

it is not, dissection proceeds by gently mobilising the fascia around the gland, staying directly on the gland and not dividing anything that could be neural. The RLN will be close, often but not always behind the inferior thyroid artery (approximately 70%). By remaining vigilant, never dividing any structure that could remotely be neural and slowly dissecting fascia, the lobe can be delivered from above and below , mobilising in the direc tion of Berry’s ligament. Using this approach, the RLN will be identified and can be confirmed with the nerve stimulator. Once the nerve has been identified a number of approaches are possible. Ideally the nerve is largely lateral to the gland. T his allows dissection to progress until only Berry’s ligament remains. However, if the nerve lies medially , it may actually lie on the thyroid and require gentle dissection to free it from the thyroid surface. If this is the case, stay directly on the nerve and slowly dissect the nerve free of the surrounding tissue, endeav ouring not to injure the nerve by direct pressure. The nerve should be traced towards the cricothyroid joint as it enters the larynx. The pretracheal fascia condenses into Berry’s ligament at this point. Small vessels within the ligament retract if not controlled with bipolar cautery or ties, and the r esulting bleeding can disorientate the surgeon, placing the nerve at risk. In order to avoid this, pre-emptive diathermy to the ligament and careful layer-by-layer dissection allows final mobilisation of the thyroid lobe. Some surgeons prefer to iso late the ligament and apply a careful tie to achieve haemostasis. Whichever method is preferred, great care must be taken at this point. The exact anatomy her e will depend on how extensive the condensation of fascia (Berry’s ligament) is and how it rela tes to the RLN. This is are. In some the ligament is distant from the nerve. In others the nerve runs up to and even through the ligament. Keeping the nerv e in direct vision, minimal division of the ligament allows the RLN to move back and expose more of the liga - ment, allowing the process to continue, layer by layer, until the nerve is well lateral and the ligament has been divided. If, during this process, bleeding is encountered the use of targeted pressure and occasionally fine-tip suction to identify the specific bleeding point and careful use of bipolar cautery will achie ve haemostasis. This must be meticulous as re-exploration of this ar ea for bleeding puts the RLN at significant risk. Loose pretrachea fascia can now be opened with monopolar diathermy over the trachea to the midline and beyond to remove the isthmus, which is divided, encompassing any pyramidal lobe tissue . The residual isthmus is either oversewn or sealed with bipolar cautery . If a total thyroidectomy is required, the procedure is repeated on the other side. The operative field should be inspected. Irrigation with saline helps identification of small bleeding points. The anatomy should be confirmed, ideally with confirmation of neural integrity by stimulating the v agus (if previously located). Bipolar cautery is used carefully to avoid nerve or parathyroid injury . Most surgeons do not place a drain. Interrupted sutures are placed through the sternohyoid muscle to prevent adhesion betw een the trachea and skin. The aim is not to perform a watertight closure of the muscle in case this promotes pressure in the event of a haematoma. The platysma closure is followed by subcuticular skin clo - sure with an absorbable suture. - New technology in thyroidectomy The major immediate risk following thyroidectomy is haem - orrhage; conventionally , artery forceps, ligatures and sutures have been used to secure the meticulous haemostasis necessary to minimise the risk of this potentially life-threatening compli - cation. Ultrasonic shears , enhanced bipolar diathermy and harmonic vessel sealing devices are increasingly used in thyroid surgery and may be advantageous in complex procedures. - Monitoring of the RLN and v agus nerve has become available over the last few years. By placing electrodes on the endotracheal tube between the vocal cords, movements can be detected when the nerv e is stimulated. Such intermittent nerve monitoring is gaining in popularity . Advocates consider the monitor particularly useful in recurrent operations where scar tissue makes the nerve di ffi cult to identify . In addition, some find that operative time is reduced and that this is a valuable tool for training. There is also some support for the use of nerve - monitoring during bilateral thyroid surgery , as the information provided can aid in the identification of a unilateral palsy to prevent bilateral palsy that can require tracheostomy . Those who do not support the use of the nerve monitor highlight the lack of evidence that there is any real di ff erence in outcome associated with this practice. In addition, there is the expense of the base machine and the electrodes.

