Efficacy of Botulinum Toxin Type A in Trigeminal Neuralgia in a South Asian Cohort

Introduction: The antinociceptive effect of botulinum toxin-A (BTX-A) in trigeminal neuralgia (TN) has been described. We evaluated effects of BTX-A in relieving pain in patients with refractory TN at National Hospital of Sri Lanka. Materials and Methods: Pain in patients with TN was assessed using a visual analog from 0 to 10. Three months after commencement of drug therapy with >= 2 drugs including one first-line drug (carbamazepine/oxcarbazepine), pain scores were re-assessed. Twenty-two patients who did not report improvement of >= 50% at 90 days' posttreatment were recruited. They were given adjunct BTX-A directly to the trigger point (if identified) or intradermal. Pain scores were assessed at 10, 20, 30, 60, and 90 days' posttreatment. Results: There was a statistically significant improvement in mean pain scores at 10, 20, 30, 60, and 90 days' posttreatment (5.59 [standard deviation (SD) = 2.7], 5.68 [SD = 2.6], 5.27 [SD = 3.2], 4.77 [SD = 3.7], and 5.32 [SD = 4.0]) compared to pre-BTX-A treatment (7.14, SD = 2.2). Percentage reduction in mean pain score ranged from 20.4% to 33.1%. Maximum response was at day 60 post-BTX-A (50% had >= 50% reduction in pain). No significant difference was found in response with higher doses and injection strategy. Conclusion: Consistent statistically significant reductions in pain scores at the aforesaid intervals compared to pretreatment means that there is a place for BTX in refractory TN.