Thyroid Surgery - المنصورة

• Thyroid surgery

Principles of Thyroidectomy

• Absolute haemostasis should be achieved
• All vessels need to be ligated individually, avoid mass ligation
• Ligate the middle thyroid vein, the superior thyroid artery and vein, and the inferior thyroid vessels
• Use bipolar cautery
• Avoid using monopolar cautery in the main dissection because the lateral heat may damage the RLN or parathyroid blood supply
• Identify the RLN & ELN during dissection to prevent injury
• Preserve the parathyroid glands
• Cosmesis
• Use a meticulous surgical technique

Types of Thyroidectomy

• Hemithyroidectomy
  • Removes entire one lateral lobe & entire isthmus
  • Retains the other lobe
  • Done for benign diseases of one lobe, follicular neoplasm in one lobe, solitary nodules, and thyroid cysts
• Subtotal Thyroidectomy
  • Most of the gland is removed
  • Retains only about 8g or finger pulp-sized tissue on both lower poles
  • Done for toxic thyroid commonly, and multinodular goiters that are either nontoxic (often) or toxic
• Partial Thyroidectomy
  • The gland in front of the trachea (after mobilization) is removed, this procedure is controversial
  • Tissue in the tracheoesophageal groove is retained
  • Done for nontoxic multinodular goiters
• Near Total Thyroidectomy
  • Most of both lobes is removed
  • Retains the lower pole of one side or both sides (< 2 grams) to safeguard the RLN & Parathyroid gland
  • Done for papillary carcinoma of the thyroid
• Total Thyroidectomy
  • The entire gland is removed
  • No tissue is retained
  • Done for follicular carcinoma and medullary carcinoma of the thyroid
• Hartley Dunhill Procedure
  • Removes one entire lateral lobe, the isthmus, and partial/subtotal of opposite lateral lobe
  • Retains 4 grams of tissue of the opposite lobe
  • Done for nontoxic multinodular goiters
• Isthmectomy
  • The isthmus needs to be removed entirely in any type of thyroidectomy
  • Prevents adherence to the wound and creating a cosmetically poor scar
  • Advanced carcinoma and Riedel's thyroiditis (to treat severe stridor due to tracheal narrowing) are indications

Surgery for Thyrotoxicosis

• Pre-Operative Preparations
  • The patient must be euthyroid, preparation is usually outpatient
  • Antithyroid Drugs
    • Carbimazole is the drug of choice
    • The dose is 30-40mg per day
    • Once the patient is euthyroid (after 8-12 weeks) the dose is decreased to 5mg every 8 hours
    • Last dose may be given the evening before surgery
    • The mechanism is to act on target organs, and not on the gland itself
    • Inhibits the peripheral conversion of T4 to T3
  • B-Adrenergic Blocking Drugs
    • Propranolol is given at 40mg three times a day
    • Clinical response is rapid
    • Beta-blockers don't affect thyroid hormone synthesis, so continue for 7 days post-operative
  • Iodine
    • May be given with carbimazole or a Beta-adrenergic blocking drug for the 10 days before operation
    • Iodide alone produces a transient remission & may decrease vascularity and marginally improving safety
• Pre-Operative Investigations
  • Thyroid function tests
  • Laryngoscopy
  • Thyroid antibodies
  • Serum calcium estimation
  • Isotope scan is needed for toxic nodular goiter if total thyroidectomy is not planned, helps to locate the nodule(s)
• Operative Procedure
  • The patient is put under general anesthesia in a supine position with neck hyperextended, and with the table tilted to a 15-degree head up position
  • Kocher's Thyroid Incision
    • A horizontal crease incision is made two fingers above the sternal notch, from one sternomastoid to the other
  • Procedure
    • Skin & platysma are incised
    • The upper flap is raised up to the thyroid cartilage and the lower flap up to the sternoclavicular joint
    • Deep fascia is opened vertically in the midline
    • Superior pedicle is dissected; ligate and divide the artery and the vein
    • In the past, mass ligation at the superior pole increased the chance of ELN injury and AV fistula
    • Identifying the ELN nerve is preferred
  • Identify and retain the parathyroids (yellowish brown / orange brown) and their blood supply from the inferior thyroid artery
  • The RLN should be identified with careful dissection through its entire course
    • Only use bipolar cautery to avoid monopolar cautery
    • The nerve crosses the inferior thyroid artery, with common variations
    • Posterior extension near Berry's ligament is called Zuckerkandl tubercle, seen in 40% of cases
    • The nerve runs upwards in a fissure between zuckerkandl tubercle and trachea or main thyroid gland
    • The recurrent laryngeal nerve is in close contact with the suspensory ligament of berry
  • The inferior thyroid artery, a branch of the thyrocervical trunk, ascends to the gland's lower pole behind the carotid artery
  • The Ligation is done at the capsular level to preserve parathyroid blood supply
    • After origins of the branches to superior & inferior parathyroid glands: Away from gland immediately after coming behind the CCA
    • Ligation in continuity absorbable (catgut) suture: Mobilized gland is removed
      • IDEAL AND BETTER - written
  • Critical points of recurrent laryngeal nerve injury
    • At the entry of the inferior thyroid artery
    • At suspensory ligament of Berry
    • At the lower pole of the gland
    • The sandbag is removed and haemostasis is confirmed
  • Closure
    • A suction drain is placed through a separate incision or the main wound, passing under strap muscles to the thyroid fossa
    • Strap muscles and platysma are sutured with interrupted, 3 zero vicryl sutures
    • Subcuticular absorbable, 3 zero monocryl suture is used on the skin
    • Placing a soft light dressing may be ideal
  • Minimally Invasive Video-Assisted Thyroidectomy (MIVAT) is becoming popular for small nodules and gland without thyroiditis, but it is costly

