Pathogenesis and manual therapy of contracture of the facial muscles

Prof. Ivanichev G.A Kazan, Russia Much controversy exists concerning the problems of mimic musculature contracture due to acute facial nerve neuropathy. Rather a significant incidence of contracture (25 — 30% of cases are facial nerve affection) makes it nessesary to look for some new methods of prevention and treatement of this desease. In resent literature on etiology and pathogenesis of contractures it was generally agreed that this defect is a result of heterotopic nerve regeneration at the place of injury. The neural scar which has the trigger zone properties distorts the character and the direction of impulses going to the facial muscles. It is assumed that this pathologic process develops against the background of the changed proprioceptive impulses from the same musculature provided that there is a disfunction of limbico — reticulo complex. However, the clinical experience makes us doubt whether the above viewpoint is correct. First of all the participation of the muscles themselves in the pathogenesis of contracture is not taken into consideration. Contracture is known to occur very early during onsets of pains in facial nerve neuritis as well as during early administration of anticholinesterase agents and electrostimulation in the absence of neural scar and though disfunction of limbico — reticulo complex is not yet formed. However, at this stage of the disease /10-12 days/ local hypertonicity — myogelosus tend to manifest in muscles. They turned out to be functionally active formations with the complex of clinical and electrophysiological characteristics. The main characteristics of the hypertonicities are tenderness in palpation, particularly in muscle distension, increased mechanical stimulation during palpation which is a favoirite localization in some certain muscles. Form electrophysiologic point of view the local hypertonicities are characterized bu the combination of bioelectrical characteristics tipical both for musclar and neural level of affection. It is in the hypertonicity zone that interferential bioelectrical activity is characterized by the voluntary activity. At the same time passive muscle distension is accompanied by some significant activity exceeding the amplitude of biopotential oscilations of the voluntary contraction by 1,5 — 2 times. In biopotentials hypertonicity investigation using coaxial needle electrodes the spontaneous electric activity was detected which is tipical for the neural affection. At the same time at the stage of complete contracture in the spectrum of potentials of motor units action (PMUA) both elongated and shortened potentials are manifest. It is assumed that the increased period of PMUA is tipical for the neural pathlogy, while the decreased period — for the muscular one. Therefore, facial muscle hypertonicity has the manifestations of both groups of diseases. It is its first neurophysiologic characteristic. The second characteristic consists of « the stamped » complexes of polyphase potentials with the frequency of 1 — 5 hertz in the structure of potentials of motor units action which form the spontaneous activity (fig.2). Clinically they correspond to the spontaneous muscle hyperkinesis. In synkinesis of the facial muscles they are not revealed against the voluntary activity background. We beleive that these «stamped» complexes are the electromyographic evidence of the impulse transport from muscle to muscle, that is ephaptic intermuscular electric relations are present. This injured relationship is possible under pathologic conditions only when electric isolation among fascicles is lost. In polymyositis such potentials were found by Lambert and B.Gekht. The above clinical and electromyographic findings are the basis of all assumptions which made it possible to give new considerations on the pathogenesis of the secondary contracture of the facial musculature. Muscle hypertonicity is stated to occur always if there is efferent denervation in the affected musculature. Their formation takes place in the way of the Vulpian — Rogovich tonomotor effect is realized. The same rule is evidenced by the increased contractile ability of the denervated muscles to the humoral factors, to their reverse development from the point of view of phylogenetic origin. The most diverse factors both endogenous and exogenous may act as activator contractions. The early prescribed neostigmine methylsulfate markedly enhances the contratile process. When the nerve is slightly affected and its function is readily restored the hypertonicities thus formed undergo regression, facial musculature restores its function without any defect. In severe affection both the formed hypertonicities and the affected musculature are rather quickly subjected to the subsequent degenerative changes with muscle destruction. When the affection is medium then some complex of phenomenon develops in which the nerve restoration is delayed as regards the processes that take place in muscles. The area of muscle contraction thus formed which is active as regards the neighbouring ones produces the development of the currents of action in these muscles. In this connection it is worth mentioning that the so called secondary contraction of the resting muscle is known to occur next to the contracting one. Transmission of stimulation from one muscle to another easily occurs when there is a slight insulator between them. The denervated mimic symplast gives for that adequate conditions. Relaxation of the induced contraction is a passive process, it is rather prolonged. Delay in relaxation is maintained by the relative autonomy of the contractile process which is characteristic of the contractures in general. The resulting current which is called contractural prolongs the time of muscle relaxation. The contractile process supported for a long time in isolated muscle groups, thus indicates the formation of the local hypertonicity. Then, in what way does synkinesis occur? None of the sceletal muscles with hupertonicity has any evidence of synkinesis. The participation of the facial nerve nucleus, the neural cicatrix at the site of nerve regeneration were confirmed neither clinically nor electrophysiologically. This phenomenon is better understood only when the peculiar features of the facial muscle itself aree taken into account. The facial muscles are known to contain no fascial elements and are