Synkinesis is when one part of the face moves involuntarily along with another, for example the eye closing when you smile, or the mouth pulling when you blink. It develops after a long recovery from Bell’s palsy or Ramsay Hunt syndrome, as the facial nerve regrows. It does not go away by itself, but in our experience it can be reduced, even many years later.
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Key Facts
- Synkinesis only develops when the nerve fibres themselves were damaged and had to regrow, not after a quick recovery.
- In a large study, about 1 in 6 people with peripheral facial palsy developed it (Peitersen, 2002).
- It usually appears 3 to 6 months after the onset, as the movements return.
- The most common forms are the eye closing when you smile or talk, and the mouth moving when you blink.
- In our experience it is not permanent. It can be reduced with the right rehabilitation, without surgery.
Synkinesis symptoms
Synkinesis can show up in different ways, often more than one at a time:
- Oral-ocular synkinesis: the eye narrows or closes when you smile, talk, purse your lips or puff your cheeks.
- Ocular-oral synkinesis: the mouth corner moves when you blink or close your eye.
- Other muscles: the forehead, the neck (platysma) or the muscle around the mouth can also join in.
- Related effects: tightness, a face that tires quickly, facial pain, neck and mouth tension and crocodile tears often come with it.
What causes synkinesis?
Researchers agree that synkinesis develops only when nerve fibres were damaged and had to regrow. How exactly it happens is still debated (Guntinas-Lichius et al., 2022).
The common explanation: aberrant regeneration
The most widely accepted theory is that regrowing nerve fibres reach the wrong muscles. A fibre that used to serve the smile muscles might now also reach the eye muscles. If that were the whole story, synkinesis would be permanent.
Our view: synkinesis as a learned habit
Our research leads us to a different conclusion for Bell’s palsy. Each nerve fibre regrows inside its own protective tube, and fibres for the same muscle run together in a shared sheath. When the nerve trunk is not cut, as in Bell’s palsy, regrowing fibres can only follow their own tubes back to their own muscles. Wrong reconnections are possible after surgery or trauma, when the nerve is cut. Read more in our scientific research.
We believe synkinesis is mostly a habit the brain forms during a long recovery:
- While the nerve regrows, you try harder and harder to move the affected side, and nothing happens.
- The brain turns up every signal. The extra activity spills over to nearby muscles, much like a weightlifter whose face tenses while lifting.
- When the first movements return, the over-strong signals finally produce a result. That reward makes the pattern automatic.
In photos of 13 facial expressions from over 800 of our patients, we see the same pattern: the muscles that pull in the opposite direction contract along with the intended ones. When you smile, the muscles that pull the mouth corner down work against those that pull it up.
Here are two examples. On the first image (Example 1) you can see that when these patients try to squeeze their eyes, the frontalis muscle (forehead), which is the antagonist in this scenario, overpowers the circular muscle of the eye and raises the eyebrow instead of squeezing the eye.
On the second image (Example 2), you can see that when these patients smile, together with the zygomatic muscles, their antagonist-muscles, which are m. Depressor Anguli Oris, and also m.mentalis contract, pulling down the mouth corner. This leads to the asymmetric smile.
Other researchers also describe changes in how the brain controls the face, and recommend treating synkinesis as a movement coordination problem. This fits our view that it can be retrained.
Can synkinesis be prevented?
It is hard. In our experience, if the recovery takes longer than 2 to 3 months, some synkinesis is almost unavoidable. There are two reasons:
- In the first weeks, synkinesis is not on your mind. You are waiting for the movements to return, and you may not know synkinesis exists. Prevention has to start from day one.
- Any movement feels more important than being careful. It is natural to push for a smile. But that is exactly what teaches the brain to overdo its signals.
What helps most: do not force expressions or do facial exercises, avoid electrical stimulation, relax your face consciously every day, and use gentle massage. Read Acute Bell’s palsy: what to do and Facial exercises: what helps and what can harm.
Can synkinesis be reversed?
In our experience, yes, it can be reduced and sometimes almost fully eliminated. Like any learned habit, it can be unlearned. The brain needs consistent feedback that the extra effort is no longer needed, and time to make the natural pattern automatic again. It takes guidance and daily work, usually over 5 to 12 months.
This is what our Neuro-Proprioceptive Rehabilitation method was developed for. See our patients’ results.
Synkinesis treatment options
The main options are facial retraining, Botox injections, surgery and our rehabilitation method. They differ a lot in how long the effect lasts. Compare them in Synkinesis treatment options, and read more about Botox for synkinesis.
To start on your own, see What you can do yourself to reduce synkinesis.
Living with synkinesis? In a video consultation, Dr. Alex Pashov looks at your face and tells you what can still improve, wherever you live. Or see our synkinesis treatment in Rotterdam and online.
Synkinesis is an involuntary movement of one part of the face when you move another, such as the eye closing when you smile. It develops after a long recovery from Bell’s palsy or Ramsay Hunt syndrome.
The eye narrowing when you smile or talk, the mouth moving when you blink, and tension in the cheek, chin or neck. It often comes with tightness, facial fatigue and sometimes crocodile tears.
Usually 3 to 6 months after the onset, as the movements return. It only develops when the recovery is long. After a quick recovery of 2 to 3 weeks it is unlikely.
In our experience, no. It does not go away by itself, but it can be reduced with targeted rehabilitation, even many years after the onset.
Not fully if the recovery is long, but you can lower the risk. Do not force expressions, avoid facial exercises and electrical stimulation, and relax your face consciously every day.
The options are facial retraining, Botox injections, surgery in selected cases, and specialised rehabilitation such as the Neuro-Proprioceptive Rehabilitation method. Botox is temporary. Retraining and rehabilitation aim at the cause.
