Increasing the area and varying the dosage of Botulinum toxin a injections for effective treatment of hemifacial spasm.

[CONCLUSION] Wider-area botulinum toxin (BT) injection with the dosage depending on specific pathology is a promising approach for the treatment of hemifacial spasm (HFS), resulting in effective and long-lasting control of HFS with fewer side-effects.

[OBJECTIVE] The aim of this study was to develop a BT injection strategy that minimizes complications by considering the causes, duration, and electrophysiologic features of the disease, as well as the patient's age.

[METHODS] From July 2011 to July 2015, 26 patients were included in the strategy. The mean age was 61.8 ± 14.6. In the case of essential HFS, 2 units/injection site was the standard dosage. If a patient was aged over 60 and had a reduced electromyogram (EMG) amplitude, the dosage was reduced by 0.5 units/site. In the case of post-paralytic and tumor-induced HFS, 1.5 units/site was the standard dosage. All cases were managed by alternating injections of Botox and Dysport with no physical therapy.

[RESULTS] Most HFS patients treated with the injection strategy had complete remission of HFS within 1 week. The average number of BT injection sites was 22.6 ± 6.7. The mean total BT dosage on the affected side was 28.6 ± 4.9 units. The mean duration of BT efficacy was 28.6 ± 7.7 weeks.