In this study, the effect of paresthesia occurring during the interscalene block procedure on the incidence of postoperative neurological symptoms will be investigated. Paresthesia is defined as an abnormal sensation described as "tingling, pinprick, severe pain, or an electric feeling in the arm." The status of postoperative neurological symptoms in patients at the end of the block's effective duration will be assessed through phone interviews, evaluating symptoms such as arm numbness, tingling, abnormal sensations, pain, and weakness.

Our study includes patients aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I or II who undergo interscalene nerve block prior to arthroscopic shoulder surgery under general anesthesia. All patients will be fasting according to standard protocol. During the preoperative period, patients' age, comorbidities, gender, body mass index (BMI), ASA scores, and preoperative Quality of Recovery-15 (QoR-15) scores will be recorded.

In the operating room, possible complications related to the block (paresthesia, Horner's syndrome, dyspnea, hoarseness) will be monitored in the preoperative area. During the intraoperative period, data such as pulse, blood pressure, infusion fluids, intraoperative remifentanil requirements, anesthesia duration, and surgical time will be recorded.

In the postoperative period, postoperative pain status, block duration, postoperative nausea and vomiting, need for rescue analgesics and antiemetics, and QoR-15 scores on the first day will be assessed in the recovery room and ward. Additionally, postoperative neurological symptoms and QoR-15 scores will be followed via telephone on the 3rd, 7th, 10th, and 30th days after discharge.

For patients developing postoperative pain, pain intensity will be evaluated using an 11-point numeric rating scale, where 0 indicates no symptoms and 10 represents maximum severity.

Inclusion Criteria:

• ASA physical status I to II
• Age range of 18-65 years
• Patients planned for interscalene nerve block for analgesia prior to arthroscopic shoulder surgery in the beach chair position under general anesthesia

Exclusion Criteria:

• body mass index >35 kg/m²)
• history of drug use
• Patient's refusal to participate in the study
• Psychiatric disorders
• Central nervous system diseases
• Vestibular disorders
• Presence of diabetes, neuropathy, and paralysis
• Pregnancy
• Open shoulder surgery
• Allergy to local anesthetics
• Coagulopathy
• Severe thrombocytopenia
• Infection at the puncture site
• Pre-existing neuropathy in the limb to be operated on
• Use of opioid and antiemetic medications before surgery
• Use of dexamethasone
• Lung disease
• Low baseline oxygen saturation
• Patients who cannot cooperate in the postoperative period (e.g., mental retardation, delirium, language acquisition deficiency, etc.)

The study will include patients aged 18-65 years with ASA physical status I or II who are planned to undergo interscalene nerve block for analgesia prior to arthroscopic shoulder surgery in the beach chair position under general anesthesia.