Synkinesis is abnormal facial nerve regeneration that results in involuntary movement patterns in your facial muscles. In simple terms, synkinesis is a misdirected, rewiring, of the facial nerve after a facial nerve insult.
For example, when you smile, your affected eye involuntarily closes at the same time. Synkinesis occurs as the facial nerve recovers from injury, but in a disorganized fashion. In the example above, nerve fibers that originally traveled only to the mouth to make you smile, are now routed to both the mouth and the eye.
The result of this is involuntary eye closure with mouth movements such as smiling, eating, and speaking. Synkinesis can be mild or severe. It can occur after any facial nerve injury where the nerve remains in continuity (e.g. Bell’s palsy, vestibular schwannoma resection, Ramsay Hunt Syndrome) or after nerve repair or transfer surgeries.
Synkinesis is treated with facial rehabilitation strategies including massage, relaxation, and specific neuromuscular re-education. It is important to understand the role of synkinesis as you try to move your face. Synkinesis can be thought of as a tug of war. The synkinetic muscles are strong and overpower the weaker facial muscles. One of the goals of facial rehabilitation is to teach you how to relax or dampen the synkinetic muscles, so the weak muscles function better. Once patients have had facial nerve therapy, we often use botulinum toxin to weaken the synkinetic muscles (a.k.a. chemodenervation). Chemodenervation and facial nerve therapy are synergistic in that together they help patients more than either therapy alone!