30.2.1 Bleeding

The most dreaded complication following thyroid and parathyroid surgery is the possibility of life-threatening bleeding. Postoperative bleeding has been well described since the dawn of this operation, and, in 1866, Samuel L. Gross memorably described its horrific nature. ⁵ Although at the beginning of the 20th century, postoperative bleeding (along with infection) was the main cause of mortality, today it is a rare complication. ⁶ The actual incidence of postoperative bleeding, which occurs more after thyroidectomy than parathyroidectomy, is difficult to assess because of the diversity of findings reported in the literature. The reported incidence of postoperative bleeding requiring surgical intervention ranges from 0.3 to 4.2%. ^{7 , 8 , 9 , 10} It is commonly accepted that the true incidence is < 1%. Apart from meticulous hemostasis during the surgery, there is no evidence that there is any effective strategy that can identify patients who have a higher risk of bleeding or that can prevent its occurrence following surgery. ^{7 , 11} Therefore, neither the use of hemostatic devices, ^{12 , 13 , 14} agents, ¹⁵ or drains ¹⁶ have been shown to be effective in lowering the incidence of bleeding or the necessity for reoperation.

In conclusion, a certain rate of bleeding is unavoidable and this, in fact, is the main objection to the practice of outpatient thyroid and parathyroid surgery, which should be limited to carefully selected patients. Even though most bleeding occurs within the first 6 to 8 hours, a longer observation period is warranted because delayed bleeding has been reported. ^{7 , 10 , 11 , 17} Clinically, the acute onset of neck swelling or compressive symptoms (dyspnea and dysphonia) warrants strict evaluation and immediate treatment. From a strategic point of view, the algorithm for the management of bleeding complications is well standardized. The key points entail securing the airway and reoperation in clinically severe or even doubtful cases.

30.2.2 Infection

Infection is an extremely rare complication following thyroid and parathyroid surgery, with most series reporting an incidence well under 1%. ^{8 , 18} Therefore, the administration of prophylactic antibiotics does not appear to be necessary for all patients undergoing surgery (even if this strategy varies considerably among different centers), and should be indicated only in selected patients who are at a higher risk of developing infections.

30.2.3 Deep Venous Thrombosis

Patients undergoing thyroid and parathyroid surgery are generally mobile in the immediate postoperative period, with many centers performing the surgery on an outpatient basis. Consequently, the incidence of deep venous thrombosis results mainly from anecdotal reports. Because the potential consequences of a bleeding complication are significantly greater in thyroid and parathyroid surgery than in other types of procedures, medical prophylaxis of deep venous thrombosis is generally considered unsafe and unnecessary. However, chemical prophylaxis may be appropriate in certain carefully selected high-risk patients. ¹⁹

30.2.4 Poor Cosmetic Outcomes

In a population with a significant percentage of female patients, a good cosmetic outcome is essential when surgery is performed in such an exposed anatomical location as the anterior neck. Because cosmesis is a central issue in the overall outcome of this surgery, the possible formation of a keloid scar should be adequately discussed with the patient before surgery, together with the other morbidity-related issues. There are general principles that must be strictly followed when performing an incision on the neck that might reduce the risk of keloid formation.

First the location of the incision needs to be adequately planned, keeping in mind that, in the supine position, the scar is always lower than expected after surgery. The incision line should therefore be marked with the patient standing in the upright position while simultaneously correcting for the distortions caused by a bulky thyroid, with the aim of obtaining a symmetrical result. Traditionally, the incision should be placed on a skin crease, at an average distance of two fingerbreadths from the sternal notch (depending on the patient’s anatomy), and its length should be tailored on the size of the gland to be removed. It is worth noting that the incision can be significantly smaller than the size of the gland, because the manipulation and the devascularization of the gland will decrease its size, allowing for safe extraction. This fact has been taken to the extreme in minimally invasive techniques. ^{20 , 21} Nevertheless, the incision should not be so small that the skin edges are traumatized by excessive stretching from retractors or that the risk of undesired necrosis is increased from using energy instruments in a narrow space. In obvious or suspected cases of traumatized edges, adequate resection of the margins followed by reconstruction at the end of the procedure is highly suggested, as described by Terris and colleagues. ²²

Another significant factor leading to a poorer cosmetic outcome is the creation of a wide skin flap when entering the thyroid bed. Avoiding or limiting this dissection eliminates dead space under the skin where fluid might accumulate, and might therefore be helpful in obtaining a good cosmetic result.

