Correlation Between Poststroke Balance Function and Brain Symmetry Index in Sitting and Standing Postures

Balance problems are the main sequelae of stroke, which increases the risk of falling. The assessment of balance ability can guide doctors to formulate rehabilitation plans, thereby reducing the risk of falls. Studies have reported the role of resting-state EEG during sitting in the motor assessment of the upper extremity and prognosis of stroke patients. However, the above research in the sitting posture lacks specificity in evaluating the balance ability of the lower limbs. Herein, this article investigated whether EEG was different in sitting and standing positions with different difficulty levels and validated the feasibility of EEG in assessing body balance ability. The resting-state EEG signals were collected from 11 stroke patients. The pairwise-derived brain symmetry index (pdBSI) was used to identify the differences in EEG-quantified interhemispheric cortical power asymmetry observable in healthy versus cortical and subcortical stroke patients by calculating the absolute value of the difference in power at each pair of electrodes. Subsequently, we computed the pdBSI over different frequency bands. Balance function was assessed using the BBS (Berg Balance Scale). Stroke survivors showed higher pdBSI (1-25 Hz) values in standing posture compared to sitting (p <0.05) and the pdBSI was significantly negatively correlated with BBS (r = −0.671, p =0.034). Additionally, the pdBSI within beta band was also significantly negatively correlated with BBS (r = −0.711, p=0.017). In conclusion, stroke brain asymmetry in standing posture was significantly more severe and the pdBSIs in 1-25Hz and beta hand were related to balance function. BBS and NIHSS was significantly negatively correlated (r = −0.701, p = 0.024), and NIHSS was significantly correlated with age (r = 0.822, p = 0.004). The present study suggests that stroke can seriously affect the body's balance ability. Compared with the sitting posture, the asymmetry of cortical energy in the standing posture can better assess the patient's balance ability.