Abstract
OBJECTIVES: Cochlear implants restore functional hearing but may cause side effects like facial nerve stimulation, sound sensitivity or reactive tinnitus. The present study aimed to establish a general framework for optimizing stimulation parameters to manage these side effects while maximizing speech perception performance. A second objective was to understand how side effect origins impact treatment outcomes. METHODS: Eight adult cochlear implant subjects had intolerable side effects that rendered device usage difficult or even impossible. New maps were created by reducing stimulation levels, increasing pulse duration, reducing stimulation rate, altering channel gains and frequency maps, deactivating problematic electrodes, or a combination of the above. Outcomes were measured in terms of side effect reduction and changes in speech performance. RESULTS: Facial nerve stimulation was reduced or eliminated in five of five subjects. Sound hypersensitivity was eliminated in two of two subjects. Tinnitus was alleviated in three of four subjects, while the remaining one with cerebellar malformation experienced no change. Speech performance was either maintained or improved in all subjects. Except for the subject with cerebellar malformation who chose to explant the device, all subjects were able to use the implant effectively without bothersome side effects. DISCUSSION: Facial nerve stimulation is usually related to electric current spread on the same side, which can be effectively managed by customized strategies. In contrast, the origins of sound sensitivity and reactive tinnitus are more variable and likely more difficult to manage. CONCLUSION: Customized mapping can alleviate cochlear implant side effects without compromising speech performance.