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Long-term outcome on spoken word recognition ability of young children with cochlear implants
International Congress Series 1273 (2004) 300 – 303
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Long-term outcome on spoken word recognition ability of young children with cochlear implants Kathy Yuet Sheung Lee*, Charles Andrew van Hasselt Division of Otorhinolaryngology, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, SAR
Abstract. Objective: To study the effect of age at implantation and duration of implant use on the performance of spoken word recognition of paediatric cochlear implantees in a tonal language setting over a period of 5 years. Study design: Sixty-four children, implanted at age from 1:01 to 14:09, were divided into three age groups. They were tested on the open-set word recognition ability at seven time intervals from pre-operation to 5 years post-surgery. Results: The factor of implant experience was significant in children’s spoken word recognition across the three age groups ( Pb0.01). Children implanted below the age of three caught up with the performance of the older children at 12 months following implantation. Conclusion: Continuous improvement in spoken word recognition performance was noted in all children irrespective of their age at implantation. Children implanted below the age of three improved at a slower rate before 1 full year of implant use. By 2 years of implant use, the performance of the young children had bypassed the older children and sustained the highest scores throughout to 5 years post-operation. D 2004 Elsevier B.V. All rights reserved. Keywords: Cantonese; Word recognition; Age at implantation; Long-term outcome; Implant experience
1. Introduction Cochlear implants have shown to be superior than hearing aids in assisting profoundly hearing-impaired children to achieve better speech perception performance. Continuous improvement was noted even after 3 years of implant use [1,2]. Besides the effect of implant experience, children implanted at earlier ages were also found to have better speech perception performance [3,4]. The evidence documented so far, however, were all based on English-speaking population. Research data on outcome measures in tonal
* Corresponding author. Tel.: +852 2632 3310; fax: +852 2632 4677. E-mail address: [email protected] (K.Y.S. Lee). 0531-5131/ D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2004.09.013
K.Y.S. Lee, C.A. van Hasselt / International Congress Series 1273 (2004) 300–303
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languages were relatively scarce [5,6]. None of the study involved open-set tests with implant experience of more than 36 months. The purpose of the present study was to investigate the effect of age at implantation and implant experience on the performance of word recognition ability of a group of Cantonese-speaking children over a 5-year period. 2. Materials and methods 2.1. Subjects Sixty-four children, implanted at age from 1:01 to 14:09 (mean=6:01), were included. All subjects had unilateral cochlear implant for at least 1 year. According to their age of receiving implants, the children were divided into three groups—those received implants at below 3:00 (n=15), from 3:00 to 6:00 (n=18) and older than 6:00 (n=31). 2.2. Material An open-set word recognition test consisting of mono- and di-syllabic Cantonese words was devised. 2.3. Methods The test was performed at pre-operation, 0.5, 1, 2, 3, 4 and 5 years post-surgery. After monitored live voice presentations, subjects were asked to repeat the stimuli perceived. For subjects with limited verbal expressive ability, response modes of written words, gestures and drawings were also accepted. Scores were expressed as the percentage of words correctly perceived by the subjects. ANOVAs were employed to explore the effect of implant experience and age of implantation on the word recognition scores. 3. Results Table 1 shows the descriptive statistics of the word recognition scores of the three age groups over time. Great individual variations were noted as shown in the high values of standard deviations. The development of the subjects’ performance on word recognition was depicted in Fig. 1.
Table 1 Descriptive statistics of the word recognition scores of the three subject groups at various test time intervals 3:00–6:00
b3:00 Pre-op 6 months 1 year 2 years 3 years 4 years 5 years
N6:00
Mean
S.D.
Mean
S.D.
Mean
S.D.
0.00 10.33 38.93 76.64 88.75 83.00 85.00
0.00 27.29 42.22 28.71 14.02 15.38 11.94
3.72 16.50 37.42 51.50 67.58 67.55 76.90
15.79 34.92 43.60 40.95 29.28 34.05 24.28
4.61 37.18 41.71 42.50 49.01 66.09 57.87
13.32 40.67 42.42 39.97 32.82 26.24 33.34
302
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Fig. 1. Mean word recognition score of the three age groups across the seven test intervals.
