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PubMed1995

[Somesthetic evoked potentials and serial motor evoked potentials in the study of proximal peripheral nerve conduction. Apropos of 7 cases].

The study of proximal motor and sensory nerve conduction in the thoracic outlet syndrome is still difficult and laborious in 1994. However, these conductions can be measured at different levels by means of somaesthetic evoked potentials and motor evoked potentials, when one takes the time to perform them. The study in normal subjects demonstrates that the proximal sensory and motor conduction delays are approximately 3.2 ms and are therefore comparable to that of the median nerve at the wrist. The study of 7 cases related to various diseases shows that these techniques, performed after electromyogram of both upper limbs, an essential prerequisite to their interpretation, are able to clearly demonstrate abnormalities of proximal conduction in patients suffering from of a scalene syndrome, a cervical epiduritis, radiation plexopathy, hereditary sensible to pressure neuropathy, motor neuropathy with persistent multifocal conduction blocks, or, on the contrary, may confirm the normality of conduction, for example in anterior horn disease.

Adult↗

PubMed1998

Contribution of initial median-nerve somatosensory evoked potentials and brainstem auditory evoked potentials to prediction of clinical outcome in cerebrovascular critical care patients: a statistical evaluation.

In a prospective study of 200 patients with cerebrovascular disease (48 intracerebral hemorrhages, [ICH]; 64 subarachnoid hemorrhages, [SAH]; 48 supratentorial and 40 infratentorial ischemic strokes), we assessed the individual and combined prognostic value of median-nerve somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) within 72 hours of admission. Clinical outcome was graded in three ranked categories according to a modified Glasgow Outcome Scale. Likewise, the initial SEP and BAEP findings were graded in a three-class score. In all groups, the SEP were significantly correlated with outcome (P < 0.01). Likewise, after partialling out the prognostic effect of SEP, the contingency between BAEP and outcome was statistically significant, except in ICH (P = 0.07). The contingencies of SEP and outcome in ICH and supratentorial infarcts were higher than the corresponding partial contingencies for BAEP, while the latter were higher in infratentorial infarction and SAH. Therefore, in all disease groups except for SAH, the multiple contingency coefficients ranging from 0.67 to 0.75 were statistically significant and greater than either simple or partial contingencies alone. The results of the two evoked potential modalities combined permit statistically significant superior prognostication in most cerebrovascular diseases when compared to those of either of the modalities alone.

Cerebrovascular Disorders↗

PubMed1991

[A preliminary report of evoked potential marker study of pattern shift visual evoked potentials (PS-VEP) and auditory evoked potentials (AEP) on schizophrenic twins].

This paper reports the result of electroneurophysiological study of the pattern shift visual evoked potentials (PS-VEP) and auditory evoked potentials (AEP) on six pairs of schizophrenic twins. The result indicated that there were significant differences in the inter-pair variance between MZ and DZ in latency P2, amplitude P2-N2 and P2 of using PS-VEP. AEP was also used for this group cases, and the result showed the presence of statistical differences in the inter-pair variance of latency N2, amplitude N1-P2 and P2. The authors speculated upon that the above six electrophysiological markers may be related to genetic factors, which had been proved by the blood group, character, clinical symptoms and treatment response of those patients.

Adolescent↗

PubMed1985

Visual evoked potentials and brainstem auditory evoked potentials in migraine and transient ischemic attacks.

A study of brainstem auditory evoked potentials (BAEPs) and pattern reversal visual evoked potentials (VEPs), recorded in intercritical phase, was carried out in 20 subjects (10 suffering from common migraine and 10 suffering from vertebrobasilar TIA) in order to obtain a comparative evaluation of cortical-subcortical functions. The data we obtained demonstrate the presence of BAEPs alterations in patients with previous vertebrobasilar TIA: no abnormalities were found in the migraine group. VEPs parameters are normal in both groups. Our data show that the study of the so-called "stimulus-related" potentials, such as BAEPs and pattern reversal VEPs, is useful in evaluating the damage produced by any noxa, while it cannot clearly emphasize individual factors predisposing to a specific pathology, as the absence of specific alterations in migraine patients demonstrates.