artery External branch superior laryngeal nerve Superior parathyroid gland Recurrent laryngeal nerve Inferior thyroid artery Inferior parathyroid gland Thyroid ima artery Figure 55.19 General anatomy of a thyroidectomy. Management of Berry’s ligament. Delivery of the gland. Closure.

identification of a damaged nerve, continuous nerve moni toring has now been developed. In theory , this provides the opportunity to identify a nerve when function is threatened (by excessive traction, for example). This technique, although theoretically advantageous, requires an electrode to be placed on the vagus nerve and has not gained widespread acceptance ( Figure 55.20 ). Alternative surgical techniques Over the past two decades, increasing experience has been gained in alternative approaches to thyroid surgery . Minimally invasive video-assisted techniques have been developed that allow surgeons to operate through an incision <2 /uni00A0 cm in length. With appropriately modified dissectors, experienced operators and advanced haemostatic electrosurgical devices, such procedures o ff er reduced scar length. However, they are only appropriate for small-volume disease and as such are not suitable for many thyroid cases. Remote access thyroid surgery is of increasing interest. A number of approaches have been developed via axillary or breast incisions and also through the oral cavity . These approaches can be used with laparoscopic or r obotic tech niques to allow a magnified view of the operative site. Such ‘maximally invasive’ techniques require extended dissection over the chest wall or neck and again are most suitable for small-volume disease. Experienced centres contin ue to expand the indications for these techniques. However, they are associ ated with increased and significant time, which currently limits their application to most thyroid surgical practice. P o s t o p e r a t i v e c o m p l i c a t i o n s Haemorrhage is the most frequent life-threatening complica tion of thyroidectomy . Around 1 in 50 patients will develop a haematoma, and in almost all cases this will develop in the first 24 hours. If an arterial bleed occurs, the tension in the central compartment pressure can rise until it exceeds venous pressure . V enous oedema of the larynx can then develop and cause airway obstruction, leading to death. Although improve ments in understanding of the blood supply to the larynx and technical developments in terms of haemostatic technologies - Although many surgeons worldwide practise da y case thyroid - ectomy , bleeding is the reason that, in the UK, thyroidectom y emains an inpatient procedure. r Intraoperative attention to detail in terms of haemostasis is critical. When closing the wound, avoiding a watertight closure of the strap muscles ma y allow a haematoma to escape into the subcutaneous tissues. Wound drains have not been shown to hav e a protective e ff ect. Close monitoring of the wound is advised postoperatively . If a haematoma develops, clinical sta ff should know to remove skin sutures in order to release some pressure and seek senior advice immediately . Endotra - cheal intubation should be used to secure the airway while the haematoma is evacuated and the bleeding point controlled. RLN paralysis and voice change RLN injury may be unila teral or bilateral, transient or permanent. Early routine postoperative laryngoscopy reveals a much higher incidence of transient cord paralysis than is detectable b y simple assess - ment of the integrity of the voice and cough. Such tempo - rary dysfunction is not clinically important, however, but voice and cord function should be assessed at first follow-up 4 weeks postoperatively . A British Association of Endocrine and Thyroid Surgeons audit re vealed an RLN palsy rate of 1.8% at 1 month, declining to 0.5% at 3 months for first-time operations. Permanent paralysis is rare if the nerve has been identified at operation. If an RLN is injured during surgery and the transected ends are identified, they should be reanastomosed. In the event that a length of nerve is excised (owing to invasion by malig - nancy , for e xample), anastomosis of the ansa cervicalis may be considered. This does not return mobility of the vocal cord but maintains neurological input to the muscles of the larynx. By avoiding denervation and rela ted muscle atrophy , the vocal quality is improved. Permanent vocal cord paralysis should be treated conservatively with speech therapy . If voice quality is unacceptable, medialisation procedures can be performed. Nerve grafting has shown promise but experience is limited. Injury to the external branch of the superior laryngeal nerve is more common because of its proximity to the superior - thyroid artery . This leads to loss of tension in the vocal cord with diminished power and range in the voice. P atients, particularly those who use their voice professionally , must be advised that any thyroid operation will result in change to the voice even in the absence of nerve trauma. Fortunately , for most patients - the changes are subtle and only demonstrable on formal voice assessment. Thyroxine replacement will be required following total thyroidectomy . Around one in three - patients who has a lobectomy will require supplementation; rates ar e higher in those with thyroid autoantibodies. Subtotal thyroidectomy was at one time performed with the aim of leaving su ffi cient tissue to maintain thyroid function. However, this is di ffi cult to judge and, over the years, the benign process that necessitated primary surgery may recur, requiring di ffi cult - revision procedures. For this reason, the practice of subtotal thyroidectomy has been more or less abandoned outside envi - ronments where exogenous thyroxine is not available.

