Abstract
ObjectiveSensory deficiency of fine touch limits the restoration of motor functions after stroke, and its evaluation was seldom investigated from a neurological perspective. In this study, we investigated the cortical response measured by electroencephalography (EEG) on the fine touch sensory impairment during textile fabric stimulation after stroke.ApproachBoth participants with chronic stroke (n = 12, stroke group) and those unimpaired (n = 15, control group) were recruited. To investigate fine touch during textile fabric stimulations, full brain EEG recordings (64-channel) were used, as well as the touch sensation questionnaires based on the American Association of Textile Chemists and Colorists (AATCC) Evaluation Procedure 5. During the EEG measurement, relative spectral power (RSP) and EEG topography were used to evaluate the neural responses toward the fabric stimuli. In the subjective questionnaire, the fine touch for fabric stimuli was rated and represented by 13 different sensation parameters. The correlation between the fine touch evaluated by the EEG and the questionnaire was also investigated.Main resultsThe neural responses of individuals with fine touch impairments after stroke were characterized by a shifted power spectrum to a higher frequency band, enlarged sensory cortical areas and higher RSP intensity (P < 0.05). Asymmetric neural responses were obtained when stimulating different upper limbs for both unimpaired participants and stroke participants (P < 0.05). The fine touch sensation of the stroke participants was impaired even in the unaffected limb. However, as a result of different neural processes, the correlation between the EEG and the questionnaire was weak (r < 0.2).SignificanceEEG RSP was able to capture the varied cortical responses induced by textile fabric fine touch stimulations related to the fine touch sensory impairment after stroke.
Highlights
85% of stroke survivors experience sensory deficiency
There was no statistical difference in relative spectral power (RSP) in any frequency band toward the fabric stimuli for those with right hemiplegia (figure 4(C)). These results suggested that the brain lesion in different hemispheres might result in variations in fine touch impairments, and the neural response measured by EEG RSP was more sensitive in touch discrimination for stroke participants with left hemiplegia than those with right hemiplegia
In comparison with the EEG RSP features of the unimpaired control, deviated patterns in the stroke group were (1) representative power spectrum shifted to higher frequency bands, (2) enlarged sensory cortical areas in somatosensory association cortex, (3) higher RSP intensity in high frequency bands
Summary
85% of stroke survivors experience sensory deficiency. This deficiency is typically characterized by a reduced tactile perception of pain, temperature, touch, and proprioception [1, 2]. In a longitudinal study on stroke survivors, a significantly higher prevalence of severe motor deficiency was found among individuals who experienced sensory deficiency following a stroke. Sim et al [6] reported the immediate training effects of hand function following stroke with several types of somatosensory stimulation. They found that the hand function could be significantly improved after the stimulation of fine touch. Fine touch is known to affect motor recovery in individuals after stroke, its evaluation and the associated rehabilitation effects are usually underestimated and overlooked in traditional stroke rehabilitation programs, which are mainly emphasizing on motor treatments
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