title: Auditory brainstem implants in neurofibromatosis Type 2: is open speech perception feasible?
abstract: OBJECTIVE
  Patients with bilateral auditory nerve destruction may perceive some auditory input with auditory brainstem implants (ABIs). Despite technological developments and trials in new stimulation sites, hearing is very variable and of limited quality. The goal of this study was to identify advantageous and critical factors that influence the quality of auditory function, especially speech perception.
  
  
  METHODS
  The authors conducted a prospective study on ABI operations performed with the aid of multimodality neuromonitoring between 2005 and 2009 in 18 patients with neurofibromatosis Type 2. Outcome was evaluated by testing word recognition (monotrochee-polysyllabic word test at auditory-only mode [MTPa]) and open speech perception (Hochmair-Schulz-Moser [HSM] sentence test), both in pure auditory mode. The primary outcome was the HSM score at 24 months. The predictive meaning of general clinical data, tumor volume, number of active electrodes, duration of deafness, and early hearing data was examined.
  
  
  RESULTS
  In 16 successful ABI activations the average score for MTPa was 89% (SD 13%), and for HSM it was 41% (SD 32%) at 24 months. There were 2 nonresponders, 1 after radiosurgery and the other in an anatomical variant. Direct facial nerve reconstruction during the same surgery was followed by successful nerve recovery in 2 patients, with a simultaneous very good HSM result. Patients' age, tumor extension, and tumor volume were not negative predictors. There was an inverse relationship between HSM scores and deafness duration; 50% or higher HSM scores were found only in patients with ipsilateral deafness duration up to 24 months. The higher the deafness sum of both sides, the less likely that any HSM score will be achieved (p = 0.034). In patients with total deafness duration of less than 240 months, higher numbers of active electrodes were significantly associated with better outcomes. The strongest cross-correlation was identified between early MTPa score at 3 months and 24-month HSM outcome.
  
  
  CONCLUSIONS
  This study documents that open-set speech recognition in pure auditory mode is feasible in patients with ABIs. Large tumor volumes do not prevent good outcome. Positive preconditions are short ipsilateral and short bilateral deafness periods and high number of auditory electrodes. Early ability in pure auditory word recognition tests indicates long-term capability of open speech perception.
authors: Departments of Neurosurgery.
authors: Cordula
authors: C
authors: Matthies
authors: Stefan
authors: S
authors: Brill
authors: Csanad
authors: C
authors: Varallyay
authors: Laszlo
authors: L
authors: Solymosi
authors: Goetz
authors: G
authors: Gelbrich
authors: Klaus
authors: K
authors: Roosen
authors: Ralf-Ingo
authors: RI
authors: Ernestus
authors: Jan
authors: J
authors: Helms
authors: Rudolf
authors: R
authors: Hagen
authors: Robert
authors: R
authors: Mlynski
authors: Wafaa
authors: W
authors: Shehata-Dieler
authors: Joachim
authors: J
authors: Müller
mesh_terms: D000328:Adult; D000368:Aged; D038263:Auditory Brain Stem Implantation / Q000379:methods*; D038262:Auditory Brain Stem Implants; D003627:Data Interpretation, Statistical; D003638:Deafness / Q000209:etiology / Q000628:therapy; D004566:Electrodes; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006309:Hearing / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D016518:Neurofibromatosis 2 / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D009464:Neuroma, Acoustic / Q000150:complications; D019635:Neurosurgical Procedures / Q000379:methods; D010348:Patient Care Team; D011379:Prognosis; D013067:Speech Perception / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult