A Double-Blind, Placebo-Controlled Study of Appropriate Site of Botulinum Toxin Therapy in Hemifacial Spasm

Hemifacial spasm (HFS) is a condition causing poor quality of life. Treatment with botulinum toxin A (BTX) injection is effective. Only one randomized controlled trial with a single-blind fashion has evaluated if oral injection is needed in HFS. The present study aimed to evaluate the necessity of oral BTX injection in HFS by a randomized, double-blind, placebo-controlled method.

We conducted a double-blind, placebo-controlled trial in patients with HFS who never received BTX treatment. Eligible patients randomly received either 15 units of BTX around the eye and normal saline around the mouth (group A) or 15 units of BTX around both the eye and the mouth (group B). The primary outcomes were self-reported symptoms and observed frequency of spasms, while the secondary outcome was the duration of improvement or the time between the injection and the recurrence of symptoms to the same condition as before treatment. Student t test and survival analyses were used to compare the duration of symptoms between both groups. The mean changes were compared to secondary outcomes between the two groups.

There were 60 patients enrolled, half in each group. Baseline characteristics between both groups were similar. The mean (SD) of the duration of improvement in group A and B was 22.97 (18.85) and 17.53 (14.90) weeks, respectively (p = 0.220). There was no difference between both groups by survival analysis. Group B had a higher percentage of mouth improvement but there was no difference in the percentage of eye improvement, visual analog scale of eye and mouth spasm, or frequency of eye and mouth spasm. Group B had a higher incidence of side effects particularly mouth drooping (30% vs 10%) than group A (p = 0.053).

The mouth injection of BTX may not be necessary for HFS. It may be beneficial to reduce mouth symptoms with a higher rate of mouth drooping.