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Difference between revisions of "Bilateral Trigeminal neuromotor organic symmetry"
Bilateral Trigeminal neuromotor organic symmetry (view source)
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[[File:Potenziale Evocato della Radice Trigeminale.jpg | [[File:Potenziale Evocato della Radice Trigeminale.jpg|left]] | ||
In order to achieve a complete clinical evaluation of mastication, an in-depth neurophysiopathological assessment of masticatory muscles control is required. Electromyography technique (EMG) is widely used for this purpose, but failed to provide convincing results. | <translate>In order to achieve a complete clinical evaluation of mastication, an in-depth neurophysiopathological assessment of masticatory muscles control is required. Electromyography technique (EMG) is widely used for this purpose, but failed to provide convincing results</translate>. | ||
<translate>The aim of this work was to describe our quantitative objectivation of the motor control of the masticatory muscles and to verify the hypothesis to consider the bilateral Root Motor Evoked Potentials as an electrophysiological normalization factor</translate>. | |||
{{ArtBy| | {{ArtBy| | ||
| autore = Gianni Frisardi | | autore = Gianni Frisardi | ||
| autore2 = | | autore2 = Şükrü Okkesim | ||
| autore3 = | | autore3 = Alice Bisirri | ||
| autore4 = | | autore4 = Flavio Frisardi | ||
| autore5 = | | autore5 = Pier Paolo Valentini | ||
| autore6 = | | autore6 = | ||
}} | }} | ||
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Some authors have tried to test the hypothesis that normalization of the jaw-stretch reflex amplitude with respect to the voluntary EMG activity preceding the reflex stimulus (EMG pre-stimulus) makes the amplitude more independent by the electrode location over the masseter muscle. In this experimental study, the reflex amplitude was also normalized with respect to the mean pre-stimulus EMG activity.<ref>Koutris M, Naeije M, Lobbezoo F, Wang K, Arendt-Nielsen L, et al. (2010) Normalization reduces the spatial dependency of the jaw-stretch reflex activity in the human masseter muscle. Muscle Nerve 41: 78-84.</ref> | Some authors have tried to test the hypothesis that normalization of the jaw-stretch reflex amplitude with respect to the voluntary EMG activity preceding the reflex stimulus (EMG pre-stimulus) makes the amplitude more independent by the electrode location over the masseter muscle. In this experimental study, the reflex amplitude was also normalized with respect to the mean pre-stimulus EMG activity.<ref>Koutris M, Naeije M, Lobbezoo F, Wang K, Arendt-Nielsen L, et al. (2010) Normalization reduces the spatial dependency of the jaw-stretch reflex activity in the human masseter muscle. Muscle Nerve 41: 78-84.</ref> | ||
Unfortunately, the proposed model gave us few neurophysiological indications being the P-P amplitude of the jaw in excess, respect to unity or 100% as aforementioned <ref name=":0" /> | Unfortunately, the proposed model gave us few neurophysiological indications being the P-P amplitude of the jaw in excess, respect to unity or 100% as aforementioned <ref name=":0" />. Why not use the masseteric <math>M-wave</math> as a normalization factor, higher in amplitude and more stable than the MVC?<ref name=":1">Arabadzhiev TI, Dimitrov VG, Dimitrova NA, Dimitrov GV (2010) Interpretation of EMG integral or RMS and estimates of “neuromuscular efficiency” can be misleading in fatiguing contraction. J Electromyogr Kinesiol 20: 223-232.</ref> | ||
The technical execution of <math>M-wave</math> for the trigeminal nervous system is much more painful and invasive than that of the spinal cord. To evoke a direct response from the masseter muscle, in fact, it is necessary to insert an insulated in-tip needle electrode about 2 cm deep in the temporal fossa and this makes the technique not clinically applicable, although it could obtain more detailed information for the neurophysiological interpretation data. | The technical execution of <math>M-wave</math> for the trigeminal nervous system is much more painful and invasive than that of the spinal cord. To evoke a direct response from the masseter muscle, in fact, it is necessary to insert an insulated in-tip needle electrode about 2 cm deep in the temporal fossa and this makes the technique not clinically applicable, although it could obtain more detailed information for the neurophysiological interpretation data. | ||
