Effect of Interscalene Block Methods on Rebound Pain

Effect of Intraplexus and Extraplexus Interscalene Block Approaches on the Incidence of Rebound Pain in Arthroscopic Shoulder Surgery: A Prospective, Randomized, Double-Blind Clinical Study

In this study, the hypothesis that local anesthesia, not directly injected into the nerve root, may reduce the incidence of rebound pain in the interscalene block with an extraplexus approach during arthroscopic shoulder surgeries will be investigated. Rebound pain is defined as a short-term but severe pain before and after the resolution of the interscalene block and will be evaluated using the Numerical Rating Scale (NRS) (NRS ≥ 7).

The study will include patients aged 18-65 years, with an American Society of Anesthesiologists (ASA) physical status of I or II, scheduled for arthroscopic shoulder surgery in the lateral decubitus position, accompanied by interscalene nerve block performed by the same surgeon. Patient characteristics (age, gender, body mass index, etc.), block procedure duration, number of needle passes, onset time of sensory block, onset time of motor block, and possible complications related to the block (paresthesia, Horner's syndrome, dyspnea, hoarseness), postoperative nausea and vomiting (PONV) status, and Quality of Recovery-15 (QoR-15) scores on the preoperative first day and postoperative days 1 and 7 will be recorded. The primary outcome parameter will be the incidence of rebound pain. Rebound pain will be defined as a short-term but severe pain before and after the resolution of the interscalene block, assessed using the Numerical Rating Scale (NRS) (NRS ≥ 7). Secondary outcomes will include the number of needle passes, block application time, onset time of sensory block, onset time of motor block, intraoperative dexmedetomidine requirement, duration of block effectiveness, postoperative pain, PONV, need for rescue analgesics, incidence of paresthesia and Horner's syndrome, dyspnea, hoarseness, duration of stay in the recovery room, duration of rebound pain, and postoperative Quality of Recovery-15 (QoR-15) scores.

Inclusion Criteria:

• Patients aged 18-65 years.
• Patients with ASA physical status I or II.
• Patients planned for arthroscopic shoulder surgery in the lateral decubitus position with interscalene nerve block.

Exclusion Criteria:

• Patients who do not consent to participate in the study.
• Block failure.
• Language acquisition deficiency.
• Obesity (body mass index > 35 kg/m²).
• Diabetes.
• Psychiatric disorders.
• Central nervous system diseases.
• Vestibular diseases.
• Presence of neuropathy and paralysis.
• Pregnancy.
• Previous open shoulder surgery.
• Allergy to local anesthetics.
• Coagulopathy.
• Severe thrombocytopenia.
• Infection at the puncture site.
• Pre-existing neuropathy in the limb to be operated.
• Use of dexamethasone.
• Use of opioid and antiemetic medications before surgery.
• Severe cardiopulmonary disease.
• Low baseline oxygen saturation.
• Conditions that prevent cooperation in the postoperative period (e.g., mental retardation, delirium).