Aim and Objective: This study aims to evaluate the impact of demographic parameters (age, gender) and physiological factors (Body Mass Index [BMI], ASA Physical Status [ASA PS]) on the incidence and severity of neurological injuries following an ultrasound-guided interscalene brachial plexus nerve block. Additionally, it will investigate how comorbidities affect these neurological outcomes to provide a comprehensive understanding of risk factors associated with this procedure. Methodology: This retrospective chart review analyzed 1,500 patients who underwent shoulder surgery with single-shot ultrasound-guided interscalene brachial plexus block (US-ISB) between January 2017 and May 2021. General anesthesia was administered before the US-guided ISB, following a standardized protocol by experienced anesthesiologists. Neurological complications following surgery were assessed at 38 hours, 48 hours, approximately 2 weeks, 1 month, 3 months, 6 months, and until the symptoms resolved. Result: In a cohort of 1,500 subjects, paraesthesia and muscle weakness were initially reported by 5.9% at 36 hours but decreased to 0.1% by 6 months, with time being a significant factor in their reduction. While younger individuals experienced higher rates of these symptoms early on, age did not impact long-term prevalence. Higher BMI was associated with paraesthesia in the 0-1 month period, and ASA II showed higher percentages, but these associations were not statistically significant. Overall, the symptoms are transient and primarily influenced by time rather than demographic or physiological factors. Conclusion: Paraesthesia and muscle weakness, initially reported by 5.9% of subjects at 36 hours, significantly decreased to 0.1% by 6 months. While these symptoms were more prevalent in younger individuals and those with higher BMI early on, they generally resolved over time, with no significant long-term associations with age or comorbid conditions.

Brachial Plexus Block, BMI, Interscalene brachial plexus block, ASA, Ultrasound-Guided Interscalene Brachial Plexus Block