gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Electrical stimulation of the cochlear nucleus for restoration of hearing – anatomy, surgical technique and results in 117 patients

Meeting Abstract

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  • W.-P. Sollmann - Neurochirurgische Klinik, Städtisches Klinikum Braunschweig

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocMI.02-01

DOI: 10.3205/09dgnc176, URN: urn:nbn:de:0183-09dgnc1769

Published: May 20, 2009

© 2009 Sollmann.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Objective: Hearing restoration using auditory brainstem implants is not limited to NF2-patients with bilateral acoustic neuromas any more but as well successful in other indications. Following a 3 year microanatomical study of the topography and variations of the region of the cochlear nucleus in 144 specimens and a pilot study of 10 cases the method was established in 27 centers in Europe and Asia using a 21-channel-auditory brainstem implant (NUCLEUS 22 and 24, Cochlear Pty. Sydney).

Methods: 117 patients have been operated by the author between 1992 and 2008. Indications were functional hearing loss in NF2-patients with bilateral acoustic neuromas, after previous surgery of AN, bilateral ossified cochlea, trauma to the cochlear nerve, axonal neuropathy, congenital aplasia of the cochlear nerve, and hyoperostosis cranialis interna. Either the lateral suboccipital or the translabyrinthine approach were used for the tumor cases, for the non tumor cases the lateral suboccipital approach was preferred. The size of the electrode carrier (2.5x8.0mm) matches the surface of the cochlear nucleus. Intraoperative EABR-monitoring supported the positioning of the ABI. Initial stimulation and fitting of the implant was carried out 4–6 weeks after surgery.

Results: The lateral recess can be easily opened in 58% of the patients by arachnoid dissection and retraction of the flocculus together with the choroid plexus but also be occluded by overlying flocculus, branches of the AICA, veins or scars after previous surgery. In 117 out of 121 cases the implantation was possible. 91% of the patients had useful hearing with perception of environmental sounds, different frequencies, closed set word understanding, 48% had some open set speech understanding, 9% were able to use the telephone. Complications were caused primarily by the tumor surgery and not by the insertion of the ABI itself. Pulmonary embolism was the most serious complication in 3 patients, followed by CSF-leakage, disturbed wound healing and dislocation of the implant in 2 cases.

Conclusions: ABI-implantation is safely possible with useful functional results. The surgical and rehabilitational results are better in non-tumor patients than in NF2. In tumor patients there should be a stable disease, not too much distortion and impression of the brainstem and a preserved anatomy after previous surgeries. Due to variations of the anatomy and pathology close cooperation between centers and disciplines is essential.