## 4 Discussion  
### Current State of the Use of FES in UMN Diseases  
The studies in this scoping review report the main findings on the practice and use of FES for the functional rehabilitation of the upper or lower extremities in patients with post-stroke disorders, SCI or MS. Although the analyzed studies were carried out with different devices, on different pathologies, and using various durations of therapy, the review describes the current state of the use of FES in upper motor neuron disease. Regarding the quality of the analyzed papers (Table 4), two of them do not provide detailed information on the statistical analysis, in particular on the baseline comparison to control groups, sample sizes and effect. If such an in-depth analysis is not carried out, the final results may not be statistically significant. Only six out of the fourteen papers reported the verification of the normality of the data distribution. On the other hand, the other eight articles, even if they used non-parametric tests (Wilcoxon, Mann-Whitney, Friedman), did not specify anything about the normality of the distribution of data. In one study, the power of the sample size and effect size was reported, both a priori and a posteriori [34]. Although in five pieces of research ANOVA was used to identify pre- and post-therapy modifications, none of the authors reported the effect size for every measured parameter. However, partial eta squared can be obtained within ANOVA and provide an effect size of the data. With regard to the process of blinding in physiotherapy or rehabilitation, it is often challenging to use since many participants may be used to the techniques or procedures of applying electrophysical agents. However, most of the analyzed papers provided sufficient information for the reproducibility of the intervention and the use of inclusion and exclusion criteria. Additionally, the therapists can identify the groups by carefully analyzing the patients' exercise protocols. A significant obstacle in post-stroke rehabilitation reviews and meta-analysis is linked to the research outcomes. As can be seen in Table 4, for SCI and MS, ASIA and EDSS are used. However, for post-stroke rehabilitation, numerous statistically validated scales with good psychometric properties are available, making the extraction of specific data into a more robust framework or statistical analysis challenging. A higher-qualitative and specific design for more types of post-stroke rehabilitation assessment is needed. The reliance on FES as a potential tool for lower extremity impairment in UMN injuries was related to gait, primarily to improve gait parameters, as recent research also suggests [36; 37]. The recorded results showed improvement in gait parameters, especially in the study where the patients were trained on an FES-assisted cycle ergometer. Additionally, improved balance and decreased spasticity were identified in the FES-assisted training progress in gait parameters [37]. The connection point in the studies carried out on post-stroke patients is represented by the research of gait parameters after the application of FES. The results are promising, with a significant increase in gait speed, but not all the studies use the same types of tests and measurements, and the results cannot be generalized. Another obstacle in data collection and interpretation is the small number of participants. For the patients with MS and SCI, the duration of FES therapy was longer than for post-stroke patients. Although the sample sizes of patients and the primary disease are different, after six months of use in MS [30] and incomplete SCI [33] for lower extremity dysfunctions, the results of these two studies suggest that FES could be used to improve gait speed by daily use in both MS or incomplete SCI patients. Recent research on SCI suggests that lumbar and incomplete SCI have better rehabilitation outcomes than cervical or thoracic injuries, either complete or incomplete [42].