===<sub>maximal</sub>Absolute Neural Evoked Energy <math>_mANEE</math>=== | ===<sub>maximal</sub>Absolute Neural Evoked Energy <math>_mANEE</math>=== | ||
[[File:Potenziale Evocato della Radice Trigeminale.jpg|left|thumb|'''Figure 3:''' The figure shows the signal saturation of the root with respect to latency and amplitude.]] | [[File:Potenziale Evocato della Radice Trigeminale.jpg|left|thumb|'''Figure 3:''' The figure shows the signal saturation of the root with respect to latency and amplitude.]] | ||
like in the most recent Wavelet algorithm,<ref>Bonato P, Roy SH, Knaflitz M, De Luca CJ (2001) Time-frequency parameters of the surface myoelectric signal for assessing muscle fatigue during cyclic dynamic contractions. IEEE Trans Biomed Eng 48: 745-753.</ref> but it still remains very difficult, if not impossible in some cases, to separate the EMG signal from the unavoidable noise. | As already mentioned, the electromyographic signals show high complexity, and the mechanisms underlying the generation of EMG signals appear to be non-linear or even chaotic in nature. Researchers are trying, however, to improve the systems of mathematical filtering like in the most recent Wavelet algorithm,<ref>Bonato P, Roy SH, Knaflitz M, De Luca CJ (2001) Time-frequency parameters of the surface myoelectric signal for assessing muscle fatigue during cyclic dynamic contractions. IEEE Trans Biomed Eng 48: 745-753.</ref>, but it still remains very difficult, if not impossible in some cases, to separate the EMG signal from the unavoidable noise. | ||
In this model of normalization, the purpose is not the decomposition of the signal/noise ratio, that we prefer to consider as an entropic phenomenon,<ref>Xie HB, Guo JY, Zheng YP (2010) Fuzzy approximate entropy analysis of chaotic and natural complex systems: detecting muscle fatigue using electromyography signals. Ann Biomed Eng 38: 1483-1496.</ref> but to decouple the contents of the central drive <ref>Inghilleri M, Berardelli A, Cruccu G, Priori A, Manfredi M (1989) Corticospinal potentials after transcranial stimulation in humans. J Neurol Neurosurg Psychiatry 52: 970-974.</ref> from the peripheral drive<ref>Cruccu G, Iannetti GD, Marx JJ, Thoemke F, Truini A, et al. (2005) Brainstem reflex circuits revisited. Brain 128: 386-394.</ref><ref>Kennelly KD (2012) Electrodiagnostic approach to cranial neuropathies. Neurol Clin 30: 661-684.</ref>by normalizing them with the organic content extrapolated from the <sub>b</sub>R-MEPs. | In this model of normalization, the purpose is not the decomposition of the signal/noise ratio, that we prefer to consider as an entropic phenomenon,<ref>Xie HB, Guo JY, Zheng YP (2010) Fuzzy approximate entropy analysis of chaotic and natural complex systems: detecting muscle fatigue using electromyography signals. Ann Biomed Eng 38: 1483-1496.</ref> but to decouple the contents of the central drive <ref>Inghilleri M, Berardelli A, Cruccu G, Priori A, Manfredi M (1989) Corticospinal potentials after transcranial stimulation in humans. J Neurol Neurosurg Psychiatry 52: 970-974.</ref> from the peripheral drive<ref>Cruccu G, Iannetti GD, Marx JJ, Thoemke F, Truini A, et al. (2005) Brainstem reflex circuits revisited. Brain 128: 386-394.</ref><ref>Kennelly KD (2012) Electrodiagnostic approach to cranial neuropathies. Neurol Clin 30: 661-684.</ref>by normalizing them with the organic content extrapolated from the <sub>b</sub>R-MEPs. | ||
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===<sub>b</sub>R-MEPs stability and synchronicity=== | ===<sub>b</sub>R-MEPs stability and synchronicity=== | ||
[[File:TCS - Motor Evoked Potentials of trigeminal roots in open bite patient.jpg|thumb|'''Figure 2''': Motor evoked potentials elicited by transcranial electrical stimulation of both trigeminal roots]] | [[File:TCS - Motor Evoked Potentials of trigeminal roots in open bite patient.jpg|thumb|'''Figure 2''': Motor evoked potentials elicited by transcranial electrical stimulation of both trigeminal roots]] | ||
Another essential element to support the proposed normalization factor is its stability and synchronicity in the neuromuscular response. | Another essential element to support the proposed normalization factor is its stability and synchronicity in the neuromuscular response. | ||