Using the mean word recognition score as the dependent variable, ANOVA results indicated a significant main effect of implant experience across all the three age groups with P-values b0.01. As for the age at implantation, the effect was significant at 6 months, 2 years and 3 years post-operation with P-values of 0.04, 0.03 and 0.00, respectively, as shown in Table 2. Post-hoc tests were subsequently performed on the three time intervals. Significant group differences were noted between children implanted below 3 and above 6 years old at P-value b0.05. All other between group differences were insignificant. Results of the posthoc tests were summarized in Table 3. 4. Discussion 4.1. Implant experience In general, a positive relationship between a child’s implant experience and his word recognition performance was noted. The improvement in performance was particularly marked when compared with one’s pre-operative condition where hearing aids were used. The results obtained were consistent with those found in the English-speaking and Frenchspeaking children [2–4]. The benefit of cochlear implant seems be able to apply to children over a diversified language background including Cantonese. Further improvement on children’s word recognition ability is expected based on the fact that scores have been increasing continuously over the years. We believe a child’s word recognition score could serve as a good outcome indicator for long-term measurement as it entails and captures the speech perception development with no ceiling effect being noted within our 5-year period. Table 2 P-values of the age at implantation on word recognition scores as revealed by ANOVA at different time intervals P-value Pre-op 6 months 1 year 2 years 3 years 4 years 5 years
0.50 0.04 0.94 0.03 0.00 0.34 0.18
K.Y.S. Lee, C.A. van Hasselt / International Congress Series 1273 (2004) 300–303
303
Table 3 P-values of the age at implantation on word recognition scores as revealed by post-hoc multiple group comparisons at the three time intervals 6 months 2 years 3 years
b3:00
3:00–6:00
N6:00
b3:00 3:00–6:00 b3:00 3:00–6:00 b3:00 3:00–6:00
0.92
0.04 0.21 0.01 0.87 0.00 0.08
0.17 0.12
4.2. Age at implantation The present study showed significant differences in the word recognition performance between the groups of children who received their implant early (b3:00) and late (N6:00) at 6 months, 2 years and 3 years post-operatively. The superior performance of the older children at 6-month interval may be due to (1) their better language skills, (2) their readiness to take formal tests and (3) the fact that they represented the group who were relatively easy to map and therefore attained the most suitable level of stimulation at the shortest period of time required. For children who received their implant below the age of three, the improvement rate was slower in the first year. Over time, when these younger children began to build sufficient language foundation, together with improved test compliance, they bypassed the older children and had significantly higher scores at 2 and 3 years post-surgery. The younger children remained as the group with the highest score throughout 5 years postoperation. The results suggest that children receive implant at earlier age have better outcomes in the long run. Time for development of cognitive and basic language skills is, nevertheless, essential before the benefits on the speech perception could be noted. References [1] A. Geers, J. Moog, Spoken language results: vocabulary, syntax, and communication, Volta Review 96 (5) (1994) 131 – 148. [2] M. Mondain, et al., Speech perception skills and speech production intelligibility in French children with prelingual deafness and cochlear implants, Archives of Otolaryngology-Head and Neck Surgery 123 (2) (1997) 181 – 184. [3] I.K. Kirk, et al., Effect of age at implantation in young children, Annals of Otology, Rhinology and Laryngology 111 (2002) 69 – 73. [4] T.A. Zwolan, et al., Pediatric cochlear implant patient performance as a function of age at implantation, Otology and Neurotology 25 (2) (2004) 112 – 120. [5] J.L. Wu, H.M. Yang, Speech perception of Mandarin Chinese speaking young children after multichannel cochlear implantation, in: T. Kubo, Y. Takahashi, T. Iwaki (Eds.), Cochlear implants—an update, Kugler, the Hague, The Netherlands, 2002, pp. 353 – 359. [6] V. Yue, et al., Cochlear implantation in Chinese children, Advances in Oto-Rhino-Laryngology 57 (2000) 220 – 223.
