Which cochlear implant

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Which cochlear implant?

• Making the right choice

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(No Transcript)
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Issues for consideration

• Manufacturers
• Implant technology
• Speech processors
• Speech coding strategies
• Performance

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Cochlear Implant manufacturers
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Implant numbers by manufacturer
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Advanced Bionics Corporation (ABC)

• 1993 USA
• 350 employees
• FY00 1,900 units, A50M
• Business to be floated or sold
• Est gt 5000 recipients

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Med El

• 1994 Austria
• 250 employees
• FY00 1,000 units A20M
• Family business
• Est gt 3000 recipients

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Cochlear

• 1981 - Australia
• Global business 600 employees
• FY00 5000 units, A120M
• Public company (ASX)
• gt 28,000 Nucleus recipients

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Implant technology
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Advanced Bionics Corporation

• Clarion Hi-focus with Electrode Positioning
  System (EPS)
• Ceramic
• Non-removable magnet
• 8 hard-wired electrode pairs
• Straight array with positioning device
• Telemetry impedence

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Med-El

• Combi 40
• Ceramic
• Non-removable magnet
• 12 electrode pairs
• Standard, short, split-compressed, ABI
• Telemetry impedance

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Cochlear

• Nucleus 24
• Titanium
• Removable magnet
• 22 electrodes
• Straight array, Contour Electrode, Double Array,
  ABI
• Telemetry impedance, compliance, NRT?

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Implant technology
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What is the ideal placement of the array?

• Spiral ganglion cells
• 1.75 turns
• 250Hz 4 kHz

• Array should overlay these cells
• Optimal insertion depth
• 25mm (lateral wall) or 540o 
• (measured from the cochleostomy)
• Proximity to modiolus
• Maximum number of sites of stimulation

• Spiral ganglion cells
• Basilar membrane
• Ariyasua et al. 1989 Otol Head Neck Surg
  10087-91

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1. The optimal depth of insertion

• X-ray reconstruction of human temporal bone
  showing placement of the Nucleus straight array

Stimulation of spiral ganglion cells
Image courtesy of The University of Melbourne
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The ideal depth of insertion is deeper better?
Combi 40
Nucleus (ST)

• Maximum No. channels next to S.G. cells in speech
  range
• Deeper insertion only accesses very low freq
• Poor frequency representation due to clumping of
  S.G. cells

Image courtesy of The University of Melbourne
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2. Array closer to spiral ganglion cells
Two ways

• Design a shape to fit cochlea curvature and use
  insertion tool

• Use device to force a straight array closer to
  modiolus

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What is the difference?

• Device to force array closer
• Exert continuous pressure
• Risk destroying residual hearing

• Clarion HiFocus
• Completely fills scala tympani
• Larger cochleostomy

• Fills lt half the scala tympani
• Reimplantation simple
• Preservation of residual hearing
• No force on cochlea structures

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3. Providing maximum number of stimulation sites
(straight array)

• Nucleus (ST) array
• 22 sites of stimulation
• 17mm active array
• Electrode spacing 0.75mm

Spiral ganglion cells
standard

• Combi 40
• 12 paired sites
• 26 mm active array (std)
• Electrode spacing - 2.4mm (std)1.1mm (compressed)

compressed
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Providing maximum number of stimulation sites
(peri-modiolar array)

• Nucleus 24 Contour
• 22 stimulation sites
• 15 mm active array
• Optimal electrode spacing
• 500 insertion depth

• Clarion HiFocus
• 8 stimulation sites
• 17 mm active array
• Evenly spaced electrodes
• Insertion depth 630 (from apex)

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Implant drill bed - does size matter?
CI24R
Ceramic Devices
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Bone Excavation Comparison
Combi 40
Clarion
CI24R
CI24M
VOLUME (cc)
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Magnet/coil design

• Ceramic
• Internal Magnet/coil
• Non-removable magnet

• Titanium
• External magnet/coil
• Removable magnet
• Pedestal design for protection