Figure 55.20 Continuous monitoring of the vagus nerve (adapted from an image provided by Inomed UK Ltd). Thyroid insuf /f_i ciency.

thyroid glands or infarction through damage to the parathyroid end arteries; often both factors occur together. Vascular injury is probably far more important than inadvertent removal. The incidence of permanent hypopara thyroidism should be less than 1% and most cases present dramatically 2–5 days after operation; very rarely , the onset is delayed for 2–3 weeks or a patient with marked hypocalcaemia may be asymptomatic. The complication is limited to total thyroidectomy , as when lobectomy is performed the contralateral parathyroid glands are su ffi cient to maintain calcium levels. In particular, total thyroidectomy with central neck dissection places the parathy roid glands and their vascular supply at great risk and should only be performed when there is evidence of metastatic disease or high risk of occult disease in the regional lymph nodes. This is an acute exacerbation of hyperthyr oidism. It occurs if a thyrotoxic patient has been inadequately prepared for thyroidectom y and is now extremely rare. V ery rarely , a thyrotoxic patient presents in a crisis and this may follow an unrelated operation. Symptomatic and supportive treatment is for dehydration, hyperpyrexia and restlessness. This requires the administration of intravenous fluids, cooling the patient with ice packs, administration of oxygen, diuretics for cardiac failure, digoxin for uncontrolled atrial fibrillation, sedation and intravenous hydrocortisone. Specific treatment is by carbimazole 10–20 /uni00A0 mg 6-hourly , Lugol’s iodine 10 drops 8-hourly by mouth or sodium iodide 1 /uni00A0 g intravenously . Propranolol intravenously (1–2 /uni00A0 mg) or orally (40 /uni00A0 g 6-hourly) will block β -adrenergic e ff ects. Cellulitis requiring prescription of anti biotics, often by the general practitioner, is more common than most surgeons appreciate. A significant subcutaneous or deep cervical abscess is exceptionally rare and should be drained. This is more likely to form if the incision ov erlies the sternum and in dark-skinned individu als. Intradermal injections of corticosteroid should be given at once and repeated monthly if necessar y . Scar revision rarely results in significant long-term improvement. This may occur with or without sin formation and is seen after the use of non-absorbable, partic ularly silk, suture material. Absorbable ligatures and sutures should be used throughout thyr oid surgery . Postoperative care Following surgery , the patient should be returned to the recovery room and nursed overnight on the ward. Wound care should include vigilance for signs of a haematoma. Following total thyroidectomy , calcium levels should be checked postop eratively . Not all patients develop immediate hypocalcaemia and they should be educated about the signs (paraesthesia of the fingers and toes or around the mouth). Serial calcium monitoring should be recommended for those at highest risk. Jean Guillaume Auguste Lugol , 1786–1851, Physician, Hôpital Saint-Louis, Paris, France. replacement, which should start on day 1 postoperatively . On clinic review , in addition to checking the histology report, the wound should be inspected and the larynx e xamined for vocal cord function. Biochemical assessment of thyroid function and calcium, if required, should be arranged.

Thyrotoxic crisis (storm). Wound infection. Hypertrophic or keloid scar. Stitch granuloma.