Arthroscopic shoulder surgery in the beach chair position under single interscalene block does not affect patients' cognitive function.

Background: Longitudinal epidemiological studies have shown that postoperative delirium is associated with an increased development of dementia; therefore, preventing delirium is important. The beach chair position (BCP) is commonly used for shoulder surgery; however, neurocognitive complications have been reported in patients who underwent shoulder surgery under general anesthesia, as the upright position adopted in the BCP is a risk factor for cerebral hypoperfusion, which may cause postoperative delirium. In contrast, regional anesthesia provides greater hemodynamic stability, even in the BCP. Therefore, this study aimed to investigate whether arthroscopic shoulder surgery in the BCP under interscalene block (ISB) influences the onset of postoperative delirium. Methods: A total of 863 consecutive patients who underwent arthroscopic shoulder surgery under ultrasound-guided single ISB were included. Delirium was evaluated preoperatively and at 7 days, and 1, 6, 12, and 24 months postoperatively using the Delirium Rating Scale-Revised-98 (DRS-R98), with a score of 10 or higher defined as delirium. Results: There were no significant differences between the pre- and postoperative DRS-R98 scores. Three patients met the diagnostic criteria for delirium at 7 days postoperatively. All these patients were over 80 years old and had a preoperative DRS-R98 score of at least 8 points; however, it returned to preoperative levels by 12 months postoperatively. Conclusion: Arthroscopic shoulder surgery with a single ISB did not affect cognitive function. Considering the increasing opportunities for surgery in the elderly, ISB may be a safe, viable alternative to general anesthesia.