gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

Intraoperative measures and speech perception in adult ABI patients

Meeting Abstract

Search Medline for

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci069

The electronic version of this article is the complete one and can be found online at:

Published: May 31, 2005

© 2005 Colletti.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




Application of an auditory brainstem implant (ABI) on the cochlear nuclei is to date considered an established technique for rehabilitating subjects with neurofibromatosis type 2 (NF2). Recently this device has been proposed for patients suffering from a variety of non-tumoral disorders caracterized by disconnection from the world of sound and central nervous system (Colletti et al, 2000).

Materials and Methods

Intraoperative recording of electrically evoked auditory brainstem responses (EABRs) is an essential tool to verify correct placement of the electrode array and to predict the electrodes which may be utilized at the activation of the ABI. This is particularly useful in children which are unable to cooperate.


From April 1997 to May 2005, 73 patients, 57 adults and 16 children, were fitted with ABIs at the ENT Department of the University of Verona. Their ages ranged from 14 months to 70 years. Twenty-six subjects showed acoustic tumor due to either NF2 or solitary unilateral vestibular schwannoma in the only hearing ear. The remaining 47 patients showed different types of inner ear or cochlear nerve abnormalities. All subjects were operated on via the retrosigmoid approach. The stimulation of a variable number of electrodes (8 to 21) elicited EABRs intraoperatively. At the first activation only electrode yielding EABRs were turned on. Electrodes yielding non-auditory effects (vertigo, tingling sensation in the arms and/or legs, etc) were deactivated. Therefore after the first session 5 to 18 electrodes were functioning. In the subsequent evaluations of the MAP, non auditory effects diminished and additional electrodes could be activated for a total of 7 to 21.


Postoperative auditory performance, evaluated at 6 months and 1 year, based upon a battery of appropriate closed- and open-set measures included in the Italian version of "The Manual of Auditory Rehabilitation" (Ed. Cochlear AG Basel, 1997) are illustrated. Speech perception performances were compared both for tumor and non-tumor groups with the intraoperative outcomes obtained at the EABRs. In particular the number of electrodes eliciting EABRs, threshold and input-output functions are reported in detail.