Dependence of cochlear implants settings on the components of the evoked compound action potentials.

Objectives. It has been suggested that the density of spiral ganglion neurons will affect on speech intelligibility. The results of previous studies shows that the supra-threshold characteristics of the Evoked Compound Action Potentials (ECAP) characterize the condition of spiral ganglion neurons. Aim of this paper is to evaluate the dependence of maximum comfort levels on ECAP parameters (threshold and amplitude). Materials and methods. The study included fitting data of 20 patients with sensorineural hearing loss with unilateral cochlear implantation. All patients were implanted with the Med-El (Sonata or Concerto) CI system with a standard electrode array. The results of electrodes impedance did not exceed 10 kΩ. Auditory development was assessed depending on the age of the patient and the condition of the hearing skills. Recognition results exceeded 90%. Results. A correlation between comfort levels and ECAP thresholds was found. The values of the comfort levels were reduced when ECAP amplitude was increased. Conclusions. ECAP thresholds can not be considered as an absolute reference point for determining the CI comfort levels. The amplitude of the ECAP response is one of the indicators of the preservation of the neurons of the auditory nerve. The correlation of the ECAP thresholds and comfort levels higher when ECAP amplitude values increase. [ABSTRACT FROM AUTHOR]