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Stability of motor problems in young children with or at risk of autism spectrum disorders, ADHD, and/or developmental coordination disorder

HILDE VAN WAELVELDE1; ANN OOSTRA2; GRIET DEWITTE2; CHRISTINE VAN DEN BROECK1; MARIAN J 3

1  Rehabilitation Sciences and Physiotherapy, Arteveldehogeschool and Ghent University, Belgium. 2 Centre for Developmental Disabilities, University Hospital, Ghent, Belgium. 3 Department of Paediatric Psychology, University Medical Centre Utrecht and Department of Special Education, University of Utrecht, the Netherlands.

Aim  The aim of this study was to investigate the stability of motor problems in a clinically referred sample of children with, or at risk of, autism spectrum disorders (ASDs), attention-deficit–hyperactivity disorder (ADHD), and/or developmental coordination disorder (DCD).

Method  Participants were 49 children (39 males, 10 females; mean age 5y 6mo, SD 10mo) with various developmental problems, a Movement Assessment Battery for Children (M-ABC) score on or below the 15th centile, and an IQ of 70 or more. Sixteen children were at risk of developing ADHD, 15 children had a diagnosis of, or were at risk of developing, ASD, and 18 children had neither diagnosis. Children were reassessed 2 to 3 years later.

Results  At follow-up (mean age 7y 11mo; SD 1y), the mean M-ABC score was significantly increased, and in 22 children was no longer below the 15th centile. A general linear model to compare the difference in M-ABC scores in the three groups of children demonstrated a significant difference between groups (p=0.013), with the age at the initial assessment as a significant covariate (p=0.052). The group of children with or at risk of ASD showed less improvement in motor performance.

Interpretation  Motor problems among preschool age children are not always stable, but appear to be so in most children with ASDs.

PUBLICATION DATA
Accepted for publication 22nd November 2009. Published online 28th January 2010.
Cite this as: Dev Med Child Neurol 52: e174–e178. This article is commented on by Rinehart and McGinley on p. 697 of this issue

A preliminary transcranial magnetic stimulation study of cortical inhibition and excitability in high-functioning autism and Asperger disorder

PETER G ENTICOTT1,2; NICOLE J RINEHART2; BRUCE J TONGE2; JOHN L BRADSHAW2; PAUL B FITZGERALD1

1  Monash Alfred Psychiatry Research Centre, School of Psychology and Psychiatry, Monash University and the Alfred, Melbourne, Australia. 2 Centre for Developmental Psychiatry and Psychology, School of Psychology and Psychiatry, Monash University, Clayton, Australia.

Aim  Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS).

Method  Participants were diagnosed by experienced clinicians strictly according to DSM-IV criteria. Participants with HFA (nine males, two females; mean age 16y 8mo, SD 4y 5mo) or Asperger disorder (11 males, three females; mean age 19y 1mo, SD 4y 2mo) and neurotypical participants (eight males, three females; mean age 19y 0mo, SD 3y 1mo) were administered a paired-pulse TMS paradigm intended to assess motor cortical inhibition and excitability. Responses to TMS were recorded by electromyography.

Results  Cortical inhibition was significantly reduced in the HFA group compared with both the Asperger disorder (p<0.001) and neurotypical (p<0.001) groups, suggesting disruption of activity at gamma-aminobutyric acid A (GABAA) receptors. There was no group difference in cortical excitability.

Interpretation  Cortical inhibition deficits may underlie motor dysfunction in autism, and perhaps even relate to specific clinical symptoms (e.g. repetitive behaviours). These findings provide novel evidence for a possible neurobiological dissociation between HFA and Asperger disorder based on GABAergic function.

