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P25.4 Changes in nerve excitability properties associated with axonal regeneration: Part 2. Human axonal neuropathy
Posters / Clinical Neurophysiology 117 (2006) S121–S336
using the automatic threshold tracking program (QTRAC, Ó Prof. Hugh Bostock, Institute of Neurology, London). The measurements were made before, and 6 and 8 weeks after nerve crush. Compound muscle action potentials (CMAP) were recorded from the foot muscle after ankle stimulation. The results were compared with those of age-matched controls. Results: SDTC became longer in the recovery phase (weeks 6 and 8) than those of controls, presumably reflecting increased expression of persistent sodium channels associated with axonal regeneration. In threshold electrotonus studies, threshold changes in the hyperpolarizing direction were significantly greater than those of controls in weeks 6 and 8, probably due to increases in the axonal (internodal) resistance or decreases in the myelin resistance. Conclusion: During axonal regeneration, persistent sodium conductance and passive membrane properties change substantially. These findings could provide new insights into the ion channel expression and altered membrane properties associated with axonal growth. doi:10.1016/j.clinph.2006.06.452
P25.4 Changes in nerve excitability properties associated with axonal regeneration: Part 2. Human axonal neuropathy K. Kanai, S. Sawai, M. Nakata, A. Hiraga, N. Tamura, S. Misawa, T. Hattori, S. Kuwabara Chiba University Graduate School of Medicine, Department of Neurology, Japan Background: In the 1990s, the technique of computerized threshold tracking was developed to investigate multiple axonal excitability indices which reflect sodium and potassium channel function, and passive membrane properties. Objective: To study changes in membrane excitability properties associated with peripheral nerve regeneration in human. Patients and method: Multiple excitability indices (strength-duration time constant [SDTC], threshold electrotonus, refractoriness, supernormality, and late subnormality) were measured using the automatic threshold tracking program (QTRAC, ÓProf. Hugh Bostock, Institute of Neurology, London) in 25 patients with acute axonal neuropathy (axonal Guillain-Barre syndrome, or vasculitic neuropathy) in their recovery stage. Results were compared with those of 25 normal subjects. Compound muscle action potentials (CMAPs) were recorded from the abductor pollicis brevis after median nerve stimulation at the wrist. Result: During recovery, patients with axonal neuropathy showed prolonged SDTC and greater threshold changes in hyperpolarizing threshold electrotonus. These patterns of excitability changes, especially in vasculitic neuropathy group, were similar to findings of experimental
S233
wallerian degeneration (Part.1 study in the nerve crush model using C57BL6J mice). Conclusion: During the recovery phase of human axonal neuropathy, persistent sodium conductance could increase with a fanning out of threshold electrotonus, and these findings are consistent with the changes observed in the nerve crush model using mice. doi:10.1016/j.clinph.2006.06.453
P26.1 Importance of thalamic reticular nucleus in the generation of myoclonic movements in Creutzfeldt–Jakob disease patients: A simultaneous coregistration EEG/fMRI study F. Monti 1, M. Naccarato 1, A. Draisci 1, M. Ukmar 2, L. Weiss 3, G. Pizzolato 1 1
Universiy Hospital Cattinara, Department of Neurology, Italy 2 University Hospital Cattinara, Department of Radiology, Italy 3 University of Trieste, Brain Centre for Neuroscience, Italy One of the most characteristic features of the Creutzfeldt–Jakob disease is the presence of myoclonus, associated with a peculiar pseudo-periodic EEG. A study has demonstrated a partial malfunctioning of some thalamic nuclei, possibly causing a reduction in physiological inhibition on cortical structures like the limbic system. Here we describe a patient, 60-years-old, affected by CJD, presenting with myoclonus and pseudo-periodic EEG, who has been studied with combined EEG/fMRI, during passive rest, with eyes closed, with an event-related design, with acquisition of 200 images. The EEG data was acquired with an BE-MRI System (EB Neuro, Florence); EEG and fMRI have been analysed with SPM5 (The Mathworks Inc, USA). The EEG was subdivided in normal alpha rhythm periods(A), diphasic sharp wave discharges (B) and pre-pseudo-periodic myoclonic related periods(B). The corresponding fMRI images have then been identified and all the images underwent the normal pre-processing steps, inc. spatial normalisation and smoothing. The statistical analysis was performed with a t-test, studying differences in brain activity between B and A and C and A periods (p = 0.05 corrected for multiple comparisons). Before the beginning of the myoclonic jerks the patient showed a statistically significant higher BOLD signal in the anterior cingulate and bilaterally in the precunei. The thalamic reticular nucleus could have a primary importance in the generation of myoclonic movements in CJD patients; it show a physiological pacemaker activity, and its inhibitory connections are mainly oriented towards the limbic system. A reduction in thalamic inhibitory tone could lead to an overactivation of cingulated gyrus and other motor and non-motor regions, leading to the onset of myoclonus. The increase in BOLD
