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Biomedical subjects

B Maassen

Publications and source records attributed to B Maassen.

At least 19 recordsLinked to original sources
PubMed2006

Arnold-Chiari-II malformation and cognitive functioning in spina bifida.

Spina bifida is a multifaceted neurological condition with complex neuropsychological sequelae. The cognitive outcome in spina bifida has frequently been attributed to the severity of the hydrocephalus. However, because of complex neuropathology, the influence of hydrocephalus alone does not sufficiently explain the deficits in the cognitive profile in spina bifida. To date, little is known of the role of Arnold-Chiari-II malformation (ACM) in the cognitive profile of these patients. Aim of the current study is to delineate the specific contribution of the ACM in spina bifida by comparing children with ACM and those without ACM. 46 children between 6 and 15 years of age underwent a neuropsychological assessment covering intelligence and a wide range of cognitive functions, such as visuo-motor processing, attention, memory, word fluency and speed of information processing. Comparisons were made between patients with ACM (ACM+) and those without ACM (ACM-); all children with ACM+ also had hydrocephalus. Confounding effects of global cognitive impairment were excluded, such that groups were matched on verbal IQ. Because of complex neuropathology, which is inherent to spina bifida, the method applied was based on a comparison of cognitive profiles of the study group with profiles of patients with cerebellar damage and hydrocephalus found in the literature. Impaired visual analysis and synthesis, verbal memory, and verbal fluency, even after correction for global cognitive impairment, were observed in children with ACM. The hypothesis that in addition to impairment in visual analysis and synthesis, which are related to both hydrocephalus and ACM, specific deficiencies in verbal memory and fluency may be attributed to ACM is supported.

Adolescent↗
PubMed1999

The maturation of auditory cortical evoked responses between (preterm) birth and 14 years of age.

In this study we report on the maturation of the auditory cortical evoked response (ACR) waveform between (preterm) birth and 14 years of age. From the results it can be concluded that the ACR waveform morphology shows substantial age-dependent changes until the age of 14 years. Two transitional periods could be recognized. The first between 36 and 41 weeks conceptional age; the second between 4 and 6 years of age. The adult waveform complex is achieved between 14 and 16 years of age. Further research is needed to determine whether these transitional periods in the maturation of ACRs correspond with important functional changes of the central auditory system.

Adolescent↗
PubMed1998

Neonatal risk factors and risk scores including auditory evoked responses.

UNLABELLED: In a prospective study, 81 preterm infants and 25 healthy term infants were neurologically and neurophysiologically evaluated in the neonatal period. At 5-7 years of age the neurodevelopmental outcome was assessed. The validity and predictive value of the Neonatal Neurological Inventory (NNI) and the Neurobiological Risk Score (NBRS), including an additional gestational age factor (GAF) and an auditory evoked response factor (AERF) were assessed. Three of the 53 surviving preterm infants showed major neurological abnormalities at 5-7 years. Five infants showed neuropsychological abnormalities and 12 infants showed both neurological and neuropsychological abnormalities. An important subgroup of preterm infants could be identified as high-risk using the NNI and NBRS. The low sensitivity and negative predictive value resulted in a number of false-negative results. Logistic regression showed that intraventricular haemorrhage (IVH) and bilirubin levels contributed highly to the prediction of neurological outcome. For neuropsychological outcome these factors were IVH and assisted ventilation. Addition of the GAF and AERF as separate items to the NBRS did not affect the predictive power. Combined addition of the GAF and AERF showed improvement of both validity and predictive value. CONCLUSION: This study shows that IVH, bilirubin and assisted ventilation contribute most to the validity and predictive value of the NBRS. Furthermore, regarding neurological outcome addition of a GAF in combination with an AERF resulted in a substantial improvement of the validity and predictive value. The shortcomings of the current neonatal risk scores require a careful interpretation of clinical perinatal data regarding the prediction of neurodevelopmental outcome in preterm infants.

Child↗
PubMed1998

Neurodevelopmental profile in low-risk preterm infants at 5 years of age.

