Clinical and anatomical rationale for brainstem implantation in deafness – Kh.M. Diab, N.A. Daikhes, V.V. Belousov, O.A. Pashchinina, O.S. Panina, M. Hariri

The aim of the study: to investigate the microsurgical anatomy of the cochlear nuclei, the anatomy of the brainstem visible through the translabyrinthine and retrosigmoid accesses during auditory brainstem implantation. Material and methods. The study of the surgical anatomy of the cerebellopontine cistern (CPC) was performed at the National Medical Research Center for Otorhinolaryngology of the Federal Medical and Biological Agency (RF) on 10 cadavers (10 heads – 20 sides). Translabyrinthine and retrosigmoid accesses to the CPC were performed with identification of the lateral recess and foramen of Luschka. Brainstem structures that provide an anatomic basis for brainstem implantation were studied on 2 formalin-fixed adult cadaver brain preparations. Results. Both translabyrinthine and retrosigmoid accesses make it possible to perform brainstem implantation in the cochlear nuclei. The translabyrinthine approach provides an access (without cerebellar retraction) and a direct view of the ventral cochlear nuclei and foramen of Luschka. By lifting the flocculus, opening the choroid plexus, it is possible to reach the dorsal cochlear nucleus in the lateral recess. Identification of the lateral recess from below may provide better access to the cochlear nuclei in cases where the standard lateral landmarks adjacent to the foramen of Luschka are deformed. However, opening the lateral recess from below increases the risks of caudal migration of the implant electrode. Conclusions. Detailed knowledge of the anatomy according at different accesses can improve surgical planning and surgical results. Keywords: auditory brainstem implantation, hearing rehabilitation, cadaver dissection, cerebellopontine angle anatomy, cochlear nucleus Conflicts of interest. The authors have no conflicts of interest to declare. Funding. There was no funding for this study