directly incorporated into the face skin. The pathologic deflection of muscle bundles producing hypertonicity brings together both the neighbouring and the remote muscle fibers. The absence of a reliable insulator between muscle bundles and fibers, the abundance of interstitial fluid around the denervated tissue and sarcoplasm with its dystrophic changes, endo and perymysia, all this makes the impulse transmission possible from one muscle fiber to another. In other words, an artificial false synapse originates between muscles, but not between nerve trunks. The existence of plexuses, muscle overlapping areas at the site of the hypertonicity, create conditions for transversal transmission of motor impulse to remote muscle strata while forming typical and uniform synergias. The participation of limbico — articular complex seems to be secondary to this scheme. Taking into accout the hypertonicity of muscles themselves we modificated postisometric relaxation technique. The following description is presented. The nuclei of the forming hypertonicities are determined by kinesthetical palpation. The skin of the face is defatted and pieces of plaster are stuck on it / sometimes without /. The state of hypertonicity is checked by the doctor's index finger or the thumb of the left hand in the oral cavity: other fingers which are outside perform the main manipulation — hypertonicity distension. The patient makes any mimic movement directed against external resistance exerted by the physician's fingers / i.e. muscle isometric tension is produced /, while mild intensity effort is maintained within 5 — 6 sec. It is better to use muscle breathing activity. Counteraction must be adequate to the force of the affected muscles. Then comes an active relaxation and a passive distention of the facial muscles with the help of the physician's fingers. Then the doctor holding the distended muscle in the above position asks the patient to repeat the exercise. Usially folowing 4 — 5 exersises, a stable muscle relaxation occurs which lasts 12 — 24 h. Patients describe this condition as relaxation, disappearance of tightness and a pleasant lassitude. According to the intensity and the severity of the hypertonicities the course of treatment includes from 2 — 4 to 10 — 15 procedures. Subsequently a maintaining relaxation is advisable 1 — 2 times a week. When the muscle forces are mild its simple distention is satisfactory (without an active contraction) in the phase of deep expiration. Most failures are related to the excessive activity of the procedure itself particularly to the forced muscle distention. The effectiveness of manual therapy is very high: it eliminates the pain syndrom and the sensation of the facial strain irrespective of the severity of affection. As to facial asymmetry it nearly disappears when the disease is mild and has no significant changes when the disease is rather serious or severe, huperkinesis are most persistent. Immediately following relaxation their intensity is even rather increased and is being retained during 10 — 15 min., then it is reduced to the initial level or even less, but hyperkinesis do not disappear completely. However it is worth mentioning, patients never discribe hyperkinesis as severe symptoms. The marked analgesic and myorelaxing effect of the manual therapy are evident by two factors: firstly, muscle relaxation is rather functional then the structural phenomenon related to the normalization of architectonics of proprioceptors. Secondly there is a normalization of the afferent balance of proprioceptive and extraceptive sensitivity of the facial musculature with the restoration mechanism of «gate control» which produces an analgesic effect. Myorelaxation is the resulting effect of the same mechanisms. All manipulations of the manual therapy of the facial muscles may be done by the patients themselves. They are trained in all relaxation technique with control of their own feelings (pain and face tightening with the purpose to achieve face relaxation and disappearence of the local tenderness). It is advisable to employ the relaxation procedures 2 — 3 times a day particularly in cold season. The most effecient is the treatement of the secondary contracture of the facial muscles in combination of postisometric relaxation and acupuncture. This combination is justified by the physiologic mechanism of auricular acupuncture (AA). Intensive afferent transmission into the brain axis and subcortical structures is known to be due to auricular acupuncture procedure, when varied functional systems are mobilized into the trigemino — facial complex. The limbic system is supposed to be one of the structures on the basis of which the emotional assessment of the afferent process on the face is made. It is evident that during secondary contracture of the facial muscles there is distorsion of both the afferent process and realization of the motor effects when emotinal reactions are realized. From this point of view the auricular acupuncture is more preferable then the corporal one. The most significant for the secondary contracture of the facial muscles treatment in combination with postisometric relaxation are the following auricular points (AP): 3,4,5,6,7,8,11,13,33,34,35,36,55,84,97,121, as well as the areas of the first, fourth and seventh portions of the lobule of the ear, where there is motor and frontal cortex region reprisentation. Postisometric relaxation is performed before acupuncture. Not more than 3 — 4 AP on one flour of the auricule where the pain is, are performed at a visit but when there is no change in the state of health — on both flours of the auricule. During 1 — 2 visits only AP — 33,55 are subjected to auricular acupuncture. Subsequently acupuncture points are chosen on the basis of their relation to the facial area with the highest local tenderness and with the most marked hupertonicity. Acupuncture procedures are performed in 5 — 6 min. following relaxation. The course of treatment consists of 8 — 12 therapeutic prosedures every day or every other day. Special emphasis must be laid that patients must perform all these manipulations dealing with relaxation of the affected muscles themselves irrespective of auricular acupuncture procedures. Our experience makes it possible to conclude that the positive stable effect is achieved due to the combination of the above methods of therapy.

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