The skin closure can be performed using several different techniques and materials. There is no large, prospective, randomized study that clearly demonstrates the superiority of any one method. Every material (monofilament, staples, or cyanoacrylate) and every technique (stitches or intradermic sutures) has its own pros and cons. Therefore, the choice of which method to adopt depends on the surgeon’s personal preference.

A few words should also be devoted to the placement of the drains, which do nothing to prevent postoperative bleeding (see earlier). Drains can be responsible for cosmetic impairments if incorrectly placed. The correct positions are generally considered those that are separate from but in line horizontally with the main incision. This technique makes the drain incision less noticeable and often leads to healing without a visible scar. Placing the drain beneath the incision line or, worse, inferiorly and medially, is not suggested, because the risk of a keloid scar is higher in this location and the incision is less likely to be hidden. Lastly, the placement of a drain in the middle of the incision is discouraged because it can create a widened scar at its point of entry.

30.3.1 Recurrent Laryngeal Nerve Injury

Recurrent laryngeal nerve injury is the most universally known complication following thyroid and parathyroid surgery and has been described since the first reports of patients undergoing thyroid surgery who survived the operation. It is also the most obvious complication that seriously impacts the patient’s quality of life due to its immediate impairment of vocal cord functioning, ventilation, or swallowing.

Even though the incidence of RLN injury is frequently reported to be approximately 1%, the actual rate is far greater for several reasons:

• 
  

  The lowest incidences reported in the literature are derived from studies with a limited number of patients. These studies do not have the statistical power to arrive at definitive conclusions about the true incidence of such a rare event.

  
  
• 
  

  These same studies are generally performed with aims other than evaluating morbidity. Therefore, the incidence of RLN injury, although correctly reported, cannot be considered significant.

  
  
• 
  

  Even though an incidence of RLN injury of approximately 1% may be achievable when dealing with benign thyroid or parathyroid disease, the studies that focus only on these disorders are uncommon. Thyroid surgery performed for malignant disease will invariably have a worse injury rate.

  
  
• 
  

  The results are often reported without the contribution of a routine pre- and postoperative laryngoscopic evaluation, and thus rely only on the patient’s postoperative symptoms for diagnosis. Because it is well described that damage to the RLN can exist in the presence of a remarkably normal voice, the real incidence of injuries cannot be adequately assessed in the absence of postoperative laryngoscopy. In a series that was not limited to patients who had undergone previous neck surgery, it was shown that asymptomatic paralysis of the vocal cords is present in as high as 1.8% of patients preoperatively. ²³

Taken together, these observations place the reported incidence of RLN injury between 0.3% as described by Bergamaschi et al ²⁴ and 6.6% as reported by Echternach et al. ²³ Although it is reasonable to assume that the true incidence lies somewhere between these two extremes, to our knowledge, no study has included a large enough sample size (arguably consisting on more than 1,000 nerves-at-risk) to allow a definitive conclusion. The incidence of transient and permanent RLN injury in studies with a significant amount of nerves-at-risk is summarized in Table 30.1. ^{8 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31}

A detailed analysis of these studies reveals that, once the extreme results are eliminated, the incidence of RLN injury is quite similar across all experienced groups. Further, a reasonable rate can be placed at less than 1% during thyroidectomies for benign disease, and approximately 2% for patients undergoing surgery for malignant disease. Regarding the latter, it is interesting that a huge multicenter Italian study by Rosato and colleagues ⁸ found that the incidence of paralysis increased with the more aggressive tumors, reaching a high of 16.5% in patients with anaplastic thyroid cancer, followed by 5.4% in those with medullary thyroid cancer and finally 1.4% in patients with papillary thyroid cancer. Given the rarity of both medullary and anaplastic thyroid cancer, this result could only have been obtained with confidence based on the large sample size of approximately 15,000 patients. Further, these results confirm that the more aggressive the surgery the higher the rate of iatrogenic injuries.

