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P150: A complex evoked cortical response is induced by the relief of air flow interruption
S86
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
for non-invasive imaging of the magnitude and spatiotemporal spread of nerve-evoked currents in the spinal cord and spinal nerves. In this study, we aimed to visualize evoked currents from the cervical spine in response to median nerve stimulation. Methods: Using a newly developed 120 channel SQUID fluxmeter, the neuromagnetic fields of 5 healthy volunteers were measured at the surface of the cervical spine in response to surface stimulation of the median nerve at the elbow. We also measured neuromagnetic fields after stimulation a few centimeters lateral to the median nerve and adopted a newly developed algorithm to reduce artifacts arising from surface electrical stimulation. Current sources were estimated using spatial filter techniques and the current field superimposed on X-ray images of the cervical spine. Results: Neuromagnetic fields were successfully imaged in all subjects. Neural currents entered the lateral cervical spine and ascended in the spinal canal from caudal to cranial, followed by currents propagating in the opposite direction. Discussion: We visualized neural activity patterns in the intervertebral foramen and spinal canal evoked by median nerve stimulation. Magnetospinography is expected to contribute to the clinical diagnosis and treatment of spinal cord and spinal nerve disorders.
P147 SSEP revisited: The significance of absolute N20 amplitudes for prognosis following cardiac arrest 1
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C. Endisch , C.J. Ploner , C. Storm , C. Leithner Charite, Neurology, Berlin, Germany; 2 Charite, Nephrology and Intensive Care Medicine, Berlin, Germany
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Question: Absence of cortical SSEP (N20) after stimulation of the median nerves predicts poor outcome after cardiac arrest with high specificity. This may also apply to patients with minimally detectable N20, but cut-off levels for N20 amplitudes below which good outcome becomes very unlikely have not been determined. Methods: Peripheral, spinal and cortical SSEP were recorded following stimulation of the median nerve at the wrist one to three days after cardiac arrest in patients treated with mild hypothermia (33°C for 24 hours). We measured N20P25 amplitudes and noise levels from all recordings and determined neurological outcome at discharge from the intensive care unit. Outcome was dichotomized in good outcome and poor outcome according to the cerebral performance category (CPC). Results: SSEP from 297 consecutive patients were available. Preliminary analysis was performed on 117 patients. Of those, 51% had good outcome and 49% had poor outcome. Within this limited cohort, only one of 60 patients with good outcome had cortical amplitudes below 0.47 μV. Among patients with poor outcome, 24 of 57 patients had amplitudes below 0.4 μV or no detectable N20. Conclusions: Our preliminary analysis of 117 cardiac arrest patients treated with hypothermia suggests that beyond the mere presence of a cortical potential, absolute amplitudes yield valuable prognostic information. Our data further indicate co-variation of outcome with N20 amplitudes and the existence of cut-off values, below which good outcome is improbable.
parietal or central region after stimulation of the hands (N1) and on Cz or Pz after stimulation of the feet (P1). Long latency vertex EP recording: Two series of 20 stimulations delivered at 0.2 Hz, BP: 0.3 to 100 Hz, TA: 1s, RE on the nose and GE on FPz. Latencies and amplitudes of the responses N2 and P2 were mesured on Cz. Normative values were defined as mean + 2.5 SD. Results: Short latency EP: A reproducible potential was obtained bilaterally in 10 subjects after stimulation of the hands and in 18 after stimulation of the feet. N1 and P1 mean latencies were 47.2 (SD 0.7) and 66 (SD 0.4) ms after stimulation of hand and foot respectively. Mean amplitude from baseline was 0.73 mV (SD 0.41) after hand stimulation and 1.1 mV (SD 0.9) after foot stimulation. When comparing the difference in latencies after hand or foot stimulation, the mean conduction velocity was 38 m/s consistent with a conduction of air puff related-responses by A beta fibers. Long latency vertex EP: A reproducible potential was obtained bilaterally in 18 subjects after stimulation of the hands and in 14 after stimulation of the feet. N2 and P2 mean latencies were 139 (SD 7.1) and 196 (SD 22.5) ms after stimulation of hand and foot respectively. Mean N2/P2 pick to pick amplitude was 11 mV (SD 6.2) after hand stimulation and 10 mV (SD 3.8) after foot stimulation. Conclusion: These normative data are useful for the assessment of patients suffering from neuropathic pain such as air-puff triggered allodynia.
