Potencial Cognitivo P300 em pacientes com lesão isquêmica do hemisfério direito

Masking Level Difference and Electrophysiological Evaluation in Adults with Normal Hearing

Introduction  The auditory structures of the brainstem are involved in binaural interaction, which contributes to sound location and auditory figure-background perception. Objective  To investigate the performance of young adults in the masking level difference (MLD) test, brainstem auditory-evoked potentials (BAEPs) with click stimulus, and frequency-following response (FFR), as well as to verify the correlation between the findings, considering the topographic origin of the components of these procedures. Methods  A total of 20 female subjects between 18 and 30 years of age, with normal hearing and no complaints concerning central auditory processing underwent a basic audiological evaluation, as well as the MLD test, BAEP and FFR. Results  The mean result on the MLD test was of 10.70 dB. There was a statistically significant difference in the absolute latencies of waves I, III and V in the BAEPs of the ears. A change in the FFR characterized by the absence of the C, E and F waves was noticed. There was a statistically significant difference in the positive correlation of wave V in the BAEPs with the MLD. There was a statistically significant difference in the positive correlation of the mean MLD and the V, A and F components of the FFR. Conclusion  The mean MLD was adequate. In the BAEPs, we observed that the click stimulus transmission occurred faster in the right ear. The FFR showed absence of some components. The mean MLD correlated positively with the BAEPs and FFR.

Variables in P300 recording: task type and electrode position

PURPOSE

To analyze the latency and amplitude of P300 responses obtained with electrodes positioned at Cz and Fz and in different tasks of infrequent stimulus identification in normal hearing individuals.

METHODS

Forty adults of both genders participated in the study. Three recordings with three different tasks were obtained for the identification of the infrequent stimulus; simultaneous recordings were obtained from Cz and Fz positions.

RESULTS

Cz position showed significantly greater amplitudes and lower latencies than Fz. Regarding the three tasks, only "pronouncing the word 'thin'" was different from "raising a finger", with lowest latencies for the verbal task. Regarding amplitude, significantly higher values were observed for "raising a finger", followed by "pronouncing the word 'thin'" and mental counting.

CONCLUSION

Cz obtained the best values, highest amplitude and lowest latency. Lowest latencies were obtained for the task of "pronouncing the word 'thin'" and the highest amplitudes were obtained for "raising a finger".

[The modern approaches to the prognostication of rehabilitation of the patients after stroke on an individual basis: a review of the literature and the results of original investigations]

This article was designed to analyze the results of the investigations with the purpose of elucidation of the prognostic factors relevant to the rehabilitation of the patients who survived after stroke. Special attention is given to the role of demographic (age and sex) factors and the data of the clinical, neurological, psychological, cognitive, and instrumental examination of the patients. The results of the original studies based on the treatment of 203 stroke patients are discussed in the context of modern concepts of the significance of the factors contributing to the recovery of the patients in the course of the post-stroke rehabilitation. The prognostic value of the selected factors, such as leukoareosis (for the patients presenting with hemorrhagic stroke), has been demonstrated for the first time. The new data on the duration of the rehabilitation period are presented with reference to its dependence on the type of stroke and localization of the lesions. Specifically, it is estimated to be 2 years for the patients who suffered from ischemic stroke in the brain stem, 31 months for those with ischemic stroke of the hemispherical localization, and 38 months for the patients presenting with hemorrhagic stroke (hemispherical hematoma). In addition, the data on the magnitude of the post-ischemic atrophic changes of prognostic values are presented.

P300 in workers exposed to occupational noise

The harm upon the central auditory pathways of workers exposed to occupational noise has been scarcely studied.

OBJECTIVE

To assess the central auditory pathways by testing the long latency auditory evoked potentials (P300) of individuals exposed to occupational noise and controls.

METHOD

This prospective study enrolled 25 individuals with normal hearing thresholds. The subjects were divided into two groups: individuals exposed to occupational noise (13 subjects; case group) and individuals not exposed to occupational noise (12 subjects; control group). The P300 test was used with verbal and non-verbal stimuli.

RESULTS

No statistically significant differences were found between ears for any of the stimuli or between groups. The groups had no statistically significant difference for verbal or non-verbal stimuli. Case group subjects had longer latencies than controls. In qualitative analysis, a greater number of altered P300 test results for verbal and non-verbal stimuli was seen in the case group, despite the absence of statistically significant differences between case and control subjects.

CONCLUSION

Individuals exposed to high sound pressure levels had longer P300 latencies in verbal and non-verbal stimuli when compared to controls.