the importance of bilateral cochlear implantation in
TRANSCRIPT
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
The Importance of Bilateral Cochlear
Implantation in Children who are
Profoundly Deaf in Both Ears
Karen A. Gordon
TEAM CLINICIANS
Sharon Cushing
Adrian James
Susan Blaser
Gina Sohn
Naureen Sohail
Cochlear Implant Team DIRECTORS
Blake Papsin
Karen Gordon
Vicky
Papaioannou
RESEARCH
ASSISTANT
Stephanie Jewell
STUDENTS
Daniel Wong
Patrick Yoo
Michael Deighton
Salima Jiwani
Parvaneh Abbasalipour
Nikolaus Wolter
Francis Manno
Melissa Polonenko
Morrison Steele
Carol Duong
Gurvinder Toor
Hena Kazmi
Katie McCann
Brian Wong
Laurie MacDonald
Mary Lynn Feness
Pat Di Santos
Valerie Simard
Nancy Greenwald-
Hood
Susan Druker
COLLABORATORS
Local - SickKids
Bob Harrison
Tracy Stockley
Mark Crawford
Maureen Dennis
Local - external
Sandra Trehub
Frank Russo
International
Robert Cowan
Richard van Hoesel
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Children need binaural hearing
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Can we promote binaural hearing
with bilateral cochlear implants?
Sequential
implants
n=156
Age at 1st implant
= 3.3 ± 3.1 yrs
Age at 2nd implant
= 9.3 ± 4.7 yrs
Inter-implant delay
= 5.9 ± 3.8 yrs
Simultaneous
implants
n=166
Age at implant
= 2.8 ± 3.2
Recruitment as of May 2012
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Spatial unmasking:
better hearing in noise
(noise at 0°) vs. (noise at 90°)
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
(noise at 0°) vs. (noise at 90°)
Spatial unmasking:
better hearing in noise
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
(noise at 0°) vs. (noise at 90°)
Spatial unmasking:
better hearing in noise
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
0
1
2
3
4
5
6
7
8
9
10
11
sequential simultaneous normal
Sp
ati
al u
nm
as
kin
g S
NR
(d
B)
Noise moved to 1st implanted ear
Noise moved to 2nd implanted ear
Spatial release from masking
Chadha et al., Otol NeuroOtol, 2011
P<0.001
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
0
1
2
3
4
5
6
7
8
9
10
11
sequential simultaneous normal
Sp
ati
al u
nm
as
kin
g S
NR
(d
B)
Noise moved to 1st implanted ear
Noise moved to 2nd implanted ear
Spatial release from masking
Chadha et al., Otol NeuroOtol, 2011
P<0.05
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
0
1
2
3
4
5
6
7
8
9
10
11
sequential simultaneous normal
Sp
ati
al u
nm
as
kin
g S
NR
(d
B)
Noise moved to 1st implanted ear
Noise moved to 2nd implanted ear
Spatial release from masking
Chadha et al., Otol NeuroOtol, 2011
P>0.05 P=0.001
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
How does binaural hearing work?
Sound reach one ear before the other and at
different levels
These cues must be detected by the central
auditory system
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Can we promote binaural hearing with
bilateral cochlear implants?
Lateral Lemniscus
Inferior Colliculus
Superior Olivary
Complex
Medial
Geniculate Body
Auditory Cortex
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Reduced
activity
Activity no longer
reduced
Lee, et al., Nature, 2001
Will binaural processing be limited by
deafness in early development?
