Devices

A paddle electrode array placed on the cochlear nucleus of the brainstem to restore sound awareness when a cochlear implant cannot work. First implanted 1979, FDA approved in 2000 for NF2. The current US device has 21 platinum contacts on an 8.5 by 3.0 mm paddle.

Device — Other

Auditory brainstem implant (ABI)

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auditory · brainstem · cochlear nucleus · NF2 · Cochlear Corporation · surface array · academic · human

Auditory brainstem implant (ABI)

One-line verdict: The most widely placed surface stimulator in the central nervous system, and a 45-year-old example of a neural prosthesis that skips the nerve entirely.

Quick tags: Stimulation · Brainstem surface · Human · First implanted 1979

Overview

What it is: A surgically implanted auditory prosthesis for people with profound sensorineural hearing loss who cannot use a cochlear implant because the cochlear nerves or cochleae are not intact. A multielectrode surface array sits in the lateral recess of the fourth ventricle along the brainstem and stimulates the cochlear nucleus directly, bypassing the peripheral auditory system. The external parts (microphone, battery, speech processor, magnet and transmitter antenna) are like a cochlear implant. The internal parts are a magnet, antenna, receiver-stimulator and the electrode array.

History (as reported):

  • 1957: Djourno and Eyries produced hearing sensations by stimulating the cochlear nerve with electrodes.
  • 1979: House and Hitselberger placed the first ABI during removal of a vestibular schwannoma, in a 51-year-old woman with NF2. It was a single-channel bipolar pair of platinum ball electrodes, 0.5 mm balls separated by 1.5 mm, near the cochlear nucleus. She first gained lip-reading help and environmental sound awareness. Performance later fell, which was attributed to electrode migration.
  • 1980: Huntington Medical Research Institute built a two-plate design on polyethylene terephthalate mesh.
  • 1991: Laszig and colleagues, with Cochlear Ltd, described a multichannel mesh array with three platinum plates.
  • From 1992: the Nucleus multichannel ABI replaced older models in North America and abroad. In the US series, 71 NF2 patients received the 8-electrode version.
  • 1997: Behr in Wurzburg implanted a 12-electrode array with a processor based on the MED-EL C40+ cochlear implant.
  • 2000: FDA approved a multichannel ABI for patients 12 and older with NF2.
  • 2013: FDA approved clinical trials of ABIs in children (per Wikipedia, not a primary source).

Current device: The only FDA-approved ABI is from Cochlear Corporation. The latest model, ABI541, has 21 platinum contacts on a paddle measuring 8.5 by 3.0 mm and works with the Nucleus 6 sound processor. MED-EL and Oticon Medical make ABIs used outside the US.

Limits: The sources describe outcomes as sound awareness and improved pattern recognition for most users, with closed-set word recognition above chance. They are not a substitute for cochlear implant results.

Spec Card Grid

Hardware (ABI541)

  • Contacts: 21, platinum
  • Paddle: 8.5 x 3.0 mm
  • Target: cochlear nucleus, via the lateral recess of the fourth ventricle
  • Processor: Nucleus 6

Regulatory

  • US: FDA approval in 2000, NF2, age 12 and older
  • Outside the US: MED-EL and Oticon Medical devices in use

Evidence and limits

  • Over one thousand ABIs placed worldwide, per one review
  • Not covered here: paddle thickness and contact diameter; no 3D model yet

References