Long-term facial improvement after repeated BoNT-A injections and mirror biofeedback exercises for chronic facial synkinesis: a case-series study

BACKGROUND: Only few studies have considered the effects of the combined treatment with onabotulinumtoxinA (BoNT-A) injections and biofeedback (BFB) rehabilitation in the recovery of postparetic facial synkinesis (PPFS). AIM: To explore the presence of a persistent improvement in facial function out of the pharmacological effect of BoNT-A in subjects with established PPFS, after repeated sessions of BoNT-A injections combined with an educational facial training program using mirror biofeedback (BFB) exercises. Secondary objective was to investigate the trend of the presumed persistent improvement. STUDY DESIGN: Case-series study. SETTING: Outpatient Clinic of Physical Medicine and Rehabilitation Unit. POPULATION: Twenty-seven patients (22 females; mean age 45±16 years) affected by an established peripheral facial palsy, treated with a minimum of three BoNT-A injections in association with mirror BFB rehabilitation. The interval between consecutive BoNT-A injections was at least five months. METHODS: At baseline and before every BoNT-A injection+mirror BFB session (when the effect of the previous BoNT-A injection had vanished), patients were assessed with the Italian version of Sunnybrook Facial Grading System (SB). The statistical analysis considered SB composite and partial scores before each treatment session compared to the baseline scores. RESULTS: A significant improvement of the SB composite and partial scores was observed until the fourth session. Considering the "Symmetry of Voluntary Movement" partial score, the main improvement was observed in the muscles of the lower part of the face. CONCLUSIONS: In a chronic stage of postparetic facial synkinesis, patients may benefit from a combined therapy with repeated BoNT-A injections and an educational facial training program with mirror BFB exercises, gaining an improvement of the facial function up to the fourth session. This improvement reflects the acquired ability to use facial muscle correctly. It doesn't involve the injected muscles but those trained with mirror biofeedback exercises and it persists also when BoNT-A action has vanished. CLINICAL REHABILITATION IMPACT: The combined therapy with repeated BoNT-A injections and an educational facial training program using mirror BFB exercises may be useful in the motor recovery of the muscles of the lower part of the face not injected but trained