Facial nerve electromyography: a useful tool in detecting nonauditory side effects of cochlear implantation

Facial nerve stimulation is a known complication of cochlear implantation. Until recently, the assessment of facial nerve stimulation was primarily based on self reports which can be problematic in a pediatric setting. For children with facial nerve stimulation, the long-term implications implant use are unclear.

To illustrate the clinical utility of facial electromyography (EMG) in avoiding nonauditory stimulation evoked by cochlear implant use and to assess the potential for change in these responses over time with chronic electrical stimulation.

Midline evoked auditory brainstem responses and surface EMG of the facial musculature were performed in three children suspected clinically of having electrically evoked facial nerve stimulation. Each child had a different clinical presentation; the first complained of pain, the second experienced involuntary facial movements, and the third experienced nonspecific discomfort after sequential bilateral cochlear implantation.

All three children had EMG evidence of facial nerve stimulation. However, based on thresholds and patterns of responses in specific facial nerve branches, stimulation was responsible for the subjective and behavioural responses in only two of the three children.

Pediatric cochlear implant users are unreliable in their reports of facial nerve stimulation. Evoked surface EMG is an objective and useful clinical tool in patients with known or suspected facial nerve stimulation and can lead to improved implant use.