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

Bleeding

In the event of massive intraoperative bleeding (e.g., from Kocher's vein or the inferior thyroid artery), initial tamponade is performed, and continuous suction is used to attempt to identify the vessel in order to clamp and ligate it.

Note: In every thyroid surgery, it is recommended to check for hemostasis under PEEP ventilation of the patient before wound closure. 

Detection of Signal Loss in IONM (Intraoperative Neuromonitoring)

If it occurs on the first side of a planned bilateral resection, the resection of the contralateral side should be avoided to prevent the risk of bilateral recurrent laryngeal nerve palsy.

Hypoperfusion or Accidental Removal of a Parathyroid Gland (PG)

Typically, autotransplantation is performed after histological confirmation of the organ in 1 mm³ cubes into a pocket of the ipsilateral sternocleidomastoid muscle (do not forget documentation!).

Prophylaxis:

In addition to the gold standard of visual identification, at least in complex cases, an additional detection method with spontaneous or induced fluorescence is recommended (autofluorescence, ICG fluorescence, PT-EYE).

A statement about the vascularization or devascularization of the parathyroid gland can only be made with ICG fluorescence angiography. 

Tracheal Injury

Immediate suturing if possible, suture coverage with additional material (pericardium, pleura, sternocleidomastoid muscle, fleece-bound tissue adhesive), possibly stent, peri- and postoperative antibiotic therapy 

Esophageal Injury 

in extensive tumor or goiter surgeries, direct suture, antibiotics, drainage

Pleural Injuries/Tension Pneumothorax (in deep cervical resection)

Suture, possibly chest drainage

Recurrent Laryngeal Nerve Palsy/Vocal Cord Paralysis

Incidence

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

Cause

• mostly intraoperative stretching and compression of the recurrent laryngeal nerve (RLN) with a good prognosis and recovery of vocal cord function within days to weeks
• rarely continuity interruption
• pressure damage after postoperative bleeding
• intubation-related non-neural impairments of vocal cord mobility: Not only intraoperative manipulations can damage vocal cord function, but also endotracheal intubation: incorrect positioning of the cuff (e.g., within the larynx), extubation with a blocked cuff, rough positioning of the head with the tube in place. Injuries to the vocal cords such as pressure damage, mucosal injuries, hematomas up to dislocation of the arytenoid cartilages are possible.

Consequences

• incomplete closure of the vocal cord on the affected side
• hoarseness, swallowing disorders, and respiratory impairments, especially in bilateral paralysis due to significant narrowing of the glottis. The primary concern is securing the airway, which may necessitate a tracheostomy.
• in symptomatic vocal cord paresis, speech therapy voice training

Prophylaxis

• Avoidance of recurrent laryngeal nerve palsy is considered a quality feature of the operation.
• Prevent damage through precise anatomical knowledge with possible variations in nerve course, as well as careful visual representation and preparation to safely preserve the nerve.
• Use of neuromonitoring to identify the nerve and detect functional damage that may not be visually apparent.
• If signal loss occurs on the first operated side, consecutive suspension of resection on the opposite side.
• To preserve the vocal cord nerve, the following also contribute:
  1. so-called microdissection technique using optical instruments (magnifying glasses)
  2. the use of gentle hemostatic procedures (bipolar coagulation, vascular clips, “vessel sealing”, ultrasonic dissection) 

Damage to the Superior Laryngeal Nerve

• The superior laryngeal nerve is a branch of the vagus nerve, which divides medially to the carotid artery into a motor external branch for the motor innervation of the cricothyroid muscle and a sensory internal branch for the laryngeal mucosa.
• The external branch of the superior laryngeal nerve crosses, recrosses, or traverses the polar vessels in close proximity to the upper thyroid pole.
  
  
  • A lesion of this 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 capsule-near and gentle preparation of the upper thyroid pole.
  • Use of EBSLN monitoring in thyroid surgeries with difficult anatomy and in patients with high vocal demands. 

Basic information about intraoperative neuromonitoring can be found at:Link IONM

Sympathetic Nerve Damage

Rare complication in very large goiters or reoperations, evident as Horner's syndrome (partial ptosis, miosis, and facial anhidrosis)

Dysphagia

• Causes: arytenoid trauma after intubation, surgical trauma to the straight neck muscles or the cricothyroid muscle, changes in laryngeal blood flow, scar and adhesion formation with disturbance of hyoid mobility or laryngotracheal fixation to soft tissues and skin, psychogenic, damage to the extrinsic perithyroidal nerve plexus
• Therapy: mostly self-limiting, lateralization of the straight neck muscles

 Postoperative Bleeding

• Incidence (1 - 2%): Most postoperative bleedings occur within the first 6 hours after the procedure. Data show that 54% of all patients in thyroid and parathyroid surgery experience nausea and vomiting for more than 24 hours postoperatively and are at increased risk of postoperative bleeding during this phase. A significant risk of postoperative bleeding (about 20%) also exists beyond the 24-hour mark.
• Risk factors: use of anticoagulants, coagulation disorders, extensive resections, older patient age, male gender, reoperation
• Prevention through meticulous intraoperative hemostasis and careful surgical technique. At the end of the operation, Valsalva maneuver and adequate blood pressure to check for dryness. Calm, uneventful emergence and extubation.
• Postoperative bleeding in thyroid surgery is a procedure-specific complication that can lead to a life-threatening situation. In arterial bleeding, blood enters the neck compartment under high pressure and can cause compression, swelling, intubation-requiring respiratory distress, and asystole due to vagal pressure.
• First signs of bleeding: cervical pressure and tightness, muffled speech, swallowing difficulties. In case of sweating, shortness of breath, stridor, tachycardia, and hypotension, immediate surgical revision is necessary. Laboratory tests and sonography are not reliable diagnostic measures for detecting bleeding and should be deferred or omitted due to the acute nature.
• Therapy: Securing the airway takes precedence, but timely transfer to the operating room is preferable to perform orderly reintubation and revision under sterile conditions. Mucosal swelling in the larynx and trachea can significantly complicate intubation, making an emergency tracheotomy necessary.
• Asymptomatic hematomas without significant increase in neck circumference should be treated conservatively, provided that close monitoring of the patient is ensured to allow intervention at any time.

