The vestibular system may be affected by various pathologies causing disabling symptoms such as vertigo, nausea, postural instability, and falls. The life-long prevalence of dizziness in the general population is about 30%, the vestibular system function worsens with aging (1), and one subject out of three aged 65 or more experiences at least one fall per year (2). The diagnosis of the common vestibular pathologies as benign paroxysmal positional vertigo (BPPV), vestibular migraine (3), vertigo of central origin, vestibular neuritis or Meniere’s disease, is relatively simple during the acute phase based on the anamnesis and the clinical signs. Yet, after the acute phase or in the chronic patient, vestibular assessment becomes more difficult as the central nervous system activates very efficient adaptive and compensation mechanisms (4–9). Thus, a stabilized vestibular deficit can correspond either to a completely compensated condition, allowing the subject to perform even demanding tasks, or to a serious impairment, which may in turn improve with rehabilitation and still not change the neurophysiologic measurement. Actually, recovery of the vestibular function in patients with both peripheral and central vestibular disorders may be effectively stimulated using specific rehabilitation protocols (10–19). Outcome measures of vestibular rehabilitation are provided by questionnaires on the impact of disability in everyday life (20, 21). Several questionnaires are designed to measure these aspects, addressing different functional domains, and the aim of this study was to validate the use of three complementary instruments for the assessment of Italian patients with disequilibrium.

The original version of the Dizziness Handicap Inventory (DHI) is a 25-item questionnaire that asks the patients to rate their self-perception of disability from dizziness (20) and is the only one for which an Italian translation has been validated, but this was tested on a small group of patients, all suffering from peripheral vertigo and all evaluated in the acute phase of the disease (22). DHI consists of a 7-item physical subscale, a 9-item emotional subscale, and a 9-item functional subscale. A score of 4 points is assigned to a “yes” response, 2 points to “sometimes,” and 0 points to “no” response. Thus, the total score ranges from 0 (no perceived disability) to 100 (maximum perceived disability). The developers of the DHI ask to fill the questionnaire to 106 consecutive patients examined for vestibular testing, in whom, the mean score and SD was 32.7 ± 21.9. Scores of 60 or higher are associated with a greater fall risk in subjects with vestibular disorders (23) and the DHI score is sensitive to the effects of a 6- to 8-week course of vestibular rehabilitation in patients with unilateral, bilateral, central, or non-specific vestibular dysfunction (24).

The Activities-specific Balance Confidence scale (25) is a 16-item questionnaire designed for evaluating the risk of falls in everyday activities. The patient is asked to rate his perceived confidence in performing 16 activities that can take place inside and outside the house. Each activity can be scored from 0 (no confidence) to 100 (100% confident). The ABC scale and the DHI have been shown to have a moderately negative correlation, indicating that the ABC scale is a valid tool that can be administered to persons with vestibular dysfunction (26, 27). Older adults should be able to perform most of the 16 ABC activities with great confidence. Subjects who score less than 80% on the ABC scale are somewhat impaired (28), those who score less than 50% are often home-bound individuals, and older adults who score 66% or less are at high risk for falling (27). Furthermore, the ABC scale has also been shown to be sensitive to changes over the course of rehabilitation (23).

The Situational Vertigo Questionnaire (SVQ) [(29), adapted from Ref. (30)] is a 19-item questionnaire specifically aimed at identifying the presence of visual vertigo, a condition attributable to a defective vestibular compensation strategy, which is too dependent on the available visual information. “Visual vertigo” (31) is reported by patients with balance disorders in which symptoms are provoked or aggravated by specific disorienting visual context such as supermarkets (30), driving (32), movement of objects, or of the visual scene (33), which provoke abnormally large perceptual and postural responses. Visual vertigo is considered to be due to increased visual dependence with difficulty in resolving conflicts between visual and vestibule–proprioceptive inputs. The SVQ asks the patients to rate how much vertigo symptoms are provoked or exacerbated in environments with visual–vestibular conflict, or intense visual motion, and yields a score for each item between 0 (not at all) to 4 (very much); a “never experienced” answer can be given if the patient has never experienced the described situation. The total score will be then calculated as the sum of single item scores divided per 19 minus the number of never experienced situations (total score/19-number of “never experienced” answer).

The three questionnaires were translated into Italian and given to patients with acute or chronic dizziness for peripheral or central vestibular disorders. Internal consistency and reliability were analyzed for the translated questionnaires and their subscales. We then evaluated the correlation between the questionnaires’ scores and, for each questionnaire, the effects of demographical and clinical variables.

