Free papers 21 - Neurorehabilitation| Volume 405, SUPPLEMENT , 94-96, October 15, 2019

Facial synkinesis in patients with long-standing Bell’s palsy is a reversible consequence of disruption of reciprocal inhibition caused by prolonged absence of proprioceptive feedback


      To analyze inconsistencies in existing theories of synkinesis. Using the new quantitative instrumental method of Synkinetic Correlation (SC), to research, define and substantiate probable cause of synkinesis after long-standing Bell’s palsy. To investigate the resulting possibility to reverse facial synkinesis regardless of the time passed since the onset.


      For 75 Bell’s palsy patients (65 female and 10 male, age 18–78, time since onset >1 year) measured oral-ocular and ocular-oral synkinesis, using Synkinetic Correlation method. Results were compared with measurements from the same patients’ healthy side. Duration and amplitude of contraction efforts from facial muscles on both sides analyzed for 13 standard facial expressions.
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      Both “muscles-Masters” and “muscles-Slaves” in measured synkinetic pairs of antagonists have shown significantly higher amplitudes and duration of contractions on the affected side, compared to healthy side of same patients.
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      During early stages of Bell’s palsy patient exerts constant mental efforts of high intensity, trying to produce facial movements. Due to high intensity, those efforts cannot be finely differentiated between proper facial muscles. This leads to a “mass-contraction” pattern of resulting efferent signals and suppresses natural mechanism of reciprocal inhibition of antagonists. Volitional mimetic center of the brain begins to form new, Pathological Amplification Mimetic Pattern (PAMP). When the regenerating nerve fibers finally reconnect to their facial muscles, PAMP manifests itself in synkinesis, rigidity of facial muscles, and gradually solidifies into a conditioned reflex. As any conditioned reflex, facial synkinesis can therefore be reversed by negative feedback, as demonstrated by results of our patients.
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