Is it always necessary to apply botulinum toxin into the lower facial muscles in hemifacial spasm?: a randomized,...

Botulinum toxin (BTX) injections are accepted as safe and efficacious in the treatment of hemifacial spasm (HFS), but it is still debated whether BTX treatment of lower facial muscles should be performed or not.

The study aims to evaluate the necessity of BTX administration into lower facial muscles in patients with HFS.

A randomized, single-blind, crossover, clinical trial was conducted. Twenty-three HFS patients were randomly allocated to two different application methods. The patients were administered BTX type A into both the orbicularis oculi and perioral muscles in the first method and BTX type A into the orbicularis oculi but placebo into the perioral muscles in the second method. Subjects were crossed over to the alternate method when they needed BTX injection with a minimum of 3 months' duration. All the patients underwent both methods with no change in the total dose of BTX.

All the patients benefited from BTX treatment regardless of the methods. However, in the patients with severe lower facial muscle involvement, the application of BTX into both orbicularis oculi and lower facial muscles led to better results.

Our data suggest that BTX application to lower facial muscles might not be necessary in patients with mild lower facial involvement.