Impact of Bilateral Vestibulopathy on Spatial and Nonspatial Cognition: A Systematic Review

Hearing loss is considered an independent risk factor for dementia. Growing evidence in animal and human studies suggest that not only hearing loss but also vestibular loss might result in cognitive deficits. The objective of this study is to evaluate the presence of spatial and nonspatial cognitive deficits in patients with bilateral vestibulopathy. As different causes of bilateral vestibulopathy are associated with hearing loss, the objective is to evaluate if these cognitive deficits are due to the vestibular loss of the patients with bilateral vestibulopathy, or to their hearing loss, or both.

We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. (1) Data sources: MEDLINE and the Cochrane Library. (2) Study selection: Cross-sectional studies investigating cognitive performances in human patients with bilateral vestibulopathy confirmed by quantitative vestibular testing. (3) Data extraction: Independent extraction of articles by three authors using predefined data fields, including patient- and control characteristics and cognitive outcomes.

Ten studies reporting on 126 patients with bilateral vestibulopathy matched the inclusion criteria. Cognitive domains evaluated in patients with bilateral vestibulopathy included visuospatial abilities, memory, language, attention, and executive function. In only three studies, hearing performance of the included patients was briefly described. Nearly all studies demonstrated a significant impairment of spatial cognition in patients with bilateral vestibulopathy. In the few papers investigating nonspatial cognition, worse outcome was demonstrated in patients with bilateral vestibular loss performing cognitive tasks assessing attentional performance, memory, and executive function.

Strong evidence exists that patients with bilateral vestibulopathy suffer from impaired spatial cognition. Recent studies even suggest impairment in other cognitive domains than spatial cognition. However, in all previous studies, conclusions on the link between cognitive performance and vestibular loss were drawn without taken hearing loss into consideration as a possible cause of the cognitive impairment.