Adult↗

PubMed2001

[Changes in somatosensory evoked potentials and brainstem auditory evoked potentials during acute intracranial hypertension in rabbits].

OBJECTIVE: To study the changes in somatosensory evoked potentials (SEPs) and brainstem auditory evoked potentials (BAEPs) during intracranial hypertension. METHOD: A rabbit model of acute intracranial hypertension was developed. Thirty New Zealand rabbits were divided into 3 group. Both Group A and B were groups with intracranial hypertension; Group C was the control group. In Group A, balloons were placed to the right parietal lobe beneath the dura mater; in Group B, to temporal at the middle fossa near the brainstem. RESULT: (1) In Group A, when ICP rose to (1.48 +/- 0.35) kPa, P1 amplitude of SEPs was significantly changed, whereas latencies of Wave IV, V, and VII of BAEPs were prolonged when ICP rose to (9.40 +/- 1.60) kPa. In group B, P1 amplitude of SEPs was changed when ICP reached (8.10 +/- 1.25) kPa, and latency of Wave III of BAEPs was prolonged when ICP rose to (3.11 +/- 0.80) kPa. (2) P1 amplitude increased with ICP value when the balloon volume increased from V = 0.0 ml, ICP = (0.43 +/- 0.10) kPa to V = 0.4 ml, ICP = (2.44 +/- 0.65) kPa and then decreased afterward. CONCLUSIONS: (1) Changes in SEPs and BAEPs relate to not only ICP value but also the location of the balloon. (2) With the increasing of ICP, P1 amplitude increases firstly and then decreases.

Animals↗

PubMed2005

Effects of upper airway anaesthesia on respiratory-related evoked potentials in humans.

Cortical potentials evoked by mid-inspiratory occlusion arise from numerous receptors, many of which are probably within the upper airway. Their precise nature is not known. The aim of the current study was to improve knowledge of this by studying the effects of topical upper airway anaesthesia on respiratory-related evoked potentials. Respiratory-related evoked potentials were described through the averaging of electroencephalogram (EEG) epochs following mid-inspiratory occlusions (C3-CZ; C4-CZ). A total of 21 healthy volunteers (13 male, aged 22-52 yrs) were studied during mouth breathing, before and after topical upper airway anaesthesia (lidocaine). Moreover, 15 subjects were studied during nose breathing with and without anaesthesia. Six subjects were studied whilst inhaling L-menthol. Typical potentials were present in all the subjects, their components featuring normal amplitudes and latencies. The route of breathing and upper airway anaesthesia did not modify the EEG responses to inspiratory occlusions, qualitatively or quantitatively, during mouth or nose breathing. L-menthol had no effect. Upper airway receptors sensitive to topical anaesthesia are unlikely to contribute significantly to mid-inspiratory occlusion-evoked potentials. On the contrary, deeper receptors, such as joint and muscle receptors, could contribute dominantly to these potentials.

Administration, Inhalation↗

PubMed1998

Air- and bone-conduction brainstem auditory evoked potentials and flash visual evoked potentials in cats.

OBJECTIVE: To document normal values for air- and bone-conducted brainstem auditory evoked potentials (BAEP) and for flash visual evoked potentials (VEP) in cats. ANIMALS: 10 mixed-breed cats (5 males) with normal physical, neurologic, otoscopic, and funduscopic examination results. PROCEDURE: BAEP in response to air- and bone-conducted click stimuli and VEP in response to flash stimuli were recorded to document species normative data. Mean and SD values were calculated for amplitudes and latencies of 4 peaks in the BAEP in response to air- and bone-conducted stimuli, and for latencies to 5 peaks and the 4 associated peak-to-peak amplitudes in the VEP. RESULTS: BAEP peak latencies increased and peak amplitudes decreased with decreasing stimulus intensity. Latencies were shorter for bone-conducted stimuli owing to the shorter transit time to the cochlea through bone, compared with air, but there were no differences for interpeak latencies. The BAEP and VEP recordings were similar to those reported for cats in other reports and were similar to those seen in other species. CLINICAL RELEVANCE: Normative data will permit performance of noninvasive electrodiagnostic evaluation of feline auditory and visual systems.

Acoustic Stimulation↗

PubMed1985

Opiates and opioid peptides modify sensory evoked potentials and synaptic excitability in the rat dentate gyrus.

