Effect of electroacupuncture at different frequencies on motor function in patients with post-stroke hemiplegia based on BOLD-fMRI

To investigate the effect of electroacupuncture (EA) at different frequencies on motor function in the patients with post-stroke hemiplegia based on blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI).

A total of 134 patients with post-stroke hemiplegia were divided into a low-frequency group (47 cases), a disperse-dense wave group (42 cases), and a high-frequency group (45 cases), and were all treated with EA. The scalp motor function area on the contralateral cerebral hemisphere opposite to the affected foci was chosen as the target point for EA stimulation. The frequencies of 2 Hz, 2 Hz/15 Hz, and 100 Hz were delivered in the low-frequency group, disperse-dense wave group and high-frequency group, respectively; and the current intensity was adjusted according to the patients’ tolerance. The intervention was operated for 30 min in each session, once daily and for 30 consecutive days. The scores on the modified Ashworth scale (MAS), Fugl-Meyer assessment scale (FMA), modified Barthel index (MBI), and Berg balance scale (BBS), and the results of timed up and go test (TUGT) were observed before and after treatment in each group. BOLD-fMRI was conducted before and after treatment, the ratio of affected local cerebral blood flow to whole brain blood flow was calculated in each group. The differences in the distribution of major brain regions and the functional connectivity of motor networks after EA were compared among the groups. A correlation analysis was performed between the functional connectivity of motor networks and each index.

Compared with before treatment, the MAS scores on wrist flexor, elbow flexor, knee extensor and ankle flexor were reduced (P<0.05), the scores on FMA, MBI and BBS were elevated (P<0.05), and TUGT was shortened (P<0.05) in each group after treatment. When compared with the low-frequency group and the high-frequency group, the MAS scores on wrist flexor, elbow flexor, knee extensor and ankle flexor decreased (P<0.05), the scores for FMA, MBI and BBS increased (P<0.05), TUGT was reduced (P<0.05) in the disperse-dense wave group after treatment. After treatment, the ratio of the affected local cerebral blood flow to the whole brain blood flow was higher in each group (P<0.05) in comparison with that before treatment, and this ratio in the disperse-dense wave group was higher than that in either the low-frequency group or the high-frequency group (P<0.05). The disperse-dense wave group exhibited the significant changes of functional connectivity in the left cerebellar regions 6 and 8, as well as the right insular lobe; and the changes in functional connectivity intensity on the healthy side of M1 in the disperse-dense wave group were more pronounced when compared with those in the low-frequency and the high-frequency groups (P<0.05). The left cerebellar zones 6 and 8, as well as the right insular lobe were negatively correlated with MAS scores on wrist flexor, elbow flexor, knee extensor and ankle flexor, as well as TUGT (P<0.05), and positively correlated with the scores on FMA, MBI and BBS (P<0.05).

Electroacupuncture at disperse-dense wave (a frequency of 2 Hz/15 Hz) may induce the activation of motor function in brain regions, thereby promoting the recovery of motor function in patients with post-stroke hemiplegia.