The goal of this study is to determine the neurodevelopmental profile of a group of low-risk preterm infants and to determine whether the potentially unfavourable outcome is due to a few infants with moderate to severe impairments or to a majority of infants with only slight impairments. In a prospective study 44 low-risk preterm infants, i.e. infants with a neonatal risk score indicating a favourable outcome, born between 25-34 weeks gestational age, and 18 healthy term infants were examined neurologically and tested neuropsychologically at 5 years of age. The more unfavourable outcome in the group of low-risk preterm infants compared with the term infants was largely attributable to a poorer outcome in 12 of the 44 low-risk preterm infants. The remaining low-risk preterm infants showed similar test scores compared with the term infants. From these results we conclude that the unfavourable neurodevelopmental outcome of low-risk preterm infants is due to moderate to severe impairment in a few low-risk preterm infants, rather than slight impairment in the majority. The low-risk preterm infants with an unfavourable outcome showed particular impairment on measures of visual-motor integration, concentration and auditory memory in combination with integrative functions.

Birth Weight↗
PubMed1997

Diagnostic and predictive value of auditory evoked responses in preterm infants: I. Patient characteristics and long-term neurodevelopmental outcome.

The diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses, obtained in the neonatal period, in 81 preterm infants was assessed in relation to neurodevelopmental outcome. Eighteen healthy term infants served as a control group. In this report the patient characteristics and neurodevelopmental outcome are presented. The preterm infants were neonatally classified according to risk category and gestational age. At 5 y of age the neurodevelopmental outcome was assessed based on neurologic and neuropsychologic evaluations. The neuropsychologic test results showed the highest IQ scores in term infants, intermediate IQ scores in low risk preterm infants, and lowest IQ scores in high risk preterm infants. The intermediate IQ scores in the low risk preterm group were due to significantly lower test scores in a small subgroup of low risk preterm infants. In a post hoc analysis 12 low risk preterm infants with an unfavorable outcome could be identified. The neuropsychologic test results of the remaining low risk infants showed no clear differences compared with the term infants. The results suggest that the unfavorable outcome of the low risk preterm group as a whole is due to moderate to severe impairment of the few, rather than slight impairment of the majority.

Evoked Potentials, Auditory↗
PubMed1997

Diagnostic and predictive value of auditory evoked responses in preterm infants: II. Auditory evoked responses.

In this study, the diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses (BMC-AERs) obtained in the neonatal period in 81 preterm infants was assessed in relation to neurodevelopmental outcome. The preterm infants were neonatally classified according to risk category and gestational age. The BMC-AERs were analyzed with respect to detectability, latencies, and amplitudes as well as derived latency and amplitude measures. At 5 y of age the neurodevelopmental outcome was assessed from neurologic and neuropsychologic evaluations. The results showed that BMC-AER differences mainly correlated with risk category (low risk/high risk) and to some extent with degree of prematurity. In view of these findings the degree of prematurity and the effect of risk category have to be taken into account, when BMC-AERs are applied in the preterm period to predict neurodevelopmental outcome. In this study the BMC-AERs for infants with abnormal neurodevelopmental outcome were scarcely distinguishable from the BMC-AERs for infants with normal neurodevelopmental outcome. Thus far, this and previous reports have indicated that BMC-AERs in preterm infants are useful in maturational studies and with infants showing symptoms related to lesions or dysfunction of the peripheral and/or central auditory system. For predicting neurodevelopmental outcome in preterm infants, BMC-AERs are of limited clinical value.

Evoked Potentials, Auditory↗
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

Perception of voicing cues by children with early otitis media with and without language impairment.

Research on the relationship between early otitis media with effusion (OME), language impairment, and central auditory processing has been equivocal. Identification and discrimination tasks provide us with a sensitive method of assessing speech perception on both an auditory and a phonetic level. The present study examined identification and discrimination of initial bilabial stop consonants differing in voicing by 9-year-old children with a history of severe OME. The groups studied were controlled for language impairment. The ability of these children to perceive major and minor voicing cues was examined using multiple voicing cues. Long-term effects of OME were found for both identification and discrimination performance. Children with OME produced an overall inconsistency in categorization, which suggests poorer phonetic processing. Discrimination was measured by means of "just noticeable differences" (JND). Children with early OME experience demonstrated a greater mean JND than children without early OME experience. Finally, in cases of language impairment with early OME, there was no additional deterioration of auditory or phonetic processing. It appears that either early OME or language impairment can lead to poorer perception.

Adult↗
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↗
PubMed1996

The effects of early and late preterm birth on brainstem and middle-latency auditory evoked responses in children with normal neurodevelopment.

