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PS-3-6 Fractionation of compound peripheral nerve action potentials using repetitive stimulation method
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Poster session 3. Nerve conduction studies (l)
stimulated via clip electrode with a pulse width of 200 microseconds at a frequency of 3 Hz with an intensity of approximately 1.5-2.0 times the sensory threshold. Recordings were made by averaging 200 sweeps (Nihon Koden, Neuropack-4). The distance from the stimulation electrode to the jaw joint along the inferior alveolar nerve on the skin was measured as the suppositional conduction distance. Results: The subjects included 7 males and 7 females, and the mean age was 38.9 years. The findings (averages + SD) were as follows; latency from stimulation to onset of the potential was 2.47 4- 0.15 ms; latency to peak of the potential was 3.18 4- 0.15 ms; nerve conduction velocity to onset of the potential was 64.6 4- 5.9 m/s; nerve conduction velocity at peak of the potential was 50.0 44.2 m/s; amplitude of the potential was 1,28 4- 0.47 microvolts. Conclusions: The findings of this study are regarded as representing the orthodromic sensory nerve function of the mandibular nerve and a branch of it, the inferior alveolar nerve. The conduction velocity in this study was consistent with Colin's data. This nasopharyngeal electrode technique may be applied to clinical studies on the orofacial sensory functions.
~ T h e
cold-induced increase in amplitude of compound sensory nerve action potentials is due to reduced phase cancellation
Wilhelm Schulte-Mattier, Stephan Zierz. Neurologische Klinik und Poliklinik, Martin-Luther-Universittit, Halle (Saale), Germany The amplitude of compound sensory nerve action potentials (compound SNAP) increases with decreasing nerve temperature. This effect is much more pronounced in antidromic sensory nerve conduction studies compared to orthodromic recordings. It has been suggested, that the increase is mainly caused by increased duration and amplitude of the generating nerve fiber action potentials. In order to study these influences quantitatively and to explain the difference between antidromic and orthodromic recordings, we created a mathematical model of compound SNAP generation. There was a good match between the SNAPs given by the model and SNAPs recorded in healthy persons at different temperatures. Analysis of the influence of input variables of the model, i.e. distribution of conduction velocities, action potential amplitude and duration of single nerve fibers, showed that the cold-induced increase in duration of the nerve fiber action potentials at the recording site of the SNAP, results in reduced phase cancellation which is responsible for the increased SNAP amplitude. The difference between antidromic and orthodromic recordings is explained by the different nerve temperature at the different recording site. The cold-induced change of nerve fiber action potential amplitude does not substantially influence the SNAP amplitude.
~-~
Fractionation of compound peripheral nerve action potentials using repetitive stimulation method
Ryutaro Kohira, Thoru Yamada, Atsushi Araki, Shih-Pin Hsu, Malcolm Yeh, Hiroyuki Kawamura. Department of Neurology,
Division of Clinical Electrophysiology, University of Iowa, College of Medicine Iowa City, IA (USA) We examined the effect of repetitive stimulation upon sensory nerve action potential (SNAP). Submaximal repetitive stimuli were applied to finger nerve branches of indices and small fingers at proximal phalanges. A total of 2100 stimuli were continuously delivered at four different rates: 1.9, 4.9, 13.1 and 23.1 Hz. Subjects were given three minutes of rest period between each rate
session. SNAPs were recorded at the wrist. O n e SNAP consisted of three hundred averaged responses, thus obtaining seven SNAPs from each session. The amplitude ratios of each block response to the initial block response of 1.9 Hz session were measured. The mean amplitude ratio progressively decreased from 1.9 to 23.1 Hz and was statistically different (ANOVA, P < 0.01) at 13.1 and 23.1 Hz compared to 1.9 Hz. We then subtracted each block response from the initial block of 1.9 Hz session. Despite that there was no statistically significant differences in latencies of the original response from 1.9 to 23.1 Hz, the subtracted wave forms showed progressively shorter latency from 1.9 to 23.1 Hz, indicating that the ',drop out" components with increasing stimulus rates included faster conducting fibers. The conduction velocities of this "drop out" components were statistically significant at 13.1 to 23.1 Hz (P < 0.01) and the difference from 1.9 to 23.1 Hz was estimated about 5 m/see. The above described subtraction method may thus reveal fractionated components of different conduction velocities from compound action potential.
