Endoscopic Thyroidectomy

1. Introduction and Historical Context

1. The development of high-definition miniaturized endoscopes
2. Energy-sealing devices capable of working in a confined operative space

• Scott-Brown's Otorhinolaryngology HNS, Chapter 69, p. 858

2. Classification / Nomenclature

3. Minimally Invasive Thyroidectomy - Techniques

3a. The Miccoli Technique (MIVAT / Gas-less Method)

• A 2-3 cm midline incision is made in the neck
• Endoscopic dissection of the superior pole is performed under direct visualization
• The superior pole is delivered into the neck
• Dissection of the lower pole and completion thyroidectomy is then carried out in a conventional (open) manner once the thyroid is delivered through the incision

• A 30-degree, 4 mm endoscope
• Specially designed suction dissectors, spatulas, and retractors (see Figure 69.1)
• Requires two competent assistants and video stacks

• Excellent visualization of the recurrent laryngeal nerve (RLN), external laryngeal nerve (ELN), and parathyroid glands
• Avoids complications of gas insufflation
• Total thyroidectomy is possible through a single incision

• Solitary nodules up to 3 cm in diameter
• Total thyroid lobe volume should not exceed 20 mL (nodule volume up to 14 mL)
• Selected Graves' disease and thyroid cancer (in highly experienced hands)

• History of thyroiditis
• Prior thyroid surgery
• Known thyroid cancer (relative, in general practice)

• Suitable for only approximately 8% of a UK surgeon's thyroid practice
• Steep learning curve: >50 cases required before achieving expert status
• 86% of BAETS (British Association of Endocrine and Thyroid Surgeons) members perform fewer than 50 thyroidectomies per year, limiting adoption
• Excessive traction through the small incision may cause hyperpigmentation or hypertrophy of the scar - the opposite of the cosmetic goal

3b. The Henry Technique (Insufflation / CO2 Gas Method)

• Creates three lateral ports along the anterior border of the sternocleidomastoid muscle:
  • Two 3 mm ports for instrumentation
  • One 1 cm port for introduction of the insufflator-endoscope
• CO2 insufflation at a pressure of 8 mmHg creates the working space and achieves a bloodless operative field

• Dissection takes place entirely within the neck
• Delivery of the thyroid lobe (once dissection is complete) is through the endoscope port
• An assistant holds and manipulates the endoscope while dissection proceeds via the other ports

• Total thyroidectomy is not possible by this method
• Technically more challenging than the Miccoli method
• Potential complication of hypercarbia from CO2 insufflation, which can be serious
• While excellent for parathyroidectomy, it has not been widely adopted for thyroid surgery

4. Scarless in the Neck Techniques

4a. Transaxillary Approach

• Multiple Asian studies report on endoscopic transaxillary thyroidectomy
• Entry through the axilla avoids any neck incision
• Both gasless and CO2 insufflation variants are used
• Hypercarbia is a recognized serious potential complication of insufflation in this approach
• Korean surgeons (notably Chung at Yonsei University, Seoul) pioneered the transaxillary route - by 2013 they had experience exceeding 3,000 patients

4b. Facelift Approach

• Described by Terris et al.
• The incision is placed within the facelift crease, completely hiding the scar
• Feasibility compared favorably against transaxillary approach in a series of 15 patients
• Demonstrated decreased operative time and potential for outpatient thyroidectomy without drain placement

4c. Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA)

• Access via oral vestibular incisions - truly scarless
• A shorter and less expensive operation compared to robotic transoral approaches
• Avoids any cutaneous scar entirely
• Indications, safety, and long-term outcomes continue to be defined in the literature

5. Evidence Base for Minimally Invasive Thyroidectomy

• Complications were no higher than conventional thyroidectomy
• Superior cosmetic outcomes were supported
• Operating time was longer
• Scar cosmesis was assessed only in the early post-operative period; validated scar assessment methods were not used

6. Robotic-Assisted Thyroidectomy (RAT)

Background and Technology

• Three-dimensional display with 30-degree optics
• 540-degree wristed instrumentation - surpasses human wrist range of motion
• Improved operative dexterity, field exposure, and visualization
• Motion scaling and tremor filtration

Surgical Approaches for Robotic Thyroidectomy

1. Transaxillary - the dominant approach, pioneered by Chung and Korean surgeons
2. Facelift - demonstrated by Terris (2012)
3. Combined endoscopic-robotic transaxillary - reported by Chang et al.
4. Transoral robotic - emerging approach via oral vestibule

Clinical Evidence

• A recent meta-analysis of 5,200 patients showed an equivalent adverse event and complication rate for robotic thyroidectomy compared to conventional approaches
• Rates of cord palsy and hypocalcaemia were not significantly different from conventional thyroidectomy
• Chung's Korean series reported superior cosmetic outcomes and better post-operative swallowing function
• Safety in papillary thyroid cancer has been studied; however, mean tumour size was only 8 mm (microcarcinoma category), limiting generalizability
• Studies are heavily weighted toward pioneering Korean units, with significant publication bias (complications of RAT tend not to be published)

Caution

• Conventional open thyroidectomy remains safe and effective
• The technique adds cost and operative time
• The learning curve is significant
• Prospective cohort data are limited outside high-volume Korean centres

7. Indications Summary

8. Complications Specific to Endoscopic/Robotic Approaches

• Hypercarbia - from CO2 insufflation, potentially serious; monitored with end-tidal CO2
• Hypertrophic scarring / hyperpigmentation - paradoxically caused by excessive traction through a small cervical incision
• Brachial plexus injury - with transaxillary approach (arm positioning)
• Skin flap injury - with remote access approaches creating subcutaneous tunnels
• Longer operative time - consistent finding across all minimally invasive techniques
• Higher cost - particularly for robotic systems

9. Practical Considerations and Training

• Both Miccoli and Henry techniques require a large volume thyroid practice to maintain competency
• Volume-outcome data indicate only surgeons with high-volume practices should adopt these techniques
• Steep learning curve requiring >50 cases for MIVAT expert status
• With 86% of UK thyroid surgeons performing <50 cases/year, few centres in the UK perform truly minimally invasive thyroidectomy
• These techniques are best suited to centres with dedicated endocrine surgery units

10. Conclusion

• Scott-Brown's Otorhinolaryngology Head & Neck Surgery (7th ed.), Chapter 69 - Minimally Invasive and Robotic-Assisted Thyroidectomy, Neil S. Tolley, pp. 858-817
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol 2, Chapter 29 - Robotic Thyroidectomy
• Cummings Otolaryngology Head and Neck Surgery, Chapter on Thyroid Surgery