The effects of morphine and the synthetic opioid peptide D-Ala2-MePhe4-Met-O-ol-enkephalin (FK 33-824) on averaged (AEPS) potentials evoked by a tone and extracellular synaptic potentials (EPSs) in the perforant path, recorded from the outer molecular layer (OM) of the dentate gyrus, were examined in rats trained to respond in an auditory discrimination task. Potentials evoked by a tone were systematically altered by both peripheral (intraperitoneal) and central (intracerebroventricular) administration of opioids. The short-latency negative (N1) component of the average evoked potential was increased in amplitude and the longer-latency negative (N2) component was decreased in amplitude by administration of opioids. At the same time, perforant path extracellular synaptic potentials were enhanced after administration of opioids. The changes in the average evoked potential and extracellular synaptic potentials in the perforant path were reversed by subsequent administration of naloxone. The significance of these results is discussed in terms of a possible role of endogenous opioid peptides in modulating the synaptic efficacy of the perforant path during the transmission of sensory information to the hippocampus from the entorhinal cortex.

Animals↗

PubMed1999

Influence of segmental and extra-segmental conditioning, stimuli on cortical potentials evoked by painful electrical stimulation.

This study evaluated the effects of two different types of segmental/extra-segmental conditioning stimuli (tonic muscle pain and non-painful vibration) on the subjective experience (perceived pain intensity) and on the cortical evoked potentials to standardized test stimuli (cutaneous electrical stimuli). Twelve subjects participated in two separate sessions to investigate the effects of tonic muscle pain or cutaneous vibration on experimental test stimuli. The experimental protocol contained a baseline registration (test stimuli only), a registration with the test stimuli in combination with the conditioning stimuli, followed by a registration with the test stimuli only. In addition, the effects of the conditioning stimuli were examined at two anatomically separated locations (segmental and extra-segmental). Compared with the test stimulus alone, the perceived pain intensity and peak-to-peak amplitudes of the evoked potentials were unchanged in the presence of non-painful conditioning stimuli at either location. In contrast, a significant decrease of the perceived pain intensity and peak-to-peak amplitudes was found in the presence of painful conditioning stimuli at the extra-segmental sites. Moreover, the topographic maps of the 32-channel recordings suggested that the distribution of the scalp evoked potentials was almost symmetrical around the vertex Cz in the baseline registration. The evoked potentials were generally decreased during hypertonic saline infusion at the extra-segmental sites, but the distribution of the topographic maps did not appear to change. Vibration has previously been shown to inhibit pain, but in the present study the perceived intensity of phasic painful electrical stimuli was unchanged. The reduced perceived pain intensity and the smaller peak-to-peak amplitude of the evoked potential in the presence of extra-segmental conditioning pain are in accordance with the concept of diffuse noxious inhibitory control.

Adult↗

PubMed1992

Cerebral potentials evoked by oesophageal distension in patients with non-cardiac chest pain.

Cerebral evoked potential recording was used to study the oesophagus-brain axis in 10 controls and 10 patients with non-cardiac chest pain with a manometric diagnosis of either nutcracker oesophagus or diffuse spasm and a positive edrophonium test. A series of 50 inflations (10/minute; inflation rate of 170 ml/second) of an intraoesophageal balloon (5 cm proximal to the lower oesophageal sphincter) was performed in each subject. Three different inflation volumes were used and were individually determined to cause no sensation, slight sensation, and definite sensation, respectively (volume ranges: 2-8 ml, 5-18 ml, and 8-22 ml). All signals were coded and their quality was scored on a scale from 0 (no recognisable pattern) to 5 (well defined potential of good quality) by four 'blinded' observers. The evoked potential quality scores and amplitude of the major peaks increased significantly (p less than 0.01) with increasing sensation, both in patients and in controls. In the patients, quality score and amplitude of all four peaks of the evoked potentials were lower (p less than 0.05) and latencies of two of the four peaks were longer (p less than 0.02) than in the controls. The volumes of air required to produce the various sensations were lower in the patients (p less than 0.01). When divided by the balloon volume, amplitude and quality of the evoked potential were no longer significantly different between the groups. These results suggest that the increased perception of oesophageal distension in patients with non-cardiac chest pain is caused by altered central processing rather than (functionally) abnormal receptors in the oesophageal wall.