Post-Operative Complications

• Haemorrhage
• Respiratory obstruction
• Recurrent laryngeal nerve paralysis and voice change
• Thyroid insufficiency
• Parathyroid insufficiency
• Thyrotoxic crisis (storm)
• Wound infection
• Hypertrophic or keloid scar
• Stitch granuloma
• Haemorrhage
  • Causes: slipping of ligatures either of the superior thyroid artery or other pedicles or small veins
  • Presentation: tachycardia, hypotension, dyspnea and compression over the trachea (may cause severe stridor, respiratory obstruction due to tension hematoma obstruct)
  • Management: open the sutures as first aid, then shift the patient to the operation theater under general anesthesia and ligate the bleeders (blood transfusion may be required)
• Respiratory Obstruction
  • Causes
    • Laryngeal edema, (commonest cause) may be due to hematoma, intubation injury, or surgical trauma
    • Bilateral RLN palsy (emergency endotracheal intubation is done along with steroid injections)
    • Tracheomalacia
  • Often requires emergency tracheostomy as a life-saving procedure
• Recurrent Laryngeal Nerve Palsy:
  • Includes paralysis of laryngeal muscles
  • Unilateral
    • No specific treatment is required, but steroid at 20 mg tid for 10 days can be administered, with gradual tapering over 10 days
    • Paralysis occurs in all intrinsic muscles except cricothyroid
    • Vocal cord becomes median or paramedian in position
    • Mild clinical features
      • Asymptomatic in 33% of cases
      • Some change in voice
      • Aspiration never occurs
      • Airway obstruction never occurs
      • Change in voice
  • Bilateral
    • Emergency tracheostomy is required
    • Lateralization of cord is preformed by:
      • Arytenoidectomy (open or endoscopic)
      • Vocal cord lateralization (endoscopic)
      • Excision or laser cordectomy
      • Sternohyoid implantation
      • Thyroplasty
    • Paralysis occurs in all intrinsic muscles
    • Vocal cord position is median or paramedian due to unopposed actions of both side cricothyroid
    • More severe clinical features
      • Severe dyspnea and stridor (more during exertion) leading to airway block and respiratory arrest
  • Combined Recurrent Laryngeal & Superior Laryngeal N. Palsy
    • Speech therapy
    • Injection of Teflon to the paralyzed cord
    • Muscle or cartilage implant to the paralyzed cord
    • Arthrodesis of cricoarytenoid joint
    • Paralysis occurs in all muscles on one side
    • Vocal cord position is in the cadaveric position, 3-5 mm from the midline
    • Aphonia (no voice)
    • Aspiration due to severe glottis incompetence and laryngeal anesthesia
    • Retention of secretions in chest
    • Emergency tracheostomy
    • Fixing epiglottis over the arytenoids to prevent aspiration
    • Plication of vocal cords to prevent aspiration
    • Total laryngectomy.
    • Paralysis occurs in all total of the intrinsic muscles
  • Hypoparathyroidism
    • Rare, 0.5% common
    • Most often, it is temporary due to vascular spasm of parathyroid glands, occurs in the 2nd-5th post-operative day
    • Symptoms
      • Weakness
      • +ve Chvostek's sign
      • Carpopedal spasm
      • Convulsions
    • Management: Serum calcium is measured and then 10 ml of 10% calcium gluconate is given IV 8th hourly, later supplemented by oral calcium carbonate 500 mg 8th hourly.
      • After 3-6 weeks, the patient is admitted, drug is stopped and serum calcium level is repeated
    • Note: Earliest symptom of hypocalcaemia is muscle weakness
  • Thyrotoxic Crisis
    • Occurs in inadequately prepared thyrotoxic patients, often triggered by stress or surgery
    • Other causes: infection; trauma; preeclampsia; diabetic ketosis; emergency surgery
    • Clinical features start showing within 12-24 hours after surgery
      • Severe dehydration
      • Hypotension- Palpitation
      • Tachypnea- Hyperventilation
      • Diarrhea- vomiting
      • Circulatory collapse
      • Hyperpyrexia
      • Restlessness- tremor- delirium
      • Cardiac failure- later coma
    • Treatment involves
      • Injection Hydrocortisone
      • Cooling of whole body
      • Oral antithyroid drugs and oral iodides
      • The use of beta-blocker injection, oral iodides
      • IV fluids for rehydration, Digoxin
      • Cardiac monitor and ventilator support, with close observation
    • Has a high mortality rate with a critical period of 72 hours
    • Other Complications
      • Hypothyroidism: Revealed clinically after 6 months
      • Wound infection
      • Keloid formation
      • Recurrent thyrotoxicosis 5% common
        • More thyroid tissue has been retained, manage by using antithyroid drugs or radioiodine therapy
      • Injury to the external laryngeal nerve: Causes voice changes and voice fatigue
  • Post-operative care for thyroidectomy
    • Observe for signs and symptoms of RLN palsy & hypoparathyroidism
    • Discharge on second post-operative day
    • Remove drain if serous and minimal 24 hours after surgery