Biomedical subjects

G Thoonen

Publications and source records attributed to G Thoonen.

7 recordsLinked to original sources

PubMed2003

[The Noonan syndrome from a pediatric perspective].

Noonan syndrome is a relatively common autosomal dominant condition characterised by cardiac defects, short stature, feeding difficulties during the first year of life, and learning and behavioural problems later in life. The diagnosis is clinical and in 50% of cases it can be confirmed by a mutation in the PTPN11 gene. Studies into the effect of growth hormone treatment on final height have yet to provide any definite conclusions. Therefore, for the time being this treatment should be carried out in a research setting. Early-childhood feeding difficulties are troublesome. However, these disappear spontaneously and do not seem to negatively affect growth. Specific developmental patterns, resulting in behavioural and learning problems (non-verbal learning disability) are frequently encountered and require a specific approach.

Body Height↗

PubMed1999

Patterns of cognitive functioning in school-aged children with Noonan syndrome associated with variability in phenotypic expression.

OBJECTIVE: To evaluate the cognitive profiles of children with Noonan syndrome (NS) and to relate these profiles to measures of overall clinical severity. STUDY DESIGN: Thirty-five children with NS between the ages of 7 and 18 years were tested on their intellectual, psychosocial, and academic functioning. The diagnosis of NS was established on the presence of a typical face, the characteristic heart defect, thorax deformity, short stature, affected first-degree relative(s), and cryptorchidism in male subjects. RESULTS: The total group of children with NS (n = 35) achieved significantly lower mean full-scale IQ, verbal IQ (VIQ), and performance IQ (PIQ) scores (between 85.9 and 89.3) than expected based on normative data. The individual full-scale IQ scores varied between 48 and 130. Because of this wide range of individual scores, the mean group values are not extremely informative. The mean full-scale IQ for the group with moderate NS (n = 19) is 90.8; for the children with severe NS (n = 16) the mean full-scale IQ is 80.6. The patterns of discrepancies between VIQ and PIQ are: (1) an extreme discrepancy between VIQ and PIQ is most likely to emerge in children with severe NS with (low) average intellectual abilities; (2) children with moderate NS are more likely to attain similarities in VIQ and PIQ scores; and (3) children with moderate NS demonstrate a particular pattern of discrepancy between VIQ and PIQ (ie, VIQ > PIQ). CONCLUSION: For children with NS, the findings on physical examination are indicative of the pattern of cognitive abilities. NS is not associated with substantial deficits in the level of intellectual functioning or with a single/unitary cognitive pattern. Severe NS expression, however, predicts in part a specific pattern of deficits and capacities in cognitive functioning.

Adolescent↗

PubMed1997

Towards a standardised assessment procedure for developmental apraxia of speech.

This study addresses the assessment of developmental apraxia of speech (DAS) in children. For this, 11 children with a clear diagnosis of DAS were selected, based on documented speech history and perceptual evaluation of speech. The children with DAS, as well as 11 normal-speaking children, produced singleton real word and nonsense word imitations elicited in a standardised way. Phonetic transcriptions were analysed and errors in consonants classified. The results showed, firstly, that the children with DAS produced similar types of consonant errors as has been reported in the literature, which corroborates the method of elicitation as a valid procedure to assess relevant speech symptoms of DAS. Secondly, a large quantitative difference between children with DAS and normal-speaking children was found, in that children with DAS produced an overall higher rate of singleton consonant errors (substitutions, omissions, distortions) and cluster errors (cluster reductions) than the normal-speaking children. For the DAS group, the substitution-rate, particularly in real words (as opposed to nonsense words), was significantly correlated with severity as rated by two speech and language pathologists. This suggests that substitution-rate yields an adequate measure of severity of DAS. Thirdly, a qualitative difference between both subject groups emerged. Children with DAS did not benefit from the lexical status of the utterance (real versus nonsense word) to the same extent as normal-speaking children. Based on these findings the nature of the underlying deficits in speech production in DAS is discussed.

Apraxias↗

PubMed1996

The specific relation between perception and production errors for place of articulation in developmental apraxia of speech.

