Safe intraoperative neurophysiologic monitoring during posterior spinal fusion in a patient with cochlear implants

Objective: Cochlear implants are generally considered a contraindication for any procedure requiring electrical stimulation near the implant. We present a case of a patient undergoing intraoperative transcranial electrical motor-evoked potential monitoring with a cochlear implant without adverse outcomes. Patient: A 12-year-old girl with a history of VACTERL presented with worsening congenital kyphosis and bilateral severe-to-profound hearing loss. Since age 7 the patient used a cochlear implant in the right ear and hearing aid in the left ear. Physical examination and magnetic resonance imaging in 2016 revealed a left-sided 66-degree thoracolumbar kyphosis at T11 making the patient a candidate for surgical correction. Interventions: She underwent a posterior spinal fusion surgery, performed with intraoperative transcranial electrical motor-evoked potential monitoring. Steps were taken to mitigate electrical stimulation of the patient's cochlear implant. Main Outcome Measures: Postoperative impedance of individual channels, audiometry, and neural response testing were compared with preoperative measurements. Results: Significant (>10%) impedance changes were observed postoperatively in channels 1, 2, 4, and 6; however, the net variation across all the channels was low (3%). The patient reported no hearing changes, and no significant changes in hearing threshold were seen in postoperative audiometric testing or neural response testing. Conclusion: We present a case of successful posterior spinal fusion with intraoperative neurophysiological monitoring via transcranial electrical stimulation, in a patient with a cochlear implant. With proper precautions, motor-evoked potential monitoring can be safely performed in a patient with a cochlear implant.