What is the recommended guideline for thyroid surgery?

Guidelines for Thyroid Surgery

Preoperative Assessment and Preparation

All patients undergoing thyroid surgery must have preoperative voice assessment and laryngeal examination to establish baseline vocal fold mobility. 1, 2, 3

Voice Documentation

• Record the patient's voice in a quiet environment with a microphone within 4 cm of the mouth, capturing sustained "ah" and "ee" for 3-5 seconds each, standard sentences, and 30-60 seconds of conversational speech. 3
• A HIPAA-compliant smartphone recording is acceptable if professional equipment is unavailable. 3

Laryngeal Examination Requirements

• Examine vocal fold mobility or refer for laryngoscopy in ALL patients with: 1, 3

  • Any voice impairment (dysphonia, hoarseness, vocal fatigue)
  • Thyroid cancer with suspected extrathyroidal extension
  • Prior neck surgery (carotid endarterectomy, anterior cervical spine surgery, cervical esophagectomy, prior thyroid/parathyroid surgery)

• Flexible laryngoscopy is superior to mirror examination as it allows video recording and detection of subtle motion abnormalities. 1, 3

• Preoperative vocal fold paralysis occurs in 6.5% of patients and strongly suggests invasive malignancy (>70% in invasive disease vs 0.3% in noninvasive disease), fundamentally changing surgical planning. 1, 2, 3

• Critical pitfall: One-third of patients with vocal fold paralysis are asymptomatic, making examination more reliable than symptoms alone. 3

Patient Education

• Educate all patients about potential voice changes, including recurrent laryngeal nerve (RLN) injury rates: 0-5% for nerve-sparing surgery, 13% for cancer operations, and 30% for revision surgery. 1, 3, 4
• Temporary vocal fold paralysis occurs in 5.2-9.8% of patients; permanent paralysis occurs in 0.9-2.5%. 2, 4

Preoperative Laboratory and Imaging

• Document baseline thyroid function tests (TSH, FT3, FT4) to guide postoperative hormone replacement. 2
• For suspected medullary thyroid carcinoma: obtain baseline serum calcitonin, CEA, calcium, and plasma/urine metanephrines to screen for pheochromocytoma. 2
• For differentiated thyroid cancer: perform neck ultrasound to assess lymph node involvement. 2

Anesthesia Communication

• Inform the anesthesiologist of any abnormal preoperative laryngeal findings to prevent additional airway injury during intubation. 1

Intraoperative Management

Nerve Identification and Preservation

The surgeon MUST identify the recurrent laryngeal nerve(s) during thyroid surgery. This is a strong recommendation that significantly decreases the risk of permanent RLN injury and vocal fold paralysis. 1

• Routine RLN identification reduces permanent nerve injury rates to 0.9-1.4%. 4
• Risk factors for RLN injury include: larger extent of resection, recurrent goiter, abnormal anatomy, bulky disease, and surgeon inexperience. 1

Superior Laryngeal Nerve Protection

• Take specific steps to preserve the external branch of the superior laryngeal nerve (EBSLN) during thyroid surgery. 1
• Utilize the avascular plane between the superior pole and cricothyroid muscle to identify and preserve the EBSLN. 5
• EBSLN injury causes loss of vocal projection and high frequencies. 1

Surgical Technique

• Perform "capsular dissection" by ligating tertiary branches of the inferior thyroid artery on the gland surface to protect RLN and preserve parathyroid blood supply. 5
• If a parathyroid gland cannot be preserved or becomes ischemic, immediately mince and autotransplant it into the ipsilateral sternocleidomastoid muscle. 5

Intraoperative Nerve Monitoring

• Laryngeal electromyography monitoring during thyroid surgery is an option but not a requirement. 1

Postoperative Management

Immediate Postoperative Period (0-24 hours)

Place a post-thyroid surgery emergency box at bedside containing wound opening supplies, and ensure front-of-neck airway equipment (scalpel, bougie, tracheal tube) is readily available on the ward. 1, 2

Monitoring Protocol

• Perform routine patient observations at least hourly for the first 6 hours postoperatively. 1
• Haemorrhage and hematoma most frequently occur within the first 24 hours, with approximately half occurring within 6 hours. 1
• After the initial 6-hour period, tailor observation frequency according to individual patient risk. 1

Hematoma Recognition and Management

• Postoperative hematoma occurs in 0.45-4.2% of cases and can cause rapid airway obstruction. 2
• Monitor for: wound inspection abnormalities, respiratory distress, agitation, anxiety, difficulty breathing, or discomfort. 1, 2
• If airway compromise from hematoma is suspected, use the SCOOP approach at bedside: 2
  • Skin exposure
  • Cut sutures
  • Open skin
  • Open muscles (superficial and deep layers)
  • Pack wound

Ward Placement

• Nurse patients in a bed where they can easily attract nursing staff attention, preferably in an open ward or near the nursing station. 1
• Staff must have training in recognition and management of postoperative hematoma. 1

Hypocalcemia Monitoring

• Check serum calcium levels postoperatively, as temporary hypocalcemia occurs in approximately 8.1% of patients after total thyroidectomy. 2
• Early postoperative hypocalcemia (≤8.0 mg/dl) requires calcium and vitamin D supplementation. 2, 6
• Permanent hypoparathyroidism is rare with meticulous surgical technique. 6

Voice Assessment (2 Weeks to 2 Months Post-Surgery)

Systematically document whether there has been a change in voice between 2 weeks and 2 months following thyroid surgery. 1, 2

• Examine vocal fold mobility or refer for laryngoscopy in any patient with voice change after surgery. 1, 2
• Refer patients to an otolaryngologist when abnormal vocal fold mobility is identified. 1
• Counsel patients with voice change or abnormal vocal fold mobility on options for voice rehabilitation. 1
• Voice disturbances can occur even without RLN injury due to EBSLN injury, cricothyroid muscle injury, strap muscle trauma, or regional soft tissue scarring. 4

Long-Term Management

Thyroid Hormone Replacement for Differentiated Thyroid Cancer

• Initiate levothyroxine (L-T4) immediately after surgery for both replacement and TSH suppression. 2
• TSH suppression targets based on risk stratification: 2
  • Low-risk patients (papillary microcarcinoma ≤1 cm, no invasion/metastases): TSH 0.5-2.0 mIU/L
  • Intermediate-risk patients: TSH 0.1-0.5 mIU/L
  • High-risk patients: TSH <0.1 mIU/L
• Check thyroid function tests at 2-3 months post-surgery to verify adequate L-T4 dosing. 2

Medullary Thyroid Cancer Management

• Do NOT use TSH suppression therapy for medullary thyroid cancer—MTC cells lack TSH receptors. 2
• Maintain TSH in normal range with replacement-dose levothyroxine only. 2
• Radioactive iodine (RAI) is contraindicated as MTC does not concentrate iodine. 2

Radioactive Iodine Ablation

• High-risk differentiated thyroid cancer: RAI ablation is indicated. 2
• Low-risk patients (papillary microcarcinoma): RAI is NOT indicated. 2
• Intermediate-risk patients: individualize decision based on specific risk factors. 2

Surveillance

• For differentiated thyroid cancer at 6-12 months: physical examination, neck ultrasound, basal and rhTSH-stimulated serum thyroglobulin measurement. 2
• For patients free of disease: annual physical examination, basal serum thyroglobulin on L-T4 therapy, and neck ultrasound. 2
• For medullary thyroid cancer: measure serum calcitonin every 6 months for first 2-3 years, then annually. 2
• If basal calcitonin >150 pg/ml: screen for distant metastases with comprehensive imaging. 2