Peripheral facial palsy: muscle activity in different onset times.

PURPOSE To assess, through surface electromyography (sEMG), the activity of the risorius and zygomaticus muscles, during the production of voluntary smiles and to compare these data between two groups of individuals with different onset times of peripheral facial palsy (PFP). METHODS A total of 140 adults were divided into three groups: G1 (35 individuals with PFP onset time between 0 and 3 months); G2 (35 individuals with PFP onset time between 3 and 6 months); CG (control group) (70 healthy controls). All of the participants were submitted to the following assessments: clinical protocol for the assessment of facial mimic and sEMG of the risorius and zygomaticus muscles. RESULTS The results suggest that the groups of individuals with PFP differed from the control group considering muscle activity during rest and during the production of voluntary smiles, regardless of the onset time of the disease. The groups with PFP did not differ between themselves in any of the tested situations. The group with PFP with longer onset time presented greater muscle activation asymmetry during the production of the voluntary smiles when compared to the other two groups. Muscle asymmetry was more evident when considering the results for the risorius muscle. CONCLUSION The results of the sEMG do not distinguish the groups when considering PFP onset times.