Auditory Brainstem Implant
Electrode array inside cochlea
NucleusArrayInSitu- showing22channelssafelyplacedinspeechfrequencyrange
The Auditory Pathway Diagram showing relative positions of a cochlear implant and an auditory brainstem implant
Nucleus 24 Auditory Brainstem Implant CI24M receiver-stimulator Monopolar reference electrodes (ball & plate) Microcoiled electrode wires Electrode array (21 platinum disks 0.7mm diameter) T-shaped Dacron mesh Removeable magnet
Position of ABI in the Brainstem
WPS / BLN Position of ABI in the Brainstem
Penetrating Auditory Brainstem Implant PABI Electrode ABI Electrode
Penetrating ABI Location
Indication: –life threatening bilateral tumours (cerebello-pontine angle tumours) - eg. Neurofibromatosic Type 2 –head trauma 18 years or older Surgery on first or second side either at same time as tumour removal or as separate procedure Should not have had stereotactic radiosurgery (eg, gamma knife) ABI implantation on 1 side only Medically and psychologically suitable Patient Selection
Rikke Pedersen 20 y
ABI Surgical Procedure Patient Preparation (30m) Nerve Monitoring (30m) Nerve Monitoring (30m) Preparing site (15M) Approach + Implant bed (1h) Approach + Implant bed (1h) Tumor removal & ABI placement (3h) Tumor removal & ABI placement (3h) EABR recording (30m) EABR recording (30m) Close approach & flap (1h) Close approach & flap (1h) TOTAL = 6¾ hours (Range h)
Nucleus ABI’s in Europe 177 Registrations by Country (Europe), Jul.04
Performance (1) 91.7% (A) received at least some lipreading enhancement on simple stress- pattern tests (n=12) 62.5% (B) received lipreading enhancement on open-set words (n=8) 90.9% (C) received lipreading enhancement on open-set sentences (n=11) 86.7% (D) were able to detect basic speech pattern information in speech using their implant alone (n=15) 35.3% (E) received limited modified open- set speech understanding (n=17) 7.7% (F) receive sufficient open-set speech understanding to be able to communicate by telephone (n=17)
Device Use 96.2% (A) received auditory sensations during programming and could detect sound after switch-on (n=27) 88.5% (B) subjects found the ABI useful for communication or environmental awareness (n=26) 63.0% (C) subjects could use their ABI for 8 hours or more per day (n=26) 36.4% (D) subjects would never switch off their processor throughout the day (n=11) 96.2% 88.5% 63.0% 36.4%
ABI 24 Advantages and Benefits Optimizes stimulation using 21 distinct sites. Potential to Confirm placement using NRT. Widest choice of Coding strategies.
MRI Considerations
MRI Static Magnetic Field (1.5T) Magnetic Switched Gradients (20 T/s) Radio Frequency (RF) Energy (2-16KW 64 MHz) FORCE in Magnetic components CURRENT in conducting components HEAT
Removal of Nucleus 24 ABI Magnet
Tests to Ensure Reliability Impact Test Cochlear routinely conducts tests to ensure the reliability of our products. For example, the CI24M implant has undergone extreme impact testing to verify ruggedness by simulating a blow to the head of a T-ball travelling at 65.0km/h (40.4mph). Test rig: impact hammer with T-ball with a mass of 3.6 kg (7.9lb), dropped through 450mm (17.7in).
Nucleus 24 Auditory Brainstem Implant CI24M receiver-stimulator Monopolar reference electrodes (ball & plate) Microcoiled electrode wires Electrode array (21 platinum disks 0.7mm diameter) T-shaped Dacron mesh Removeable magnet