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PS-7-11 Lower limb somatosensory evoked potentials in amyotrophic lateral sclerosis
Postersession 8. Visual evoked potentials
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gion), 2. diminished or absent response (mostly in tumours in the central region), 3. enhanced response (mostly in tumours near the central region). The e n h a n c e m e n t was claimed either when the amplitude of N20/P25 exceeded 1 2 / z V (upper limit of the normative value of our laboratory), or when the amplitude of N20/P25 at the site of the tumour was higher by more than 50% in relation to the healthy side. The first case was labelled as an "absolute enhancement", the second one as an "relative enhancement". The absolute enhancement was ascertained in 12 patients and the relative in 12 others, altogether 24, i.e. in 11% of all patients suffering from hemispheral tumours. The localization of the tumour according to the central sulcus was in 13 cases posterior, in 5 anterior and in 6 the tumour occupied the central region itself. In all cases the CT scanning and MRI imaging revealed edema in the central region. The edema is discussed in relation to the enhanced SEPs. Absolute e n h a n c e m e n t of SEPs strongly correlated with occurrence of partial or generalized convulsive (sensorimotor) seizures. The e n h a n c e m e n t of SEPs was in 50% accompanied by abnormality of their waveform and this correlated with occurrence of sensorimotor defects (astereognosia, hemiparesis).
I PS-7-10 1 Intercostal somatosensory evoked potentials in patients with spinal cord lesions Sei-Joo Kim, Myeong-Heun Lee. Department of Rehabilitation Medicine, Korea University, Seoul, Korea Although sensory examinations have been used for thoracic spinal cord lesions, it is difficult to define the level of thoracic lesion, clinically and electrophysiologically. Intercostal somatosensory evoked potentials (SEPs) are easy to elicit and can evaluate the focal lesion from the intercostal nerve to the cortex. The purpose of this study was to determine the clinical usefulness of intercostal SEPs in thoracic cord lesions. We examined 19 healthy controls and 10 patients with spinal cord lesions. The causes of the lesions were spine fractures (6), tumors (2), syringomyelia (1), and arachnoid cyst (1). In controls, the mean P1 latencies were 22.98 4- 1.56 msec for the third intercostal SEPs (T3), 24.57 + 1.73 msec for the fifth intercostal SEPs (T5), 27.72 4- 2.07 msec for the seventh intercostal SEPs (T7), and 28.07 -I- 3.34 msec for the ninth intercostal SEPs (T9). The P1 latencies increased gradually from T3 to T9 segment. The P1-N1 amplitudes in controls for T3, T5, T7, and T9 were 1.65 4- 0.78 uV, 1.30 4- 0.57 uV, 1.37 4- 0.60 uV, and 1.39 4- 0.59 uV, respectively. All patients with complete spinal cord lesions showed no response below the level of lesions. For the patients with incomplete cord lesions, the intercostal SEPs showed delayed latency, decreased amplitude or inconsistency of potentials. The inconsistency of waveforms and no response at certain level were the most important findings because latencies and amplitudes were much variable. In conclusion, the intercostal SEPs study is a complementary examination to evaluate the thoracic cord lesions in addition to clinical and needle electromyographic examinations.
I PS-7-11
I Lower limb somatosensory evoked potentials in amyotrophic lateral sclerosis
M. Georgesco
1,2,
m. Salerno 1. 1Laboratoire
d'Electromyographie, Service de NeurologieB, Hopital Gui de Chauliac, France; 2 INSERM U300, MontpeUier, France We studied somatosens0ry evoked potentials (SEPs) following lower limb stimulation: tibialis posterior, sural nerve, saphenous
internous nerve and medial plantar nerve on both sides in 14 amyotrophic lateral sclerosis (ALS) patients and compared them with those obtained in normal subjects. All recordings were performed in the 10-20 International system range. In normal subjects and for all nerves tested, the first cortical peak was positive and called PI. We noted: 1) each nerve had its own i n d e p e n d e n t cortical dipole; 2) the scalp orientation of the dipole of the same nerve may be asymmetrical when both sides were compared; 3) the cortical generators of the tibialis posterior and sural nerve could be composed of multiple generators. In ALS patients, despite peripheral normal sensory nerve conduction, the P1 were absent for at least one nerve: P1 of the medial plantar nerve and saphenous internous nerve was the most frequently affected. We hypothesize that the lesions were located in the somatosensory cortical areas. We concluded that ALS disturbances were not restricted to upper and lower motoneurons but the sensory system is constantly affected.
