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The 'CNN' loop closure analy of course is based on the terminal article which basically describe five patients with cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) with chronic cough and lower limb muscle stretch reflexes preserve yourself.<ref name=":0">Jon Infante, Antonio García, Karla M Serrano-Cárdenas, Rocío González-Aguado, José Gazulla, Enrique M de Lucas, José Berciano. Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) with chronic cough and preserved muscle stretch reflexes: evidence for selective sparing of afferent Ia fibres.J Neurol . 2018 Jun;265(6):1454-1462. doi: 10.1007/s00415-018-8872-1.Epub 2018 Apr 25. | The 'CNN' loop closure analy of course is based on the terminal article which basically describe five patients with cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) with chronic cough and lower limb muscle stretch reflexes preserve yourself.<ref name=":0">Jon Infante, Antonio García, Karla M Serrano-Cárdenas, Rocío González-Aguado, José Gazulla, Enrique M de Lucas, José Berciano. Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) with chronic cough and preserved muscle stretch reflexes: evidence for selective sparing of afferent Ia fibres.J Neurol . 2018 Jun;265(6):1454-1462. doi: 10.1007/s00415-018-8872-1.Epub 2018 Apr 25. | ||
</ref> In particular, somatosensory evoked potentials were absent or severely attenuated. Biceps and hamstring T-reflex recordings were normal, while the masseter reflex was absent or attenuated.<blockquote>[[File:Meningioma 2 by Gianni Frisardi.jpeg|link=link=Special:FilePath/Meningioma_2_by_Gianni_Frisardi.jpg|alt=|thumb|'''Figure 1:''' Neurological statement highlighting a severe right jaw jerk latency and amplitude abnormality]]The first observation to be made is that the patients were suffering from chronic spasmodic cough and the second observation was the preservation of the tendon reflexes of the lower limbs. In our patient 'Balancer', on the other hand, there was a total absence of the mandibular tendon reflex<ref>The history of examination of reflexes. | </ref> In particular, somatosensory evoked potentials were absent or severely attenuated. Biceps and hamstring T-reflex recordings were normal, while the masseter reflex was absent or attenuated.<blockquote>[[File:Meningioma 2 by Gianni Frisardi.jpeg|link=link=Special:FilePath/Meningioma_2_by_Gianni_Frisardi.jpg|alt=|thumb|'''Figure 1:''' Neurological statement highlighting a severe right jaw jerk latency and amplitude abnormality]]The first observation to be made is that the patients were suffering from chronic spasmodic cough and the second observation was the preservation of the tendon reflexes of the lower limbs. In our patient 'Balancer', on the other hand, there was a total absence of the mandibular tendon reflex<ref>Boes CJ. The history of examination of reflexes. .J Neurol. 2014 Dec;261(12):2264-74. doi: 10.1007/s00415-014-7326-7. Epub 2014 Apr 3.PMID: 24695995 </ref> (<math>\gamma_1</math>) so that the neurological damage was very evident at the trigeminal midbrain level. (Figure 1) The multifunctional contribution of the midbrain synaptic circuitry by the proprioceptive nerve endings ( <math>1a</math> e <math>\gamma</math>) are of primary importance both for posture and for cervico-oculomotor reflexes. A very interesting article by Yongmei Chen et al.<ref>Chen Y, Gong X, Ibrahim SIA, Liang H, Zhang J.. [https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/36441755/ Convergent innervations of mesencephalic trigeminal and vestibular nuclei neurons onto oculomotor and pre-oculomotor neurons-Tract tracing and triple labeling in rats.] PLoS One. 2022 Nov 28;17(11):e0278205. doi: 10.1371/journal.pone.0278205. eCollection 2022.PMID: 36441755 </ref> showed, through markers, how neurons afferent to the trigeminal mesencephalic nucleus (Vme) from the jaw muscles project to the oculomotor nuclei (III/IV) and their premotor neurons in the interstitial nucleus of Cajal (INC), a well-known pre-oculomotor center that vertically manipulates torsional eye movements. | ||
The conceptual conclusion of the authors was that the Vme proprioceptive neurons of the masticatory projecting muscles at III/IV and INC would detect spindle activity to spatial changes of the jaw conditioned by the force of gravity and/or by the connection between the mandible during rotation of the head. Thus, the convergent innervation of Vme and MVN neurons on the oculomotor and pre-oculomotor nuclei would be a neuroanatomical substrate for the interaction of masticatory proprioception with vestibulo-ocular signals on the oculomotor system during vertical-torsional VOR. The contribution of this article obviously allows us to consider a correlation between the trigeminal system, posture and gait, therefore, the abnormal asymmetry of the jaw jerk could be related to a postural disorder of our patient 'Balancer' | The