Study population included 316 patients (124 males, 192 females; mean age 53.5 years, SD 15.6 years); mean symptoms duration was 1.6 years (SD 3 years.). Vestibular signs and diagnosis were distributed as reported in Figure 1. Visual vertigo was identified in 0.2%, and migraine in 47.8% of the patients, but vestibular migraine was diagnosed only in 8% of the patients as the cause of dizziness and vestibular signs. Test–retest reliability group was composed by 17 males, 13 females; mean age 45.8 years, SD 18.5 years; mean symptom duration was 2 years (SD 4.5 years). Visual vertigo was identified in 0%, and migraine in 50% of these patients’ group. All patients completely and correctly filled out the questionnaires.

The ease of use and reliability of the three questionnaires were confirmed. Given that Cronbach’s alpha, a widely used measure of reliability, is considered good when values are above 0.70, the value obtained by the DHI, the ABC, and the SVQ emerges as an excellent result. The previous paper (22), which dealt with the validation of a DHI Italian version showed even higher Cronbach’s alpha scores as compared to ours. However, that paper considered a smaller number of patients, all of whom were in the acute phase of a peripheral vestibular disorder. We considered our sample to better match the situation in which the questionnaires are likely to be useful: we included patients with central vestibular disorders, and this can explain a larger variability than that which can be expected in a single disease, and, more importantly, we considered patients with long-lasting symptoms, namely, a condition in which the vestibular clinical and instrumental signs are not usually correlated to the subject’s self-feeling of imbalance.

Correlations between questionnaire scores and clinical data showed that age is associated with higher scores in all the DHI subscales and in the ABC scale, indicating that the physical, emotional, and functional impact of dizziness is greater in older patients and a relation between older age and the maximum perceived disability, which is known to be associated with an increased risk of falls (27). The SVQ score did not correlate with age, indicating that vertigo can be aggravated by specific visual context at any age. The SVQ score did not correlate with the diagnosis, included psychogenic vertigo and vestibular migraine and, surprisingly, the presence of symptoms of visual vertigo was not associated with a higher score at the SVQ, which is aimed at identifying the presence of this kind of symptoms, but this finding might be explained by the rare occurrence of these symptoms in the tested population (0.2%). On the other hand, the SVQ score was the only one that correlated with the presence of migraine as an associated symptom, suggesting that migraine patients can be more susceptible to experiencing difficulty in resolving visuo–vestibular conflicts. Increased visual dependence is a factor that can perpetuate symptoms in patients with balance disorders (31, 42, 43), and administration of the SVQ could help identify it and prompt specific rehabilitation treatment, incorporating desensitization exercises and simulator-based desensitization exposure (44).

Disease duration correlated with the physical and functional scale of the DHI, indicating how physical problems and inability build up with time. As expected, the presence of vestibular signs was associated with higher scores at the DHI-p and -f, with the higher ranking between DHI-p score and brainstem or cerebellar signs, indicating that such patients have a greater physical impairment, and between the DHI-f score and unilateral peripheral vestibular signs, which provokes, thereby, a greater restriction in everyday life. The DHI-e score also correlated with vestibular signs, particularly with bilateral peripheral signs, but these were detectable only in four patients of our population.

Finally, the diagnosis of vestibular neuritis or endolymphatic hydrops was associated with higher scores at the DHI-p and -e, indicating a relevant physical and emotional impact of these diseases, characterized by violent spells of vertigo that, in the case of hydrops, can recur.

The correlation of the DHI-e subscale score with the diagnosis of endolymphatic hydrops is in accordance with the association of Ménière disease with anxiety and depression, as shown by a previous study (45).

A possible limitation of the validation process in our study is that of the administration of three questionnaires at the same time. For instance, answering the first questionnaires could affect the answers to that following, and this effect could, in turn, amplify the correlations between questionnaire scores, or hide their natural variability. Furthermore, the great number of items could lead subjects to answer inaccurately, particularly to the last ones. To avoid these potential limitations, we administered the three questionnaires in random order and we found that correlations with clinical and demographical variables differed in the three questionnaires, suggesting that they measured different aspects of dizziness, despite having been administered in the same session.

In conclusion, we provided the Italian version of three self-administered questionnaires that aim at evaluating the functional limitations caused by the vestibular disorder and reliably assess the different aspects of dizziness, i.e., psychological, physical, and functional, as well as the risk of falling. These measures are specific to vestibular or balance disorder and can be used to evaluate quality of life, disability, and outcomes of intervention.

This study was carried out in accordance with the recommendations of the local ethic committee with written informed consent from all subjects. All subjects gave written informed consent in accordance with the Declaration of Helsinki. The protocol was approved by the Ethic Committee of the National Neurological Institute C. Mondino Foundation.

SC, MV, and CR gave substantial contributions to the conception, design and interpretation of data, and drafted the work. MG and MCM gave substantial contributions to the interpretation of data and revised the work critically for important intellectual content. MMF, SQ, DN, and MMD gave substantial contributions to the acquisition of data and revised the work critically for important intellectual content. All the authors gave final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.