Experimental Study following Inactive Implantation of an Auditory Brain Stem Implant in Nonhuman Primates

Abstract

We report changes in the cochlear nuclei (CNs) after 3 months of bilateral auditory deafferentation and simultaneous unilateral implantation of a dummy auditory brain stem implant (ABI) in 6 nonhuman primates (Macaca fascicularis). These specimens were compared to CNs of 9 controls and 7 bilaterally deafferented animals without implantation. The ABI array consists of 3 platinum electrodes mounted on a silicone pad with the back side covered with Dacron. No migration of the ABI was observed. All deafferented animals showed astrocytic reorganization in the CNs. Histologic changes consisted of superficial reactions around the implant, with formation of fibrillar bundles of fusiform cells, and the presence of giant cells close to the Dacron. Other findings were related to surgical trauma. The dummy ABI did not itself provoke serious adverse reactions in the CNs. Our observations support the possibility of ABI reimplantation surgery.

Keywords

cochlear nerve deafferentation cochlear nucleus neural prosthesis neuropathology nonhuman primate stereology

References

Brackmann

Hitselberger

Nelson

. Auditory brain stem implant: I. Issues in surgical implantation. Otolaryngol Head Neck Surg 1993; 108: 624–33.

Shannon

Fayad

Moore

. Auditory brain stem implant: II. Postsurgical issues and performance. Otolaryngol Head Neck Surg 1993; 108: 634–42.

Laszig

Sollmann

Marangos

. The restoration of hearing in neurofibromatosis type 2. J Laryngol Otol 1995; 109: 385–9.

Niparko

Altschuler

Xue

Wiler

Anderson

. Surgical implantation and biocompatibility of central nervous system auditory prostheses. Ann Otol Rhinol Laryngol 1989; 98: 965–70.

Liu

McPhee

Seldon

Clark

. The histological and physiological effects of the auditory brainstem prosthesis on the auditory pathway. In: Clark

, ed. XVI World Congress of Otorhinolaryngology Head and Neck Surgery. Cochlear implants. Bologna, Italy: Monduzzi, 1997: 103–7.

Terr

Mobley

House

. Biocompatibility of the central electroauditory prosthesis and the human cochlear nuclei. Am J Otol 1989; 10: 339–42.

Gundersen

HJG

Jensen

. Efficiency of systematic sampling in stereology and its prediction. J Microsc 1987; 147: 229–63.

Michel

Cruz-Orive

. Application of the Cavalieri principle and vertical sections method to lung: estimation of volume and pleural surface area. J Microsc 1987; 150: 117–36.

Terr

Sinha

House

. Anatomical relationships of the cochlear nuclei and the pontobulbar body: possible significance for neuroprosthesis placement. Laryngoscope 1987; 97: 1009–11.

10.

Monsell

McElveen

Hitselberger

House

. Surgical approaches to the human cochlear nuclear complex. Am J Otol 1987; 8: 450–5.

11.

Powell

TPS

Erulkar

. Transneuronal cell degeneration in the auditory relay nuclei of the cat. J Anat 1962; 96: 249–68.

12.

Pasic

Rubel

. Rapid changes in cochlear nucleus cell size following blockage of auditory nerve electrical activity in gerbils. J Comp Neurol 1989; 283: 474–80.

13.

Hashisaki

Rubel

. Effects of unilateral cochlear removal on anteroventral cochlear nucleus neurons in developing gerbils. J Comp Neurol 1989; 283: 465–73.

14.

Insausti

Cruz-Orive

Jauregui

Manrique

Insausti

. Stereological assessment of the glial reaction to chronic deafferentation of the cochlear nuclei in the macaque monkey (Macaca fascicularis). J Comp Neurol (in press).