P150 A complex evoked cortical response is induced by the relief of air flow interruption G. Guihard 1 , A. Chambellan 1 , A. Pégat 1 , J. Coutureau 1 , L. LeclairVisonneau 1 , A. Magot 1 , C. Peiffer 2 , Y. Pereon 1 1 University Hospital, Department of Clinical Neurophysiology, Nantes, France; 2 Hôpital Robet Debré, Department of Physiology, Paris, France Question: To analyze brain electrical events elicited by the restoration of normal breathing after an air flow (AF) occlusion. Methods: Twenty nine subjects (21.6±3.0 years) breathed through a shutterequipped spirometer. AF was blocked for 20 seconds. Evoked potentials (EPs) were monitored after AF restoration. Amplitude and latency values were determined as a function of AF occlusion/restoration repetition. In parallel, the subjects self-evaluated their psychological discomfort (PS) at the end of the 1st and 20th AF occlusion. Results: EP were induced by AF restoration and consisted in consecutive negative (N1), positive (P1) and negative (N2) waves. N1 latency value, but not those of P1 and N2, decreased as AF occlusion/restoration was repeated. N1 and N2 amplitudes were decreased by AF occlusion/restoration repetition. P1 remained unchanged. PS decreased between the 1st and the 20th AF occlusion. No correlation was found between PS decrease and changes of N1 and N2 properties. Conclusions: Apnea relief induced a complex brain electrical activity with latency and amplitude properties suggesting the adaptive contribution of various cortical and sub-cortical structures accompanying the relief feeling. These results reveal the modification of brain activity following apnea relief, a situation that occurs during sleep-associated breath troubles.
P148 Air puff evoked potentials. Short latency response and long latency vertex response. Normative values
LP8 Vestibular myogenic and acoustical brainstem evoked potentials in neurologic practice
P. Convers 1,2 , C. Créac’h 1,2 , R. Peyron 1,2 1 Neurological Department, Hôpital Nord, Saint Etienne, France; 2 Central Integration of Pain, INSERM U879, CNRL 1028, Lyon, Saint Etienne, France
V. Gnezditskiy 1 , O. Korepina 1 , N. Alekseeva 2 Research Center of Neurology, Russian Academy of Medical Sciences, Department of Neurophysiology, Moscow, Russian Federation; 2 Research Center of Neurology, Russian Academy of Medical Sciences, Outpatient Department, Moscow, Russian Federation
Question: To determine normative values of the short latency evoked potentials (EP) and of the long latency vertex EP elicited with a pneumatic, innocuous and calibrated stimulation to the skin. Material and methods: Twenty young healthy volunteers. Air puff stimuli were delivered through a home made device. The nozzle of the pneumatic stimulator (0.5 mm diameter outlet) delivered an air impulse (10ms duration, pressure 3.5 bars). It was placed perpendiculary to the skin at one cm. The noise of the air puff was masked. The cutaneous sites of stimulation were dorsum of hands and feet (right and left). Short latency EP recording: Two series of 1000 stimulations delivered at 3Hz, band-pass (BP): 0.3 to 3000 Hz, time of analysis (TA): 100ms, reference electrode (RE) on the ear lobe and ground electrode (GE) on FPz. Latencies and amplitudes of the cortical response were mesured on controlateral
1
Question: The clinical manifestation of central and peripheral vertigo sometimes very similar: in the acute period may be system vertigo, noise and hearing loss. MRI doesn’t always reveal the impairment of the brainstem and cerebellum. The neurophysiologic tests (BAEP and VMEP) in combination with the otoneurology inspection make it possible to reveal the changes, which are significant for the peripheral and central level of the lesion of the vestibular and auditory system. Methods: 79 patients suffered from multiple sclerosis (MS) were under our observation, which had predominantly cochlear vestibular disturbance in the acute period of the disease, whereas 11 had the symptoms of unilateral hearing loss and the system vertigo similar to Meniere’s disease.