PS-8. VISUAL EVOKED POTENTIALS
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Waveform characteristics of color VEP with isoluminant condition
Sachio Kawashima, Malcolm Yeh, Michael Wall, T h o r u Yamada.
Department of Neurology, Division of Clinical Electrophysiology, University of Iowa, College of Medicine, Iowa City, IA, USA We measured isoluminant color pattern reversal visual evoked potential (VEP) in 8 normal volunteers. We identified waveform alternation of N75 and P100 component during isoluminant color stimulation. The stimulus was delivered by the computerized high resolution monitor screen. Isoluminant intensity level of each color combination was obtained by psychological and electrophysiological measures under 19 Hz stimulation. We studied the VEP components along with changes of the m e a n luminance, check size, reversal rate, color intensity and color combinations. Unlike single peaked P100 by conventional black and white checks, P100 to isoluminant color checks was consistently W wave formed and consisted of P100A, N100 and P100B components at the occipital region. It appeared that N100 corresponded with conventional P100. Mean latencies of P100A, N100 and P100B were 77.75 (SD = 7.39), 95.30 (5.98) and 110.75 (5.89) msec, respectively. Regardless the luminance and combination of isoluminant colors, the mean latencies and amplitude of major components were unchanged. The W formed response changed progressively to V wave form with the decrease of N100 amplitude and eventual disappearance of N100 as the isoluminant color combination became progressively non-isoluminant. Temporal and spacial tuning curves of P100A, N100 and P100B were different from P100 of conventional black and white pattern reversal VEE These methods and results would be useful for the evaluation of the parvoc.ellular system and color blindness.
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Visual evoked potential of front-central derivations
E. Minakuchi, S. Sanada, E. Oka, S. Ohtahara. Department of Child Neurology, Okayama University Medical School To elucidate the developmental changes in the visual evoked potentials of front-central derivations, 137 normal subjects between 0 months and 37 years of age were examined. Evoked potentials were derivated from F3, F4, C3, C4 of 10-20 electrode system. 50 responses to the 1 Hz flash stimuli were averaged.
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gion), 2. diminished or absent response (mostly in tumours in the central region), 3. enhanced response (mostly in tumours near the central region). The e n h a n c e m e n t was claimed either when the amplitude of N20/P25 exceeded 1 2 / z V (upper limit of the normative value of our laboratory), or when the amplitude of N20/P25 at the site of the tumour was higher by more than 50% in relation to the healthy side. The first case was labelled as an "absolute enhancement", the second one as an "relative enhancement". The absolute enhancement was ascertained in 12 patients and the relative in 12 others, altogether 24, i.e. in 11% of all patients suffering from hemispheral tumours. The localization of the tumour according to the central sulcus was in 13 cases posterior, in 5 anterior and in 6 the tumour occupied the central region itself. In all cases the CT scanning and MRI imaging revealed edema in the central region. The edema is discussed in relation to the enhanced SEPs. Absolute e n h a n c e m e n t of SEPs strongly correlated with occurrence of partial or generalized convulsive (sensorimotor) seizures. The e n h a n c e m e n t of SEPs was in 50% accompanied by abnormality of their waveform and this correlated with occurrence of sensorimotor defects (astereognosia, hemiparesis).
