Real-time intraoperative computed tomography to assist cochlear implant placement in the malformed inner ear.

OBJECTIVE: Cochlear implantation is increasingly being performed in children with inner ear malformations. In severe cochleovestibular anomalies, such as severe partitioning defects and common cavity dysplasia, positioning of the electrode array can be hazardous, with inadvertent placement into the internal auditory canal (IAC) or carotid canal being well known. We describe a case in which real-time intraoperative computed tomographic scanning was used to help achieve proper electrode positioning in a child with a severe malformation. PATIENT: Child with common cavity malformations undergoing cochlear implantation. INTERVENTION: Intraoperative computed tomography used during implantation procedure. MAIN OUTCOME MEASURE: Use of technique in determining electrode position.
RESULTS: A 10-year-old patient with bilateral common cavity malformations presented with declining performance in a functioning implant placed 7 years earlier. The family elected implantation of the contralateral ear. Via a posterior labyrinthotomy approach, a straight array was placed into the common cavity. Intraoperative computed tomographic scanning was immediately performed on the operating room table, showing that the array was in the IAC. A second attempt with a different insertion angle also resulted in IAC placement. In a third attempt, the electrode was advanced as a loop, grasping the tip through an adjacent second labyrinthotomy. Computed tomography confirmed good position against the outer wall of the cavity.
CONCLUSION: Real-time intraoperative computed tomography is a new technology with many potential applications in surgery. In our patient, it allowed rapid and accurate determination of electrode position and helped achieve ideal placement in a severely malformed inner ear.