The objective of this study is to compare the postoperative analgesia afforded by bilateral superficial cervical block using different concentrations of local anesthetic (ropivacaine) in patients undergoing total thyroidectomy for the mini-incision technique, performed by the same surgical team.

In this study we will evaluate the efficacy of bilateral superficial cervical block associated with balanced general anesthesia with remifentanil as opioid of choice in preventing postoperative pain in patients who underwent total thyroidectomy with mini incision without neck dissection.A hundred and twenty patients ASA I - II will be assessed and allocated randomly (through a table of random numbers) into three groups for analgesia for post-operative:

Group 1: bilateral superficial cervical block with 20 ml of 0.9% saline (placebo); Group 2: bilateral superficial cervical block with 20 ml ropivacaine 0.25%; Group 3: bilateral superficial cervical block with 20 ml ropivacaine 0.5%.

Inclusion Criteria:

• Age greater than 18 years
• Agreed to participate in the study and sign the consent form
• ASA I-II
• Scheduled to undergo total thyroidectomy without neck dissection under general balanced anesthesia.

Exclusion Criteria:

• Clinical history or laboratory tests suggestive of bleeding disorder
• Mental or cognitive deficit in existence, which makes it impossible to understand the patient visual analog scale of pain or the study protocol
• Body mass index greater than 45
• History of allergy to local anesthetics
• Intolerance or contraindication to any medication used in the study
• Skin infection at the site of the blockade
• Patients requiring neck dissection
• Pregnancy
• Preoperative use of opioid analgesics or non-opioids, corticosteroids or anti inflammatory non steroidal
• Patient's refusal to participate in the study
• Need for emergency reintervention within the first 24 hours postoperatively