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P158 Quantitative EMG analysis of muscle fatigue in pyramidal lesions
90s
C o m m u n i c a t i o n s affich6es/Posters
P156
P157
ETUDE SPATIO-TEMPORELLE DE LA DESYNCHRONISATION LIEE A L'EVENEMENT LORS D'UN MOUVEMENT AUTOCOMMANDE. P. Demmbure, J.L. Bourriez, J.J. Hauser, J.M. Jacquesson, J.D. Guieu Physiologie Facult6 de M6decine - EFNC Hbpital B - Lille
A COMPARISON BETWEEN THREE DIFFERENT METHODS FOR THE MEASUREMENT OF THERMAL THRESHOLDS
C. Swerua. B. Y. Nilsson, S6dersjukhuset,
DepL. of Clinical Neurophysiology
Stockholm (Sweden)
Measurement of bhermal thresholds is established as a method
Une 6rude spatio-temporelle de la d6synchronisation des composantes rythmiques de l'alpha associ6e h u n mouvement autocommand6 du pouce, est r6alis6e chez cinq sujets droitiers homogbnes. L'EEG est enregistr6, en r6f6rence commune, 4 secondes avant et 2 secondes apr~s le d6but du mouvement, /t partir d'un r6seau de 23 6tectrodes 6quidistantes couvrant les r6gions frontales, centmles et pad6tales du scalp ; de ces donn6es 11 d~dvations de source sont calcul~es.
for the study of small nerve fibre function.
In the present
study the warm and cold thresholds were studied in three different
ways, in aecordance-wibh commonly used methods.
A thermostimulator (Thermobest,
operating on the Peltier principle
Somedie AB) was attached to the bhenar region
of the hand. The temperature was either alternating between the warm and cold thresholds (the Marstoek mebhod)
or the
Pour chaque d6rivation, l'6volution temporelle de la puissance du signal dans la bande de fr6quence alpha, par pas de 0,25 s, associ6e b, un test statistique non pamm~trique, perrnet d'authentifier l'existence d'une d6synchronisation
stimuli were applied in the form of heat or coid pulses
L'analyse des r6sultats met en ~vidence, au niveau des r~gions centrales, deux foyers de d~synchronisation : run eontrolateml d6butant plus d'une seconde avant le mouvement et se terminant apr6s, l'autre ipsilat~ml plus bref contempomin au mouvement. Par contre, dans ces conditions exp6rimentales, aucune d6synchronisation significative n'est observ6e au niveau de la ligne m6diane.
perceived warmth or cold.
starting from an adapted temperature in the neutral region (32°C). In these two methods the temperature change was interrupted by bhe patient pressing a switch when he In the third method predetermined
warm or cold pulses of differing heighbs were delivered and the patient had to signal yes or no after each pulse. For the first two methods the temperature thresholds and the rate of sbimulabion (0.5-4°Cs -I) show almost a linear relationship but with different slopes. For the bhird method both warm and cold thresholds were Independent of the rabe of temperature change. The dependence on rate of temperature change can be
P158
interpreted
in terms of the conduction times in A-delta and
C fibres which is eliminated in the third mebhod. QUANTITATIVE EMG ANALYSIS OF MUSCLE FATIGUE IN PYRAMIDAL LESIONS Siciliano G., R o s s i B., Angelotti M., Risaliti R., M u r a t o r i o A. Institute of Neurological Clinic, University of Pisa In p y r a m i d a l system injuries, functional prognosis depends ~n the possibility of central nervous system to a d a p t n e w recruitment strategies to t h e occurrence of damage. To assess motoneurone recruitment pattern in non-acute ischemic pyramidal system lesions, we performed automatic quantitative analysis of emg i~ I0 hemiparetic patients, comparing the affected with health side. Following EMG parameters were evaluated: i) power spectrum median frequency (Fm); 2) root mean