Entropia da resposta cerebral a estimulação elétrica senoidal como marcador quantitativo em avaliação de AVC

Abstract

Stroke can cause motor and sensory dysfunction. The inference of the sensory alterations is important for the evolutionary follow-up of the motor rehabilitation of these individuals. The perception threshold (LS) test for sinusoidal electric stimulation (EES) of different frequencies is considered an alternative to measure the LS of different peripheral sensory fibers. The cerebral response to EES has already been studied in healthy participants, based on the synchronization and desynchronization of cerebral rhythms on electroencephalography (EEG) signals. However, the complexity of EES-related EEG signals was not investigated. This study aimed to investigate the complexity of the cortical response elicited by EES. EEG signals from 25 registered individuals (14 electrodes positioned according to the international system 10-10) in a previous study with 5 and 3000 Hz EES, and intensities of 1,2, 2 and 3xLS were used. EEG signals were recorded in 7 post-stroke participants with 3 kHz EES with intensity of 2xLS. The EES was applied on the superficial radial nerve in both groups. The complexity of different brain rhythms in the EEG signal was estimated by permutation entropy (EP). The results indicated higher LS of post-stroke subjects in relation to the healthy participants, at the frequency of 3 kHz. EP for healthy participants showed an increase in the complexity of EEG signals in most derivations, especially in the primary somatosensory cortical region, and in the beta rhythm. In the post-stroke group, the complexity showed great interindividual variability. However, in the beta rhythm, in 5 individuals, it was observed a greater complexity than the healthy ones in most of the derivations. In the alpha rhythm it was observed to be less complex than the healthy ones.