Electrophysiological assessment of auditory plasticity after relatively long intervals of sequential cochlear implantation

Transcription

1 Electrophysiological assessment of auditory plasticity after relatively long intervals of sequential cochlear implantation Andy J Beynon, Marloes Sparreboom, Ad FM Snik, Emmanuel Mylanus Radboud University Medical Centre - ENT Dept Donders Institute for Brain, Cognition and Behaviour Centre for Neuroscience The Netherlands KNO - NVA vergadering 18 november 2010

2 Intro Sharma et al (2002): CI after 7 years abnormal cortical development (unilateral CI) Bauer et al (2006) & Sharma et al (2005): interval between first & second CI < 1 year: second ear is able to catch up (electrophysiological data) Peters et al (2007) & Wolfe (2007): 2nd CI before age of 4 > CI1=CI2 (behavioral data)

3 Project goals Main project: a multidisciplinary approach to evaluate Psycho-acoustical capacities Language comprehension & development Neurophysiological changes from cochlea to cortex This presentation: electrophysiological data from brainstem & cortical level with relatively long period between CI1 and CI2

4 Characteristics E-EAPs Differences between ABR and EABR? Differences between ACR and EACR?

5 Characteristics E-EAPs ABR R - BERA kdrempel 70 EABR L - N24 AS (tr1) V I II I III III IV III V V V IPSI ms 500nV 70 dbnhl 2000(40) IPSI ms 500nV 50 dbnhl 2000(16) IPSI ms 500nV 30 dbnhl 2000 V IPSI ms 500nV 20 dbnhl 2000(17) V IPSI ms 500nV 10 dbnhl V 2000(13) IPSI ms 500nV 5 dbnhl 2000 > I/O slope EABR steeper compared to ABR II II II II II II III III III III III III V V V V V ms 1µV 1906( ms 1µV 1536(8) ms 1µV 885(5) ms 1µV ms 1µV ms 1µV 1015(2) ms 500nV 1952(

6 Characteristics E-EAPs Electrically-evoked auditory cortical response (EACR) Characteristics of EACR = ACR

7 Interpretation of EACRs (effect pulse train duration) t 0 P1 P2 Single pulse N1 5 ms pulse train 10 ms p.t. 20 ms p.t. 80 ms p.t. 100 ms p.t. 300 ms p.t. Beynon AJ, internal report 2008

8 Aims present study Determine whether: 1. EABR/EACR latencies evoked by stimulation with CI2 become comparable with those evoked by CI1? 2. inter-implant delay between CI1-CI2 influence auditory maturation after extended unilateral deafness? 3. maturation is age-appropriate and whether it is comparable with those of the children with unilateral CI

9 Subjects N = 30 Children Bilaterally-implanted Nucleus 24 CI system First CI (CI1) received between 11m 2y;8m Second CI (CI2) received between 2y;5m 8y;6m Sequentially-implanted: mean interval 42 months (i.e. relatively long period between CI1 and CI2)

10 Methods - Electrically-evoked Auditory Brainstem (EABR) and Cortical (EACR) Responses: direct electrical stimulation by the speech processor - Comparison of the 1st and 2nd implants: 6, 12 and 24 months postactivation - Analyses: - EABR: latencies of brainstem components wave III, V & IWI - EACR: latencies of cortical components P1, N1, P2 (withinand between-ear analyses)

11 Wave III latency (ms) Results EABR wave III 2,30 first implant 2,20 2,10 second implant *p <.05 ** p <.01 2,00 1,90 1,80 1,70 1,60 1,50 intraoperative n=20 6 months n=20 12 months n=18 24 months n=26

12 Wave V latency (ms) Results EABR wave V 4,30 4,20 4,10 first implant second implant *p <.05 ** p <.01 4,00 3,90 3,80 3,70 3,60 3,50 intraoperative n = 23 6 months n=25 12 months n=27 24 months n=29

13 Interwave III-V latency (ms) Results EABR IWI III-V 2,40 2,30 first implant second implant *p <.05 ** p <.01 2,20 2,10 ** 2,00 1,90 ** ** ** 1,80 1,70 1,60 intraoperative n=18 6 months n=20 12 months n=17 24 months n=26

14 Example EACR (CI1 vs CI2)

15 Results P1 latency

16 Results N1 latency

17 Results P2 latency

18 Conclusions - Maturational effects in all EAP-components - EABR: age at 2 nd implantation had no effect on the interaural latency differences of the EABR. - EACR: prolonged latencies of CI2 compared to CI1 - Improvement of neural conduction of CI1 follows normal development - Neural conduction is still in favour of CI1

19 Maturation over time CI1 vs UNI & NH

20 11-24 months CI1 93%

21 (Conclusions) - children with relatively long intervals between CI1 and CI2 are still able to catch up with respect to the first implant - critical age for CI1 surgery for children undergoing sequential implantation is likely to be before the age of 3.5 years

22 Results P1 latency Future?

23 Thanks for your attention and.

24 Welcome to Amsterdam! Dr. Emmanuel Mylanus Dr. Andy Beynon Prof. Johan Frijns Dr. Jeroen Briaire Radboud University Medical Centre Leiden University Medical Centre