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
for non-invasive imaging of the magnitude and spatiotemporal spread of nerve-evoked currents in the spinal cord and spinal nerves. In this study, we aimed to visualize evoked currents from the cervical spine in response to median nerve stimulation. Methods: Using a newly developed 120 channel SQUID fluxmeter, the neuromagnetic fields of 5 healthy volunteers were measured at the surface of the cervical spine in response to surface stimulation of the median nerve at the elbow. We also measured neuromagnetic fields after stimulation a few centimeters lateral to the median nerve and adopted a newly developed algorithm to reduce artifacts arising from surface electrical stimulation. Current sources were estimated using spatial filter techniques and the current field superimposed on X-ray images of the cervical spine. Results: Neuromagnetic fields were successfully imaged in all subjects. Neural currents entered the lateral cervical spine and ascended in the spinal canal from caudal to cranial, followed by currents propagating in the opposite direction. Discussion: We visualized neural activity patterns in the intervertebral foramen and spinal canal evoked by median nerve stimulation. Magnetospinography is expected to contribute to the clinical diagnosis and treatment of spinal cord and spinal nerve disorders.
P147 SSEP revisited: The significance of absolute N20 amplitudes for prognosis following cardiac arrest 1
1
2
1
C. Endisch , C.J. Ploner , C. Storm , C. Leithner Charite, Neurology, Berlin, Germany; 2 Charite, Nephrology and Intensive Care Medicine, Berlin, Germany
1
Question: Absence of cortical SSEP (N20) after stimulation of the median nerves predicts poor outcome after cardiac arrest with high specificity. This may also apply to patients with minimally detectable N20, but cut-off levels for N20 amplitudes below which good outcome becomes very unlikely have not been determined. Methods: Peripheral, spinal and cortical SSEP were recorded following stimulation of the median nerve at the wrist one to three days after cardiac arrest in patients treated with mild hypothermia (33°C for 24 hours). We measured N20P25 amplitudes and noise levels from all recordings and determined neurological outcome at discharge from the intensive care unit. Outcome was dichotomized in good outcome and poor outcome according to the cerebral performance category (CPC). Results: SSEP from 297 consecutive patients were available. Preliminary analysis was performed on 117 patients. Of those, 51% had good outcome and 49% had poor outcome. Within this limited cohort, only one of 60 patients with good outcome had cortical amplitudes below 0.47 μV. Among patients with poor outcome, 24 of 57 patients had amplitudes below 0.4 μV or no detectable N20. Conclusions: Our preliminary analysis of 117 cardiac arrest patients treated with hypothermia suggests that beyond the mere presence of a cortical potential, absolute amplitudes yield valuable prognostic information. Our data further indicate co-variation of outcome with N20 amplitudes and the existence of cut-off values, below which good outcome is improbable.
parietal or central region after stimulation of the hands (N1) and on Cz or Pz after stimulation of the feet (P1). Long latency vertex EP recording: Two series of 20 stimulations delivered at 0.2 Hz, BP: 0.3 to 100 Hz, TA: 1s, RE on the nose and GE on FPz. Latencies and amplitudes of the responses N2 and P2 were mesured on Cz. Normative values were defined as mean + 2.5 SD. Results: Short latency EP: A reproducible potential was obtained bilaterally in 10 subjects after stimulation of the hands and in 18 after stimulation of the feet. N1 and P1 mean latencies were 47.2 (SD 0.7) and 66 (SD 0.4) ms after stimulation of hand and foot respectively. Mean amplitude from baseline was 0.73 mV (SD 0.41) after hand stimulation and 1.1 mV (SD 0.9) after foot stimulation. When comparing the difference in latencies after hand or foot stimulation, the mean conduction velocity was 38 m/s consistent with a conduction of air puff related-responses by A beta fibers. Long latency vertex EP: A reproducible potential was obtained bilaterally in 18 subjects after stimulation of the hands and in 14 after stimulation of the feet. N2 and P2 mean latencies were 139 (SD 7.1) and 196 (SD 22.5) ms after stimulation of hand and foot respectively. Mean N2/P2 pick to pick amplitude was 11 mV (SD 6.2) after hand stimulation and 10 mV (SD 3.8) after foot stimulation. Conclusion: These normative data are useful for the assessment of patients suffering from neuropathic pain such as air-puff triggered allodynia.
