**4. Conclusion**

Thus, the signs of facial expression asymmetry in facial nerve neuropathy include weakness of the facial muscles innervated by the affected facial nerve, as well as hypertonicity of the facial expression muscles of the healthy hemiface. The proposed method of injections of botulinum toxin type A into hyperactive facial expression muscles of the unaffected ("healthy") hemiface in case of facial nerve neuropathy contributes to the formation of a balance between both hemifaces and the joint work of the nervous structures of the face. Botulinum toxin therapy is a pathogenetically substantiated method of restoring facial symmetry. Due to this method, it is possible to achieve an increase in the motor activity of the muscles of facial expression of the affected hemiface both in the acute phase of Bell's palsy, and with remaining effects in the long-term period. This method is also applicable for the treatment of facial expression asymmetry of another etiology, for example, as a result of an iatrogenic injury (found in cosmetology, plastic surgery, and maxillofacial surgery). The efficacy of botulinum toxin therapy is explained by other impacts besides the local muscle relaxant effect of botulinum toxin type A. It is known that the action of botulinum toxin type A causes peripheral deafferentation. This suggests a neuroplastic effect on the segmental, suprasegmental structures of the facial nerve system when performing injections in the face.

The use of the proposed method for the treatment of pathological synkinesis using monofilament mesothreads showed a good result. The creation of a mesh-frame between the facial muscles and the skin in the area of involuntary muscle contractions reduces the external manifestations of synkinesis. The use of monofilament mesothreads makes it possible to obtain a longer and more stable clinical effect, which is manifested by a decrease in the severity and amplitude of pathological muscle contractions of facial muscles, even in 2 years after the treatment.
