Complications - Restthyroidectomy with partial central lymph node dissection on the left

Bleeding

Bleeding from the inferior thyroid artery or Kocher's vein can make it impossible to maintain a clear view of the surgical site.

• avoid frantic attempts to grasp the presumed source of bleeding with clamps in an unclear wound area
• initially tamponade the wound with compresses, ensure optimal positioning of the surgical area (Langenbeck retractor!)
• gradually remove the compresses using a suction device and attempt to grasp the bleeding vessel precisely with a clamp
• for every thyroid procedure, the check for hemostasis should be performed under PEEP ventilation of the patient before wound closure

2.1. Lesions of the Recurrent Laryngeal Nerve (“Recurrent Palsy”)

Incidence:

• 1-2%, in reoperations 2-8%
• Patients with thyroid malignancy have the highest risk of permanent recurrent palsy

Cause

• mostly intraoperative stretching and compression of the recurrent laryngeal nerve (RLN)
• rarely continuity interruption
• also due to pressure damage after postoperative bleeding and endotracheal intubation

Endotracheal Intubation

The nerve can be damaged not only by intraoperative manipulations but also by endotracheal intubation (intubation-related recurrent palsy rate 1.4% transient, 0.5% permanent). This is evidenced by cases of postoperative recurrent palsy after surgeries distant from the neck. Possible reasons: intralaryngeal, submucosal branching of the recurrent laryngeal nerve, incorrect positioning of the cuff (e.g., within the larynx), extubation with a blocked cuff. It is therefore recommended to check the cuff for symmetry before intubation, occasional deflation, regular pressure checks especially during longer procedures, and very careful positioning of the patient with the tube in place to prevent pressure damage to the RLN adjacent to the tracheal wall.

Other causes of intubation-related hoarseness without RLN lesion: It may be “normal” postoperative hoarseness after ITN (occurring in about 30% of all patients after ITN) or intubation-related injuries such as mucosal injuries, hematomas, vocal cord injuries, and arytenoid cartilage dislocation.

Consequences

• Voice disorders, swallowing disorders, and respiratory impairments
• in bilateral recurrent palsy, a tracheotomy is often required

Prophylaxis

The risk of accidental injury to the RLN can be reduced by two complementary measures:

• consistent visualization of the RLN, especially in total lobectomies: visual identification as the gold standard
• intraoperative neuromonitoring (IONM): electromyographic functional representation of RLN and vagus nerve

To protect the vocal cord nerve and also the parathyroid glands, the following also contribute:

• so-called microdissection technique using optical instruments (magnifying glasses)
• the use of gentle hemostatic procedures (bipolar coagulation, vascular clips, “vessel sealing”, ultrasonic dissection)

Basic information about intraoperative neuromonitoring can be found at: IONM

Predilection sites of an RLN lesion are:

• upper pole: at mass ligatures where the nerve enters the pars cricopharyngea of the inferior pharyngeal constrictor muscle
• lower pole: with abrupt dislocation of the pole with the finger

Superior Laryngeal Nerve

• the external branch of the superior laryngeal nerve crosses, recrosses, or intersects the polar vessels in close proximity to the upper thyroid pole
• a lesion of the nerve branch can result in dysphonia with reduced vocal performance in terms of reduced vocal range and rapid voice fatigue
• the special anatomy should be taken into account by a capsular and gentle preparation of the upper pole
• routine visualization of the nerve branch cannot be justified by the data available so far and is therefore not recommended by current guidelines

2.2. Postoperative Bleeding

Incidence:

• 0.3-5%
• most bleedings develop within the first 12-24 hours postoperatively
• most sensitive period for postoperative bleeding: awakening phase after extubation due to increased intrathoracic pressure
• variable extent of bleeding: skin ecchymoses, hematomas under the platysma, life-threatening bleedings with asphyxia

Postoperative bleeding is the only surgery-specific complication in thyroid surgery that can lead to a life-threatening situation. In arterial bleedings, blood enters the neck compartment under high pressure and can lead to compression, swelling, intubation-requiring respiratory distress, and asystole due to vagus pressure.

• Asymptomatic hematomas without significant increase in neck circumference can remain conservative, but close monitoring of the patient is required to intervene at any time.

• Caution is advised with hematomas that develop insidiously and lead to an increase in neck circumference. Here, mucosal swelling in the larynx and trachea can massively complicate intubation, making an emergency tracheotomy necessary.

• In the case of acute arterial postoperative bleeding, immediate surgical intervention is required.

To minimize morbidity, early diagnosis and prompt, courageous intervention are required. It is therefore advisable to establish a postoperative bleeding management plan, about which you can learn more here Emergency Plan – Postoperative Bleeding after Thyroid Surgery

2.3. Hypoparathyroidism

Incidence

• transient 7.3-8.3%
• permanent 1.5-1.7%
• increased frequency of permanent hypocalcemia in thyroid malignancies (up to 4%) and in Graves' disease (up to 2%)

Cause

• accidental resection of one or more parathyroid glands
• circulatory disturbances due to injury to the vessels supplying the parathyroid glands
• if fewer than 2 or 3 parathyroid glands are preserved, the risk of permanent hypoparathyroidism increases significantly

Information on the management of postoperative hypoparathyroidism can be found at: Postoperative Hypoparathyroidism

Prophylaxis

• secure identification of the parathyroid glands through targeted visualization
• not only orientational exclusion of non-visible parathyroid tissue in situ or on the resectate
• autotransplantation of circulation-impaired parathyroid glands (cut into 1 mm³ cubes and simultaneously autotransplant into a pocket of the ipsilateral sternocleidomastoid muscle; do not forget documentation!)
• the parathyroid glands are mainly supplied by the inferior thyroid artery, so ligation should be as close to the thyroid as possible after secure identification of the recurrent laryngeal nerve

2.4. Infections

Incidence:

• 0.2-1.4%
• Wound infections usually occur as secondarily infected hematomas, abscesses, and fistula formations occur
• with good wound management, infections generally do not cause major difficulties, hematogenous spread and septic course are exceptions
• a significant but rare infection is mediastinitis, which can develop after thyroid surgery with a transsternal approach

After a lateral neck lymph node dissection, which is usually required in lymphogenically metastasizing thyroid carcinomas, the following rare complications are possible:

• Injury to the accessory nerve
• Injury to the phrenic nerve
• Injury to the thoracic duct with the formation of a chyle fistula and very rarely a chylothorax