title: The High Rate CIS Auditory Brainstem Implant for Restoration of Hearing in NF-2 Patients.
abstract: OBJECTIVE
  Hearing preservation is one of the major goals of acoustic neuroma surgery. In NF-2 patients, bilateral hearing loss is frequently caused by the disease or results from its treatment. Several implant devices for electrical stimulation of the cochlear nucleus have been developed to restore serviceable hearing in these patients. We report our experience and results using a high rate continuous interleaved sampling (CIS) auditory brainstem implant (ABI).
  
  
  METHODS
  Between June 1997 and May 2004, 24 NF-2 patients were managed by our group. In 20 patients an ABI was implanted successfully. The cochlear nucleus was located using anatomical landmarks and E-ABR recordings after resection of the neuroma via a retrosigmoid approach in the semi-sitting position. The 12-channel stimulating electrode array was inserted and fixed in the lateral recess. There were no surgical complications related to implantation apart from pseudomeningo that were managed by lumbar drainage.
  
  
  RESULTS
  In one patient the electrode array became dislocated and this necessitated revision surgery which was successful. One patient failed to gain benefit from the implant. Overall, 70% of electrodes were found to be serviceable for auditory stimulation, 5.3% of electrodes were primarily nonauditory, and in 7.8% side effects during stimulation were observed. Lip reading was improved by more than 100% as a result of the additional auditory input. For many patients, comprehension of open speech was restored to a useful level. Almost all patients were able to perceive environmental sounds and tinnitus was masked.
  
  
  CONCLUSIONS
  Restoration of hearing using ABIs in NF-2 patients is a safe and promising procedure for those who would otherwise be totally deaf. The high rate CIS speech processing strategy has proven to be very useful and effective in direct cochlear nucleus stimulation.
authors.affiliation: Department of Neurosurgery, Klinikum Fulda gAG, Academic Hospital of the University of Marburg, Fulda, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Behr
authors.forename: Joachim
authors.initials: J
authors.lastname: Müller
authors.forename: Wafaa
authors.initials: W
authors.lastname: Shehata-Dieler
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Schlake
authors.forename: Jan
authors.initials: J
authors.lastname: Helms
authors.forename: Klaus
authors.initials: K
authors.lastname: Roosen
authors.forename: Norfrid
authors.initials: N
authors.lastname: Klug
authors.forename: Bernd
authors.initials: B
authors.lastname: Hölper
authors.forename: Artur
authors.initials: A
authors.lastname: Lorens