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MRI issues

• Stimulation
• Potential for stimulation if close to RF
  transmission frequency
• Nucleus 24 5 MHz
• Combi 40 12 MHz
• Clarion 50 MHz
• Torque
• Potential for device to move
• Shadowing
• Half head at worst case

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Implant reliability

• Other manufacturers
• Only report current model at 1 year
• Reporting methods may not be standardised
• External impact excluded

• Cochlear
• Complete records of ALL devices
• ISO 5841/2 standards
• External impact also included
• No reported implant case fractures (gt 28,000
  Nucleus recipients)

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Speech processors
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Advanced Bionics Corporation

• Clarion Platinum series
• Omni-directional microphone
• No lockable controls
• 2 Assistive listening devices (ALDs) (Lapel
  mic, Telecoil)
• Custom battery only - approx 11 hours SAS

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Med-El

• CIS PRO
• Omni-directional microphone
• No ALDs
• 2 x AA batteries - one day

• TEMPO
• Weight approx 19g with batteries
• Omni-directional mic
• 2 ALDs(FM cable, External audio input cable)
• 3 x HP675 batteries 36 hours

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Cochlear

• SPrint
• Directional microphone
• LCD display
• Full range of ALDs supplied
• AA batteries - up to 27 hrs

• ESPrit
• Weight 11 g with batteries
• Directional microphone
• Full range of ALDs supplied
• 2 x HP675 batteries - 80 hrs

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Implant technology
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What is a full capability BTE?
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Speech coding strategies
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Speech coding strategies
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CIS
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CIS
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Analog
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PPS
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n-of-m

• Med El - CIS PRO
• Stimulate n maxima of m channels
• Only 12 channels to choose from
• Widely spaced electrodes
• Clinical trials (n6)
• Equivalent to CIS
• Worse than CIS if n 4 or less

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SPEAK
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ACE
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Implant technology
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How much sound should cochlear implants capture?

• Can a wide Input Dynamic Range (IDR) improve
  performance?
• Normal speech 60dB
• Quiet conversation 55dB
• Background noise 40dB

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How much sound should be processed and delivered?
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Stimulation rate - is faster better?

• Patients prefer different rates

Adapted from Arndt, P et al 1999
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How is stimulation rate measured?

• pulsatile
• rate pulses per sec x No. channels
• Max rate Clarion 6,500 Nucleus 14,400 Combi
  40 18,200

• Analog
• Rate changes of output per sec x no. channels
• Sample rate Clarion 104,000

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Are all CISs the same?
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Isnt ACE (and SPEAK) just n-of-m?

• Emphasis on spectral information
• Require many sites of stimulation
• n-of-m n of up to 12 channels only
• SPEAK 6-8 maxima on 20 channels
• ACE up to 22 maxima on any of 22 channels

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Performance
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Cochlear implant performance

• Med El Combi 40/40
• with Tempo
• n 92 adults 6m
• 67 HINT (quiet)
• 48 HINT (noise)

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Implant technology
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Which strategy do recipients prefer?

• Nucleus 24
• ACE 60
• SPEAK 23
• CIS 8
• Clarion HiFocus
• SAS 52
• PPS 33
• CIS 15
• MedEl Combi 40
• Reported differences between CIS and n-of-m

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Which strategy provides the best performance?
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Perimodiolar arrays T C levels
Most Comfortable Levels (Monopolar Pulsatile
Stimulation)
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Neural Response Telemetry

• Unique to Nucleus 24
• Assurance at time of surgery
• Supports initial programming
• Aids longer term management

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Should patients receive two cochlear implants?

• Disadvantages
• Ongoing management of binaural summation
• More hardware
• To see and wear
• To maintain
• To keep optimally programmed

• Advantages
• Use info from two ears
• Captures the better ear
• Potential for improved sound localisation

Is it is cost-effective
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Conclusion
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Why choose Nucleus?
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Only one Company can make this promise
Partners in Hearing for Life