Averaged photic evoked responses and their dispersion pattern in multiple sclerosis.
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Evoked Potentials↗
Biomedical subjects
M Matei
Publications and source records attributed to M Matei.
Influence of opto-chiasmal lesions in organization of responses to flashes of different intensities in the striate and peristriate neocortical areas.
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Adolescent↗
Cerebral evoked potentials in the chronic vertebrobasilar insufficiency.
The syndrome of chronic vertebrobasilar insufficiency (VBI) consists in a complex of symptoms, often mild and transient, and lacks a complementary system of objective paraclinical investigations able to certify its existence. The study of somato-sensory, auditory and visual evoked potentials in VBI showed the occurrence of changes regardless of the symptom importance both in disorders due to extrinsic causes: a) compression by a damage of the cervical column (92.9%, 50% and 63.9%, respectively; b) diseases of the cervical spinal cord (92.9% and 46.6%, respectively) and in disorders due to some intrinsic vascular causes such as atherosclerosis (62.5%, 88.8% and 87.5%, respectively). We described: a) local and far field modifications for the somesthetic evoked potentials (SEPs); b) modifications due to brain stem hypoxia (vestibular and auditory centres) or of the internal ear for the early and middle auditory potentials (AEPs); c) modifications due to lower perfusion of the occipital lobes and of the nonspecific centres in the brain stem for the visual evoked potentials (VEPs). The N0-P0-Na component of the middle auditory response was considered to represent a vestibular response and it was significantly affected in cases with VBI and clinical manifestations like: equilibrium disorders, nystagmus and vertigo. Typical images of the sensory evoked responses affected by VBI are reproduced considering their evidence as an elective method in the paraclinical examination of this syndrome.
Adult↗
Investigation of P300 in various forms of epilepsy.
The problem of the late EP components generator localization has not yet been solved. This study aims to find out if a focal cortical epilepsy of the frontal (FLE) or of the temporal lobe (TLE) can modify the P300 component of the evoked response (either visual or auditory). Our data rely mainly on the selective differentiation test of an 80 dB click alternatively applied on the right or left ear, the patient having to give a motor response to those stimuli which have been chosen as target stimuli (probability of administration, 1:4). Under these circumstances, in normal subjects, evoked potentials showed deep P300 and an attenuated N2b in case of target stimulation and high, delayed N2b and an attenuated P300 for the nontarget stimulation, FLE did not abolish the late components of the EP; on the contrary, these were significantly augmented by the task. TLE, in exchange, severely attenuated differences between N2b-P300 components recorded from the scalp in case of target and nontarget stimulation. P300 was even higher at rest (possibly an effect of defective habituation). Rare or rapid stimuli application which was separately investigated gave another type of EPs modification compared to that specific for the auditory discrimination task. These facts are corroborated with the complete abolition of late EP components after lateral brain stem lesions. The conclusion is that N2a component has a reticular brain stem generator while N2b and P3 have initial generators in the temporal lobe (hippocampus).
Adolescent↗