In preterm and term infants, brainstem and middle latency auditory evoked responses (ABR and MLR) were obtained at 40 and 52 weeks conceptional age (CA) and at 5 years of age. A neurological and neuropsychological evaluation was performed at 5 years of age. To study the effect of preterm birth on the maturation of the ABR and MLR, the preterm infants were divided into early and late preterm groups. Only children with a normal neurodevelopmental outcome at 5 years of age were entered into the study. For ABR, the late preterm group showed significantly longer mean latencies IIc, III, V, and Vc when compared with the term group at 52 weeks CA. There was a trend to longer ABR latencies I in the early preterm group compared with the term group. At 52 weeks CA, the late preterm group showed longer mean interpeak latencies III-I and V-I when compared with the term as well as the early preterm group. At 5 years, the late preterm group showed significantly longer mean ABR latencies IIc and III when compared to the early preterm group. For MLR, the early preterm group showed significantly longer mean latencies of MLR component PO when compared with the term group at 40 weeks CA. At 52 weeks, the late preterm group also had longer mean MLR latencies P0 than the term group. At 5 years of age, the term group showed higher mean peak-to-peak amplitudes Na-P0 than the early as well as the late preterm group. To a large extent, the ABR results support the hypothesis that middle ear effusions in combination with retarded myelination of the central auditory pathway are responsible for the ABR differences found between term and preterm infants with a normal neurodevelopmental outcome at 5 years of age. The longer latencies and interpeak latencies found in late preterm infants when compared with early preterm infants might be explained by an augmented vulnerability of the auditory pathway between 30 and 34 weeks CA. The MLR differences found between term and preterm infants might be explained by a difference in the maturation of primary and nonprimary MLR components.

Auditory Cortex↗
PubMed1994

Focal dystonia and speech impairment responding to anticholinergic therapy.

Focal dystonia of the right hand and speech impairment as a result of a circumscribed left-sided anterior thalamic lesion is reported in a 9-year-old girl with borderline normal psychomotor development. Both focal dystonia and speech impairment improved during anticholinergic treatment and worsened after drug withdrawal.

Cerebral Infarction↗
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↗
PubMed1991

Word deafness and auditory cortical function. A case history and hypothesis.

A patient who already had Wernicke's aphasia due to a left temporal lobe lesion suffered a severe deterioration specifically of auditory language comprehension, subsequent to right temporal lobe infarction. A detailed comparison of his new condition with his language status before the second stroke revealed that the newly acquired deficit was limited to tasks related to auditory input. Further investigations demonstrated a speech perceptual disorder, which we analysed as due to deficits both at the level of general auditory processes and at the level of phonetic analysis. We discuss some arguments related to hemisphere specialization of phonetic processing and to the disconnection explanation of word deafness that support the hypothesis of word deafness being generally caused by mixed deficits.

Aphasia, Wernicke↗
PubMed1986

Marking word boundaries to improve the intelligibility of the speech of the deaf.

Speech of deaf talkers has often been characterized as staccato, leading to the perception of improper grouping of syllables. In an attempt to compensate for this syllabication, word boundaries of 30 sentences spoken by 10 deaf children were acoustically marked by means of silent pauses with a duration of 160 ms inserted between words. Subsequent tests with normal-hearing listeners demonstrated that after insertion of pauses the intelligibility of the sentences increased significantly (p less than .01) from 27% to 31%. A control measure showed that this increase was not merely due to a general deceleration of speech rate: When all phonemes were lengthened until the same sentence duration was obtained as after insertion of pauses, a (nonsignificant) decrease in intelligibility (M = 26%) resulted. The results are compared to earlier studies of speech of the deaf in which segmental and suprasegmental aspects were manipulated.

Adolescent↗
PubMed1985

The effect of segmental and suprasegmental corrections on the intelligibility of deaf speech.

Three experiments were conducted to study the effect of segmental and suprasegmental corrections on the intelligibility and judged quality of deaf speech. By means of digital signal processing techniques, including LPC analysis, transformations of separate speech sounds, temporal structure, and intonation were carried out on 30 Dutch sentences spoken by ten deaf children. The transformed sentences were tested for intelligibility and acceptability by presenting them to inexperienced listeners. In experiment 1, LPC based reflection coefficients describing segmental characteristics of deaf speakers were replaced by those of hearing speakers. A complete segmental correction caused a dramatic increase in intelligibility from 24% to 72%, which, for a major part, was due to correction of vowels. Experiment 2 revealed that correction of temporal structure and intonation caused only a small improvement from 24% to about 34%. Combination of segmental and suprasegmental corrections yielded almost perfectly understandable sentences, due to a more than additive effect of the two corrections. Quality judgments, collected in experiment 3, were in close agreement with the intelligibility measures. The results show that, in order for these speakers to become more intelligible, improving their articulation is more important than improving their production of temporal structure and intonation.

Adolescent↗