**2.2 The use of monofilament mesothreads for the treatment of synkinesis**

Patients, suffering from the lesion of the facial nerve, develop the synkinesis and contractures on the affected side of the face in 4–6 months amid already existing weakness of muscles of facial expression. Synkinesis is involuntary movements of the facial muscles of one muscle group in response to voluntary movements of another muscle group of the face [12, 13, 15]. Currently, there are three hypotheses for the occurrence of synkinesis. The theory that has received the greatest recognition is that

**Figure 12.** *Bell's palsy. Patient B. before injections.*

**Figure 13.** *Patient B, 1 month after injection.*

after damage, axons undergo aberrant regeneration forming the innervation of those muscles they had not previously been innervated. The second potential pathological mechanism involves ephaptic signaling, in which neighboring axons in the affected area stimulate each other, probably as a result of loss of myelin sheath. Finally, some studies indicate the possibility of a central mechanism of synkinesis origin as a result of overexcitation of the motor nucleus of the facial nerve [14, 15].

In clinical practice, the most common cases of synkinesis are oculo-oral (movement of the zygomaticus major and minor muscles, the orbicularis oris muscle while *Comprehensive Rehabilitation of Patients with Facial Expression Asymmetry and Synkinesis… DOI: http://dx.doi.org/10.5772/intechopen.106694*

**Figure 14.** *Bell's palsy. Patient B. before injections.*

**Figure 15.** *Patient B, 1 month after injection.*

the arbitrary closure of the palpebral fissure) and oral-ocular (narrowing of the palpebral fissure during mouth movement). To diagnose oculo-oral synkinesis, we use the "frequent blinking" test, when the patient is asked to blink frequently. In this case, there is a contraction of the zygomatic, buccal and perioral muscles observed. To diagnose oral-ocular synkinesis, the "u-e" or "b-p" test is used, which allows to trace the narrowing of the palpebral fissure on the side of the lesion, which manifests in the patient "winking" during a conversation.

**Figure 16.** *Bell's palsy. Patient А. before injections.*

**Figure 17.** *Patient А., 1 month after injection.*

Due to the fact that synkinesis is usually manifested by interchanging hyper- and hypokinesis zones, the applied methods of treatment should be aimed both at suppressing excessive muscle activity, depending on the area of the face, and at restoring mobility. Such physiotherapy methods as physiotherapy exercises, massage, electrical stimulations are very arduous and often do not bring the desired results, because they do not influence the pathological "chain of synkinesis," which is defined by the sequence of involvement of involuntary muscle contractions on the affected side in response to voluntary movement [12, 15]. Botulinum toxin type A is used to selectively suppress the

*Comprehensive Rehabilitation of Patients with Facial Expression Asymmetry and Synkinesis… DOI: http://dx.doi.org/10.5772/intechopen.106694*

**Figure 18.** *Bell's palsy. Patient А. before injections.*

**Figure 19.** *Patient А., 1 month after injection.*

activity of muscle fibers and is effectively used to correct synkinesis [11, 14]. However, after botulinum toxin therapy, temporary weakness of the facial muscles on the affected side may develop, which aggravates the asymmetry and causes frustration (anxiety) in patients. They start feeling as if the symptoms of the disease have reappeared, which makes many of them to refuse subsequent injections. Additionally, the effect of injections is short term (2–3 months). There are also known methods of surgical correction of synkinesis [12, 16], but they require the excision of areas of synkinesis and hospitalization in a surgical department. This can lead to persistent weakness of facial muscles and the formation of muscle contractures [11, 14].

**Figure 20.** *Bell's palsy. Patient А. before injections.*

**Figure 21.** *Patient А., 1 month after injection.*

We observed two groups of patients with Bell's palsy. All patients had oculo-oral and oral-ocular synkinesis, which developed within a year after the disease. The first group of patients received injections of botulinum toxin type A in the areas of synkinesis, while the second group of patients underwent implantation of monofilament mesothreads. The severity of pathological synkinesis was assessed using the Synkinesis Assessment Questionaire (SAQ, 2007).

*Comprehensive Rehabilitation of Patients with Facial Expression Asymmetry and Synkinesis… DOI: http://dx.doi.org/10.5772/intechopen.106694*

**Figure 22.** *Bell's palsy. Patient А. before injections.*

**Figure 23.** *Patient А., 1 month after injection.*