Hypoparathyroidism

Common complication after bilateral thyroid procedures, reoperations, or central cervical lymphadenectomy. Defined as a laboratory diagnosis with PTH < 15 pg/ml and simultaneously normal, low normal, or decreased serum calcium (protein-corrected). To detect postoperative hypoparathyroidism early, serum calcium and intact parathyroid hormone should be determined directly postoperatively or on the morning of the first postoperative day. Calcium on the first postoperative day alone does not correlate with the prognosis regarding the development of hypoparathyroidism.

Incidence

• in thyroidectomy transient up to 33.6%, permanent around 10%
• In transient hypoparathyroidism, parathyroid function normalizes within the first 6 months postoperatively.
• increased frequency in thyroid malignancies and Graves' disease

Cause

• accidental removal of one or more parathyroid glands Note: In about 7%, parathyroid glands are found on the surgical specimen!
• Circulatory disorders due to injury to the vessels supplying the parathyroid glands, devascularization of the parathyroid glands, especially through extensive exposure of the RLN or proximal ligation of the inferior thyroid artery. In central cervical lymphadenectomy, the blood supply to the lower parathyroid glands is particularly at risk.
• If fewer than 2 or 3 parathyroid glands are preserved, the risk of permanent hypoparathyroidism increases significantly.

Prevention

• Thyroid capsule-near vascular interruptions to avoid devascularization of the parathyroid glands.
• Secure identification of the parathyroid glands and capsule-near dissection, often on a branch of the inferior thyroid artery.
• Careful preparation using so-called microdissection technique with optical instruments (surgical loupes).
• Use of gentle hemostatic procedures (bipolar coagulation, vascular clips, “vessel sealing”, ultrasonic dissection)
• In addition to the gold standard of visual identification, at least in complex cases, an additional detection method with spontaneous or induced fluorescence is recommended (autofluorescence, ICG fluorescence, PT-EYE).
  
  Autofluorescence: Parathyroid tissue emits a weak but specific fluorescence signal when stimulated with near-infrared light (wavelength often 785 nm). No dye is needed. Real-time display during surgery, special camera required.
  
  Indocyanine green (ICG) fluorescence angiography: Intravenous injection of indocyanine green (ICG), a fluorescent dye. ICG binds to plasma proteins and shows vascularized structures. The parathyroid glands become visible due to their particularly high vascular density with a special camera for near-infrared light (NIR light). Allows assessment of gland perfusion → prognosis of postoperative function.
   
• autotransplantation of parathyroid glands with impaired circulation after histological organ confirmation (in 1 mm³ cubes in a pocket of the ipsilateral sternocleidomastoid muscle; do not forget documentation!).
• In principle, each parathyroid gland should be treated as if it were the last!

Therapy

• In postoperative inadequately decreased parathyroid hormone (< 15 pg/ml), oral medication with calcium (e.g., calcium carbonate up to 3 x 500 mg/d; calcitriol 2 - 3 x 0.25 - 1 µg/d) should be initiated. If concomitant therapy with proton pump inhibitors is present, calcium citrate can be switched to. Medication can be supplemented with additional magnesium, as serum magnesium concentration is also reduced in hypoparathyroidism. In persistent symptoms under maximum oral medication, temporary intravenous therapy may be required.
• If the patient is discharged with high-dose calcium and vitamin D medication, regular monitoring and early adjustment/reduction of medication should be performed to avoid iatrogenic hypercalcemia. Avoidance of nephrotoxic hypercalcemia by adjusting serum calcium below 2.3 mmol/L. Higher serum calcium levels lead to increased urinary calcium excretion and suppression of parathyroid function with low or subnormal PTH.

Infections

Incidence

• 0.3 - 2.9%
• Wound infections usually occur as secondarily infected hematomas, abscesses can occur.
• With good wound management in addition to antibiotic treatment, infections generally do not pose major difficulties.
• Hematogenous spread and septic course are exceptions. In deeper cervical phlegmon, extensive and possibly repeated debridement is required.

Chyle Fistula/Chylothorax

Injury to the thoracic duct in large goiters with retrosternal extension, or when lymph nodes in the lateral neck triangle are removed.

Diagnosis/Therapy: conservative measures (drainage, compression bandages, total parenteral nutrition, special enteral diet); lymphangiography and possibly embolization of the thoracic duct

Extremely Rare Complications

• A potentially life-threatening rapidly spreading infection with mediastinitis can be triggered early postoperatively, especially by group A β-hemolytic streptococci. Rapid diagnosis and therapy with wound opening, wound swab, and targeted antibiotic therapy are required. Risk factors include diabetes, immunosuppression, obesity, sternotomy, and long operation duration (> 2 - 3 hours).
• Injury to the accessory nerve or phrenic nerve in the lateral neck triangle