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van Ool J.S.,Kempenhaeghe Epilepsy Center | Hurks P.P.M.,Maastricht University | Snoeijen-Schouwenaars F.M.,Kempenhaeghe Epilepsy Center | Tan I.Y.,Kempenhaeghe Epilepsy Center | And 5 more authors.
Developmental Neurorehabilitation | Year: 2017

The assessment of intellectual abilities is intensive, time-consuming, and might be considered burdensome for patients. We examined psychometric qualities of short forms (SFs) of the Wechsler Intelligence Scales for Children (WISC-third edition) and for adults (WAIS-fourth edition), in children (n = 986; Mage = 10.9) and adults (n = 324; Mage = 40.9) with neurological disorders. SF estimates were compared with Full Scale IQ (FSIQ), obtained by a complete administration, for the entire sample and for the subgroups FSIQ < 80 and FSIQ ≥ 80. The FSIQ was correctly identified within ± 7 points in 86% of children and 87% of adults. There were, however, some differences regarding the optimal SF subtest combination between subgroups. Although clinical inferences should not be made, SFs may be useful in research settings to obtain a global estimate of intelligence, and in clinical settings to screen periodically for possible intellectual deterioration. © 2017 Taylor & Francis


Peijnenborgh J.C.A.W.,Maastricht University | Peijnenborgh J.C.A.W.,Kempenhaeghe Epilepsy Center | Hurks P.M.,Maastricht University | Aldenkamp A.P.,Maastricht University | And 5 more authors.
Neuropsychological Rehabilitation | Year: 2016

The effectiveness of working memory (WM) training programmes is still a subject of debate. Previous reviews were heterogeneous with regard to participant characteristics of the studies included. To examine whether these programmes are of added value for children with learning disabilities (LDs), a systematic meta-analytic review was undertaken focusing specifically on LDs. Thirteen randomised controlled studies were included, with a total of 307 participants (age range = 5.5–17, Mean age across studies = 10.61, SD = 1.77). Potential moderator variables were examined, i.e., age, type of LD, training programme, training dose, design type, and type of control group. The meta-analysis indicated reliable short-term improvements in verbal WM, visuo-spatial WM, and word decoding in children with LDs after training (effect sizes ranged between 0.36 and 0.63), when compared to the untrained control group. These improvements sustained over time for up to eight months. Furthermore, children > 10 years seemed to benefit more in terms of verbal WM than younger children, both immediately after training as well as in the long-term. Other moderator variables did not have an effect on treatment efficacy. © 2015 Informa UK Limited, trading as Taylor & Francis Group.


van Ool J.S.,Kempenhaeghe Epilepsy Center | Snoeijen-Schouwenaars F.M.,Kempenhaeghe Epilepsy Center | Schelhaas H.J.,Academic Center for Epileptology Kempenhaeghe | Tan I.Y.,Kempenhaeghe Epilepsy Center | And 6 more authors.
Epilepsy and Behavior | Year: 2016

Epilepsy is a neurological condition that is particularly common in people with intellectual disability (ID). The care for people with both epilepsy and ID is often complicated by the presence of neuropsychiatric disorders, defined as psychiatric symptoms, psychiatric disorders, and behavioral problems. The aim of this study was to investigate associations between epilepsy or epilepsy-related factors and neuropsychiatric comorbidities in patients with ID and between ID and neuropsychiatric comorbidities in patients with epilepsy. We performed a systematic review of the literature, published between January 1995 and January 2015 and retrieved from PubMed/Medline, PsycINFO, and ERIC and assessed the risk of bias using the SIGN-50 methodology. Forty-two studies were identified, fifteen of which were assessed as having a low or acceptable risk-of-bias evaluation. Neuropsychiatric comorbidities were examined in relation to epilepsy in nine studies; in relation to epilepsy-related factors, such as seizure activity, seizure type, and medication in four studies; and in relation to the presence and degree of ID in five studies. We conclude that the presence of epilepsy only was not a clear determinant of neuropsychiatric comorbidity in patients with ID, although a tendency towards negative mood symptoms was identified. Epilepsy-related factors indicating a more severe form of epilepsy were associated with neuropsychiatric comorbidity as was the presence of ID as compared to those without ID in patients with epilepsy, although this should be validated in future research. A large proportion of the studies in this area is associated with a substantial risk of bias. There is a need for high quality studies using standardized methods to enable clear conclusions to be drawn that might assist in improving the quality of care for this population. © 2016 Elsevier Inc.


Hendriksen J.G.M.,Kempenhaeghe | Hendriksen J.G.M.,Kempenhaeghe Epilepsy Center | Hendriksen J.G.M.,Maastricht University | Peijnenborgh J.C.A.W.,Kempenhaeghe | And 7 more authors.
European Journal of Paediatric Neurology | Year: 2015

Abstract Aim Diagnostic overshadowing refers to the underdiagnosis of comorbid conditions in children with known neurological diagnoses. To demonstrate diagnostic overshadowing we determined the prevalence of attention deficit-hyperactivity disorders (ADHD) in a cohort of children with a wide range of neurological disabilities. Method The study cohort consisted of 685 children (mean age 10.3 years, SD: 3.1; 425 boys and 260 girls) who visited a tertiary outpatient multidisciplinary clinic for neurological learning disabilities. Patients with ADHD were identified by retrospective chart review using DSM-IV criteria. Results The prevalence of ADHD in this cohort was 38.8% (266 children); of these children only 28.2% (75 children) were diagnosed with ADHD before referral. Interpretation ADHD is a common problem in children with neurological disabilities and may be underdiagnosed due to overshadowing of somatic, physical or syndromal features of the disability. In our heterogeneous population ADHD was overshadowed in 71.8% of the cases. This finding may have important implications for diagnosis and treatment of mental health needs in children with neurological disabilities. © 2015 European Paediatric Neurology Society.