www.ics-elsevier.com
Long-term outcome on spoken word recognition ability of young children with cochlear implants Kathy Yuet Sheung Lee*, Charles Andrew van Hasselt Division of Otorhinolaryngology, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, SAR
Abstract. Objective: To study the effect of age at implantation and duration of implant use on the performance of spoken word recognition of paediatric cochlear implantees in a tonal language setting over a period of 5 years. Study design: Sixty-four children, implanted at age from 1:01 to 14:09, were divided into three age groups. They were tested on the open-set word recognition ability at seven time intervals from pre-operation to 5 years post-surgery. Results: The factor of implant experience was significant in children’s spoken word recognition across the three age groups ( Pb0.01). Children implanted below the age of three caught up with the performance of the older children at 12 months following implantation. Conclusion: Continuous improvement in spoken word recognition performance was noted in all children irrespective of their age at implantation. Children implanted below the age of three improved at a slower rate before 1 full year of implant use. By 2 years of implant use, the performance of the young children had bypassed the older children and sustained the highest scores throughout to 5 years post-operation. D 2004 Elsevier B.V. All rights reserved. Keywords: Cantonese; Word recognition; Age at implantation; Long-term outcome; Implant experience
1. Introduction Cochlear implants have shown to be superior than hearing aids in assisting profoundly hearing-impaired children to achieve better speech perception performance. Continuous improvement was noted even after 3 years of implant use [1,2]. Besides the effect of implant experience, children implanted at earlier ages were also found to have better speech perception performance [3,4]. The evidence documented so far, however, were all based on English-speaking population. Research data on outcome measures in tonal
* Corresponding author. Tel.: +852 2632 3310; fax: +852 2632 4677. E-mail address: [email protected] (K.Y.S. Lee). 0531-5131/ D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2004.09.013
K.Y.S. Lee, C.A. van Hasselt / International Congress Series 1273 (2004) 300–303
301
languages were relatively scarce [5,6]. None of the study involved open-set tests with implant experience of more than 36 months. The purpose of the present study was to investigate the effect of age at implantation and implant experience on the performance of word recognition ability of a group of Cantonese-speaking children over a 5-year period. 2. Materials and methods 2.1. Subjects Sixty-four children, implanted at age from 1:01 to 14:09 (mean=6:01), were included. All subjects had unilateral cochlear implant for at least 1 year. According to their age of receiving implants, the children were divided into three groups—those received implants at below 3:00 (n=15), from 3:00 to 6:00 (n=18) and older than 6:00 (n=31). 2.2. Material An open-set word recognition test consisting of mono- and di-syllabic Cantonese words was devised. 2.3. Methods The test was performed at pre-operation, 0.5, 1, 2, 3, 4 and 5 years post-surgery. After monitored live voice presentations, subjects were asked to repeat the stimuli perceived. For subjects with limited verbal expressive ability, response modes of written words, gestures and drawings were also accepted. Scores were expressed as the percentage of words correctly perceived by the subjects. ANOVAs were employed to explore the effect of implant experience and age of implantation on the word recognition scores. 3. Results Table 1 shows the descriptive statistics of the word recognition scores of the three age groups over time. Great individual variations were noted as shown in the high values of standard deviations. The development of the subjects’ performance on word recognition was depicted in Fig. 1.
Table 1 Descriptive statistics of the word recognition scores of the three subject groups at various test time intervals 3:00–6:00
b3:00 Pre-op 6 months 1 year 2 years 3 years 4 years 5 years
N6:00
Mean
S.D.
Mean
S.D.
Mean
S.D.
0.00 10.33 38.93 76.64 88.75 83.00 85.00
0.00 27.29 42.22 28.71 14.02 15.38 11.94
3.72 16.50 37.42 51.50 67.58 67.55 76.90
15.79 34.92 43.60 40.95 29.28 34.05 24.28
4.61 37.18 41.71 42.50 49.01 66.09 57.87
13.32 40.67 42.42 39.97 32.82 26.24 33.34
302
K.Y.S. Lee, C.A. van Hasselt / International Congress Series 1273 (2004) 300–303
Fig. 1. Mean word recognition score of the three age groups across the seven test intervals.
