Efficacy of functional electrical stimulation in rehabilitating patients with foot drop symptoms after stroke and its correlation with somatosensory evoked potentials—a crossover randomised controlled trial

Objective The connectivity between somatosensory evoked potentials (SEPs) and cortical plasticity remains elusive due to a lack of supporting data. This study investigates changes in pathological latencies and amplitudes of SEPs caused by an acute stroke after 2 weeks of rehabilitation with functional electrical stimulation (FES). Furthermore, changes in SEPs and the efficacy of FES against foot drop (FD) stroke symptoms were correlated using the 10-m walk test and foot–ankle strength. Methods A randomised controlled two-period crossover design plus a control group (group C) was designed. Group A ( n = 16) was directly treated with FES, while group B ( n = 16) was treated after 2 weeks. The untreated control group of 20 healthy adults underwent repeated SEP measurements for evaluation only. Results The repeated-measures ANOVA showed a decrease in tibial nerve (TN) P40 and N50 latencies in group A after the intervention, followed by a decline in non-paretic TN SEP in latency N50 ( p < 0.05). Moreover, compared to groups B and C from baseline to 4 weeks, group A showed a decrease in paretic TN latency P40 and N50 ( p < 0.05). An increase in FD strength and a reduction in step cadence in group B ( p < 0.05) and a positive tendency in FD strength ( p = 0.12) and step cadence ( p = 0.08) in group A were observed after the treatment time. The data showed a moderate ( r = 0.50–0.70) correlation between non-paretic TN latency N50 and step cadence in groups A and B after the intervention time. Conclusion The FES intervention modified the pathological gait in association with improved SEP afferent feedback. Registered on 25 February 2021 on ClinicalTrials.gov under identifier number: NCT04767360.