Contents

Chapter 1 [contents]

Chapter 1 is a general introduction to the thesis. It describes the controversy regarding the relevance of intra-oral infant orthopaedics, a treatment that is used throughout the world in managing babies with cleft lip and palate. Proponents of IO believe that it enhances feeding, narrows the cleft, results in better facial aesthetics, and leads to better speech development. Opponents state that the treatment is expensive, inhibits maxillary growth, and increases dental caries. Most of these statements are based on case reports, clinical intuition, and personal preference. In order to provide the discussion on the value of IO with sound, scientifically based arguments, the Dutchcleft study started in 1993. It comprises four research areas: general aspects, surgical and orthodontic aspects, speech and language development, and a cost-effectiveness analysis. A total number of 54 children with complete UCLP participated in the trial. One group (n=27) received IO according to a modified Zurich approach in the first 12 months of life (IO group), and the other group (n=27) was not treated with IO (non-IO group).

Chapter 2 [contents]

Chapter 2 focuses on the effects of IO on pre-lexical development at age 1 and 1.5. It was hypothesised that during the application of IO (until age one), the child would be able to develop more normal sensori-motor patterns in babbling, because the appliance creates an artificial alveolar ridge and covers the cleft in the hard palate. Consequently, we expected to find an enhanced use of alveolar sounds and high pressure sounds in babbling of IO babies. The assessment of contoid usage showed that, at the age of one, babies in the IO group used significantly more alveolar contoid sounds in their babbling than the non-IO babies. In normal speech development, alveolar sounds are predominant at this age. So, compared to the non-IO group, the IO children used a phonetic repertoire that was closer to normal than the non-IO children at age one. At 1.5 years of age, when the IO group did no longer use the orthopaedic appliance, there were no apparent differences in characteristics of babbling between the two groups. This seemed to suggest that the effects of IO were temporary and only present during the period in which the IO is applied.

Chapter 3 [contents]

In Chapter 3, the phonological development of the groups between age 2 and 3 was described. Since the babbling period is demonstrated to be related to the development of later speech, a beneficial effect of IO treatment in the pre-lexical period may also influence the phonological development in meaningful speech. In this light, it was hypothesised that the better opportunities to practice and establish normal speech motor patterns in the IO group would result in a phonological development that is closer to normal than when treated without IO. The phonological skills of the children were analysed by means of a system for the assessment of phonological development of Dutch children (Fonologische Analyse van het Nederlands: FAN). The phonological analysis in this thesis included the number of acquired consonants, order of phonological development, use of phonological processes, and occurrence of nasal escape. There were no differences between the groups in the use of phonological processes or the occurrence of nasal escape at either age. Furthermore, the groups did not differ in the order of phonological development at age 2. At 2.5 years of age, however, the order of phonological development of most IO children was normal or delayed, whereas most non-IO children followed an abnormal developmental pattern. At three years of age, the IO group had acquired more initial consonants than the non-IO group. In conclusion, the children who were treated with IO during their first year of life followed a more normal path of phonological development between two and three years of age.

Chapter 4 [contents]

Chapter 4 describes an experiment with 16 lay listeners who assessed speech intelligibility of the children at age 2.5. Three groups were included in the experiment: IO (n=10), non-IO (n=10) and non-cleft (n=8). The listeners first performed a write-down task, in which they indicated in normal spelling what they had understood of the utterance. After the transcription of the sample, the listeners rated the intelligibility of the speech sample on a ten-point equal-appearing-interval (EAI) scale. From the write-down task, the percentage of words correctly understood was calculated. The ratings in this experiment did not correlate perfectly with the percentage of words correctly understood. This was manifested in the results: the IO group obtained higher intelligibility ratings when compared to the non-IO group, however, this was not reflected in a better write-down score for this group. In the write-down task, the listeners did not better understand the speech of the IO children. Furthermore, when the intelligibility ratings for both cleft groups were tested against the control group of non-cleft peers, the difference in judged intelligibility between the IO and non-IO group was not significant. Therefore, it is not clear whether the higher ratings for intelligibility in the IO actually signify that IO improved the intelligibility of the speech.