•
Pediatric values in the latency of the phrenic nerve
Julio Castafio, Maria del Carmen Martinez de Posadas.
Neuropediatric Section. Italian Hospital, Buenos Aires. Address: 688 Acoyte Avenue 10° "B'" Zipcode 1405, Buenos Aires The objective of the present work is to evaluate the record of the Potential evocated from the phrenic nerve through the electrode of surface over Muscular Diaphragm and to know the latencies as regards age, weight and height of studied patients. Material and Methods: The population included here comprises children from 3 months old to 18 years old. A n u m b e r of patients, who have been introduced in a previous work, with muscular dystrophy, whose values of latency are not seriously affected, have been included, when excluding peripheral neuropathy. The method used here is the one described by Davis, Bolton. The record is done in an 8 space right Inter-Costal, over the line of the front Axillary. The stimulus is done over the back border of the sternocleidomastoid muscle. A national equipment Akonic 4001, with 2 channels and memory is used. The contraction of the homolateral M. Diaphragm is taken as a visible parameter for the certification of the stimulation of the Phrenic Nerve. The Nerve Potencials obtained after the stimulation of the brachial plexus were not taken into account. The determinations were related to weight and height. Results: A values table is obtained considering age, related to height, working with a group of children ranging from 3 months old to 6 years old and a second group over 6 years old. The certification of the record in M. Diaphragm would be evident when this is done together with muscular Ecography and/or radioscopic control of the Diaphragm. It should be pointed out the necessity to create oneself's table for the electrophysiological values related with height and weight to establish serious diagnostics when evaluating neummuscular pathology.
•
Improvement of CMAP amplitude replicability in controls and patients with diabetic neuropethy
J. Gert van Dijk 1, Aim6e Tjon-A-Tsien 1,2, H e r m a n Lemkes 2.
t Dept. of Neurology and Clinical Neurophysiology, 2 Dept. of Endocrinology, Leiden University Hospital, The Netherlands CMAP amplitude depends strongly on recording site, and siteinduced CMAP variability can be reduced with large electrodes.
Poster session 3. Nerve conduction studies (l)
stimulated via clip electrode with a pulse width of 200 microseconds at a frequency of 3 Hz with an intensity of approximately 1.5-2.0 times the sensory threshold. Recordings were made by averaging 200 sweeps (Nihon Koden, Neuropack-4). The distance from the stimulation electrode to the jaw joint along the inferior alveolar nerve on the skin was measured as the suppositional conduction distance. Results: The subjects included 7 males and 7 females, and the mean age was 38.9 years. The findings (averages + SD) were as follows; latency from stimulation to onset of the potential was 2.47 4- 0.15 ms; latency to peak of the potential was 3.18 4- 0.15 ms; nerve conduction velocity to onset of the potential was 64.6 4- 5.9 m/s; nerve conduction velocity at peak of the potential was 50.0 44.2 m/s; amplitude of the potential was 1,28 4- 0.47 microvolts. Conclusions: The findings of this study are regarded as representing the orthodromic sensory nerve function of the mandibular nerve and a branch of it, the inferior alveolar nerve. The conduction velocity in this study was consistent with Colin's data. This nasopharyngeal electrode technique may be applied to clinical studies on the orofacial sensory functions.
~ T h e
cold-induced increase in amplitude of compound sensory nerve action potentials is due to reduced phase cancellation
Wilhelm Schulte-Mattier, Stephan Zierz. Neurologische Klinik und Poliklinik, Martin-Luther-Universittit, Halle (Saale), Germany The amplitude of compound sensory nerve action potentials (compound SNAP) increases with decreasing nerve temperature. This effect is much more pronounced in antidromic sensory nerve conduction studies compared to orthodromic recordings. It has been suggested, that the increase is mainly caused by increased duration and amplitude of the generating nerve fiber action potentials. In order to study these influences quantitatively and to explain the difference between antidromic and orthodromic recordings, we created a mathematical model of compound SNAP generation. There was a good match between the SNAPs given by the model and SNAPs recorded in healthy persons at different temperatures. Analysis of the influence of input variables of the model, i.e. distribution of conduction velocities, action potential amplitude and duration of single nerve fibers, showed that the cold-induced increase in duration of the nerve fiber action potentials at the recording site of the SNAP, results in reduced phase cancellation which is responsible for the increased SNAP amplitude. The difference between antidromic and orthodromic recordings is explained by the different nerve temperature at the different recording site. The cold-induced change of nerve fiber action potential amplitude does not substantially influence the SNAP amplitude.