using the automatic threshold tracking program (QTRAC, Ó Prof. Hugh Bostock, Institute of Neurology, London). The measurements were made before, and 6 and 8 weeks after nerve crush. Compound muscle action potentials (CMAP) were recorded from the foot muscle after ankle stimulation. The results were compared with those of age-matched controls. Results: SDTC became longer in the recovery phase (weeks 6 and 8) than those of controls, presumably reflecting increased expression of persistent sodium channels associated with axonal regeneration. In threshold electrotonus studies, threshold changes in the hyperpolarizing direction were significantly greater than those of controls in weeks 6 and 8, probably due to increases in the axonal (internodal) resistance or decreases in the myelin resistance. Conclusion: During axonal regeneration, persistent sodium conductance and passive membrane properties change substantially. These findings could provide new insights into the ion channel expression and altered membrane properties associated with axonal growth. doi:10.1016/j.clinph.2006.06.452
P25.4 Changes in nerve excitability properties associated with axonal regeneration: Part 2. Human axonal neuropathy K. Kanai, S. Sawai, M. Nakata, A. Hiraga, N. Tamura, S. Misawa, T. Hattori, S. Kuwabara Chiba University Graduate School of Medicine, Department of Neurology, Japan Background: In the 1990s, the technique of computerized threshold tracking was developed to investigate multiple axonal excitability indices which reflect sodium and potassium channel function, and passive membrane properties. Objective: To study changes in membrane excitability properties associated with peripheral nerve regeneration in human. Patients and method: Multiple excitability indices (strength-duration time constant [SDTC], threshold electrotonus, refractoriness, supernormality, and late subnormality) were measured using the automatic threshold tracking program (QTRAC, ÓProf. Hugh Bostock, Institute of Neurology, London) in 25 patients with acute axonal neuropathy (axonal Guillain-Barre syndrome, or vasculitic neuropathy) in their recovery stage. Results were compared with those of 25 normal subjects. Compound muscle action potentials (CMAPs) were recorded from the abductor pollicis brevis after median nerve stimulation at the wrist. Result: During recovery, patients with axonal neuropathy showed prolonged SDTC and greater threshold changes in hyperpolarizing threshold electrotonus. These patterns of excitability changes, especially in vasculitic neuropathy group, were similar to findings of experimental
S233
wallerian degeneration (Part.1 study in the nerve crush model using C57BL6J mice). Conclusion: During the recovery phase of human axonal neuropathy, persistent sodium conductance could increase with a fanning out of threshold electrotonus, and these findings are consistent with the changes observed in the nerve crush model using mice. doi:10.1016/j.clinph.2006.06.453
P26.1 Importance of thalamic reticular nucleus in the generation of myoclonic movements in Creutzfeldt–Jakob disease patients: A simultaneous coregistration EEG/fMRI study F. Monti 1, M. Naccarato 1, A. Draisci 1, M. Ukmar 2, L. Weiss 3, G. Pizzolato 1 1
Universiy Hospital Cattinara, Department of Neurology, Italy 2 University Hospital Cattinara, Department of Radiology, Italy 3 University of Trieste, Brain Centre for Neuroscience, Italy One of the most characteristic features of the Creutzfeldt–Jakob disease is the presence of myoclonus, associated with a peculiar pseudo-periodic EEG. A study has demonstrated a partial malfunctioning of some thalamic nuclei, possibly causing a reduction in physiological inhibition on cortical structures like the limbic system. Here we describe a patient, 60-years-old, affected by CJD, presenting with myoclonus and pseudo-periodic EEG, who has been studied with combined EEG/fMRI, during passive rest, with eyes closed, with an event-related design, with acquisition of 200 images. The EEG data was acquired with an BE-MRI System (EB Neuro, Florence); EEG and fMRI have been analysed with SPM5 (The Mathworks Inc, USA). The EEG was subdivided in normal alpha rhythm periods(A), diphasic sharp wave discharges (B) and pre-pseudo-periodic myoclonic related periods(B). The corresponding fMRI images have then been identified and all the images underwent the normal pre-processing steps, inc. spatial normalisation and smoothing. The statistical analysis was performed with a t-test, studying differences in brain activity between B and A and C and A periods (p = 0.05 corrected for multiple comparisons). Before the beginning of the myoclonic jerks the patient showed a statistically significant higher BOLD signal in the anterior cingulate and bilaterally in the precunei. The thalamic reticular nucleus could have a primary importance in the generation of myoclonic movements in CJD patients; it show a physiological pacemaker activity, and its inhibitory connections are mainly oriented towards the limbic system. A reduction in thalamic inhibitory tone could lead to an overactivation of cingulated gyrus and other motor and non-motor regions, leading to the onset of myoclonus. The increase in BOLD