An Evaluation of Cognitive Abilities in Vestibular Disorders

Research evidence suggests the role of the vestibular system in cognitive functions like visuospatial memory, objective memory, spatial navigation, etc. Vestibular cortices send projection to the hippocampus and to the medial entorhinal cortex (MEC); the latter houses place cells, grid cells, and head direction cells, which play a major role in the formation of a cognitive map based on inputs from the vestibular apparatus. So, the present study aimed to assess cognitive functions in vestibular disorder patients.

All patients with vestibular disorders were included after bedside tests like the Dix Hallpike test, head impulse test, Romberg test on foam with eyes closed/the clinical test of sensory interaction and balance (CTSIB) and timed up and go test. After that, a dizziness handicap inventory (DHI) was used to assess the severity of the vestibular dysfunction. Patients with diagnosed neurological disorders were excluded from the study. Cognitive function assessment was done using the trail making test (TMT) and the digit symbol substitution test (DSST). The assessment results were correlated with the severity of the vestibular dysfunction using Pearson correlation.

Out of a total of 40 patients, 26 (62.5%) were males and 14 (37.5%) females. The results of TMT part A and part B were 86.14±11.00 and 247.07±39.0, respectively, in mild handicap score patients, and 102.7±10.69 and 290.0±10.35 in moderate handicap score patients, which was significantly (p<0.05) higher when compared to mild handicap patients. Even DSST scores in moderately handicapped subjects were significantly (p<0.05) lower than those with a mild handicap.

Patients with vestibular dysfunction have significant cognitive decline, and cognition is decreasing with the severity of the vestibular dysfunction.