Abstract
Hemifacial spasm (HFS) is a movement disorder characterized by involuntary contractions of the facial muscles innervated by the seventh cranial nerve. Generally, it is associated with a poor quality of life due to social embarrassment and can lead to functional blindness. Moreover, it is a chronic condition, and spontaneous recovery is rare. Intramuscular injections of Botulinum Toxin (BoNT) are routinely used as HFS treatment. Methods: We reviewed published articles between 1991 and 2021 regarding the effectiveness and safety of BoNT in HFS as well as any reported differences among BoNT formulations. Results: The efficacy of BoNT for HFS treatment ranged from 73% to 98.4%. The mean duration of the effect was around 12 weeks. Effectiveness did not decrease over time. Adverse effects were usually mild and transient. The efficacy and tolerability of the different preparations appeared to be similar. Among the studies, dosage, injected muscles, intervals of treatment, and rating scales were variable, thus leading to challenges in comparing the results. Conclusions: BoNT was the treatment of choice for HFS due to its efficacy and safety profile. Further studies are needed to investigate the factors that influence the outcome, including the optimal timing of treatment, injection techniques, dosage, and the best selection criteria for formulations.
Highlights
Key Contribution: Botulinum toxin is reported as the most efficacious therapy for hemifacial spasm
Hemifacial spasm (HFS) is a hyperkinetic movement disorder characterized by short or persistent, intermittent synchronous twitching of the muscles innervated by the facial nerve [1], which is a chronic condition, and spontaneous recovery is rare [2,3]
The surgical treatment can be reserved for those patients who do not respond to Botulinum Toxin (BoNT) therapy or desire a long-lasting solution
Summary
Hemifacial spasm (HFS) is a hyperkinetic movement disorder characterized by short or persistent, intermittent synchronous twitching of the muscles innervated by the facial nerve [1], which is a chronic condition, and spontaneous recovery is rare [2,3]. HFS is classified as primary (79%) or secondary to facial nerve damage (21%) [8] The former is attributed to the compression of the facial nerve at the root exit zone in the brainstem, usually by an ectatic or aberrant blood vessel [8,9]. Concerning treatment, the most efficacious therapy has been reported to be BoNT, a biological toxin derived from the Clostridium botulinum [2,21] It is active on the presynaptic region of the neuromuscular junction, inhibiting the calcium-mediated release of acetylcholine at the nerve terminal, therein avoiding impulse generation downstream, resulting in neuroparalysis [22]. The surgical treatment can be reserved for those patients who do not respond to BoNT therapy or desire a long-lasting solution
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