Innovative Approaches and Key Findings in the inner ear

Hearing and vestibular systems are crucial not only for auditory perception and balance but also for supporting a range of cognitive functions. Studies have consistently shown that hearing loss is associated with structural and functional changes in brain regions critical for cognition, including the hippocampus. Similarly, vestibular dysfunction has been linked to impairments in spatial memory, navigation, numerical cognition, and attention, independent of auditory deficits. Notably, experimental studies controlling for hearing loss have demonstrated that vestibular impairment alone can lead to deficits in spatial orientation, visuospatial memory, and executive functions—likely due to disrupted input to hippocampal and parietal regions responsible for spatial representation and body schema.

A central challenge in the literature is disentangling the individual contributions of auditory and vestibular systems, particularly given their anatomical and functional interconnections in the brainstem and shared presence in many otologic conditions. Nonetheless, approximately 43% of published studies on vestibular-related cognitive dysfunction have controlled for hearing status and still report significant cognitive impairments associated with vestibular loss. For example, Brandt et al. (2005) and Kremmyda et al. (2016) showed that patients with bilateral vestibular loss exhibited hippocampal atrophy and impaired performance in spatial memory tasks, even in the absence of significant hearing impairment. Moreover, Moser et al. (2017) demonstrated that patients with acute vestibular neuritis performed worse on mathematical reasoning tasks, suggesting deficits in spatial-numerical processing linked to vestibular disruption.

On the other hand, hearing loss has also been independently associated with impairments in working memory, language processing, and learning, often through mechanisms such as increased cognitive load, reduced sensory stimulation, or neural reorganization. These effects can be compounded when hearing and vestibular impairments co-occur, though most existing studies lack well-defined patient groups to analyze these interactions systematically.

Given the growing recognition that vestibular and auditory inputs are integral to cognitive processing, there is a pressing need to incorporate comprehensive sensory assessment in cognitive evaluations. This presentation will outline an integrated framework for studying multisensory contributions to cognition and advocate for including vestibular function as a standard variable in cognitive research and clinical screening.

In conclusion, hearing loss and vestibular dysfunction should not be seen merely as peripheral sensory issues but as central factors influencing cognitive health. A better understanding of their independent and combined effects may not only illuminate the neurobiology of cognitive decline but also open new avenues for multisensory rehabilitation strategies.