Influence of electrical cochlear implant co-stimulation on vestibular function and sense of balance (vCIC)

• Applicant: Dr. Laura Fröhlich
• Subject Area: Otolaryngology, Phoniatrics and Audiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542106288

The rehabilitation of sensory modalities by bionic prostheses is a rapidly developing and highly relevant research field. Especially the cochlear implant (CI) has been successfully used over the last decades for hearing rehabilitation in patients with profound sensorineural hearing loss or deafness. The key element of the CI is the electrode array inside the cochlea by which spiral ganglion cells in the modiolus are electrically stimulated. Based on this principle prototypes for the rehabilitation of bilateral vestibular loss have been developed – the vestibular implants. Vestibular loss leads to chronic instability inducing a high risk for falls. The vestibular implant development mainly focused on implantation into the semicircular canals for restoration of the vestibulo-ocular reflex (VOR). However, electrical stimulation of the otoliths might have potential effects on more complex and highly relevant integrative behaviors of postural control (posture and gait). Beside vestibular implants, another option of electrical vestibular stimulation is co-stimulation by a CI, which can be confirmed clinically by the recording of electrically elicited vestibular evoked myogenic responses (e-VEMPs). However, the effect of CI co-stimulation of the vestibular system and the implications for balance and for postural control in particular are unknown. Especially in case of (unilateral) vestibular loss following CI surgery, vestibular rehabilitation by vestibular (co-) stimulation using the CI would be an important and advantageous option with the potential to be beneficial in restoration of balance and reducing the risk of falls. This could improve the patients’ quality of life significantly. Thus, the objective of the proposed research project is to investigate the influence of electrical vestibular co-stimulation by a CI on balance. The optimal stimulation parameters for confirmation of vestibular co-stimulation by e-VEMP recordings in patients treated with a CI model A are specified in a pilot study including 20 patients. 105 patients scheduled for CI surgery (models A and B) are then included in an explorative, experimental study. Vestibular test data are collected at 4 study visits between preoperative diagnostics and 3 months postoperatively. In patients with and without vestibular dysfunction, where vestibular CI co-stimulation can be confirmed by presence of e-VEMPs, postural control is measured with and without co-stimulation as the primary study objective. This is done under dynamic conditions by mobile posturography and under static conditions by the recording the subjective visual vertical (SVV). Different CI co-stimulation intensities are applied and analyzed. The observed change in functional SVV and mobile posturography results are correlated with patient reported outcome measures regarding the subjective impression of the impact of vestibular CI co-stimulation on balance.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Sebastian Strieth