Adult↗

PubMed1976

Development of cerebellar somatosensory evoked potentials in the rat.

In lobule VIa of the vermis cerebelli of 69 male albino rats aged from 7 to 90 days we studied the somatosensory potential evoked by electrical stimulation of the sciatic nerve. A response consisting of a marked positive wave and a small negative wave was constantly present in the group of 9- to 10-day-old animals. At the end of the second week, an initial negative wave appeared. The response of 18-day-old animals consisted of 5 waves of alternating polarity and started with a small positive wave as in adult rats. During subsequent development only the relative size of the individual components changed, the later negative wave, N2, being the most marked component in adult animals. An attempted explanation of the possible origin of evoked potentials in young animals, based on the available data on the morphological development of the cerebellar cortex, is submitted. The latent periods, measured to the maxima of the individual waves, shorten abruptly between the 10th and 20th day and then undergo little change. Greater fatigability of the responses of young animals can be demonstrated by using rhythmical stimulation and paired stimuli. Somatosensory responses appear sooner than visual evoked potentials in the cerebellum, but they develop later than somatosensory evoked potentials in the cerebral cortex.

Aging↗

PubMed2002

Proprioception-related evoked potentials: origin and sensitivity to movement parameters.

Reafferent electroencephalography (EEG) potentials evoked by active or passive movement are largely dependent on muscle spindle input, which projects to postrolandic sensory areas as well as the precentral motor cortex. The origin of these proprioception-related evoked potentials has previously been studied by using N20-P20 source locations of the median nerve somatosensory evoked potential as an landmark for postcentral area 3b. As this approach has yielded contradictory findings, likely due to spatial undersampling, we applied dipole source analysis on two independently collected sets of high-density EEG data, containing the proprioception-related N90 elicited by passive finger movement, and the N20-P20 elicited by median nerve stimulation. In addition, the influence of movement parameters on the N90 was explored by varying amplitude/duration and direction of passive movements. The results showed that the proprioceptive N90 component was not influenced by movement direction, but had a duration that covaried with the duration of the movement. Sources were localized in the precentral cortex, located on average 10 mm anterior to the N20-P20 sources. The latter result supports earlier claims that the motor cortex is involved in the generation of proprioception-related EEG potentials.

Adult↗

PubMed1978

Iontophoresis of enkephalins potentiates evoked field potentials in the in vitro rat hippocampus.

Effects of iontophoresis of an active opioid peptide, D-Ala2-Met-enkephalinamide (2dA), on evoked field potentials were studied in the hippocampus in vitro preparation. Population spike responses which correspond to the summatory firing of the pyramidal neurons were recorded with glass microelectrodes from the CA1 cell layer. It is found that 2dA greatly enhanced the amplitude of population spike. The excitatory effect was opiate-specific, because it was antagonized by iontophoretically applied naloxone, a potent narcotic antagonist. On the contrary, an inactive enkephalin analog, N-acetyl-(D-Ala2, Lys3)-Met-enkephalinamide, was without effect. It is concluded that opioid peptides exert a specific excitatory action on the pyramidal neurons in the in vitro hippocampus.

Action Potentials↗

PubMed1978

[Brain potentials evoked by stimuli of different intensities in normal subjects and in hysterical psychopathy].

The author studied evoked potentials of 5 different intensitities to electroskin stimula in normals and psychopathic personalities of a hysterical type. It was established that different in their genesis the components of evoked potentials change differently in a change of the stimula intensity. The highest intensity of the stimula is reflected in the early sensory component of evoked potentials, the amplitude of which in normals in an increase of intensity successionaly rises. In hysterical personalities the amplitude of early sensorial components of evoked potentials in an increase of stimula intensity increases only to a certain limit, after which it begins to drop. This phenomenon called "reducing" indicates to a weakness of the sensory systems and relative prevalence of nonspecific brain systems in hysterical psycopathy.

Antisocial Personality Disorder↗

PubMed2001

Spectral analysis of visual potentials evoked by pattern-reversal checkerboard in juvenile patients with headache.