Chapter 5 [contents]

Chapter 5 describes a more comprehensive perceptual evaluation with a panel of five expert listeners. In this experiment too, the speech of the two cleft groups (IO, n=10; non-IO, n=10) was compared to a non-cleft control group (n=8) of the same age. It was expected that treatment with IO would positively influence speech quality because IO facilitates the development of more normal speech patterns. In order to assess all relevant characteristics of cleft palate speech, the panel of expert listeners judged 13 specific speech aspects on seven-point EAI scales. Furthermore, they indicated their total impression of the children’s speech quality on a ten-point scale. Finally, they estimated the number of speech therapy sessions that in their opinion were needed in the year following the assessment.The reliability and consistency of 12 of the rating scales was good. Three scales: ‘fronting’, ‘nasal snort’, and ‘nasal realisation’ were excluded from analysis because of low reliability or consistency. Significant differences between the non-cleft group and the cleft groups were present on all 12 scales except for the characteristics ‘palatalisation’ and ‘lateralisation’. These speech characteristics were equally present in all three groups. All other speech errors were scored as being most distinct in the two groups with cleft. The non-cleft children’s speech obtained the highest scores for ‘intelligibility’ and ‘correctness of articulation’. There was only one speech aspect that distinguished the IO group from the non-IO group, i.e. the scale ‘intelligibility’. The IO group obtained significantly higher intelligibility ratings than the non-IO group, indicating that the intelligibility of the speech in the IO group was judged to be superior by the expert listeners.

Chapter 6 [contents]

Chapter 6 focuses on the language development. At the age of 2, 2.5, and 3 years language development was evaluated in 12 children (6 IO and 6 non-IO). Eleven of these children (6 IO and 5 non-IO) were also assessed in a follow-up at age six. Receptive language skills were assessed by means of the Dutch version of the Reynell Developmental Language Scales. Expressive language skills of the toddlers were evaluated by calculating mean length of utterance (MLU) and mean length of longest utterances (MLLU); in the 6-year-olds the expressive language skills were measured by means of standardised Dutch language tests (Taaltests voor Kinderen and Schlichting test). The results showed no differences in receptive language skills between the IO and non-IO group. The expressive language measures MLU and MLLU, however, were influenced by IO treatment. At age 2.5 and 3 years, the children who were treated with IO in their first year of life produced statistically significant longer utterances than the non-IO group. In the follow-up at six years, the difference in productive language between the two groups was no longer significant. Hence, in this relatively small group, IO treatment did not prove to have long lasting effects on language development.

Chapter 7 [contents]

Chapter 7 discusses the relationship between phonetic characteristics in the pre-lexical period and development of speech and language at age 2.5 years in the light of IO treatment. Such a relationship may have important implications for therapeutic management and speech intervention, and it may help to understand the effects of IO on speech and language development. In this evaluation only the two groups of children with UCLP were involved. Phonetic characteristics that were included as predictors were the use of alveolar contoids and oral plosives in babbling at age 1 and 1.5. Outcome variables were measured at 2.5 years and comprised two aspects of phonological development (i.e. the number of acquired consonants and the complexity of the phonological system of contrasts), expert judgements on four rating scales (i.e. intelligibility, palatalisation, lateralisation, and backing), and the mean length of utterance (MLU). The results indicated that a higher use of oral plosives in babbling of 1.5-year-old children with UCLP was associated with better intelligibility and higher MLU at age 2.5. Furthermore, a higher occurrence of alveolar contoids in babbling at age 1.5 predicted less compensatory articulation (i.e. less palatalisation, less lateralisation, and less backing) in speech at age 2.5. It could not be established in this investigation whether the correlation between alveolar contoids in babbling at age 1.5 and less compensatory articulation at age 2.5 was directly related to treatment with the infant orthopaedic.

Chapter 8 [contents]

In Chapter 8 the cost-effectiveness analysis of IO treatment compared to no such treatment focusing on the speech of the children at the age of 2.5 years is described. The measure for effectiveness on speech was the ‘total impression of speech quality’ rated by the panel of expert listeners (see Chapter 5). There was a statistically significant beneficial effect of IO on this effect measure. Since a statistically significant difference may not be synonymous with a clinically important change, the clinical importance was determined by calculating the magnitude or the size of the effect produced by the intervention. The effect size in this investigation showed that the effect of IO on the ‘total impression of speech quality’ was large, indicating that the improvement was clinically important. Obviously, the costs for treatment by the orthodontist in the IO group were significantly higher than in the non-IO group. For both groups the mean cost were related to the mean rating for ‘total impression of speech quality’. The resulting cost-effectiveness for IO compared to non-IO was € 1,041 for 1.34 point speech quality improvement. Relative to the costs that are spent on the comprehensive treatment of children with cleft lip and palate, the financial investment that is necessary to obtain this improvement seems limited. Moreover, since it is plausible that children in the IO group would need less intensive speech therapy, part of the costs for IO treatment may be outweighed by costs prevented for speech therapy in later years. Thus it was concluded that from the perspective of speech development the cost-effectiveness of IO over non-IO seems acceptable.

Chapter 9  [contents]