gms | German Medical Science

Introduction: Children born with severe cochlear malformation, cochlear aplasia or hypoplasia/aplasia of the cochlear nerve are no good candidates for cochlear implantation (CI). The only possibility for restoration of hearing in these cases is direct stimulation of the hearing pathways at brainstem level. Objective: To demonstrate the effectiveness of auditory brainstem implantation (ABI) even in very small children with prelingual deafness for restoration of hearing and speech.

Methods: A 12 channel ABI system (MedEl, Austria), which has proofen effectiveness and safety in neurofibromatosis patients since the last 16 years was used for implantation. The pediatric ABI program started in 2009. Meanwhile 25 implantations in 294 children, 10 male and 14 female were performed by the first author. Two children had a successful revision surgery after a fall on the implant side or a spontaneous breakdown of an other ABI system. The mean age was 3.3 years, median 2.8. The youngest was 1.25, the oldest 6.5 yrs. Surgery was performed in supine position using a retrosigmoid approach and multimodal neuromonitoring. In all cases intraoperative E-BERA were recorded.

Results: The preoperative evaluation with high resolution MRI and CT revealed in 16 children aplasia of the cochlear nerve. The others had cochlear dys-aplasia together with hypoplasia of the 8th nerve or syndromal lesions like Goldenhar Syndrome. In most cases surgery was difficult due to complete or partial occlusion of the lateral recess of the forth ventricle ( foramen of Luschkae). In 75% branches of the AICA or the vessel itself were crossing the implant site and had to be dissected. In every case the electrode paddle was small enough to fit properly into the recess. E-BERA recordings could be derived in each case. There were no neurologic complications and only minor surgical complications as subcutaneous CSF leaks in 4 children. All children in whom the device was activated so far regained sound awareness and insisted using the implant all day. The category of auditory performance scores (CAP) showed in 58.8% values better than CAP 3, in 23.5% equal to CAP 3 and in 17.6% below CAP 3.

Conclusion: ABI is a safe and successful surgical procedure for restoration of hearing and speach in prelingual deaf children. Precious time of plasticity of the auditory pathways should be used as early and intensively as possible. Therefore in doubtful CI candidates ABI should be the primary indication.