gms | German Medical Science

Objective: On the basis of the excellent results in CI patients, the 12 channel Med-El device Combi 40 / 40+ was used and a special electrode for insertion into the lateral recess of the 4^th ventricle for stimulation of the cochlear nucleus was developped. Hearing sensation and speech understanding should be restored by electrical stimulation of the cochlear nucleus.

Methods: 34 NF-2 patients were included up to now. In 29 patients 32 ABI probes were implanted, 3 patients were operated twice, 2 due to probe dislocation, one due to implant failure. For several reasons 5 patients were not implanted.

One of the implanted patients is a non user from the beginning; another patient experienced a deterioration of the disease and could not benefit from the implant any longer, before she used the device on a basic level.

Until now, 7 patients were implanted with the new Pulsar 100 device and will be reported separately. In 3 patients contralateral hearing was present and 3 patients were implanted in Asia, they were not tested, or from the latter no detailed data exist.

Results: The others use the implant on a daily basis. They have tonotopy, sound discrimination and are able to perceive daily life and warning sounds. In the first 6 months period, the average increase of sentence lip reading ranges from 19.4% without implant to 59.6% with ABI (n=9). The average rate of Freiburg numbers in open set ABI only users was 40.1% (n=8), and 46% sentences (n=4). In those and ABI plus rip reading patients the rate was 58.5% sentences (n=12) and 53.3% numbers (n=9). In the 2 years period in lip reading plus ABI mode, sentence recognition was 67.5 (n=9) and numbers 81.3 (n=5). ABI only results were 42.7% sentences (n=8) and 51.7 numbers (n=9). Both groups together scored 71.1% correct sentences (n=12) and 78.5% numbers (n=11). More than 50% of the evaluated patients have open speech understanding at different performance levels. Three patients are able to use the telephone on a basic level. Complications attributed to ABI implantation are mainly CSF leakage, no neurological or other major complications occurred.

Conclusions: ABI implantation, and the device used, is a reliable and safe method for hearing rehabilitation and restoration in NF-2 patients.