Thyroidectomy

Laryngeal examination

• Pre-operative laryngoscopy can be performed to look for occult RLN paresis/vocal cord paralysis pre-operatively.
• Routine laryngoscopy has not been shown to be useful - should be performed for patients at elevated risk of baseline vocal cord dysfunction.

High risk patients

• Pre-op hoarseness
• Prior neck or mediastinal surgery - thyroid and non-thyroid.
• Extrathyroidal extension or tumour posteriorly.
• Bulky lymphadenopathy in central compartment

Pre-operative management of hyperthyroidism

Patients should receive

• Pre-op anti-thyroid medications and/or beta blockage - to avoid thyroid storm.
• Pre-operative Lugols iodine solution (which is potassium iodide) - blocks iodine uptake and thus the secretion of thyroid hormone - which decreases vascularity and decreases bleeding.
• Pre-operative Vitamin D and calcium

Operative steps

• Preperation
  • Patient is position supine, with a roll beneath the shoulders to extend the neck
  • The sternal notch, cricoid cartilage, and prominence of the thyroid cartilage is marked.
• Entry
  • The incision is made below the cricoid cartilage in a natural skin crease.
  • The subcutaneous tissue and platysma is divided
  • Superior and inferior subplatysmal flaps are raised.
  • Jolls retractor or Star retractor
  • The strap muscles are separated along the median raphe
  • The strap muscles are mobilised off the lobes of the thyroid.
• Thyroid dissection
  • The middle thyroid vein is identified, and ligated - care is taken as this drains directly into the internal jugular vein.
  • Superior pole
    • Ligate branches of the superior thyroid artery close to the thyroid taking care to not injury the external branch of the superior laryngeal nerve
    • Superior parathyroid identified
  • Inferior pole
    • Dissected free and branches of the inferior thyroid vein and artery are ligated
    • Inferior parathyroid identified
    • Anterior surface of the trachea now exposed.
  • Medial
    • Retract gland medially
    • Identify the RLN
    • Dissect the thyroid off the trachea/ligament of Berry
• Exit
  • If you are doing a hemi-thyroidectomy, the cut edge of the thyroid gland is oversewn 
  • The strap muscles are re-approximated, leaving a 3cm opening inferiorly.
  • The platsyma is re-approximated - Vicryl 3/0
  • The skin is closed with a subcuticular suture - monocryl 3/0
  • A clear dressing is applied.

What to do with an enlarged parathyroid found at surgery

• If only one - should excise - perform an intra-operative PTH and post-operative PTH
• If four enlarged glands are found - DO NOT EXCISE

Intra-operative nerve monitoring

• Routine use remains controversial.
• NIM - neural integrity monitor
• May help in identification, dissection, and prediction of post-operative function of the RLN.
• Can either be using a handheld nerve stimulator or have a probe on the vocal cords which signals when the nerve is being irritated (i.e. from retraction or dissection around the tissues).
• ?Does it reduce RLN injury - controversial. Cochrane reviewed in 2019 did not find a difference

Intra-operative frozen section

Used for

• Diagnose thyroid malignancies
• Diagnose lymph node metastasis.
• Confirm parathyroid tissue

Drains

• Routine use hasn’t been shown to reduce risk of haematoma or seroma. 

Thyroxine supplementation after lobectomy

• Patients are generally not routinely started on thyroxine.
• 25% of patients after hemi may require thyroxine supplementation to maintain a normal TSH.

Calcium supplementation after thyroid surgery

• Some surgeons will prescribe calcium for all patients after thyroidectomy whereas some will only prescribe it if PTH or calcium is low.
• Measure PTH and calcium at 6pm and 6am
• Typically given calcium carbonate - 1250-2500mg daily - in 2-4 divided doses. Requires gastric acid to be absorbed.
• Patients who have had a previous gastric bypass or who take PPI’s should be given calcium citrate
• Patients with hypocalcemia should also be given magnesium.

Complications

Haematoma

• Rare but can be fatal.
• If associated with airway compromise - open at the bedside
• If not associated with airway compromise - can be monitored or evacuated in theatre.

Hypocalcemia

• “CRAMPS” - confusion, reflexes hyperactive, arrhythmias, muscle spasms, positive Trosseaus (carpo-pedal spasm with a blood pressure cuff)
• Hypocalcemia is relatively common after thyroidectomy - is rare to be severe.

Hoarseness

• Usually caused by the ET and resolves after 48 hours.
• Can be caused by RLN injury.
• Can also be caused by arytenoid dislocation - consequence of intubation - can be treated with reduction of the arytenoid cartilage.
• Injury to superior laryngeal neve - results in voice weakness or fatigue as well as change to the pitch of voice.
• RLN - hoarse voice, swallowing difficultly, and risk of aspiration pneumonia.
• Bilateral RLN injury - may need long term tracheostomy.
• Vagus nerve - high transection paralysis both nerves - significant risk of subsequent aspiration events

Horner syndrome

• Can occur due to disruption of the sympathetic chain during a lateral neck dissection.
• Results in miosis (small pupil), ptosis, and anhidrosis (absence of sweating)

Other injuries

• Chyle leak - more common with a lateral lymph node dissection
• Tracheal injury
• Oesophageal injury

Hypoparathyroidism

• Transient hypoparathyroidism occurs in 20% of patients after total thyroidectomy for thyroid cancer. 
• Permanent hypothyroidism occurs in 1-3%.