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Neural competition in development
Sherman, Nature Neuroscience 3, 525 - 527 (2000)
Development
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Sherman, Nature Neuroscience 3, 525 - 527 (2000)
Development Maturity
Neural competition in development
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Unilaterally driven development
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Sherman, Nature Neuroscience 3, 525 - 527 (2000)
Development Maturity in auditory brainstem
with 2 years CI use
Neural competition in development
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Restricted auditory brainstem plasticity
after 2 years of unilateral implant use
Unilateral CI use: nil Unilateral CI use: 6-12 months Unilateral CI use: > 2 years
Gordon, et al., 2010
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Auditory evoked cortical responses
are abnormal in the naïve ear
P2 naive
N1 naive
P CI naïve
N CI naïve
N1
P2
P1
Experienced ear Naïve ear
Cz All other channels
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Imaging brain activity in cochlear
implant users
Latency (ms)
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Imaging brain activity in cochlear
implant users
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Abnormal cortical activity after
right cochlear implant use
% Activity in Left Auditory Cortex [(R-L)/(R+L)x100]
Right CI Users (n=8)
Normal
Hearing
(n=7)
Clicks/pulses presented to right ear
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Normal cortical lateralization after
simultaneous bilateral cochlear
implantation C
on
tra
late
ral
Con
trala
tera
l
Co
ntr
alat
eral
Ip
sila
tera
l
Co
ntr
alat
eral
Ip
sila
tera
l
Increasing abnormality in cortical
activity with unilateral cochlear
implant use
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Co
ntr
alat
eral
Ip
sila
tera
l
1.48 yrs 1.37 yrs
Co
ntr
alat
eral
Ip
sila
tera
l
Significant change in cortical
activity with ≥1.5 years unilateral
cochlear implant use
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Bilateral input goes to dominant hemisphere
after 2+ years unilateral stimulation
-50 -40 -30 -20 -10 0 10 20 30 40 50
Normal
Simultaneous
Short Delay
Long Delay
Lateralization %
Particip
an
t G
ro
up
Lateralization of Cortical Responses by Stimulus Side
Left/CI-2 Stim
Bilateral
Right/CI-1 Stim
Left cortex Right cortex Dipole in each hemisphere
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Abnormal auditory development
with unilateral implant use
Dominance of
contralateral auditory
cortex
Lack of inhibitory binaural
processing during
development
Sequential
bilateral CI 1st
CI
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Abnormal auditory development
with unilateral implant use
Dominance of
contralateral auditory
cortex
Ipsilateral cortex?
Sequential
bilateral CI 1st
CI
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
CI1 CI1
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Perception of binaural cues restored
by simultaneous bilateral implantation
Normal Hearing Sequential bilateral
(n=9) cochlear implant (n=19)
Pro
port
ion o
f re
sponses
Inter-aural Timing Differences (us)
Left Responses Right Responses
Left leading Right leading Left leading Right leading
Salloum et al., Ear and Hearing , 2010
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Perception of binaural cues restored
by simultaneous bilateral implantation
Normal Hearing Sequential bilateral Simultaneous bilateral
(n=9) cochlear implant (n=19) cochlear implant (n=8)
Pro
port
ion o
f re
sponses
Inter-aural Timing Differences (us)
Left Responses Right Responses
Left leading Right leading Left leading Right leading Left leading Right leading
Salloum et al., Ear and Hearing , 2010
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Perception of binaural cues restored
by simultaneous bilateral implantation
Left Responses Right Responses - - - Normal Hearing
Left Responses Right Responses Simultaneous Bilateral CI
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Left +10 +6 +2 0 -2 -6 -10 Right
Res
po
nse
Rat
e
Inter-aural/implant Level Difference (dB/CU)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
+1000 us +400 us 0 -400 us -1000 us
Res
po
nse
Rat
e
Inter-aural/implant Timing Difference
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Non-auditory benefits of
simultaneous implantation
Hospital cost-savings
35% over sequential procedures
Similar length of stay as unilateral procedures
(~ 1 day)
No increased complications (Ramsden, et al., 2009)
Increased parental satisfaction compared with 2
surgeries in short period.
One course of programming and therapy
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Summary and Conclusions
There is a sensitive developmental period for
bilateral auditory input
Simultaneous bilateral cochlear implantation
Allows symmetric development of auditory brainstem and
cortex
Protects the brain from abnormal reorganization
Promotes binaural hearing
Provides significant cost savings over sequential procedures
Sequential bilateral cochlear implantation
Does not reverse effects of unilateral stimulation
Abnormal asymmetry of brainstem and cortical activity
Abnormal binaural processing
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Conclusion
Simultaneous bilateral cochlear implantation
offers a cost-effective way to promote
symmetric development and function along
the bilateral auditory pathways and to
establish binaural hearing for children who
are deaf.
Phonak Latin American Pediatric Conference III, Buenos Aires, Argentina, October 11-13, 2012
Thank you to all of our participants