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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|thumb|left|'''Figure 3:''' The signal saturation of the root, with respect to latency and amplitude.]]
[[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>.
 


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.


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| '''Method:'''<br />25 healthy people (15 males, 10 females; mean age 29 years ± 5), with normal occlusion and no history of temporomandibular disorders and orofacial pain, underwent a transcranical electrical stimulation; this allowed a direct bilateral stimulation of the motor roots of the trigeminal motor system, called bilateral Root Motor Evoked Potentials (bR- MEPs). The maximal Absolute Neural Evoked Energy, symmetry and synchrony properties of the resulting bR-MEPs were studied using measures like latency, amplitude and integrated area of the collected signal. An Artificial Neural Network computational model was used to estimate the correlation coefficient with the EMG values of each of both sides to predict the values from the right side by inputting values from the left side.
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| '''Results:'''<br />With regard to the descriptive statistical aspect the mean and SD values were for onset latency (1.96 msec ± 0.18 msec vs''.'' 2.01 msec ± 0.21 msec), amplitude (5.76 mV ± 2.01 mV vs''.'' 5.89 mV ± 2.51 mV) and integral area (11.09 mV/msec ± 4.45 mV/msec vs''.'' 11.27 mV/msec ± 4.34 mV/msec) for right and left masseter muscle, respectively. The Kruskal-Wallis test shows not statistically significant difference between the medians (confidence level 95%) in fact the ''P''–value was 0.33, 0.96 and 0.86 between sides for latency, amplitude and the EMG integral area, respectively for the bR-MEPs. The similarity between sides of the data sampled, studied in terms of mean squared error and correlation coefficients for latency (R2=0.955, SME=0,032) amplitude (R2=0.948, SME=0.162) and integrated area (R2=0.947, SME=0.212), indicates an organic symmetry of the trigeminal motor nervous system.
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| '''Conclusion:'''<br />These results show the high efficiency in terms of symmetry and stability of the bR-MEPs as a normalization factor.
|}


{{ArtBy|
{{ArtBy|
| autore = Gianni Frisardi
| autore = Gianni Frisardi
| autore2 =  
| autore2 = Şükrü Okkesim
| autore3 = Akdemir B
| autore3 = Alice Bisirri
| autore4 =  
| autore4 = Flavio Frisardi
| autore5 = Alice Bisirri
| autore5 = Pier Paolo Valentini
| autore6 = Flavio Frisardi
| autore6 =  
}}
}}


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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> have shown that peripheral stimulation evokes inhibitory postsynaptic potentials (IPSPs) in bilateral jaw-closer motor neurons. 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 <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> 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.
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.
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