# Modification of Hand Muscular Synergies in Stroke Patients After Robot-Aided Rehabilitation
## 3 Results  
Data about the clinical evaluation acquired at admission and discharge of the patients are reported in Table 2. All the patients showed an increase in the FM and MP scores between admission and discharge with the Gloreha Sinfornia. The average increase was \(7.3\pm 3.7\) for the FM and \(3.1\pm 2.1\) for the MP. This underlines the improvement in the mobilization of the injured limb in the selected population, and this improvement is statistically significant (single comparison, significance achieved for \(p<0.05\); in this case, \(p=0.02\) for FM and \(p=0.03\) for MP with Wilcoxon paired-sample test).  
Figure 5 shows the trend of \(R^{2}\) for the selected tasks as the number of synergies increases. In particular, the \(R^{2}\) between the EMG signals and the reconstructed ones (\(W*H\)) is shown for the healthy limb and the injured limb before and after treatment with the Gloreha robot. It is evident that for \(N=3\), the \(R^{2}>80\%\), therefore three synergies were extracted from the EMG signal in order to allow the comparisons between the different conditions examined (i.e., H, BR, and AR).  
Muscle synergies were extracted and compared with the recorded EMG data of the 7 muscles selected at the beginning and at the end of the treatment on each subject and on the contralateral limb. Since the synergies are subject-specific, multiple comparisons were made between the beginning and the end of the rehabilitation treatment of the affected and the sound hands. For the sake of brevity, the results concerning contributions of each muscle synergy are shown, for a representative subject, in Figures 6-9. Similar results were obtained for the other involved subjects. In particular, the first bar is the rate of the corresponding muscle in the healthy limb (H), and the second and the third bars are the rate of each muscle before and after rehabilitation (BR and AR), respectively.  
The results concerning the performance indices for each exercise are summarized in Table 3 for all the involved patients. The monitored patients show a very high degree of similarity of the involved synergies (mean CS values: H-BR: 0.74 \(\pm\) 0.09; H-AR: 0.91 \(\pm\) 0.06; BR-AR: 0.82 \(\pm\) 0.09).  
\begin{table}
\begin{tabular}{l l l l l} \hline  & \multicolumn{2}{c}{**FM *} & \multicolumn{2}{c}{**MP *} \\ \hline  & **BR** & **AR** & **BR** & **AR** \\ \hline
1 & 39 & 45 & 5 & 10 \\
2 & 37 & 48 & 9 & 12 \\
3 & 36 & 48 & 6 & 12 \\
4 & 45 & 51 & 15 & 18 \\
5 & 34 & 37 & 4 & 8 \\
6 & 31 & 34 & 16 & 16 \\
7 & 26 & 36 & 14 & 15 \\ \hline  & 35.4 \(\pm\) 6.0 & 42.7 \(\pm\) 6.9 & 9.9 \(\pm\) 5.1 & 13.0 \(\pm\) 3.5 \\ \hline \end{tabular}
\end{table}
Table 2: Clinical data of patients involved in the study. BR = before rehabilitation; AR = after rehabilitation; * denotes statistical significance.  
Figure 5: The coefficient of determination \(R^{2}\) computed between mean EMG data and reconstructed EMG data for healthy limb and affected one at the admission and discharge. For N = 3, \(R^{2}\) is above the threshold (0.8) in all the assessed conditions.  
Figure 6: Comparison of the muscular synergies of the sound hand (in green) vs. the impaired hand (in the box) before (red) and after (blue) the rehabilitation treatment with the Gloreha robot for pencil-grasping.  
Figure 7: Comparison of the muscular synergies of the sound hand (in green) vs. the impaired hand (in the box) before (red) and after (blue) the rehabilitation treatment with the Gloreha robot for sheet-grasping.