I PS-7-10 1 Intercostal somatosensory evoked potentials in patients with spinal cord lesions Sei-Joo Kim, Myeong-Heun Lee. Department of Rehabilitation Medicine, Korea University, Seoul, Korea Although sensory examinations have been used for thoracic spinal cord lesions, it is difficult to define the level of thoracic lesion, clinically and electrophysiologically. Intercostal somatosensory evoked potentials (SEPs) are easy to elicit and can evaluate the focal lesion from the intercostal nerve to the cortex. The purpose of this study was to determine the clinical usefulness of intercostal SEPs in thoracic cord lesions. We examined 19 healthy controls and 10 patients with spinal cord lesions. The causes of the lesions were spine fractures (6), tumors (2), syringomyelia (1), and arachnoid cyst (1). In controls, the mean P1 latencies were 22.98 4- 1.56 msec for the third intercostal SEPs (T3), 24.57 + 1.73 msec for the fifth intercostal SEPs (T5), 27.72 4- 2.07 msec for the seventh intercostal SEPs (T7), and 28.07 -I- 3.34 msec for the ninth intercostal SEPs (T9). The P1 latencies increased gradually from T3 to T9 segment. The P1-N1 amplitudes in controls for T3, T5, T7, and T9 were 1.65 4- 0.78 uV, 1.30 4- 0.57 uV, 1.37 4- 0.60 uV, and 1.39 4- 0.59 uV, respectively. All patients with complete spinal cord lesions showed no response below the level of lesions. For the patients with incomplete cord lesions, the intercostal SEPs showed delayed latency, decreased amplitude or inconsistency of potentials. The inconsistency of waveforms and no response at certain level were the most important findings because latencies and amplitudes were much variable. In conclusion, the intercostal SEPs study is a complementary examination to evaluate the thoracic cord lesions in addition to clinical and needle electromyographic examinations.
I PS-7-11
I Lower limb somatosensory evoked potentials in amyotrophic lateral sclerosis
M. Georgesco
1,2,
m. Salerno 1. 1Laboratoire
d'Electromyographie, Service de NeurologieB, Hopital Gui de Chauliac, France; 2 INSERM U300, MontpeUier, France We studied somatosens0ry evoked potentials (SEPs) following lower limb stimulation: tibialis posterior, sural nerve, saphenous
internous nerve and medial plantar nerve on both sides in 14 amyotrophic lateral sclerosis (ALS) patients and compared them with those obtained in normal subjects. All recordings were performed in the 10-20 International system range. In normal subjects and for all nerves tested, the first cortical peak was positive and called PI. We noted: 1) each nerve had its own i n d e p e n d e n t cortical dipole; 2) the scalp orientation of the dipole of the same nerve may be asymmetrical when both sides were compared; 3) the cortical generators of the tibialis posterior and sural nerve could be composed of multiple generators. In ALS patients, despite peripheral normal sensory nerve conduction, the P1 were absent for at least one nerve: P1 of the medial plantar nerve and saphenous internous nerve was the most frequently affected. We hypothesize that the lesions were located in the somatosensory cortical areas. We concluded that ALS disturbances were not restricted to upper and lower motoneurons but the sensory system is constantly affected.
PS-8. VISUAL EVOKED POTENTIALS
~
Waveform characteristics of color VEP with isoluminant condition
Sachio Kawashima, Malcolm Yeh, Michael Wall, T h o r u Yamada.
Department of Neurology, Division of Clinical Electrophysiology, University of Iowa, College of Medicine, Iowa City, IA, USA We measured isoluminant color pattern reversal visual evoked potential (VEP) in 8 normal volunteers. We identified waveform alternation of N75 and P100 component during isoluminant color stimulation. The stimulus was delivered by the computerized high resolution monitor screen. Isoluminant intensity level of each color combination was obtained by psychological and electrophysiological measures under 19 Hz stimulation. We studied the VEP components along with changes of the m e a n luminance, check size, reversal rate, color intensity and color combinations. Unlike single peaked P100 by conventional black and white checks, P100 to isoluminant color checks was consistently W wave formed and consisted of P100A, N100 and P100B components at the occipital region. It appeared that N100 corresponded with conventional P100. Mean latencies of P100A, N100 and P100B were 77.75 (SD = 7.39), 95.30 (5.98) and 110.75 (5.89) msec, respectively. Regardless the luminance and combination of isoluminant colors, the mean latencies and amplitude of major components were unchanged. The W formed response changed progressively to V wave form with the decrease of N100 amplitude and eventual disappearance of N100 as the isoluminant color combination became progressively non-isoluminant. Temporal and spacial tuning curves of P100A, N100 and P100B were different from P100 of conventional black and white pattern reversal VEE These methods and results would be useful for the evaluation of the parvoc.ellular system and color blindness.
•
Visual evoked potential of front-central derivations
E. Minakuchi, S. Sanada, E. Oka, S. Ohtahara. Department of Child Neurology, Okayama University Medical School To elucidate the developmental changes in the visual evoked potentials of front-central derivations, 137 normal subjects between 0 months and 37 years of age were examined. Evoked potentials were derivated from F3, F4, C3, C4 of 10-20 electrode system. 50 responses to the 1 Hz flash stimuli were averaged.