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We have to add to these biases an even more limiting phenomenon than the intracranial current distribution with vectorial summation and collision current phenomena. However, the morphology of the <sub>b</sub>R-MEPs (Figure 2) and the difference in latency and amplitude (0.04 msec and 400 μV, respectively) reported in Table 2, confirm the high stability and synchronicity of the <sub>b</sub>R-MEPs. Keep in mind that, in order to extract the maximum efficiency from the normalization model proposed, any functional tests, such as trigeminal reflexes, must be performed in the same session and, therefore, with the same electrode arrangement. This way it will significantly reduce distortion due to the recording geometry. | We have to add to these biases an even more limiting phenomenon than the intracranial current distribution with vectorial summation and collision current phenomena. However, the morphology of the <sub>b</sub>R-MEPs (Figure 2) and the difference in latency and amplitude (0.04 msec and 400 μV, respectively) reported in Table 2, confirm the high stability and synchronicity of the <sub>b</sub>R-MEPs. Keep in mind that, in order to extract the maximum efficiency from the normalization model proposed, any functional tests, such as trigeminal reflexes, must be performed in the same session and, therefore, with the same electrode arrangement. This way it will significantly reduce distortion due to the recording geometry. | ||
====Organic symmetry==== | ====Organic symmetry==== | ||
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A reflex opening of the jaw, resulting from the simultaneous relaxation of jaw closers and contraction of jaw openers, not only helps to avoid injuries to the oral tissues, but also could contribute to coordinating rhythmic masticatory movements.<ref>Shigenaga Y, Yoshida A, Mitsuhiro Y, Tsuru K, Doe K (1988) Morphological and functional properties of trigeminal nucleus oralis neurons projecting to the trigeminal motor nucleus of the cat. Brain Res 461: 143-149.</ref>The stimulus applied to one side evokes the reflex bilaterally in a nearly symmetrical fashion. The symmetrical output is characteristic of most of the jaw movements induced by sensory signals both from the peripheral tissue and from those generated by signals coming from the cerebral cortex. | A reflex opening of the jaw, resulting from the simultaneous relaxation of jaw closers and contraction of jaw openers, not only helps to avoid injuries to the oral tissues, but also could contribute to coordinating rhythmic masticatory movements.<ref>Shigenaga Y, Yoshida A, Mitsuhiro Y, Tsuru K, Doe K (1988) Morphological and functional properties of trigeminal nucleus oralis neurons projecting to the trigeminal motor nucleus of the cat. Brain Res 461: 143-149.</ref>The stimulus applied to one side evokes the reflex bilaterally in a nearly symmetrical fashion. The symmetrical output is characteristic of most of the jaw movements induced by sensory signals both from the peripheral tissue and from those generated by signals coming from the cerebral cortex. | ||
Previous studies <ref>Nakamura Y, Nagashima H, Mori S (1973) Bilateral effects of the afferent impulses from the masseteric muscle on the trigeminal motoneuron of the cat. Brain Res 57: 15-27.</ref> | Previous studies have shown that peripheral stimulation evokes inhibitory postsynaptic potentials (IPSPs) in bilateral jaw-closer motor neurons.<ref>Nakamura Y, Nagashima H, Mori S (1973) Bilateral effects of the afferent impulses from the masseteric muscle on the trigeminal motoneuron of the cat. Brain Res 57: 15-27.</ref> This bilateral inhibition is mediated, at least in part, by supra- and juxta-trigeminal neurons with bifurcating axons projecting to both the right and the left masseter motor neurons. The goal of a recent study was to morphologically analyse how the functional symmetry of the masticatory system might be reflected in the organisation of pre-motor neurons and how it could be able to mediate excitation of jaw-opener motor-neurons.<ref>Yoshida A, Yamamoto M, Moritani M, Fukami H, Bae YC, et al. (2005) Bilateral projection of functionally characterized trigeminal oralis neurons to trigeminal motoneurons in cats. Brain Res 1036: 208-212.</ref> | ||
It has been demonstrated that in the masticatory system, where symmetrical motor output is the rule, employing neurons with bifurcating axons as a pre-motor element might be a common strategy for mediation of both peripheral and central signals. | It has been demonstrated that in the masticatory system, where symmetrical motor output is the rule, employing neurons with bifurcating axons as a pre-motor element might be a common strategy for mediation of both peripheral and central signals. | ||