The purpose of tihs study is to determine whether transcutaneous electric nerve stimulation (TENS) during thyroidectomy is effective in the reduction of posterior neck pain after thyroidectomy.

Thyroidectomy is performed in supine position with the neck fully extended. After thyroidectomy, 80 percent of patients experience posterior neck pain as well as the incision site pain. The posterior neck pain is thought to be due to hyperextension is continued during an average of 90 minutes of surgery. Non-steroidal anti-inflammatory agents or opioids are administrated to reduce the pain, but the pain still remained.

TENS is simple, non-invasive analgesic technique that is used extensively to reduce acute and chronic pain. TENS has beneficial effect for the reduction of postoperative pain. The conventional way of administering TENS is to use electric characteristics that selectively activate large diameter Aβ fiber mediating touch perception without activating smaller diameter Aδ and C fiber.

In this study, TENS during thyroidectomy in posterior neck pain will be evaluated.

Inclusion Criteria:

• Undergoing open total thyroidectomy under general anesthesia
• American Society of Anesthesiology physical status I or II

Exclusion Criteria:

• American Society of Anesthesiology physical status III or IV
• History of headache or neck pain within six months
• Past history of herniated cervical disc, cervical foraminal stenosis, ossification of posterior longitudinal ligament

2 days