**3. Results**

Of the total number of participants who completed the study, 111 were women and 84 were men. Twenty-eight subjects met the criteria for migraines, 74 met the criteria for TTHs, and 93 subjects were classified as healthy. The total prevalence of headaches in the present study was 52.3%, with 72.5% TTH and 27.5% migraines. The prevalence of verticality alterations was very similar between the three groups (Table 1). There were no statistically significant di fferences in the prevalence of SVV alteration (*p* = 0.480).


**Table 1.** Description of the samples and groups.

SF-12; and NDI, neck disability index.

## *Diagnostics* **2020**, *10*, 796

One-way ANOVA showed no statistically significant between-group differences in the MAE between subjects with migraines or TTHs and healthy subjects (F = 1.097, *p* = 0.336, and η2 = 0.011). The results are graphically shown in Figure 3.

**Figure 3.** Between-group differences in mean absolute error in estimating subjective visual vertical (SVV).

The logistic regression performed to identify the variables related to alterations in the perception of verticality (Table 2) and the linear regression used to establish the variables that explained the degree of deviation in the MAE (Table 3) did not show statistically significant associations. An association was only found at the limit of statistical significance (*p* = 0.054) between headache-related disability and the degree of MAE deviation.



95% CI, 95% confidence interval; OR, odds ratio; MIDAS, migraine disability assessment; SF-12, 12-Item Short Form Health Survey; PCS-12, physical component summary of the SF-12; MCS-12, mental component summary of the SF-12; and NDI, neck disability index.


**Table 3.** Univariate linear regression to analyze the factors related to the degree of deviation of the perceived vertical from the theoretical vertical.

95% CI, 95% confidence interval; B, Regression coe fficient; MIDAS, migraine disability assessment; F, frequency; SF-12, 12-Item Short Form Health Survey; PCS-12, physical component summary of the SF-12; MCS-12, mental component summary of the SF-12; and NDI, neck disability index.
