What are the key components of a pre-operative evaluation for a patient undergoing thyroidectomy?

Pre-Operative Evaluation for Thyroidectomy

All patients undergoing thyroidectomy should have a preoperative voice assessment and vocal fold mobility examination, with formal laryngoscopy required for any patient with voice impairment, suspected extrathyroidal extension, prior neck surgery, or thyroid malignancy. 1

Voice Assessment and Documentation

Baseline Voice Evaluation

• Perform a preoperative voice assessment on every patient to establish baseline function and enable postoperative comparison 1
• Document voice quality using audio recording in a quiet environment with microphone within 4 cm of patient's mouth 1
• Record sustained "ah" and "ee" for 3-5 seconds each, standard sentences, and 30-60 seconds of conversational speech 1
• A HIPAA-compliant smartphone recording is acceptable if professional equipment unavailable 1

Laryngeal Examination Indications

Mandatory Laryngoscopy

Examine vocal fold mobility (or refer for examination) in the following scenarios: 1

• Any voice impairment detected on initial assessment (hoarseness, pitch changes, vocal fatigue) 1
• Thyroid malignancy with suspected extrathyroidal extension, even with normal voice 1
  • Historical factors: voice abnormality, dysphagia, airway symptoms, hemoptysis, pain, rapid progression 1
  • Physical exam: large/firm mass, fixation to larynx or trachea 1
  • Radiographic: irregular/blurred margins with posterior extension beyond thyroid capsule 1
• Prior neck surgery including carotid endarterectomy, anterior cervical spine approach, cervical esophagectomy, or previous thyroid/parathyroid surgery 1

Clinical Significance

• Preoperative vocal fold paralysis occurs in 1% of benign thyroid disease and up to 8% of malignant disease 1
• Vocal fold paralysis strongly suggests invasive malignancy (>70% in invasive cancer vs 0.3% in noninvasive disease) 1
• One-third of patients with postoperative vocal fold paralysis are asymptomatic, making examination more reliable than symptoms alone 1
• Preoperative knowledge of vocal fold paralysis enables more detailed surgical planning, imaging, and patient counseling 1

Additional Preoperative Evaluations

Imaging and Laboratory Studies

• Neck ultrasound is associated with lower postoperative hypocalcemia rates (OR 0.5,95% CI 0.331-0.768, p=0.0014) 2
• Fine-needle aspiration cytology (FNAC) reduces hypocalcemia risk (OR 0.65,95% CI 0.459-0.911, p=0.0127) 2
• Preoperative molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) can guide extent of initial surgery and reduce need for completion thyroidectomy 3

Thyroid Function Optimization

• For hyperthyroid patients, preoperative preparation with thionamides, beta-blockers, iodine, or corticosteroids should be considered, though achieving euthyroid state is not absolutely required if cardiovascularly stable 4
• Patients receiving preoperative corticosteroids may have mildly lower calcium levels on postoperative day 1 (mean <8.5 mg/dL) but no increased rate of permanent hypoparathyroidism 5

Patient Education

Mandatory Counseling

• Educate all patients about potential voice changes after thyroid surgery once decision for surgery is made 1
• Discuss recurrent laryngeal nerve injury rates: 0-5% for nerve-sparing surgery, 13% for cancer operations, 30% for revision surgery 1
• Inform patients eligible for lobectomy of up to 30% risk of requiring completion thyroidectomy despite careful pre- and intraoperative assessment 6

Common Pitfalls

• Do not rely solely on voice symptoms to determine need for laryngoscopy—up to 68% of vocal fold paralysis cases may be asymptomatic 1
• Preoperative imaging has limited sensitivity for extrathyroidal extension (ultrasound: 42% for tracheal invasion, 29% for esophageal invasion) 1
• Flexible laryngoscopy is superior to mirror examination for detecting subtle vocal fold motion abnormalities and allows video documentation 1