conceptual conclusion of the authors was that the Vme proprioceptive neurons of the masticatory projecting muscles at III/IV and INC would detect spindle activity to spatial changes of the jaw conditioned by the force of gravity and/or by the connection between the mandible during rotation of the head. Thus, the convergent innervation of Vme and MVN neurons on the oculomotor and pre-oculomotor nuclei would be a neuroanatomical substrate for the interaction of masticatory proprioception with vestibulo-ocular signals on the oculomotor system during vertical-torsional VOR. The contribution of this article obviously allows us to consider a correlation between the trigeminal system, posture and gait, therefore, the abnormal asymmetry of the jaw jerk could be related to a postural disorder of our patient 'Balancer' | ||
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We now have evidence of both direct and indirect functional organic correlation between the trigeminal system and the vestibular system, just think of the study of mVEMP (Vestibular Evoked Myogenic Potentials) now recognized as a solid and reliable test for assessing the functional integrity of the reflex pathway vestibulo-masseteric<ref>Sangu Srinivasan Vignesh, Niraj Kumar Singh, Krishna Rajalakshmi. Tone Burst Masseter Vestibular Evoked Myogenic Potentials: Normative Values and Test-Retest Reliability. J Am Acad Audiol. 2021 May;32(5):308-314. doi: 10.1055/s-0041-1728718.Epub 2021 Jun 1. | We now have evidence of both direct and indirect functional organic correlation between the trigeminal system and the vestibular system, just think of the study of mVEMP (Vestibular Evoked Myogenic Potentials) now recognized as a solid and reliable test for assessing the functional integrity of the reflex pathway vestibulo-masseteric<ref>Sangu Srinivasan Vignesh, Niraj Kumar Singh, Krishna Rajalakshmi. Tone Burst Masseter Vestibular Evoked Myogenic Potentials: Normative Values and Test-Retest Reliability. J Am Acad Audiol. 2021 May;32(5):308-314. doi: 10.1055/s-0041-1728718.Epub 2021 Jun 1. | ||
</ref> in clinical manifestations with involvement of the trigeminal and vestibular system as in schwannomas<ref>Ashutosh Kumar, Sanjay Behari, Jayesh Sardhara, Prabhaker Mishra, Vivek Singh, Vandan Raiyani, Kamlesh Singh Bhaisora, Arun Kumar Srivastava . Quantitative assessment of brainstem distortion in vestibular schwannoma and its implication in occurrence of hydrocephalus.Br J Neurosurg . 2022 Dec;36(6):686-692. doi: 10.1080/02688697.2022.2047155.Epub 2022 Mar 7. | </ref> in clinical manifestations with involvement of the trigeminal and vestibular system as in schwannomas<ref>Ashutosh Kumar, Sanjay Behari, Jayesh Sardhara, Prabhaker Mishra, Vivek Singh, Vandan Raiyani, Kamlesh Singh Bhaisora, Arun Kumar Srivastava . Quantitative assessment of brainstem distortion in vestibular schwannoma and its implication in occurrence of hydrocephalus.Br J Neurosurg . 2022 Dec;36(6):686-692. doi: 10.1080/02688697.2022.2047155.Epub 2022 Mar 7. | ||
</ref><ref>Daniel Moualed, Jonathan Wong, Owen Thomas, Calvin Heal, Rukhtam Saqib, Cameron Choi, Simon Lloyd, Scott Rutherford, Emma Stapleton, Charlotte Hammerbeck-Ward, Omar Pathmanaban, Roger Laitt, Miriam Smith, Andrew Wallace, Mark Kellett, Gareth Evans, Andrew King, Simon Freeman. Prevalence and natural history of schwannomas in neurofibromatosis type 2 (NF2): the influence of pathogenic variants. Eur J Hum Genet. 2022 Apr;30(4):458-464. doi: 10.1038/s41431-021-01029-y.Epub 2022 Jan 24. | </ref><ref>Daniel Moualed, Jonathan Wong, Owen Thomas, Calvin Heal, Rukhtam Saqib, Cameron Choi, Simon Lloyd, Scott Rutherford, Emma Stapleton, Charlotte Hammerbeck-Ward, Omar Pathmanaban, Roger Laitt, Miriam Smith, Andrew Wallace, Mark Kellett, Gareth Evans, Andrew King, Simon Freeman. [https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/35067678/ Prevalence and natural history of schwannomas in neurofibromatosis type 2 (NF2): the influence of pathogenic variants.] Eur J Hum Genet. 2022 Apr;30(4):458-464. doi: 10.1038/s41431-021-01029-y.Epub 2022 Jan 24. | ||
</ref> or in the presence of acoustic neuromas<ref>Claudia Cassandro, Roberto Albera, Luca Debiasi, Andrea Albera, Ettore Cassandro, Alfonso Scarpa, Massimo Ralli. What factors influence treatment decision making in acoustic neuroma? Our experience on 103 cases. Int Tinnitus J. 2020 Nov 18;24(1):21-25.doi: 10.5935/0946-5448.20200004. | </ref> or in the presence of acoustic neuromas<ref>Claudia Cassandro, Roberto Albera, Luca Debiasi, Andrea Albera, Ettore Cassandro, Alfonso Scarpa, Massimo Ralli. What factors influence treatment decision making in acoustic neuroma? Our experience on 103 cases. Int Tinnitus J. 2020 Nov 18;24(1):21-25.doi: 10.5935/0946-5448.20200004. | ||