Using the mean word recognition score as the dependent variable, ANOVA results indicated a significant main effect of implant experience across all the three age groups with P-values b0.01. As for the age at implantation, the effect was significant at 6 months, 2 years and 3 years post-operation with P-values of 0.04, 0.03 and 0.00, respectively, as shown in Table 2. Post-hoc tests were subsequently performed on the three time intervals. Significant group differences were noted between children implanted below 3 and above 6 years old at P-value b0.05. All other between group differences were insignificant. Results of the posthoc tests were summarized in Table 3. 4. Discussion 4.1. Implant experience In general, a positive relationship between a child’s implant experience and his word recognition performance was noted. The improvement in performance was particularly marked when compared with one’s pre-operative condition where hearing aids were used. The results obtained were consistent with those found in the English-speaking and Frenchspeaking children [2–4]. The benefit of cochlear implant seems be able to apply to children over a diversified language background including Cantonese. Further improvement on children’s word recognition ability is expected based on the fact that scores have been increasing continuously over the years. We believe a child’s word recognition score could serve as a good outcome indicator for long-term measurement as it entails and captures the speech perception development with no ceiling effect being noted within our 5-year period. Table 2 P-values of the age at implantation on word recognition scores as revealed by ANOVA at different time intervals P-value Pre-op 6 months 1 year 2 years 3 years 4 years 5 years
0.50 0.04 0.94 0.03 0.00 0.34 0.18
K.Y.S. Lee, C.A. van Hasselt / International Congress Series 1273 (2004) 300–303
303
Table 3 P-values of the age at implantation on word recognition scores as revealed by post-hoc multiple group comparisons at the three time intervals 6 months 2 years 3 years
b3:00
3:00–6:00
N6:00
b3:00 3:00–6:00 b3:00 3:00–6:00 b3:00 3:00–6:00
0.92
0.04 0.21 0.01 0.87 0.00 0.08
0.17 0.12
4.2. Age at implantation The present study showed significant differences in the word recognition performance between the groups of children who received their implant early (b3:00) and late (N6:00) at 6 months, 2 years and 3 years post-operatively. The superior performance of the older children at 6-month interval may be due to (1) their better language skills, (2) their readiness to take formal tests and (3) the fact that they represented the group who were relatively easy to map and therefore attained the most suitable level of stimulation at the shortest period of time required. For children who received their implant below the age of three, the improvement rate was slower in the first year. Over time, when these younger children began to build sufficient language foundation, together with improved test compliance, they bypassed the older children and had significantly higher scores at 2 and 3 years post-surgery. The younger children remained as the group with the highest score throughout 5 years postoperation. The results suggest that children receive implant at earlier age have better outcomes in the long run. Time for development of cognitive and basic language skills is, nevertheless, essential before the benefits on the speech perception could be noted. References [1] A. Geers, J. Moog, Spoken language results: vocabulary, syntax, and communication, Volta Review 96 (5) (1994) 131 – 148. [2] M. Mondain, et al., Speech perception skills and speech production intelligibility in French children with prelingual deafness and cochlear implants, Archives of Otolaryngology-Head and Neck Surgery 123 (2) (1997) 181 – 184. [3] I.K. Kirk, et al., Effect of age at implantation in young children, Annals of Otology, Rhinology and Laryngology 111 (2002) 69 – 73. [4] T.A. Zwolan, et al., Pediatric cochlear implant patient performance as a function of age at implantation, Otology and Neurotology 25 (2) (2004) 112 – 120. [5] J.L. Wu, H.M. Yang, Speech perception of Mandarin Chinese speaking young children after multichannel cochlear implantation, in: T. Kubo, Y. Takahashi, T. Iwaki (Eds.), Cochlear implants—an update, Kugler, the Hague, The Netherlands, 2002, pp. 353 – 359. [6] V. Yue, et al., Cochlear implantation in Chinese children, Advances in Oto-Rhino-Laryngology 57 (2000) 220 – 223.