PUBLICATION DATA
Accepted for publication 2nd February 2010. Published online 29th March 2010
Cite this as: Dev Med Child Neurol 52: e179–e183

Visual field function in school-aged children with spastic unilateral cerebral palsy related to different patterns of brain damage

LENA JACOBSON1; AGNETA RYDBERG1; ANN-CHRISTIN ELIASSON2; ANNIKA KITS3; OLOF FLODMARK3

1  Clinical Neuroscience, Ophthalmology and Vision, Karolinska Institutet, Stockholm, Sweden. 2 Neuropaediatric Research Unit, Department of Women and Child Health, Karolinska Institutet, Stockholm, Sweden. 3 Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Aim  To relate visual field function to brain morphology in children with unilateral cerebral palsy (CP).

Method  Visual field function was assessed using the confrontation technique and Goldmann perimetry in 29 children (15 males, 14 females; age range 7–17y, median age 11y) with unilateral CP classified at Gross Motor Function Classification System (GMFCS) level I and Manual Ability Classification System levels I to III. The type and extent of brain lesions were determined using cerebral imaging.

Results  Eighteen children had subnormal visual field function. The visual fields were severely restricted in six. The underlying brain lesions were malformation (n=7), white matter damage of immaturity (WMDI; n=13), and cortical–subcortical lesions (n=9). Visual field function could be correlated with the pattern of brain damage in children with cortical–subcortical lesions or extensive lesions caused by malformation or WMDI. Total homonymous hemianopia was common in the cortical–subcortical group but rare in children with malformation or WMDI. Five children had normal visual field function despite having malformation or WMDI involving parts of the brain usually encompassing the visual system.

Interpretation  Visual field function may be preserved by plasticity of the immature brain in children with malformation and WMDI. Severely restricted visual fields were more often associated with lesions occurring later in the developing brain. All children with severely restricted visual fields were identified by the confrontation technique. Goldmann perimetry was a suitable method to identify relative visual field defects.

PUBLICATION DATA
Accepted for publication 12th January 2010. Published online 30th April 2010.
Cite this as: Dev Med Child Neurol 52: e184–e187. This article is commented on by Guzzetta on p. 699 of this issue

Factor structure of paediatric timed motor examination and its relationship with IQ

REBECCA MARTIN1; CASSIE TIGERA2; MARTHA B DENCKLA1; E MARK MAHONE1

1  Kennedy Krieger Institute, Baltimore, MD, USA. 2 Loyola College in Maryland, Baltimore, MD, USA.

Aim  Brain systems supporting higher cognitive and motor control develop in a parallel manner, dependent on functional integrity and maturation of related regions, suggesting neighbouring neural circuitry. Concurrent examination of motor and cognitive control can provide a window into neurological development. However, identification of performance-based measures that do not correlate with IQ has been a challenge.

Method  Timed motor performance from the Physical and Neurological Examination of Subtle Signs and IQ were analysed in 136 children aged 6 to 16 (mean age 10y 2.6mo, SD 2y 6.4mo; 98 female, 38 male) attending an outpatient neuropsychology clinic and 136 right-handed comparison individuals aged 6 to 16 (mean age 10y 3.1mo, SD 2y 6.1mo; 98 female, 38 male). Timed activities – three repetitive movements (toe tapping, hand patting, finger tapping) and three sequenced movements (heel–toe tap, hand pronate/supinate, finger sequencing) each performed on the right and left – were included in exploratory factor analyses.

Results  Among comparison individuals, factor analysis yielded two factors – repetitive and sequenced movements – with the sequenced factor significantly predictive of Verbal IQ (VIQ) (ΔR2=0.018, p=0.019), but not the repetitive factor (ΔR2=0.004, p=0.39). Factor analysis within the clinical group yielded two similar factors (repetitive and sequenced), both significantly predictive of VIQ, (ΔR2=0.028, p=0.015; ΔR2=0.046, p=0.002 respectively).

Interpretation  Among typical children, repetitive timed tasks may be independent of IQ; however, sequenced tasks share more variance, implying shared neural substrates. Among neurologically vulnerable populations, however, both sequenced and repetitive movements covary with IQ, suggesting that repetitive speed is more indicative of underlying neurological integrity.

PUBLICATION DATA
Accepted for publication 1st February 2010. Published online 12th April 2010.
Cite this as: Dev Med Child Neurol 52: e188–e194

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