</ref> as much as the relative correlation between dental occlusion and the vestibular system but this does not allow, given the seriousness of the diagnostic error that it would result, to consider this last clinical condition a clinically validated scientific datum. In the Appendix an example of what might happen. | </ref> as much as the relative correlation between dental occlusion and the vestibular system but this does not allow, given the seriousness of the diagnostic error that it would result, to consider this last clinical condition a clinically validated scientific datum. In the Appendix an example of what might happen. | ||
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'''Axonotmesis''' is a relatively more serious type of peripheral nerve injury and is usually caused by crushing, stretching, or percussion. In axonotmesis, the epineurium is intact, while the perineurium and endoneurium may be disrupted. The axon is separated from the soma and the axon and myelin sheath are disrupted. Wallerian degeneration occurs in the axon stump distal to the injury site within 24 to 36 hours after peripheral nerve injury. | '''Axonotmesis''' is a relatively more serious type of peripheral nerve injury and is usually caused by crushing, stretching, or percussion. In axonotmesis, the epineurium is intact, while the perineurium and endoneurium may be disrupted. The axon is separated from the soma and the axon and myelin sheath are disrupted. Wallerian degeneration occurs in the axon stump distal to the injury site within 24 to 36 hours after peripheral nerve injury. | ||
After neurotmesis, Schwann cells respond adaptively to axonal disruption, transitioning from a highly myelinated state to a dedifferentiated state. De-differentiated Schwann cells engulf axons and myelin debris and form a regenerative pathway for axon outgrowth. Additionally, activated Schwann cells secrete a group of cytokines, including tumor necrosis factor-alpha, interleukin-1 alpha, and leukemia inhibitory factor, to recruit macrophages and facilitate digestion of debris. Schwann cells also secrete a group of neurotrophic factors, including nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor, to encourage neuron survival and axon elongation.<ref>Jessen KR, Mirsky R, Lloyd AC. Schwann Cells: Development and Role in Nerve Repair. Cold Spring Harb Perspect Biol. 2015 May 08;7(7):a020487. </ref><ref>Madduri S, Gander B. Schwann cell delivery of neurotrophic factors for peripheral nerve regeneration. J Peripher Nerv Syst. 2010 Jun;15(2):93-103.</ref><ref>Yi S, Zhang Y, Gu X, Huang L, Zhang K, Qian T, Gu X. Application of stem cells in peripheral nerve regeneration. Burns Trauma. 2020;8:tkaa002</ref> | After neurotmesis, Schwann cells respond adaptively to axonal disruption, transitioning from a highly myelinated state to a dedifferentiated state. De-differentiated Schwann cells engulf axons and myelin debris and form a regenerative pathway for axon outgrowth. Additionally, activated Schwann cells secrete a group of cytokines, including tumor necrosis factor-alpha, interleukin-1 alpha, and leukemia inhibitory factor, to recruit macrophages and facilitate digestion of debris. Schwann cells also secrete a group of neurotrophic factors, including nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor, to encourage neuron survival and axon elongation.<ref>Jessen KR, Mirsky R, Lloyd AC. [https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/25957303/ Schwann Cells: Development and Role in Nerve Repair.] Cold Spring Harb Perspect Biol. 2015 May 08;7(7):a020487. </ref><ref>Madduri S, Gander B. Schwann cell delivery of neurotrophic factors for peripheral nerve regeneration. J Peripher Nerv Syst. 2010 Jun;15(2):93-103.</ref><ref>Yi S, Zhang Y, Gu X, Huang L, Zhang K, Qian T, Gu X. [https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/32346538/ Application of stem cells in peripheral nerve regeneration]. Burns Trauma. 2020;8:tkaa002</ref> | ||
Needle electromyography (EMG) is the most sensitive electrodiagnostic study for motor axon loss, and low-amplitude motor responses appear with severe injuries. Decrease in motor response amplitude begins around days 2-3 and is complete by day 6. This reflects the fact that neuromuscular junction degeneration precedes axon degeneration and motor responses are dependent on neuromuscular junction transmission.<ref>Ferrante MA. The Assessment and Management of Peripheral Nerve Trauma. Curr Treat Options Neurol. 2018 Jun 01;20(7):25.</ref> | Needle electromyography (EMG) is the most sensitive electrodiagnostic study for motor axon loss, and low-amplitude motor responses appear with severe injuries. Decrease in motor response amplitude begins around days 2-3 and is complete by day 6. This reflects the fact that neuromuscular junction degeneration precedes axon degeneration and motor responses are dependent on neuromuscular junction transmission.<ref>Ferrante MA. The Assessment and Management of Peripheral Nerve Trauma. Curr Treat Options Neurol. 2018 Jun 01;20(7):25.</ref> |
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