Functional restoration of symmetrical motor control of facial mimicry in unilateral paralysis due to nerve lesions

Unilateral facial palsy is caused by damage to the facial nerve, which is responsible for several functions, such as motor control of facial mimicry. When this nerve, which is even and symmetrical, is damaged, difficulties in movement and a marked weakness of the facial muscles occur. Symptoms of this disorder vary depending on the extent of damage to the facial nerve and may include: crossed and non-lubricated eyes, drooping of the soft tissues of the eyelid region, impaired speech articulation, drooping of the corner of the mouth, and excess saliva. Unilateral facial palsy is an extremely common condition that affects 1.81% of people during their lifetime. While in 70 per cent of cases, patients recover perfectly, in the remaining 30 per cent, important functional deficits such as basic hypertone, involuntary movements or paresis persist. In the latter case, patients are forced to undergo surgery in order to restore, at least partially, the functionality lost with unilateral facial nerve damage. The complexity, number and level of success of these surgeries has prompted basic and clinical research to find more effective innovative solutions for the treatment of unilateral paresis resulting from facial nerve damage. For instance, in recent years, ultra-rapid nerve signal transmission systems have been developed between the patient’s two hemifaces, based on the implantation of minimally invasive and maximally biocompatible devices that promise to restore symmetrical motor control of facial expressions by exploiting the transfer of the nerve impulse from the healthy facial nerve to the patient’s diseased one.

Referees: Paolo Spaiardi, Giorgia Faravelli

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