Facial synkinesis is the involuntary movement of facial muscles that accompanies purposeful movement of some other set of muscles; for example, facial synkinesis may result in the mouth involuntarily closing or grimacing when the eyes are purposefully closed.
Facial synkinesis occurs during recuperation from conditions or injuries that affect the facial nerve, for example during recovery from Bell's palsy. During recovery, as the facial nerve tries to regenerate, some new nerve twigs may accidentally regrow in close proximity to muscles that they wouldn't normally innervate (stimulate). Facial synkinesis may occur transiently, during recovery, or may become a permanent disability.
As with all facial injuries or palsies, facial synkinesis can cause considerable emotional distress. Lack of control over one's facial expressions is known to be a serious psychological stressor.
Causes and symptoms
Facial synkinesis can follow any injury or condition causing palsy or paralysis of the facial nerve. The most common associated disorder is Bell's palsy; about 40% of all individuals who are recovering from Bell's palsy will experience facial synkinesis during recovery. Other conditions that may prompt the development of facial synkinesis include stroke, head injury, birth trauma, head injury, trauma following tumor removal (such as acoustic neuroma), infection, Lyme disease, diabetes, and multiple sclerosis.
Facial synkinesis can cause a number of abnormalities in the facial muscles. For example, when a patient with facial synkinesis tries to close his or her eyes, the muscles around the mouth may twitch or grimace. Conversely, when the patient tries to smile, the eyes may involuntarily close. The phenomenon of purposeful mouth movements resulting in involuntary eye closing is often referred to as "jaw winking." Unfortunately, as with any facial deformity or disability, facial synkinesis carries with it a high risk of concomitant depression, anxiety, and disruption of interpersonal relationships and employment.
Diagnosis is usually apparent on physical examination. When the patient is asked to move certain facial muscles (i.e., smile), other facial muscles will be activated (e.g., the eyes may close involuntarily). When the underlying condition is unclear, a variety of tests may be required, such as CT or MRI scanning or EMG (electromyographic) testing to evaluate the functioning of the facial nerves and muscles.
Facial synkinesis may be treated by neurologists or otorhinolaryngologists.
Treatment may include:
- surgery, to remove causative tumors or other sources of pressure on and damage to the facial nerve
- steroid medications, to decrease inflammation of the facial nerve
- facial exercises
- electrical stimulation (this remains controversial, and may, in fact, worsen facial synkinesis in some patients)
- intensive video-assisted, electromyographic feedback facial muscle retraining
- injections of the paralytic agent botox into the muscle groups that are contracting involuntarily
The prognosis of facial synkinesis is quite variable, depending largely on the prognosis of the underlying condition that caused its development.
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Rosalyn Carson-Dewitt, MD