Multi-mode grounding stimulation with anodic monophasic pulses to treat/prevent anomalous facial nerve stimulation in cochlear implant: case report

Abstract Background A notable complication in cochlear implant (CI) users is Anomalous Facial Nerve Stimulation (AFNS), an unintended stimulation of the facial nerve causing sound-triggered involuntary facial movements. Reported in about 5.6% of users (range 0.68–43%), AFNS risk factors include otologic conditions like otosclerosis or cochlear malformations and device factors such as high stimulation levels. Initial management involves conservative programming adjustments to minimize current spread. If unsuccessful, deactivating offending electrodes is necessary. While often effective, these interventions can occasionally lead to a decline in auditory performance, sometimes resulting in device discontinuation or even explantation. This requires careful clinical consideration to balance optimal hearing outcomes with patient comfort. Case presentation Two clinical cases of CI users with severe-to-profound sensorineural hearing loss are described. The first case, a 57-year-old woman suffering chronic otitis media since childhood, required explantation because of severe AFNS and reimplantation with a device delivering using multi-mode grounding (MMG) stimulation with anodic monophasic pulses (AMP). The AFNS was controlled, and she returned to using CI with acceptable functional gain. The second case, a 27-year-old woman with bilateral otospongiosis, exhibited intraoperative facial nerve stimulation during bipolar monophasic testing, but this was prevented postoperatively using MMG-AMP. Conclusions CI reimplantation with MMG-AMP was effective in managing severe AFNS when conservative measures failed to resolve it. This electrical stimulation pattern should be a viable option for CI candidates with AFNS risk factors (otosclerosis, inner ear malformations, FN dehiscence, cochlear obliteration/ossification) or for those who have an indication for cochlear reimplantation due to severe AFNS. Further studies are required to better explore the use of MMG-AMP in a larger number of subjects.