What is synkinesis?
The synkinetic stage of recovery is defined by the development of involuntary facial movements (synkinesis), for example, the eye closing when you smile. The action of smiling causes a simultaneous movement around the eye which appears to narrow or wink. Involuntary movements can develop during any facial expression.
Synkinesis is a part of your recovery process. It is inevitable in cases of more severe nerve injury. Importantly, its development can be minimised by following rehabilitation guidance closely. It is important not to encourage further development of synkinesis.
Why do some people recover more slowly from their Bell’s palsy?
The reason why a person may not experience a full recovery is due to the degree of nerve injury. If the damage is mild, the nerve is simply stunned or concussed, and a full recovery usually takes place within the first six weeks. This is because the inflammation around the nerve resolves quickly relieving the pressure on the nerve allowing it to recover. The medical term for this type of nerve injury is ‘neuropraxia’.
If facial palsy does not recover within approximately 3 – 4 weeks this means the damage to the facial nerve is more severe (link to post Bell’s palsy: what if I don’t recover). This is because the nerve has not received sufficient oxygen and nutrients for a prolonged period. As a result, nerve degeneration or breakdown occurs and the fat (myelin) that insulates the nerve starts to dissolve. The good news is that the special tube in which the nerve fibres sit remains completely secure. This means that the nerve can recover and regrow, and myelin is replaced. Regrowth is usually at the rate of 1mm/day and the first signs of recovery are usually seen after 4 months. Recovery continues for a further 9 – 18 months albeit more slowly as time progresses. The facial nerve will recover in its own time. There is no medication to help the nerve itself recover but a balanced diet and healthy lifestyle will maximise recovery.
Why does synkinesis happen?
There are several theories as to why synkinesis happens and these are complex theories which involve our body chemistry, nerve excitability and sensitivity all of which form a fundamental part of the recovery processes. One theory is that when the nerve is poorly insulated, electrical signals can escape across the face which can then be picked up by a different muscle. For example, a message to smile may arrive at the corner of the mouth but part of that message may spread to the corner of the eye. The result is that when a person smiles, the corner of the mouth and the corner of the eye move together, and this is called ‘synkinesis’. The important part to understand is that synkinesis is an inevitable part of nerve recovery when facial nerve damage is more severe. However, there is much that can be done to minimise the amount and degree of synkinesis that may develop.
Patterns of Facial Synkinesis
Synkinesis only happens on the affected side of the face. It can occur during all or any facial expression and can occur in one or more facial muscles. For example, when whistling the eye muscles can contract causing the eye to narrow/close. Alternatively, when whistling the eye can narrow/close, the cheek can lift, the chin can contract, and thin band of neck muscles can tighten. People will experience different types of synkinesis and different intensities.
Below is a list of some potential synkinetic movement patterns:
- Narrowing or closing of the eye when smiling
- Narrowing or closing of the eye when eating, drinking, whistling or during any movement which involves rounding or protruding of the lips.
- Narrowing or closing of the eye when pressing the lips together.
- Lifting of the cheek during eye closure/blink and when raising the eyebrows.
- The brow muscle may lift when closing the eyes or during smile and whistle.
- Thin vertical bands of neck muscles (platysma) can also start to join in and contract during smiling, whistling, brow-raising and eye closure.
- The muscles in the chin can contract during a range of different facial expressions and typically appears as ‘dimpling’ in the chin which was not present before your Bell’s palsy.
- Twitching around the eye, cheek and chin is also a form of synkinesis.
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