This study aims to evaluate whether adding intravenous dexamethasone to standard intravenous dexmedetomidine improves pain control after shoulder arthroscopy performed under a superior trunk block. Shoulder arthroscopy is a common surgical procedure that can cause moderate to severe postoperative pain.

In this study, adult patients undergoing elective arthroscopic shoulder surgery will receive a nerve block called a superior trunk block to control pain during and after surgery. All participants will also receive intravenous dexmedetomidine, a medication commonly used to enhance analgesia.

Participants will be randomly assigned to one of two groups. One group will receive intravenous dexamethasone, while the other group will receive a placebo (saline solution). Neither the patients nor the healthcare providers nor the outcome assessors will know which treatment each participant receives.

The main goal of the study is to determine how long it takes before patients require their first additional pain medication after surgery. Secondary outcomes include pain scores, total pain medication use, duration of nerve block, rebound pain, side effects, and patient satisfaction.

The findings of this study may help improve postoperative pain management strategies for patients undergoing shoulder arthroscopy.

Inclusion Criteria:

• Age between 18 and 65 years
• American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled for elective arthroscopic shoulder surgery
• Body mass index (BMI) between 18.5 and 35 kg/m²
• Ability to understand the study protocol and provide written informed consent

Exclusion Criteria:

• Refusal to participate or inability to provide informed consent Contraindications to peripheral nerve block (e.g., coagulopathy, infection at the injection site) Known allergy or hypersensitivity to study medications (dexamethasone, dexmedetomidine, or local anesthetics) Pregnancy or breastfeeding Chronic opioid use or opioid dependence Pre-existing neurological deficit involving the operative upper extremity Severe hepatic or renal dysfunction Uncontrolled diabetes mellitus Body mass index (BMI) >35 kg/m² Infection at the planned block site Participation in another interventional clinical trial within the last 30 days