Developmental apraxia of speech is a disorder of phonological and articulatory output processes. However, it has been suggested that perceptual deficits may contribute to the disorder. Identification and discrimination tasks offer a fine-grained assessment of central auditory and phonetic functions. Seventeen children with developmental apraxia (mean age 8:9, years:months) and 16 control children (mean age 8:0) were administered tests of identification and discrimination of resynthesized and synthesized monosyllabic words differing in place-of-articulation of the initial voiced stop consonants. The resynthetic and synthetic words differed in the intensity of the third formant, a variable potentially enlarging their clinical value. The results of the identification task showed equal slopes for both subject groups, which indicates no phonetic processing deficit in developmental apraxia of speech. The hypothesized effect of the manipulation of the intensity of the third formant of the stimuli was not substantiated. However, the children with apraxia demonstrated poorer discrimination than the control children, which suggests affected auditory processing. Furthermore, analyses of discrimination performance and articulation data per apraxic subject demonstrated a specific relation between the degree to which auditory processing is affected and the frequency of place-of-articulation substitutions in production. This indicates the interdependence of perception and production. The results also suggest that the use of perceptual tasks has significant clinical value.

Apraxias↗

PubMed1994

Feature analysis of singleton consonant errors in developmental verbal dyspraxia (DVD).

The aim of this study is to quantify diagnostic characteristics related to consonant production of developmental verbal dyspraxia (DVD). For this, a paradigmatic and syntagmatic feature-value analysis of the consonant substitution and omission errors in DVD speech was conducted. Following a three-step procedure, eleven clear cases were selected from a group of 24 children with DVD. The consonants produced in a word and nonsense-word imitation task were phonetically transcribed and transferred to confusion matrices, which allows for a feature and feature-value analysis. The analysis revealed that children with DVD (a) show low percentages of retention for place and manner of articulation and voicing, due to high substitution and omission rates; (b) show a particularly low percentage of retention of place of articulation in words, which, together with error rate, is strongly related to severity of involvement; (c) are inconsistent in their feature realization and feature preference; and (d) show a high syntagmatic error rate. These results form a quantification of diagnostic characteristics. Unexpectedly, however, very few qualitative differences in error pattern were found between children with DVD and a group of 11 age-matched children with normal speech. Thus, although the children with DVD produced higher substitution and omission rates than children with normal speech, the speech profiles of both subject groups are similar. This result stresses the importance of interpreting profiles, not isolated symptoms. The hypothesis to consider DVD as a deficit in the phonological encoding process is discussed.

Apraxias↗

PubMed1994

Traumatic versus perinatally acquired dysarthria: assessment by means of speech-like maximum performance tasks.

The performance of two children with traumatic spastic dysarthria, aged 10 and 14 years, on maximum performance tasks was compared with that of two closely matched children with perinatal spastic dysarthria, and reference groups of five children with perinatal spastic dysarthria and five control children with normal speech. Results showed that performance of the perinatal spastic children on all three tasks was poorer than that of their peers with normal speech. In contrast, the traumatic spastic children performed within the normal limits on maximum sound prolongation and fundamental frequency range, but their maximum repetition rate was extremely slow. The overall low performance of the perinatal spastic children could be the result of inadequate motor development in addition to the neurological impairment. The traumatic spastic children--with a normal developmental history--compensated for their impairment by slowing down their speech rate. Therapeutic implications are suggested.

Adolescent↗

PubMed1993

Maximum performance tests in children with developmental spastic dysarthria.

Three noninvasive Maximum Performance Tasks (MPT)--Maximum Sound Prolongation (MSP), Fundamental Frequency Range (FFR), and Maximum Repetition Rate (MRR)--were administered to 11 children with spastic dysarthria due to cerebral palsy and to 11 control children with normal speech in order to determine the value of the tasks for differentiating between these groups of children. From the acoustic measurements, nine parameters were calculated, and in seven of them highly significant group differences were found. By adding the unweighted z-scores of four parameters (maximum sound prolongation, syllable duration, fundamental frequency range, inter-utterance variability of syllable duration), a composite z-score was constructed with nonoverlapping distributions for both groups. The authors conclude that maximum performance tasks, despite the large intrasubject and intersubject variability in both normal and pathological speakers, are powerful tools for detecting spastic dysarthria.

Age Factors↗