square, corrected according to Kranz et al. (RMSo), of time-integrated signal, assumed as an index of motor neurone output. EMG recordings were performed during 1 min i s o m e t r i c contraction of b i d e p s b r a c h i i a t 50% o f maximum v o l u n t a r y f o r c e , maintained by visual feedback. EMG signal were recorded by surface electrodes, put distally to the motor point, filtered 2-512 Hz, d i g i t a l i z e d by A / D c o n v e r t e r , sampled with 1024 Hz f r e q u e n c y and stored on a hard d i s k of PC IBM-AT for outline elaboration. During exercise a decrement of Fm v a l u e s , significantly correlated with contraction time (p
P159 NON-INVASIVE TOPOGRAPHIC MAPPING OF HUMAN HAND SENSORIMOTOR CORTEX IN THE MEG C. Baum~artner (1L A. Doppelbauer (1), J. Zeitlhofer (1), W.W. Sutherling (2), D.S. Barth (2), G. Lindinger (1), L Deecke (1); Neurological University Clinic, Vienna (Austria) (1), University of California, Los Angeles (U.S.A.) (2). The aim of our study was to investigate functional topography of human hand sensorimotor cortex non-invasively in the MEG. We recorded somatosensory evoked magnetic fields (SEF) during stimulation of median nerve, ulnar nerve, and individual digits using a 7-channel magnetometer in 5 normal volunteers. The magnetometer was placed at 9 different overlapping positions yielding 45 distinct measurement points. A probe positioning system was used to determine the exact position of the magnetom~er in relation to the subject's head. Two runs of at least 500 trials were performed to assess reproducibility. We applied dipole modeling to study functional anatomy of the sources underlying the SEFs. We found that the sources of SEFs during median nerve stimulation were more lateral than those during ulnar nerve stimulation; the digits showed a topographical organization with the sources of SERs during thumb stimulation most lateral and those during stimulation of the little finger most mesial. We conclude that MEG in conjunction with source localizalion techniques can be used to study functional topography of human hand sensorimotor cortex noninvasively. Our results may also have implications for non-invasive mapping of essential cortex in patients undergoing surgery adjacent to sensorimotor cortex. This research was supported by the Fonds zur F6rderung der wissenschaftlichen Forschnng of Austria (research project P7434), by NIH grants IR01-NS20806, I-R01-NS00678, and the Whitaker Foundation.
C o m m u n i c a t i o n s affich6es/Posters
P156
P157
ETUDE SPATIO-TEMPORELLE DE LA DESYNCHRONISATION LIEE A L'EVENEMENT LORS D'UN MOUVEMENT AUTOCOMMANDE. P. Demmbure, J.L. Bourriez, J.J. Hauser, J.M. Jacquesson, J.D. Guieu Physiologie Facult6 de M6decine - EFNC Hbpital B - Lille
A COMPARISON BETWEEN THREE DIFFERENT METHODS FOR THE MEASUREMENT OF THERMAL THRESHOLDS
C. Swerua. B. Y. Nilsson, S6dersjukhuset,
DepL. of Clinical Neurophysiology
Stockholm (Sweden)
Measurement of bhermal thresholds is established as a method
Une 6rude spatio-temporelle de la d6synchronisation des composantes rythmiques de l'alpha associ6e h u n mouvement autocommand6 du pouce, est r6alis6e chez cinq sujets droitiers homogbnes. L'EEG est enregistr6, en r6f6rence commune, 4 secondes avant et 2 secondes apr~s le d6but du mouvement, /t partir d'un r6seau de 23 6tectrodes 6quidistantes couvrant les r6gions frontales, centmles et pad6tales du scalp ; de ces donn6es 11 d~dvations de source sont calcul~es.
for the study of small nerve fibre function.
In the present
study the warm and cold thresholds were studied in three different
ways, in aecordance-wibh commonly used methods.