Reoperation for either benign or malignant disease represents another preoperative factor that significantly impacts the rate of RLN injuries. One multicenter German study also showed lobectomy as a potential higher risk factor, though this observation is difficult to justify. ²⁵ Other factors that have been traditionally associated with higher rates of RLN injuries, such as surgery performed for Graves’ disease, substernal goiter, or thyroiditis, have not been proven to increase this morbidity in well-designed studies. The risk factors associated with a higher risk of RLN injury are summarized in Table 30.2. ^{8 , 27 , 31 , 32 , 33 , 34}

Preoperatively, patients should be made aware that their risk of RLN injury in most cases is approximately 1% and that the risk of injury increases with malignant or recurrent thyroid disease. Conversely, the incidence of RLN injury is negligible in those patients undergoing parathyroid surgery. ²⁸

From a pathophysiological point of view, the precise mechanisms that lead to injury of the RLN are still unclear, except for those extremely rare situations where the nerve is purposely or accidentally sectioned. In these circumstances, suturing the transected nerve is indicated, a strategy that has been described since the first years of modern thyroid surgery. Though suturing the nerve rarely leads to a full recovery of vocal cord motility, it at least allows the affected cord to maintain some bulk and better prepares the patient for voice therapy. ³⁵

Most commonly, paralysis of the vocal cord occurs without transection of the nerve. In these cases, the damage may have resulted from excessive manipulation of the nerve, trauma from several causes (such as prolonged compression or other mechanical injuries), excessive dissection causing devascularization, thermal injuries from electrocautery or other energy instruments, or local inflammation. When a nerve is not transected, vocal cord motility generally recovers after anti-inflammatory therapy with steroids, some cycles of voice therapy, or even spontaneously, though the time to recovery may range from a few hours to 6 months. Postoperative paralysis of the vocal cords is considered temporary when present in the first 6 months after surgery and should be labeled as permanent if it persists beyond that time frame.

Other rare situations that might be responsible for unexpected vocal cord paralysis from RLN injury include the lack of recognition of the nerve during the thyroidectomy (possibly due to an earlier transection), transection of a laryngeal motor branch mistaken for an esophageal branch (laryngeal motor branches are not necessarily the largest ones, though they are generally those most anterior and closest to the thyroid gland), ³⁶ and the presence of a rare anatomical anomaly, such as a nonrecurrent variant in patients with an arteria lusoria (aberrant right subclavian artery), ³⁷ which is present in 0.5 to 1% of the population. In the latter case, if the variant is not properly recognized, the aberrant nerve can be transected in the early phases of the operation. Unfortunately, even though there are now costly preoperative techniques that can correctly identify arteria lusoria, ³⁸ these are not routinely performed for patients undergoing thyroid or parathyroid surgery.

Intraoperative nerve monitoring can be used during thyroidectomy and parathyroidectomy and is particularly useful in identifying the RLN. Though this technology might help to identify how damage to the nerve occurs, several studies have failed to show that monitoring has a significant impact on the rate of RLN injuries. ³⁹

Clinically, patients suffering from an RLN injury generally display symptoms that are primarily related to the position of the paralyzed vocal cord, which can be either medial or lateral. Overall, the voice is generally hoarse, though it may sound normal to inexperienced ears. Along with the patients themselves, however, experienced thyroid surgeons can generally perceive even minimal voice changes. The voice changes can also be described as “breathiness,” which is often a more appropriate term because it better reflects the weakness of the voice. This weakness results from the relative incompetence of the glottis during phonation caused by the lateral position of the cord so that the airflow is not effectively modulated in a symmetrical fashion to the opposite cord. The extent of the voice impairment is generally directly correlated with the degree of lateral displacement. When the cord is in the medial position, dysphonia may be less pronounced, but patients may have respiratory compromise due to a significant reduction in the caliber of the airway. This compromise is generally more apparent in situations of high respiratory demand, such as physical exertion.

In addition to the voice alterations, patients with RLN injuries may also have impairment of their swallowing ability, reflecting the damage to the sensory branches that run lateral to the motor branches and innervate the esophagus. The patients may also complain of dysphagia when the motor branches are left intact and the thinner sensory branches are not recognized and are inadvertently injured during surgery. Impaired glottic closure coupled with loss of sensation can lead to aspiration.

In conclusion, patients with RLN injury generally present with different symptoms according to the severity and the position of the paralyzed cord. These include variable degrees of voice impairment, dysphagia, respiratory distress, and, in the long run, a higher rate of respiratory infections. If a postoperative strobolaryngoscopy is not routinely performed after surgery, the presence of these symptoms warrants appropriate diagnosis and treatment.