Objective: To evaluate the efficacy and safety of a single dosage of botulinum toxin type A (BTX-A) injection as an add-on therapy in patients suffering from trigeminal neuralgia (TN).
Materials and Methods: Thirteen classical TN patients were enrolled in a 7-week long prospective open-label pilot study. A single dosage of BTX-A (25 U/1.5 mL) injection was extra orally and intradermally administered into the skin of the trigger area of TN pain. The primary outcome measures were pain severity per day, assessed by numeric rating scale (NRS), pain attack frequency and number of antiepileptic medications taken per day.
Results: A total of 8 patients (1 man and 7 women) completed the study and were all improved regarding severity and frequency of pain attack. The Wilcoxon signed-rank test showed a significant difference in frequency of pain attack before injection and at 4 weeks and 6 weeks after injection (p<0.05). Paired t-test of pain severity showed significant difference (p<0.05) between severity of pain before and after injection. Wilcoxon signed-rank test showed significant reduction in medication intake in all patients up to the end of trial at 6 weeks follow-up (p<0.05). In one patient, pain was completely eradicated and there was no need for further
medication. BTX-A was generally well tolerated and there were no serious treatment-related adverse events.
Conclusion: The present study revealed a clinical benefit in efficacy and safety of the combination of single dosing of BTX-A and pharmacotherapy for patients with TN.

Keywords: Trigeminal neuralgia, Botulinum toxin, Carbamazepine, Pain severity, Pain frequency