Background and Objectives: Balance control is maintained in stationary and dynamic conditions, with coordinated muscle responses generated by somatosensory, vestibular, and visual inputs. This study aimed to investigate how the vestibular system is affected in the presence of an optical illusion to better understand the interconnected pathways of the visual and vestibular systems. Subjects and Methods: The study involved 54 young adults (27 males and 27 females) aged 18-25 years. The recruited participants were subjected to the cervical vestibular evoked myogenic potentials (cVEMP) test and video head impulse test (vHIT). The cVEMP and vHIT tests were performed once each in the absence and presence of an optical illusion. In addition, after each test, whether the individuals felt balanced was determined using a questionnaire. Results: cVEMP results in the presence of the optical illusion showed shortened latencies and increased amplitudes for the left side in comparison to the results in the absence of the optical illusion (p≤0.05). When vHIT results were compared, it was seen that the right lateral and bilateral anterior canal gains were increased, almost to 1.0 (p<0.05). Conclusions It is thought that when the visual-vestibular inputs are incompatible with each other, the sensory reweighting mechanism is activated, and this mechanism strengthens the more reliable (vestibular) inputs, while suppressing the less reliable (visual) inputs. As long as the incompatible condition persists, the sensory reweighting mechanism will continue to operate, thanks to the feedback loop from the efferent vestibular system.

Background and Objectives: Besides evaluating the auditory and vestibular systems of patients with vestibular migraine (VM) and Meniere’s disease (MD), this study aimed to examine the clinical overlaps between these two conditions by detailed evaluation of the patient’s symptoms. Subjects and Methods: The ears of the patients with VM and MD were evaluated and patients’ vestibular and auditory complaints were questioned particularly. Pure tone audiometry, vestibular evoked myogenic potential (VEMP) responses, and caloric test results were evaluated for objective measurements. Results: The VM group had better air-conduction and boneconduction threshold and speech reception threshold and speech discrimination score test values (p<0.05). Regarding the interaural N1-P1 asymmetry ratio, the cervical VEMP between the groups had significant differences (p=0.019). The MD group had more unilateral tinnitus and ear fullness complaints and canal paresis results (p<0.01). The VM group had more motion sickness complaints (p<0.01). Conclusions If only ears with hearing loss are evaluated; there was no significant difference between VM and MD, but regardless of hearing level or only the patients with normal hearing were evaluated, the VM group had better hearing levels. It should be considered that patients with VM may have VM-independent hearing loss, and patient complaints should be sufficiently detailed to make an accurate distinction from MD.