Doorenweerd N.,Leiden University | Doorenweerd N.,Leiden Institute for Brain and Cognition | Straathof C.S.,Leiden University | Dumas E.M.,Leiden University | And 14 more authors.
Annals of Neurology | Year: 2014

Objective: Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness caused by DMD gene mutations leading to absence of the full-length dystrophin protein in muscle. Multiple dystrophin isoforms are expressed in brain, but little is known about their function. DMD is associated with specific learning and behavioral disabilities that are more prominent in patients with mutations in the distal part of the DMD gene, predicted to affect expression of shorter protein isoforms. We used quantitative magnetic resonance (MR) imaging to study brain microstructure in DMD. Methods: T1-weighted and diffusion tensor images were obtained on a 3T MR scanner from 30 patients and 22 age-matched controls (age=8-18 years). All subjects underwent neuropsychological examination. Group comparisons on tissue volume and diffusion tensor imaging parameters were made between DMD patients and controls, and between 2 DMD subgroups that were classified according to predicted Dp140 isoform expression (DMD-Dp140+and DMD-Dp140-). Results: DMD patients had smaller total brain volume, smaller gray matter volume, lower white matter fractional anisotropy, and higher white matter mean and radial diffusivity than healthy controls. DMD patients also performed worse on neuropsychological examination. Subgroup analyses showed that DMD-Dp140-subjects contributed most to the gray matter volume differences and performed worse on information processing. Interpretation: Both gray and white matter is affected in boys with DMD at a whole brain level. Differences between the DMD-Dp140-subgroup and controls indicate an important role for the Dp140 dystrophin isoform in cerebral development. © 2014 American Neurological Association.


Ferreira J.L.,TU Eindhoven | Aarts R.M.,TU Eindhoven | Aarts R.M.,Philips | Cluitmans P.J.M.,TU Eindhoven | Cluitmans P.J.M.,Kempenhaeghe Epilepsy Center
BIOSIGNALS 2014 - 7th Int. Conference on Bio-Inspired Systems and Signal Processing, Proceedings; Part of 7th Int. Joint Conference on Biomedical Engineering Systems and Technologies, BIOSTEC 2014 | Year: 2014

This paper presents a novel approach for removing gradient artefacts from the EEG signal recorded during continuous EEG-fMRI, which are influenced by transient head movements of the subject within the magnetic scanner. Transient head movements provoke abrupt changes in the gradient artefact waveform, in such a way that they compromise the estimation of an artefact waveform to be subtracted and achieve the EEG correction. According to our proposed methodology, a cubic spline waveform is used to model and represent the signal transitions components. This model is then used to change and approximate the shape of the EEG signal as homogeneous data, in order to improve the performance of the gradient artefact correction technique. The proposed approach also makes use of the signal slope adaption (SSD) method, combined with sum-of-sinusoids modelling for correction of the gradient artefact. Our methodology reveals to perform a robust and satisfactory removal of gradient artefacts under the occurrence of abrupt transient head movements. Copyright © 2014 SCITEPRESS - Science and Technology Publications. All rights reserved.


Ferreira J.L.,TU Eindhoven | Aarts R.M.,TU Eindhoven | Aarts R.M.,Philips | Cluitmans P.J.M.,TU Eindhoven | Cluitmans P.J.M.,Kempenhaeghe Epilepsy Center
ISSNIP Biosignals and Biorobotics Conference, BRC | Year: 2014

The strong capability of the combined EEG-fMRI for investigating and revealing new insights on mapping of the brain activity as well as on several other neuroscientific studies has attracted the interest of researchers and clinicians over the past years. However, its consolidation as a powerful and independent technique still depends on enhancing the quality of the EEG signal, mainly due to the occurrence of artefacts. This paper presents a simple and effective approach for removal of the gradient artefact, which is induced in the EEG by the rapidly varying gradient magnetic fields of the fMRI scanner. According to our method, a moving-average filter is used to perform the removal of the gradient artefact. Nevertheless, rather than estimation of an artefact waveform template to be subtracted and achieve the EEG restoration, we have proposed to optimize the moving-average filtering process along the entire EEG excerpt. Thereby, the restored EEG can be estimated either from a sum of partial waveform components resulting from the recursive application of the optimized moving-average filter; or from an estimative of the artefact along the entire excerpt. Our methodology shows to achieve a quite satisfactory restoration of the EEG signal, even for low signal amplitudes. Moreover, in addition to predict the variability of the artefact waveform over the time, synchronization between EEG and fMRI clocks and extensive data segmentation are not required as well. © 2014 IEEE.


Ferreira J.L.,TU Eindhoven | Cluitmans P.J.M.,TU Eindhoven | Cluitmans P.J.M.,Kempenhaeghe Epilepsy Center | Aarts R.M.,TU Eindhoven | Aarts R.M.,Philips
BIOSIGNALS 2013 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing | Year: 2013

A number of signal processing techniques make use of first-derivative-based approaches for detecting regions of interest in biological signals. For instance, central and five-point derivative-based algorithms are employed for emphasizing and identification of the QRS complex in the ECG signal. Signal differentiation approaches are also used for detection and removal of high-frequency components associated to artefacts in the EEG signal. This paper aims to present a first-derivative approach based upon differentiation of consecutive samples - signal slope adaption (SSD) - for detecting regions of sharp wave activity in biological signals. A case study is analysed whereby SSD is used to mark and select the sharp wave activity associated to the QRS complex in the electrocardiogram. Evaluation of our methodology reveals that SSD shows to be effective for identification of QRS samples and, thereby, could be also employed to detect samples associated to sharp wave activity regions of other biological signals which possess similar signal slope behaviour.

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