Hemifacial spasm (HFS) is a craniofacial movement disorder characterized by involuntary contractions of the muscles on one side of the face 1 . The most common site for the contractures is the orbicularis oculi muscle, but the corrugator supercilii, frontalis muscle, orbicularis oris, zygomaticus major and platysma can also be affected 2 . The condition is believed to be mainly due to a peripheral dysfunction of the facial nerve, occasionally associated with nerve compression by a blood vessel or tumor 3,4 . The pathophysiology, however, has yet to be fully elucidated as the condition can occur in the absence of structural alterations 3 . In a recent study, Wilkinson and Kaufmann 5 showed that HFS may be associated with central nervous system changes. Accordingly, one previous study from our group found similar profiles of obsessive and psychiatric symptoms in cases of HFS and blepharospasm, which is recognized as a movement disorders of A total of 550 BTX-A injections were administered to 100 HFS patients. Results: Mean duration of improvement following each injection session was 3.1 months, mean latency to detection of improvement was 7.1 days and mean success rate was 94.7%. Patients were evaluated at an interval of 5.8 months after each application. Adverse effects, which were mostly minor, were observed in 37% of the patients at least once during follow-up. The most frequent was ptosis (35.1%). Conclusion: Treatment of HFS with BTX-A was effective, sustainable and safe and had minimal, well-tolerated side effects.

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