The Unappreciated Morbidity of Brachial Plexus Injuries following Low Energy Shoulder Trauma: Understanding the Incidence, Risk Factors and Natural History

BACKGROUND: Brachial plexus injury (BPI) following low energy shoulder trauma is rare but complicated. The scant literature on this topic has identified these injuries to occur more commonly in older and female patients. This study seeks to determine the incidence of BPI following isolated shoulder trauma, demographics of patients most susceptible to BPIs, and finally to better understand the natural history. METHODS: Following IRB approval, 74 patients with BPI following isolated shoulder trauma were identified. A randomly selected control group of 100 patients who sustained isolated shoulder trauma without BPI was obtained and used for statistical comparison. Basic demographics and injury details were recorded from medical records. Severity of BPI was categorized based on physical exam findings. Descriptive statistics and a student’s t-test were used (p<0.05). RESULTS: Incidence of BPI following shoulder trauma was calculated to be 1.2%. The majority of patients who developed a BPI were female (n=40). The mean age was 50.9 years. High energy injuries were noted in 11 patients while low energy injuries were noted in 63 patients. Eleven patients had isolated fractures, 35 patients had isolated dislocations, and 28 patients had concurrent fracture-dislocations. When compared to the control group, patients who sustained a BPI following shoulder trauma did not significantly vary based on age, sex, comorbidities, BMI, smoking status, or energy of injury. The BPI group had significantly more fracture-dislocations than controls (<0.0001) [Table 1]. BPI symptoms were diagnosed approximately one month following shoulder trauma. 47.3% of patients had multiple affected nerves. Regarding the severity of BPI injury, 50% of patients sustained a minimal injury (one partially affected nerve), 19% sustained a moderate injury (two partially affected or one non-functional nerve) and 31% sustained a severe injury (three or more partially affected or two non-functional nerves) [Table 2]. Average time from initial to final evaluation was 10.2 months (range 1.1 - 47.9). Eight patients were lost to follow-up. Five patients underwent surgical intervention for their BPI. Among patients treated non-operatively for their BPI, only 39% of patients fully recovered after an average of 6.7 months (range 1.2 - 27.8). Recovery rate dropped to 28% among severely injured patients. CONCLUSION: Incidence of BPI following isolated shoulder trauma is 1.2%. • A fracture dislocation of the proximal humerus is more commonly associated with BPI than isolated shoulder dislocations or proximal humerus fractures. •About one-third of patients sustain a severe injury and only less than half of patients fully recover.