Mild vs. Severe Synkinesis: Treatment Decisions

Synkinesis that develops after facial paralysis does not affect every patient in the same way. While some individuals experience only mild involuntary muscle movements, others may develop more pronounced contractions that interfere with facial symmetry, facial movement coordination, and everyday activities. For this reason, there is no one-size-fits-all treatment approach. The treatment plan should be tailored to each patient based on the severity of facial paralysis involuntary movements, the muscles involved, facial function, and the patient's individual goals and expectations.

So, what are the key differences between mild and severe synkinesis? Which clinical findings influence treatment decisions? When is facial rehabilitation sufficient, and when should botulinum toxin or surgical treatment be considered? In this article, we explore the differences between mild and severe stages and explain the factors that guide personalized treatment planning.

What Is Mild Synkinesis?

Mild synkinesis is a condition characterized by subtle, involuntary facial muscle movements that may develop during the recovery process following facial paralysis. It can occur due to abnormal facial muscle rewiring, where some regenerating facial nerve fibers reconnect to different muscle groups instead of their original target muscles. As a result, when a person intentionally performs one facial movement, another muscle group may contract involuntarily. For example, the eyelid may close slightly while smiling, the corner of the mouth may move during blinking, or the neck muscles may contract mildly during lip movements.

In mild cases, these involuntary movements generally do not cause significant functional impairment or severely affect facial symmetry. However, involuntary muscle contractions that occur during activities such as speaking, smiling, eating, or making facial expressions may lead to aesthetic concerns and reduced quality of life in some patients. Therefore, even patients with mild symptoms should be evaluated by a physician experienced in facial paralysis, and when appropriate, facial rehabilitation or other suitable treatment options should be considered.

What Is Severe (Advanced) Synkinesis?

Severe synkinesis is a condition in which involuntary facial muscle movements become highly pronounced following facial paralysis, significantly affecting both facial function and facial aesthetics. At this advanced stage, involuntary muscle contractions are noticeable not only during specific facial expressions but also throughout many everyday activities. For example, multiple muscle groups may contract involuntarily at the same time during intentional movements such as smiling, speaking, blinking, or eating.

In addition, symptoms such as involuntary eye closure, excessive pulling of the corner of the mouth, prominent contraction of the neck muscles, or a constant feeling of tightness on one side of the face may occur. In some patients, muscle contractures may also develop, leading to more noticeable facial asymmetry. This condition can affect important functions such as speaking, chewing, eye closure, and facial expression. Furthermore, increasingly noticeable involuntary movements may reduce self-confidence and have a negative psychological and social impact on patients.

How Can You Tell the Difference Between Mild and Severe Synkinesis?

The differences between mild and severe synkinesis can be evaluated based on the severity of involuntary muscle movements, their impact on facial function, and their effect on quality of life. Key differences include:

• Severity of involuntary muscle movements: In mild synkinesis, involuntary movements are subtle and limited. In severe synkinesis, muscle contractions are stronger and more noticeable.
• Affected muscle groups: Mild synkinesis usually involves one or two muscle groups. Severe synkinesis may affect multiple muscle groups simultaneously, including the eyes, mouth, cheeks, and neck.
• Facial symmetry: Facial symmetry is generally preserved in mild synkinesis. In severe synkinesis, noticeable facial asymmetry may develop.
• Eye movements: In mild cases, the eyelid may close slightly while smiling. In severe cases, the eye may close involuntarily and more completely.
• Mouth movements: Mild synkinesis may cause slight involuntary movement at the corner of the mouth. In severe synkinesis, the corner of the mouth may be pulled excessively, resulting in an unnatural smile.
• Neck muscle involvement: The neck muscles are usually unaffected or only minimally affected in mild synkinesis. In severe synkinesis, significant contractions of the platysma muscle may occur.
• Muscle tightness (Contracture): Muscle stiffness is uncommon in mild synkinesis. In severe synkinesis, prolonged muscle overactivity may lead to contractures.
• Impact on daily activities: Mild synkinesis generally has little effect on everyday activities. Severe synkinesis may interfere with speaking, eating, eye closure, and facial expressions.
• Aesthetic appearance: Aesthetic changes are usually minimal in mild synkinesis. In severe synkinesis, facial expression and symmetry may be significantly affected.
• Treatment approach: Mild synkinesis is often managed with facial rehabilitation and, when appropriate, botulinum toxin injections. Severe synkinesis may require a combination of facial rehabilitation, botulinum toxin treatment, and, in selected patients, surgical intervention.

How Is The Severity Of Synkinesis Assessed?

