Cochlear Nucleus Anatomy Related to Central Electroauditory Prosthesis Implantation

Abstract

The central electroauditory prosthesis is now used to stimulate the cochlear nuclei to obtain auditory perception in patients with bilateral cochlear nerve transection who are undergoing bilateral acoustic tumor removal. In this study, we used fixed cadaver specimens to identify visible landmarks for accurate placement of the central electroauditory prosthesis through a combined suboccipital-translabyrinthine opening. Histologic features of the regions of probable implantation of the central electroauditory prosthesis were also investigated. We found that the following landmarks might have surgical significance: (1) the tenia of the inferior velum of the fourth ventricle, which crosses the surface of the ventral cochlear nucleus and the vestibulocochlear nerve; (2) the angle between the vestibulocochlear and glossopharyngeal nerves; and (3) the foramen of Luschka. It is suggested that an incision be made in the tenia for insertion of the prosthesis into the lateral recess and eventual placement on the ventral cochlear nucleus surface. To study regions of potential stimulation, we injected ink into different sites on the exposed surface of the cochlear nuclei. We then histologically examined neuronal populations adjacent to the sites. We found that a portion of the ventral cochlear nucleus localized within the lateral recess might be the most appropriate location for placement of the central electroauditory prosthesis.

Far-field responses to stimulation of the cochlear nucleus by microsurgically placed penetrating and surface electrodes in the cat

“…This finding is probably related to the fact that current passing through INSELs will not spread along superficial layers such as pia mater, pontobulbar fibers, and cerebellar peduncles overlaying portions of the CN. 26,33,36,[48][49][50] In contrast with surface electrodes, INSELs will be injected directly into the CN and-especially in the case of electrodes placed in the ventral portion-will access secondary auditory neurons and auditory nerve terminals, which are scarcely found in the dorsal CN in the species under investigation. 25 Data regarding the dynamic range of stimulation of the CN are less uniform in the literature.…”

Auditory Brainstem Implantation: The University of Verona Experience

“…We prefer the RS-transmeatal (TM) approach in VS surgery because we believe that it offers good control of bleeding, dissection of the entire tumor under direct view, easy identification of the facial and cochlear nerves at their root entry zone and at the distal end in the internal auditory canal, and, finally, adequate exposure of the foramen of Luschka. [1][2][3] However, the main advantage of the RS versus the TL approach is the possibility of intraoperative auditory monitoring [4][5][6][7][8] in an attempt to preserve hearing, with possible avoidance of ABI placement. In addition, it allows stabilization of the electrode wire by fixing it to a groove drilled in the posterior surface of the temporal bone.…”

“…The dorsal cochlear nucleus, which is the most accessible portion of the cochlear nucleus com-plex for electrical stimulation, is positioned on the surface of the lateral recess of the fourth ventricle. Various landmarks, such as the seventh, eighth, and ninth cranial nerves, may be used to locate the foramen of Luschka, 4,5,14,15 which affords access to the fourth ventricle. Usually, the choroid plexus, which covers the foramen of Luschka, lies within a triangle formed by the seventh nerve, the ninth nerve, and the lip of the foramen of Luschka.…”

Neuroprosthetic Hearing with Auditory Brainstem Implants / Wiederherstellung des Hörens durch auditorische Hirnstammimplantate

“…For these patients, researchers at HMRI and the House ear institute (HEI), Los Angeles developed a prototype device in 1979 and it was further refined in collaboration with Cochlear Ltd. in Sidney, Australia, the leading manufacturer of cochlear implants [19,20]. For these patients, researchers at HMRI and the House ear institute (HEI), Los Angeles developed a prototype device in 1979 and it was further refined in collaboration with Cochlear Ltd. in Sidney, Australia, the leading manufacturer of cochlear implants [19,20].…”