Predictors Of Relief Following Botulinum Injection For Thoracic Outlet Syndrome

PURPOSE: Given the challenges of diagnosing neurogenic thoracic outlet syndrome (nTOS), both anesthetic blocks and botulinum toxin injections (BTIs) have been used to assist in the diagnostic algorithm for nTOS prior to surgical intervention. However, data has been mixed as to the benefit of BTI as a therapeutic option. We investigated predictors of relief following BTI. METHODS: Patients diagnosed with nTOS who received a BTI at a single institution were retrospectively reviewed. Patient demographics, QuickDASH scores, and outcome following injection were collected from all charts. RESULTS: 77 patients, including 30 males and 47 females, with a mean age of 31.4 +/- 12.3 received a BTI between 2000 and 2020. 60 patients (77.8%) experienced relief after the injection, of whom 32 (41.5%) reported significant (>60%) relief. 11 patients had no relief, and 6 were missing data. Initial QuickDash score (higher), gender (female), race (non-white), history of prior shoulder injury, and having at least one positive physical examination finding for TOS were included in the multivariate analysis. Female gender (OR 6.6, p = 0.049) and a positive physical exam finding (OR 9.0, p = 0.030) were both correlated with greater likelihood of relief following BTI. In regards to which patients had significant relief after BTI (vs mild or moderate), younger age (p = 0.008) and shorter symptom duration (p = 0.027) were found to be statistically significant predictors on univariate analysis. CONCLUSION: Over three quarters of patients experienced relief after BTI, with 41.5% noting significant relief. Younger patients and those with shorter symptom duration prior to BTI were more likely to have the most benefit. Patients who did not have any positive physical examination findings for TOS may have been less likely to have a true diagnosis of nTOS, which could explain why these patients were less likely to experience relief after BTI. For many patients, particularly athletes who are trying to complete a competitive season, BTI may be an effective therapeutic treatment option. Understanding predictors of relief after BTI may help inform treatment algorithms for patients with nTOS.