The severity of synkinesis is determined not only by the patient's symptoms but also through a detailed assessment of facial movements and objective evaluation methods. Implementing standard synkinesis grading and scoring allows clinicians to analyze the degree of involuntary muscle activity, identify the affected muscle groups, and evaluate facial function in order to develop an individualized treatment plan. The main methods used in this evaluation include:

• Physical examination: The physician evaluates the patient's facial symmetry at rest as well as any involuntary muscle contractions that occur during voluntary facial movements such as smiling, closing the eyes, raising the eyebrows, and pursing the lips.
• Video analysis of facial movements: Involuntary movements occurring during different facial expressions are recorded and analyzed to assess muscle coordination and determine the severity of synkinesis in greater detail.
• Sunnybrook Facial Grading System: This is one of the most widely used clinical grading systems for assessing facial paralysis and synkinesis. The Sunnybrook score evaluates resting symmetry, voluntary facial movements, and involuntary muscle activity to generate an overall score.
• eFACE assessment system: eFACE is a standardized digital evaluation tool that helps analyze facial symmetry, movement quality, and the severity of synkinesis in a detailed and objective manner.
• Electromyography (EMG): When necessary, EMG is used to evaluate the electrical activity of the facial muscles, identify the affected muscle groups, and assess the extent of involuntary muscle contractions.
• Assessment of muscle contractures: Muscle stiffness and tightness that may develop in long-standing synkinesis are evaluated during the physical examination and taken into consideration when planning treatment.
• Assessment of the impact on daily life: Functional difficulties experienced during activities such as speaking, eating, eye closure, smiling, and social interaction are also important factors in determining the severity of synkinesis.

How Is Treatment Planned for Mild Synkinesis?

• Facial Rehabilitation:

Facial rehabilitation is the cornerstone of treatment for mild synkinesis. Through individualized exercises guided by a facial rehabilitation specialist, patients learn to improve muscle coordination, reduce involuntary movements, and restore more natural facial expressions. Consistent rehabilitation can significantly improve both facial function and overall quality of life.

• Neuromuscular Re-education:

Neuromuscular re-education focuses on retraining the facial muscles and nervous system to perform coordinated movements more efficiently. Patients practice specific exercises designed to activate the correct muscles while minimizing abnormal muscle contractions. This technique is particularly effective in mild synkinesis, where improving muscle control early may help prevent involuntary movements from becoming more pronounced over time.

• Facial Sling Surgery:

Facial sling surgery is not a routine treatment for mild synkinesis. This procedure is primarily considered for patients with significant static facial asymmetry or facial drooping resulting from facial paralysis. However, if a patient with mild synkinesis also has soft tissue sagging that affects facial symmetry at rest, facial sling surgery may be considered as part of the treatment plan in carefully selected cases. The primary goal of facial sling surgery is to improve facial symmetry at rest and enhance the overall aesthetic appearance. In patients with mild synkinesis, conservative treatment approaches are generally preferred as the first-line management.

• Botulinum Toxin For Facial Paralysis:

Botulinum toxin therapy is another commonly preferred treatment option for mild synkinesis. When involuntary muscle movements affect facial appearance or interfere with daily activities, low-dose botulinum toxin injections can be used to reduce the activity of overactive muscles. This can help make voluntary facial movements appear more natural, improve facial symmetry, and decrease the severity of involuntary muscle contractions. Botulinum toxin treatment is often combined with facial rehabilitation and neuromuscular re-education to optimize treatment outcomes.

How Is Treatment Planned for Advanced-Stage (Severe) Synkinesis?

• Botulinum Toxin for Facial Paralysis:

Botulinum toxin is one of the most commonly used treatment options for patients with severe synkinesis who experience bothersome involuntary muscle movements. Carefully targeted injections help reduce excessive muscle activity, improve facial symmetry, and make voluntary facial movements appear more natural. In advanced cases, low-dose botulinum toxin may also enhance the effectiveness of facial rehabilitation by allowing patients to better control their facial muscles.

• Selective Neurolysis (Neurectomy):

Selective neurolysis (neurectomy) is generally not considered the primary treatment method for advanced stages of synkinesis. This procedure may be considered an option only for carefully selected patients in whom involuntary muscle contractions continue to cause discomfort despite comprehensive non-surgical treatments. In this context, selective neurectomy involves the selective transection of overactive nerve branches responsible for abnormal muscle activity, while preserving normal facial function to the greatest extent possible.

• Selective Myectomies:

Selective myectomy is another surgical option that is rarely required for patients with advanced-stage synkinesis. This method may be considered in cases where a specific facial muscle continues to cause persistent involuntary contractions or muscle tension despite rehabilitation and botulinum toxin treatment. Ultimately, selective myectomy aims to improve facial balance and reduce unwanted movements by decreasing the activity of the targeted muscles.

Can Mild Synkinesis Progress Over Time?

Mild synkinesis may become more noticeable over time in some patients, although its progression varies from person to person. The course of the condition depends on several factors, including the cause of the facial paralysis, the pattern of nerve regeneration, the condition of the facial muscles, and the treatments received. In some untreated cases, involuntary muscle movements may become more frequent, muscle stiffness (contracture) may develop, and facial asymmetry may become more pronounced.

On the other hand, early intervention with facial rehabilitation, neuromuscular re-education, and, when appropriate, botulinum toxin injections can help control involuntary muscle activity and reduce the risk of progression. Therefore, even patients with mild symptoms should undergo regular follow-up, and an appropriate treatment plan should be established without unnecessary delay.