The Positive and Negative Predictive Value of Targeted Diagnostic Botox Injection in Nerve Decompression Migraine Surgery.

ABSTRACT

INTRODUCTION: Nerve decompression surgery is an effective treatment modality for patients who suffer from migraines. Botulinum toxin type A (BOTOX) injections have been traditionally used as a method to identify trigger sites, however there is a paucity in data regarding its diagnostic efficacy. The goal of this study was to assess the diagnostic capacity of BOTOX in successfully identifying migraine trigger sites and predicting surgical success. METHODS: A sensitivity analysis was performed on all patients receiving BOTOX for migraine trigger site localization followed by a surgical decompression of affected peripheral nerves. Positive and negative predictive values were calculated. RESULTS: A total of 40 patients met our inclusion criteria and underwent targeted diagnostic BOTOX injection followed by a peripheral nerve deactivation surgery with at least three months follow-up. Patients with successful BOTOX injections (defined as at least 50% improvement in Migraine Headache Index (MHI) scores post injection) had significantly higher average reduction in migraine intensity (56.7% vs 25.8%; p=0.020, respectively), frequency (78.1% vs 46.8%; p=0.018, respectively), and MHI (89.7% vs 49.2%; p=0.016, respectively) post-surgical deactivation. Sensitivity analysis shows that the use of BOTOX injection as a diagnostic modality for migraine headaches has a sensitivity of 56.7% and a specificity of 80.0%. The positive predictive value is 89.5% and the negative predictive value is 38.1%. CONCLUSION: Diagnostic targeted BOTOX injections have a very high positive predictive value. It is therefore a useful diagnostic modality that can help identify migraine trigger sites and improve pre-operative patient selection.