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

[BACKGROUND] Nerve decompression surgery is an effective treatment modality for patients who experience 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 3 months' follow-up. Patients with successful Botox injections (defined as at least 50% improvement in Migraine Headache Index scores after injection) had significantly higher average reduction in migraine intensity (56.7% versus 25.8%; P = 0.020), frequency (78.1% versus 46.8%; P = 0.018), and Migraine Headache Index (89.7% versus 49.2%; P = 0.016) postsurgical 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%.

[CONCLUSIONS] 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 preoperative patient selection.

[CLINICAL QUESTION/LEVEL OF EVIDENCE] Diagnostic, II.