## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**MAE in SVV Test**} & \multicolumn{3}{c}{**MAE in RFT**} \\ \hline
**Static and Dynamic Balance Measures** & **Mean** & **SD** & \
\begin{tabular}{c} **Correlation** \\ **(Rho)** \\ \end{tabular} & \(p\)**-Value** &
\begin{tabular}{c} **Correlation** \\ **(Rho)** \\ \end{tabular} & \(p\)**-Value** \\ \hline Sway Area Eyes Open (mm\({}^{2}\)) & 524.08 & 1096.97 & \(-\)0.007 & 0.960 & 0.042 & 0.764 \\ \hline Mean Velocity Eyes Open (mm/s) & 20.52 & 5.66 & 0.062 & 0.656 & 0.080 & 0.563 \\ \hline Medial–Lateral Root Mean Squared Eyes Open (mm) & 0.39 & 0.11 & 0.023 & 0.868 & 0.088 & 0.528 \\ \hline Posterior–Anterior Root Mean Squared Eyes Open (mm) & 0.43 & 0.14 & 0.033 & 0.811 & 0.126 & 0.366 \\ \hline Mean Medial–Lateral Oscillation Eyes Open (mm) & \(-\)1.44 & 6.34 & \(-\)0.173 & 0.210 & \(-\)0.046 & 0.739 \\ \hline Mean Posterior–Anterior Oscillation Eyes Open (mm) & \(-\)19.47 & 11.92 & \(-\)0.057 & 0.684 & \(-\)0.283 & 0.038 \({}^{*}\) \\ \hline Sway Area Eyes Closed (mm\({}^{2}\)) & 623.72 & 839.33 & 0.064 & 0.654 & 0.064 & 0.651 \\ \hline Mean Velocity Eyes Closed (mm/s) & 23.31 & 6.41 & 0.115 & 0.418 & 0.077 & 0.587 \\ \hline Medial-Lateral Root Mean Squared Eyes Closed (mm) & 0.45 & 0.16 & 0.065 & 0.649 & 0.095 & 0.504 \\ \hline Postero-anterior Root Mean Squared Eyes Closed (mm) & 0.54 & 0.17 & 0.162 & 0.253 & 0.022 & 0.874 \\ \hline Mean Medial–Lateral Oscillation Eyes Closed (mm) & \(-\)1.04 & 6.42 & \(-\)0.116 & 0.412 & \(-\)0.132 & 0.349 \\ \hline Mean Posterior–Anterior Oscillation Eyes Closed (mm) & \(-\)17.86 & 13.68 & \(-\)0.158 & 0.264 & \(-\)0.207 & 0.142 \\ \hline JAEN Total Score (0–80) & 36.85 & 10.58 & 0.224 & 0.103 & 0.268 & 0.050 \\ \hline JAEN Instability Head Movements (0–24) & 7.3 & 4.72 & 0.133 & 0.339 & \(-\)0.044 & 0.751 \\ \hline JAEN Instability Support Reduced (0–32) & 21.54 & 5.5 & 0.251 & 0.067 & 0.327 & 0.016 \({}^{*}\) \\ \hline JAEN Instability Gait Eyes Open (0–12) & 4.24 & 2.27 & 0.210 & 0.127 & 0.312 & 0.022 \({}^{*}\) \\ \hline JAEN Instability Standing and Walking Eyes Closed (0–12) & 3.78 & 1.9 & 0.050 & 0.721 & 0.184 & 0.184 \\ \hline \hline \end{tabular} MAE, Mean Absolute Error in degrees; SVV, Subjective Visual Vertical test; RFT, Rod and Frame Test; Rho, [PERSON]’s Rho non-parametric correlation coefficient; JAEN, Joint Assessment of Equilibrium and Neuro-motor Scale; \({}^{*}p<0.05\); \({}^{**}p<0.01\).  
\end{table} 
Table 3: Spearman Correlations between visual verticality perception tests and static and dynamic balance measures. study, the alteration in the RFT values in the sample of patients with FMS could be related to a greater susceptibility in this test of the female [43] and older [44] subjects. This is relevant because we know that Fibromyalgiagia is a syndrome that more characteristically affects women and that it produces effects similar to aging, and even greater effects are seen when visuo-vestibular participation in maintaining body balance is analyzed [16]. On the other hand, a recent study [41] found that 41.5% of subjects with dizziness had visual dependency as measured using the RFT. Although a correlation with headache intensity could not be found in this study, 22% of subjects with dizziness had visual dependency and complained of headache, showing a certain relationship between these health problems. FMS frequently occurs with other pain conditions such as headaches (59.01%) or chronic migraines (28.8%) [45]. These pain conditions have been shown to affect disorders related to the vestibular aspect [46]. This further supports the need for the evaluation of the vestibular component in the pathophysiology of FMS [10]. Our study showed that the alteration in the RFT correlated with greater body instability. This does not have to mean that patients with FMS have an alteration similar to peripheral vestibular disorder. In fact, the study by [PERSON] et al.