P150 A complex evoked cortical response is induced by the relief of air flow interruption G. Guihard 1 , A. Chambellan 1 , A. Pégat 1 , J. Coutureau 1 , L. LeclairVisonneau 1 , A. Magot 1 , C. Peiffer 2 , Y. Pereon 1 1 University Hospital, Department of Clinical Neurophysiology, Nantes, France; 2 Hôpital Robet Debré, Department of Physiology, Paris, France Question: To analyze brain electrical events elicited by the restoration of normal breathing after an air flow (AF) occlusion. Methods: Twenty nine subjects (21.6±3.0 years) breathed through a shutterequipped spirometer. AF was blocked for 20 seconds. Evoked potentials (EPs) were monitored after AF restoration. Amplitude and latency values were determined as a function of AF occlusion/restoration repetition. In parallel, the subjects self-evaluated their psychological discomfort (PS) at the end of the 1st and 20th AF occlusion. Results: EP were induced by AF restoration and consisted in consecutive negative (N1), positive (P1) and negative (N2) waves. N1 latency value, but not those of P1 and N2, decreased as AF occlusion/restoration was repeated. N1 and N2 amplitudes were decreased by AF occlusion/restoration repetition. P1 remained unchanged. PS decreased between the 1st and the 20th AF occlusion. No correlation was found between PS decrease and changes of N1 and N2 properties. Conclusions: Apnea relief induced a complex brain electrical activity with latency and amplitude properties suggesting the adaptive contribution of various cortical and sub-cortical structures accompanying the relief feeling. These results reveal the modification of brain activity following apnea relief, a situation that occurs during sleep-associated breath troubles.
P148 Air puff evoked potentials. Short latency response and long latency vertex response. Normative values
LP8 Vestibular myogenic and acoustical brainstem evoked potentials in neurologic practice
P. Convers 1,2 , C. Créac’h 1,2 , R. Peyron 1,2 1 Neurological Department, Hôpital Nord, Saint Etienne, France; 2 Central Integration of Pain, INSERM U879, CNRL 1028, Lyon, Saint Etienne, France
V. Gnezditskiy 1 , O. Korepina 1 , N. Alekseeva 2 Research Center of Neurology, Russian Academy of Medical Sciences, Department of Neurophysiology, Moscow, Russian Federation; 2 Research Center of Neurology, Russian Academy of Medical Sciences, Outpatient Department, Moscow, Russian Federation
Question: To determine normative values of the short latency evoked potentials (EP) and of the long latency vertex EP elicited with a pneumatic, innocuous and calibrated stimulation to the skin. Material and methods: Twenty young healthy volunteers. Air puff stimuli were delivered through a home made device. The nozzle of the pneumatic stimulator (0.5 mm diameter outlet) delivered an air impulse (10ms duration, pressure 3.5 bars). It was placed perpendiculary to the skin at one cm. The noise of the air puff was masked. The cutaneous sites of stimulation were dorsum of hands and feet (right and left). Short latency EP recording: Two series of 1000 stimulations delivered at 3Hz, band-pass (BP): 0.3 to 3000 Hz, time of analysis (TA): 100ms, reference electrode (RE) on the ear lobe and ground electrode (GE) on FPz. Latencies and amplitudes of the cortical response were mesured on controlateral
1
Question: The clinical manifestation of central and peripheral vertigo sometimes very similar: in the acute period may be system vertigo, noise and hearing loss. MRI doesn’t always reveal the impairment of the brainstem and cerebellum. The neurophysiologic tests (BAEP and VMEP) in combination with the otoneurology inspection make it possible to reveal the changes, which are significant for the peripheral and central level of the lesion of the vestibular and auditory system. Methods: 79 patients suffered from multiple sclerosis (MS) were under our observation, which had predominantly cochlear vestibular disturbance in the acute period of the disease, whereas 11 had the symptoms of unilateral hearing loss and the system vertigo similar to Meniere’s disease.