| Facial expression is an important way for human beings to affective communication. Facial expression is generated from the muscles which are dominated by facial nerve. Dysfunction of the facial nerve lead to paralysis of the facial musculature, the main symptom of facial paralysis which comes from nerve damage is movement dysfunction of facial expression muscles. Facial paralysis not only affect the patients'appearance and the social communication, but also their psychological and daily life significantly. In the USA, the incidence of facial paralysis resulting from various etiologies is approximately 50 cases per 100,000. Of those affected, more than 40% demonstrate satisfactory to complete recovery, while the remaining are left with some level of chronic impairment.The best result of the treatment for facial paralysis is to restore the function of facial expression muscles and coordinate their movements freely. Because the function of human expression muscle is highly differentiated, the degree of each muscle's contraction and different muscles coordination are vital to the performance of a variety of facial expressions. How to restore the precisely control of each facial muscle has been the bottleneck of the clinical treatment for facial paralysis all the time. Current treatments for facial paralysis include conservative treatment, surgery, physical rehabilitation therapy and Chinese traditional treatment. However, all of them have limitations, and there is still no fully effective way to cure facial paralysis. Functional electrical stimulation (FES) refers to the muscle contraction by electrical stimulation, which can compensate for the loss of body function for nerve injury. The emergence of FES makes it possible to treat facial paralysis through restore function of facial muscle by electrical stimulation. According to the above-mentioned background, we have ideas to make rat's ear movement as an animal model for the research of facial expression movement, establish the FES system based on the electromyogram(EMG) analysis, and research the feasibility of the functional reconstruction of paralyzed facial expression muscle by the aid of FES system and its clinical value in facial paralysis treatment. Follow studies were performed:①Anatomy of the rat's pinnae musculature;②Exploration of the relationship between the EMG patterns and the rat's pinnae movements;③Experimental study for electrical stimulation in the rat's pinnae muscles;④Establish the system which can restore the function of paralyzed pinnae muscles by means of FES.Objective 1. Regard ear movement of rat as an animal model for study the facial expression movement. Find out the muscles constitution in different patterns of ear movement and its nerves controlling condition. In order to provide anatomical basis for experimental study in the restoring function of paralyzed facial muscle through FES.2. Study the EMG of pinnae muscles and its real-time identification method under different ear movement patterns, in order to use it as a control signal to adjust the electrical stimulation of FES system on paralyzed pinnae muscles.3. By adjusting the parameters of electrical stimulation to observe the response of different pinnae muscle for it, and measure the threshold value of pinnae muscles to electrical stimulation. Using the value as references for FES systems to stimulate paralyzed pinnae muscles.4. Establish the FES system which based on the EMG, in order to discuss the feasibility of reconstructing the functions of paralyzed pinnae muscles and its clinical value in the treatment of facial paralysis.Methods1. Make pinnae muscles of rat as an animal model for the study of facial expression muscles and observe rat's ear movement patterns. Through anatomy of normal rat's pinnae surrounding tissue and electrical stimulation on its neuromuscular to find out the muscle composition and its innervations associated with ear movement.2. Implant microelectrodes in normal rat's ipsilateral frontoscutular muscles and cervicoauricular muscles, and collect the EMG for observing the relationship between the different ear movement patterns and their EMG. Explore the relationship between the EMG and the functional actions of the muscle via analyzing the EMG features of rat's pinnae muscles in different movement states.3. Microeletrodes were implanted into bilateral frontoscutular muscles and cervicoauricular muscles respectively in rats with unilateral peripheral facial paralysis. Biphasic rectangular current pulses were used to stimulate the muscles 7days after surgery. Adjusting the parameters to observe bilateral pinnae muscles' response to the stimulation, and get the strength-time curve of two pinnae muscles under the control of normal or paralyzed facial nerve, so to provide reference data of triggering stimulus for the FES system.4. Establish FES system, set the trigger threshold of electrical stimulation according to the myoelectricity voltage amplitude comes from normal side pinna muscles' movement, and set electrical stimulation parameters according to the response of paralyzed side pinna muscles for electrical stimulation. When the normal side pinna muscles' myoelectricity voltage reaches the threshold and recognized by the central nervous system, it will trigger electronical stimulation on corresponding pinna muscles, causing the paralyzed side pinna muscles' contraction, so to realize bilateral ear move symmetrically and synchronously.Results1. The ear movement of rat including pinna reflex and voluntary movement. Sound triggered reflex results in the main direction of backward movement, the voluntary movement of rat's ear in the direction of forward, back, inside, out or rotation. Rat has 5 Sports-related pinna muscles:contraction of cervicoauricularis muscle will cause ear inner-backward direction movement, can raise and rotate the ear; the contraction of frontoscutularis muscle will lead ear move forward; the contraction of interscutularis muscle will cause ear inside movement; the contraction of two muscles which close to the canal wall of ear mainly cause ear forward movement. Pinna reflex and voluntary movement in rat's ear come from all auricular muscles'movement which under the control of facial nerve, when facial nerve was cut, the ear movement disappear.2. In mormal rat, the myoelectric signals in the pinna muscles are different during different motion states. We can collect the normal myoelectric signals from frontoscutularis muscle when ear move forward, the peak amplitude is 0.12±0.03mV, the duration is 31±6ms; We can collect the normal myoelectric signals from the cervicoauricularis muscle when ear move for posterointernal direction, the peak amplitude is 0.31±0.08mV, the duration is 32±8ms.3. When rats with unilateral peripheral facial paralysis were sane, give biphasic rectangular current pulses of electronical stimulation in bilateral frontoscutularis muscles and cervicoauricularis muscles, and its ear will move forward or posterointernal direction respectively, the resulting intensity-time curve was approximately equilateral hyperbola. When the width of pulse is less than 0.1ms, myoelectricity stimulation threshold is bigger or difficult to derive; When the width of pulse becomes larger, the threshold of auricular myoelectricity becomes smaller; When pulse width is greater than 10ms, the threshold stabilized; When pulse width is greater than 100ms, the double-contractions of pinnae muscles become more obviously and interval become larger with the pulse width increasing.When pulse width is fixed, the range of ear movement increase according to current intensity.4. Establish FES system applied to rats with unilateral peripheral facial paralysis, electrical stimulation is set as a single rectangular pulse whose width is 2ms, the current strength is 4-8mA. When the EMG generated from the normal pinna muscles's movement reached triggering threshold and identified by the central control system, it will stimulate the corresponding paralyzed pinna muscles to be contraction, and cause bilateral ear move synchronously and symmetrically.Conclusion1. Pinnae muscles of rat are suitable for using as animal models in experimental studies for restoring facial expressions muscles'function from facial paralysis by using of FES.2. The EMG of pinna muscles is different in normal rats'different movement mode, so it can be used as the basis for computer to identify ear movement mode.3. Electrical stimulation on different pinna muscles can cause different patterns of ear movements; the pulse width of electrical stimulation should be located in 0.1-100ms.4. FES system can realize the function reconstruction of paralyzed pinna muscles. It is of significance to recover expression function and improve the appearance in the treatment of facial paralysis.
|
PDF Full Text Request