Three-Dimensional Reconstruction of the Cochlear Nuclear Complex in Humans

Abstract

accurate physical three-dimensional reconstruction of the cochlear nuclear complex (CN), we used light microscopy to analyze the CN boundaries, cell types, and myelinated nerve bundles and transferred traced contours from enlarged photographs of serial sections onto acrylic plates. We produced two models, one demonstrating the CN in relation to the brain stem and the other showing the CN completely dissected out of the brain stem. The models localized the CN boundaries on the brain-stem surface and revealed topographic characteristics of the CN and a part of the eighth nerve adjacent to the brain stem. The major parts of the CN, namely, the ventral and dorsal cochlear nuclei, are located mainly within the lateral recess. The models produced are currently used in our institution to determine the optimal surgical and electrophysiologic approach to the CN. (Arch Otolaryngol 1985;111:495-501) It is well known that the cochlear nuclear complex (CN) is the first major relay center that processes information received through syn¬ apses with the cochlear nerve and then transmits it toward the cortex.The nuclei have been the subject of several intensive investigations that mainly studied carnivores1'7 and CA 90057 (Dr Terr). rodents.811 Primates, however, have received less attention, with only a few articles describing the CN in humans.1222The CN is a highly complicated heteromorphic formation consisting of several relatively well-separated divi¬ sions, namely, the dorsal (DCN) and ventral (VCN) cochlear nuclei, with smaller subdivisions of the latter.Although a part of the CN surface can be seen by the naked eye, gross analy¬ sis makes it difficult to appreciate the shape and dimensions of the cochlear nuclei in humans. The difficulty is due to the small size of the nuclei and the fact that the CN is almost completely hidden within the brain tissue and inseparable from it as a structural entity. At the same time, it may be equally difficult to understand the CN general spatial organization by study¬ ing individual or even serial histologie sections without specific reconstruc¬ tion methods. Three-dimensional re--· construction of the CN and the accu¬ rate characterization of the CN orien¬ tation have not been done yet. The morphology of the human CN is of substantial interest to us, since evaluation of the geometry of the nuclei is essential to further develop techniques for the electrical stimula¬ tion of the CN. Our institution cur¬ rently uses electrical stimulation of the cochlear nuclei as a form of rehabilitation of individuals deafened from the bilateral loss of the auditory nerves.23 MATERIALS AND METHODSTissue blocks were dissected from post¬ mortem, normal brains of adults. Macroexamination was completed on 20 brains. Detailed histologie examination was done on six brains (left and right sides). Varia¬ tions in the shape of the CN and adjacent structures, namely, root of the eighth nerve and inferior cerebellar peduncle, were not observed. One brain was utilized for three-dimensional reconstruction.The brai...

Topographical and cellular distribution of perineuronal nets in the human cochlear nucleus

“…The stellate neurons of the PBB in no way resemble islands of granule cells that have been described in association to the CN in rat and cat (Mugnani et al, 1980). This three-dimensionally irregular arrangement of neurons has been described previously as the pontobulbar body (PBB; Terr and Edgerton, 1985;Terr and Sinha, 1987). A complete rostrocaudal examination of the human CN reveals that the subdivisions of this complex (DCN and caudal VCN), are closely associated and even intermingled with islands of neurons comprising the PBB (Figs.…”

Evaluation of Surgical Approaches to Endoscopic Auditory Brainstem Implantation

“…Clinical and surgical experiences have identified the dorsal cochlear nucleus as the preferred target for implantation 13 . The dorsal cochlear nucleus is more accessible than the ventral cochlear nucleus for placement of the electrode array, as the latter is obscured by the inferior and middle cerebellar peduncles and a portion of the pons 14–16 . In addition, placement of the electrode over the ventral cochlear nucleus has produced nonauditory stimulation of the nearby facial nerve 9 .…”

Letter

“…2 In the following years, Leonid Terr and Bradley Edgerton created 3-dimensional models based on light microscopy analysis in cadaveric specimens to determine the optimal surgical approach to the cochlear nucleus complex. 3,4 The first attempt to systematically assess the dimensions of the nucleus was published in an almost invisible German anatomy journal in 1991. 5 In the meantime, several patients had already been implanted with surface ABI electrodes in the lateral recess of the fourth ventricle.…”