Masseter Muscle Hyperactivity in Facial Synkinesis
Our facial muscles help us to express our emotions and expressions, as well as to carry out our daily functions. In some cases, however, these muscles can be activated involuntarily, resulting in a condition known as facial synkinesis. In this case, the wrong reconnection of nerves causes one muscle to activate and another muscle to contract involuntarily. This can cause both aesthetic and functional problems. If you want to get more detailed information on this subject, you can take a look at the content of “Masseter Muscle Hyperactivity in Facial Synkinesis”. We wish you all healthy days and good reading.
What is the Masseter Muscle?
The masseter muscle is one of the strongest of the masticatory muscles and lifts the lower jaw upwards, allowing the teeth to close. . Located on the side of the head, between the cheekbone (zygomatic arch) and the mandible (mandible), the masseter muscle consists of two parts, superficial and deep. One of these, the superficial part, the anterior part of the zygomatic arch, attaches to the lower corner (angle) of the mandible and mostly helps to lift the jaw forward and upwards. The deep part, on the other hand, originates from the posterior part of the zygomatic arch and attaches to the upper part of the mandible, the vertical part called the ramus. Thus, it contributes to the strong closing movement by lifting the jaw directly upwards. In addition, because it is a strong muscle, it can thicken over time due to continuous use. In some cases, this can lead to prominence on one side of the face. Therefore, it is an important muscle not only for masticatory function but also for facial symmetry and neuromuscular control.
The Role of the Masseter Muscle in Facial Mimics
Although the masseter muscle is primarily involved in masticatory function, it may become associated with facial expressions in certain neurologic and pathologic conditions. In particular, while the facial muscles receive innervation from the facial nerve (n. facialis), the masseter muscle is controlled by the mandibular branch of the trigeminal nerve and does not directly participate in facial expressions. However, in abnormal restructuring processes that develop after facial nerve paralysis, nerve fibers may be misdirected and connected to the masseter muscle. In this case, the masseter muscle is involuntarily activated while the patient is smiling, talking or trying to raise an eyebrow. This is called synkinesia. Thus, the masseter muscle can participate in facial expressions that it is not normally involved in, leading to undesirable results such as facial stiffness, pulling and asymmetry. In this case, in facial mimicry disorders, the masseter muscle contracts involuntarily, causing both aesthetic concerns and functional difficulties.
Facial Synkinesis and the Masseter Muscle Connection
Facial synkinesis is an involuntary muscle movement that occurs during recovery from facial nerve (n. facialis) paralysis when nerve fibers are incorrectly connected to the target muscles. This is characterized by the involuntary activation of one mimic muscle while another muscle is working, such as the involuntary movement of the corner of the mouth during blinking. This can manifest itself in the form of stiffness, asymmetry or increased volume on one side of the face, for example, with excessive contraction of the masseter muscle during smiling or speaking. In other words, although the masseter muscle is not directly involved in mimic functions, it can become a part of synkinesis due to neural dysregulation that develops after facial nerve damage. This connection can cause both functional and aesthetic discomfort to the patient and may need to be managed with treatments such as botox and facial physiotherapy.
Diagnosis of Masseter Muscle Hyperactivity in Facial Synkinesis
The diagnosis of masseter muscle hyperactivity in facial synkinesis is based on the patient's clinical history, history of facial paralysis and detailed neuromuscular examination. Patients usually describe involuntary contraction, stiffness or pulling sensation in the jaw area during mimic movements such as laughing, speaking and blinking. During physical examination, abnormal contractions of the masseter muscle can be observed with the movement of the facial muscles. Such involuntary movements are a typical sign of abnormal reinnervation that occurs during facial nerve regeneration. Therefore, electromyography (EMG) can be used to clarify the diagnosis. With this method, it is determined during which facial movements the masseter muscle is activated. Muscle symmetry, volume differences and signs of hypertrophy are also evaluated by comparing both sides of the face. In this way, it can be determined whether the masseter muscle plays a role in synkinesis and treatment planning can be tailored individually.
Treatment of Masseter Muscle Hyperactivity in Facial Synkinesis
In the treatment of masseter muscle hyperactivity in facial synkinesis, in addition to conservative (medication/physiotherapy) and minimally invasive methods, selective neurolysis (selective nerve release surgery) is considered as an effective treatment option in some special cases. Selective neurolysis is the surgical separation or neutralization of abnormal nerve connections that cause synkinesis. This method is especially preferred in patients who do not respond adequately to botulinum toxin applications, where muscle activity is very prominent or where aesthetic and functional disorders are advanced.
In the case of masseter muscle hyperactivity, the abnormal nerve branches that cause this muscle to involuntarily participate in mimic movements are identified and selectively cut or weakened by surgical intervention. This prevents the muscle from involuntarily participating in mimic movements while maintaining its chewing function only. This ensures that nerve functions are preserved.
In addition to these, botulinum toxin (Botox) is a commonly used method in the management of masseter muscle hyperactivity and is generally preferred as the first step. When injected intramuscularly, Botox temporarily blocks nerve-muscle conduction, preventing the muscle from overworking. In this way, involuntary contractions are reduced and facial symmetry can be significantly improved. The effect lasts for an average of 3 to 6 months and can be used as needed.
If you want to get rid of problems such as involuntary contractions, facial asymmetry and aesthetic deterioration that occur after masseter muscle hyperactivity in facial synkinesis, you can contact Dr. Be, an expert in Facial Reanimation for facial nerve paralysis, immediately.