A thermostimulator (Thermobest,
operating on the Peltier principle
Somedie AB) was attached to the bhenar region
of the hand. The temperature was either alternating between the warm and cold thresholds (the Marstoek mebhod)
or the
Pour chaque d6rivation, l'6volution temporelle de la puissance du signal dans la bande de fr6quence alpha, par pas de 0,25 s, associ6e b, un test statistique non pamm~trique, perrnet d'authentifier l'existence d'une d6synchronisation
stimuli were applied in the form of heat or coid pulses
L'analyse des r6sultats met en ~vidence, au niveau des r~gions centrales, deux foyers de d~synchronisation : run eontrolateml d6butant plus d'une seconde avant le mouvement et se terminant apr6s, l'autre ipsilat~ml plus bref contempomin au mouvement. Par contre, dans ces conditions exp6rimentales, aucune d6synchronisation significative n'est observ6e au niveau de la ligne m6diane.
perceived warmth or cold.
starting from an adapted temperature in the neutral region (32°C). In these two methods the temperature change was interrupted by bhe patient pressing a switch when he In the third method predetermined
warm or cold pulses of differing heighbs were delivered and the patient had to signal yes or no after each pulse. For the first two methods the temperature thresholds and the rate of sbimulabion (0.5-4°Cs -I) show almost a linear relationship but with different slopes. For the bhird method both warm and cold thresholds were Independent of the rabe of temperature change. The dependence on rate of temperature change can be
P158
interpreted
in terms of the conduction times in A-delta and
C fibres which is eliminated in the third mebhod. QUANTITATIVE EMG ANALYSIS OF MUSCLE FATIGUE IN PYRAMIDAL LESIONS Siciliano G., R o s s i B., Angelotti M., Risaliti R., M u r a t o r i o A. Institute of Neurological Clinic, University of Pisa In p y r a m i d a l system injuries, functional prognosis depends ~n the possibility of central nervous system to a d a p t n e w recruitment strategies to t h e occurrence of damage. To assess motoneurone recruitment pattern in non-acute ischemic pyramidal system lesions, we performed automatic quantitative analysis of emg i~ I0 hemiparetic patients, comparing the affected with health side. Following EMG parameters were evaluated: i) power spectrum median frequency (Fm); 2) root mean square, corrected according to Kranz et al. (RMSo), of time-integrated signal, assumed as an index of motor neurone output. EMG recordings were performed during 1 min i s o m e t r i c contraction of b i d e p s b r a c h i i a t 50% o f maximum v o l u n t a r y f o r c e , maintained by visual feedback. EMG signal were recorded by surface electrodes, put distally to the motor point, filtered 2-512 Hz, d i g i t a l i z e d by A / D c o n v e r t e r , sampled with 1024 Hz f r e q u e n c y and stored on a hard d i s k of PC IBM-AT for outline elaboration. During exercise a decrement of Fm v a l u e s , significantly correlated with contraction time (p
P159 NON-INVASIVE TOPOGRAPHIC MAPPING OF HUMAN HAND SENSORIMOTOR CORTEX IN THE MEG C. Baum~artner (1L A. Doppelbauer (1), J. Zeitlhofer (1), W.W. Sutherling (2), D.S. Barth (2), G. Lindinger (1), L Deecke (1); Neurological University Clinic, Vienna (Austria) (1), University of California, Los Angeles (U.S.A.) (2). The aim of our study was to investigate functional topography of human hand sensorimotor cortex non-invasively in the MEG. We recorded somatosensory evoked magnetic fields (SEF) during stimulation of median nerve, ulnar nerve, and individual digits using a 7-channel magnetometer in 5 normal volunteers. The magnetometer was placed at 9 different overlapping positions yielding 45 distinct measurement points. A probe positioning system was used to determine the exact position of the magnetom~er in relation to the subject's head. Two runs of at least 500 trials were performed to assess reproducibility. We applied dipole modeling to study functional anatomy of the sources underlying the SEFs. We found that the sources of SEFs during median nerve stimulation were more lateral than those during ulnar nerve stimulation; the digits showed a topographical organization with the sources of SERs during thumb stimulation most lateral and those during stimulation of the little finger most mesial. We conclude that MEG in conjunction with source localizalion techniques can be used to study functional topography of human hand sensorimotor cortex noninvasively. Our results may also have implications for non-invasive mapping of essential cortex in patients undergoing surgery adjacent to sensorimotor cortex. This research was supported by the Fonds zur F6rderung der wissenschaftlichen Forschnng of Austria (research project P7434), by NIH grants IR01-NS20806, I-R01-NS00678, and the Whitaker Foundation.