~-~
Fractionation of compound peripheral nerve action potentials using repetitive stimulation method
Ryutaro Kohira, Thoru Yamada, Atsushi Araki, Shih-Pin Hsu, Malcolm Yeh, Hiroyuki Kawamura. Department of Neurology,
Division of Clinical Electrophysiology, University of Iowa, College of Medicine Iowa City, IA (USA) We examined the effect of repetitive stimulation upon sensory nerve action potential (SNAP). Submaximal repetitive stimuli were applied to finger nerve branches of indices and small fingers at proximal phalanges. A total of 2100 stimuli were continuously delivered at four different rates: 1.9, 4.9, 13.1 and 23.1 Hz. Subjects were given three minutes of rest period between each rate
session. SNAPs were recorded at the wrist. O n e SNAP consisted of three hundred averaged responses, thus obtaining seven SNAPs from each session. The amplitude ratios of each block response to the initial block response of 1.9 Hz session were measured. The mean amplitude ratio progressively decreased from 1.9 to 23.1 Hz and was statistically different (ANOVA, P < 0.01) at 13.1 and 23.1 Hz compared to 1.9 Hz. We then subtracted each block response from the initial block of 1.9 Hz session. Despite that there was no statistically significant differences in latencies of the original response from 1.9 to 23.1 Hz, the subtracted wave forms showed progressively shorter latency from 1.9 to 23.1 Hz, indicating that the ',drop out" components with increasing stimulus rates included faster conducting fibers. The conduction velocities of this "drop out" components were statistically significant at 13.1 to 23.1 Hz (P < 0.01) and the difference from 1.9 to 23.1 Hz was estimated about 5 m/see. The above described subtraction method may thus reveal fractionated components of different conduction velocities from compound action potential.
•
Pediatric values in the latency of the phrenic nerve
Julio Castafio, Maria del Carmen Martinez de Posadas.
Neuropediatric Section. Italian Hospital, Buenos Aires. Address: 688 Acoyte Avenue 10° "B'" Zipcode 1405, Buenos Aires The objective of the present work is to evaluate the record of the Potential evocated from the phrenic nerve through the electrode of surface over Muscular Diaphragm and to know the latencies as regards age, weight and height of studied patients. Material and Methods: The population included here comprises children from 3 months old to 18 years old. A n u m b e r of patients, who have been introduced in a previous work, with muscular dystrophy, whose values of latency are not seriously affected, have been included, when excluding peripheral neuropathy. The method used here is the one described by Davis, Bolton. The record is done in an 8 space right Inter-Costal, over the line of the front Axillary. The stimulus is done over the back border of the sternocleidomastoid muscle. A national equipment Akonic 4001, with 2 channels and memory is used. The contraction of the homolateral M. Diaphragm is taken as a visible parameter for the certification of the stimulation of the Phrenic Nerve. The Nerve Potencials obtained after the stimulation of the brachial plexus were not taken into account. The determinations were related to weight and height. Results: A values table is obtained considering age, related to height, working with a group of children ranging from 3 months old to 6 years old and a second group over 6 years old. The certification of the record in M. Diaphragm would be evident when this is done together with muscular Ecography and/or radioscopic control of the Diaphragm. It should be pointed out the necessity to create oneself's table for the electrophysiological values related with height and weight to establish serious diagnostics when evaluating neummuscular pathology.
•
Improvement of CMAP amplitude replicability in controls and patients with diabetic neuropethy
J. Gert van Dijk 1, Aim6e Tjon-A-Tsien 1,2, H e r m a n Lemkes 2.
t Dept. of Neurology and Clinical Neurophysiology, 2 Dept. of Endocrinology, Leiden University Hospital, The Netherlands CMAP amplitude depends strongly on recording site, and siteinduced CMAP variability can be reduced with large electrodes.