Changes in visual evoked potentials, mainly affecting the amplitude of the major positive wave, are referred to by many authors and are related to the pathophysiological basis of primary headache. We performed both transient pattern-reversal visual evoked potentials and spectral analysis by means of fast Fourier transform of 8-Hz steady-state pattern-reversal visual evoked potentials in 34 children affected with migraine (14 with aura, 20 without aura), and compared them with 14 patients with tension-type headache and 10 healthy subjects. The amplitude of the response to the transient stimulation (P100) was higher and the latency shorter in the patients with headache compared with the controls, but the difference was not statistically significant. The absolute power of the first harmonic (1F) obtained by the spectral analysis of the steady-state stimulation was increased in all the patients with headache compared with the controls, and the increase was significant in patients with migraine. These data seem to confirm the hypothesis of abnormal processing of visual input in migraineurs and could be interpreted as neurophysiological support for the theory that different headache types are related conditions. Furthermore, the spectral analysis of steady-state pattern-reversal visual evoked potentials could be proposed as a test to diagnose migraine.

Child↗

PubMed1993

[Effects of the stimulating point and non-point on human cerebral evoked potential and spinal cord evoked potential].

The experiments were carried out on 36 normal subjects. Pain stimulation points are at Neiguan or Hegu and pain stimulation nonpoints are nearby Neiguan or Hegu. The Record locations are at cortex and cervical vertebrae. The feature of evoked cerebral potential (ECP) and spinal cord evoked potential (ESP) by pain stimulation the points or non-points were studied. The results have been obtained. 1. Pain stimulation point ECP generally consists of wave P1, N1, P2, N2, P3, N3, P4 and N4. There is a certain amplitude and latency of each wave. 2. The elements of pain stimulation non-point ECP are Similar to point ECP in the feature. Comparing Pain stimulation Point ECP with non-point ECP, the amplitude of wave P3-N3 of stimulation point ECP increases (P < 0.05). 3. Pain stimulation Point ESP and non-point ESP consist of wave P1, N1 and P2, N3. Comparing Pain stimulation point with non-point there are no significant changes in the amplitude and the latency of ESP.

Acupuncture Points↗

PubMed1975

Development of cortical somatosensory evoked potentials in rats.

The development of the contra- and ipsilateral cortical potential evoked by electrical sciatic nerve stimulation was studied in 77 male albino rats aged 5 to 45 days. A contralateral response was already recorded, as double negativity, in the youngest animals, while an ipsilateral evoked potential was not reliably present until the 10th day. At this time, however, both responses started with an inconstant positive wave and their shape was practically the same. During subsequent development the responses differed only in respect to their dominant component: in the contralateral response, the N1 wave had the highest amplitude for most of the time, while in the ipsilateral response the delayed N2 wave was the largest component. The latent periods of contralateral responses were somewhat shorter than those of ipsilateral evoked potentials. During development we noticed a phase of abrupt shortening of the latent period, which took place before the 15th day in the contralateral response and before the 20th day in the ipsilateral response. We also found a difference in the fatigability of the responses, which was greater in immature rats than in adult animals; in the ipsilateral evoked potential it approached adult values more slowly. The development of the ipsilateral response is thus delayed compared with the development of the contralateral response.

Age Factors↗

PubMed2002

N10 potential as an antidromic motor evoked potential in a median nerve short-latency somatosensory evoked potential study.

When stimulating the mixed nerve to record evoked potential, both sensory and motor fibers are activated before entering the spinal cord. The N10 potential has been described as an antidromic motor evoked potential based on results obtained by recording at the anterior midneck. In the present study, we examined the changes in latencies of Erb's potential, N10, and N13 by stimulating the median nerve distally at the wrist and proximally at the elbow. The conduction velocity of N10 calculated by the difference between N10 latencies at the two stimulation points was consistent with motor conduction velocity, although N13 conduction velocity estimated by the same method reflected a sensory conduction velocity. A positive relation was also observed between the indirect latency from the stimulation point to the anterior root as calculated using the equation (F - M - 1) / 2 (ms) and the direct latency to the negative peak of the N10 potential. Our data support the notion that N10 represents antidromic motor potential originating in the spinal entry zone of the anterior root.

Adolescent↗