As robotic surgery has been applied to various surgeries, the minimally invasive surgery is rapidly evolving. In particular, robot-assisted thyroidectomy is one of the leading techniques in minimally invasive surgery fields. Robot-assisted transaxillary thyroidectomy dramatically improves the cosmetic satisfaction, showing no difference in cancer control and safety comparing with conventional open thyroidectomy. However, some studies have shown that many patients complained of chest pain after robot-assisted thyroidectomy, and about 20% of patients suffered chronic pain even after three months of surgery. This might be due to the flap formation during robot-assisted thyroidectomy.

Robot-assisted transaxillary thyroidectomy does not provide visibility by injecting CO2. But it provides visibility using Chung's retractor system to make a flap between the pectoralis major muscle and subcutaneous fat layer. The flap is formed from the incision of axilla to the anterior neck to approach the thyroid gland. In this progress, it requires considerable force to maintain the Chung's retractor system, and additional pressure may be applied to the subcutaneous fat and skin constituting the skin flap. The pressure applied to the skin flap may be associated with postoperative pain and sensory abnormality, but it has not been studied yet.

Deep neuromuscular blockade The neuromuscular block for muscle relaxation during surgery is essential for general anesthesia. In general, a neuromuscular block agent is used to induce intubation during induction of anesthesia. Continuous or single injection of neuromuscular block agent is then carried out as needed during the operation.

The effect of deep neuromuscular blockade on laparoscopic surgery using carbon dioxide has already been studied. Deep neuromuscular blockade on laparoscopic surgery reduced postoperative pain and improved the surgical condition compared to conventional moderate neuromuscular blockade. However, the effect of neuromuscular blockade on robot-assisted thyroid surgery has not been studied yet.

There was concern about delayed recovery of muscle relaxation and respiratory failure due to deep neuromuscular blockade. However, the development of sugammadex (Bridion, Merck Sharp and Dohme - MSD, Oss, Netherlands) eliminated these concerns. Sugammadex dramatically reduced the recovery time from deep neuromuscular blockade.

Inclusion Criteria:

• A. 20-70 yrs old patients scheduled for robot-assisted transaxillary thyroidectomy
• B. ASA(American Society of Anesthesiologists) classification: Ⅰ-Ⅲ
• C. Patients who voluntarily agree to participate in this clinical study.

Exclusion Criteria:

• A. Patients scheduled for radical neck node dissection
• B. Patients scheduled for co-operation of other organs or Patients with other accompanying cancers
• C. Patients with BMI(Body Mass Index) > 30 kg/m2
• D. Patients with history of Liver failure, Renal failure
• E. Patients who already have pain or paresthesia on chest, axilla, or neck.
• F. Patients with history of allergy to rocuronium or sugammadex
• G. Patients who cannot read the consent form (examples: Illiterate, foreigner)
• H. Pregnant woman, Lactating woman

Participants and Care Providers will be blinded.