Efficacy of single vs. multiple botulinum toxin type A injections for trigeminal neuralgia.

[BACKGROUND] The effectiveness of Botulinum toxin type A (BTX-A) has been established in trigeminal neuralgia (TN). This study aimed to assess the therapeutic efficacy and safety of BTX-A injection within a group of TN patients who have chosen to continue BTX-A therapy.

[METHODS] This was a retrospective medical record-review study. Demographic and clinical features and severity and frequency of pain before and 4 weeks after the BTX-A administration were extracted from the patient files. BTX-A was injected into the painful area subcutaneously and/or submucosally. BTX-A injections were performed by the same physician using the same methods. Pain severity was assessed using the visual analog scale (VAS). The patient's overall response to treatment was assessed using the Patient Global Impression of Change (PGIC). Patients were divided into two groups, single-treatment (TN-S) group and multiple-treatment (TN-M) group, according to the numbers of treatment.

[RESULTS] Thirty patients were included in this study. We classified 16 (53.33%) as TN-S group and 14 (46.67%) as TN-M group. The median VAS score of all patients was 8 (6.75, 10) before the first treatment and 3 (2, 6.25) after the first treatment ( < 0.001). In the TN-M group, median of the difference of VAS before and after treatment of the first and the last treatment were 7 (5, 8) and 5 (2, 7.25), respectively, indicating a significantly better effect for the first treatment compared with the last treatment ( = 0.024). However, this difference in PGIC distributions between the two treatments was not significant ( = 0.070).

[CONCLUSION] In summary, BTX-A treatment was effective in TN. Elderly patients and patients with good response to the first treatment were more likely to choose to continue BTX-A multiple-treatments. BTX-A remains effective within a group of TN patients who have chosen to continue BTX-A therapy, but the efficacy decreases to a certain extent after multiple treatments.