Use of botulinum toxin to prevent facial nerve stimulation following cochlear implantation

Facial nerve stimulation can develop because of the electric fields generated from an activated cochlear implant. This problem can usually be ameliorated by reducing or eliminating the current through the electrodes causing the undesirable stimulation. Occasionally there may be numerous electrodes that have to be deactivated in order to eliminate the facial nerve stimulation, and this may result in a marked reduction of auditory benefit to the cochlear implant user. Botulinum toxin causes transient neuromuscular blockade and has been shown to be effective in reducing or eliminating facial nerve hyperactivity due to a variety of causes. This report details the use of botulinum toxin in a patient with a cochlear implant who developed excessive facial nerve stimulation that necessitated the deactivation of 15 of the implant's 22 electrodes. After treatment with botulinum toxin, twice as many electrodes could be comfortably activated without causing facial nerve stimulation. The dynamic range was increased in 4 of the remaining 6 electrodes that were activated prior to treatment. The patient reported a marked improvement in sound quality and understanding of speech without lipreading as compared to her pretreatment performance. Treatment with botulinum toxin appears to be useful for patients who have excessive facial nerve stimulation after cochlear implantation.