Spano Et Al. 1999 Motor and Perceptual Motor Competence in Children With Down Syndrome Variation in...

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ORIGINAL ARTICLE

Motor and perceptual±motor competence in

children with Down syndrome:variation in performance with age

MARIA SPANOÁ ,1,2 EUGENIO MERCURI,3 TERESA RANDOÁ ,1 TIZIANA PANTOÁ ,2

ANTONELLA GAGLIANO,2 SHEILA HENDERSON,4 FRANCO GUZZETTA1

1Department of Child Neurology, Catholic University, Rome; 2Department of Child Neurology, University of Messina,

Messina, Italy; 3Department of Paediatrics, Hammersmith Hospital, London; 4Institute of Education, University of London,

London, UK

The aim of this study was to determine whether perceptual±motor competence in school-age children with Downsyndrome was generally delayed or varied as a function of type of action. Twenty-two children with Down syndrome(13 males, 9 females), aged between 4.5 and 14 years were assessed on two standardized tests, the MovementAssessment Battery for Children (Movement ABC), a test of motor competence assessing gross and fine motorcoordination, and on the Developmental Test of Visual±Motor Integration, a test focusing on shape copying. In orderto obtain a profile of each child's performance on the different items contained in the Movement ABC, the test wasused in its extended form. This involves testing any child who failed an item appropriate for his/her level, atprogressively lower levels until a base-line measure was obtained.

All the children obtained scores below the 5th percentile for their age on both tests. However, superimposed on thisdelay, we found distinct variation as a function of task. Whereas some aspects of gross motor function showed agedevelopment with delayed but regular acquisitions, all the aspects of fine motor skills assessed were more severelyimpaired and showed little development with age. Accuracy and timing of tasks requiring bimanual coordinationwere most impaired in our sample while balance and ball skills showed more variability. These results suggest thatintervention in the motor domain should be varied according to each child's particular profile of performance.

Keywords: Down syndrome. Movement ABC test. Developmental Test of Visual±Motor Integration.

Introduction

Down syndrome (DS) is a condition which hasprovoked much scientific enquiry since it was first

described over a century ago as a distinct clinicalentity.1 In the area of perceptual±motor compe-tence, there is no doubt that children affected by DSare less competent than their normal peers. Slightlymore controversial is the idea that they may even be less competent on some motor tasks than otherretarded children of similar intellect (see Refs 2, 3,for reviews).

A number of studies have shown that DSchildren follow a rather different pattern of motordevelopment from normal children in the earlyyears. In addition to the fact that the majormilestones, such as sitting, standing, reaching and

grasping are generally delayed, superimposed onthis delay are some plateaux in development whichare far more prolonged and tend to occur atdifferent times than in their normal peers.3,4 Atschool age all these children have difficultyacquiring the movement skills expected of themand are often generally described as `clumsy'.5

They are slow to learn to use eating utensils and

European Journal of Paediatric Neurology 1999; 3: 7±14

1090±3798/99/03/0007+07 $18.00&

1999 European Paediatric Neurology Society

Received 15.7.98. Revised 2.10.98. Accepted 3.11.98.Correspondence: Dr Eugenio Mercuri, Department of Paediatrics, Hammersmith Hospital, Du Cane Road, London W12 0HN, UK



writing implements, they find it hard to join in withother children in the playground because activitiessuch as running or jumping are difficult.

In younger children with DS, tests such as theGriffiths or Bayley scales have been used todocument motor development.3,4,6,7 Although stu-dies of school age children with DS do exist, the

majority are experimental in nature and focus onunderlying deficits which might account for theobserved functional difficulties.4,5,8,9 Purelydescriptive studies which attempt to look atstrengths and weaknesses across a range of tasksare relatively rare. In the present study, we use awide range of perceptuomotor tasks to describe theprofiles of performance exhibited by children of school age with DS. The tasks presented to thechildren included gross motor activities, such as jumping and hopping, fine motor activities such asthreading beads and cutting with scissors, as wellas tasks requiring a combination of both gross andfine control, such as catching a ball. Our aim inexamining the profiles of performance exhibited bythe children is to determine whether the uneven-ness in the perceptuomotor development reportedto be characteristic of children with DS in the earlyyears is still present at school age or whether thevariable rates of development have evened out to be replaced by a more generalized delay.

Subjects and methods

Twenty-two children with DS, aged between 4.5and 14 years, were included in the study. Thirteenwere boys and nine were girls. All attended theRehabilitation Centre of the Department of ChildNeurology in Messina, Italy.

Background clinical information was obtainedfrom the parents or, when available, from theneonatal or paediatric files. Information aboutrehabilitative therapy preceding the attendance to

our centre was also recorded. Cognitive ability wasassessed by the centre's educational psychologistusing the appropriate versions of the Wechslerscales (WPPSI for children under six and WISC forthe others). Details of verbal, performance andglobal intelligence quotient (IQ) were made avail-able to us.

Clinical examinations

All children in the study underwent a detailedneurological examination and were assessed ontwo points, which provide contrasting but com-plementary information on perceptual±motorabilities. The first, the Movement AssessmentBattery for Children (Movement ABC)10 is a globaltest of motor competence, assessing both gross andfine motor coordination. The second, the Develop-mental Test of Visual±Motor Integration11 is a much

more narrowly focused test, requiring the child tocopy a series of shapes of increasing difficulty.

Movement Assessment Battery for Children

The standardized test in the Movement ABC isdesigned for use with children aged 4 to 12+ years.A total of 32 items are divided into four sets of eight, each intended for use with children of specific ages. The first set of items, labelled age band 1 is designed for use with 4- to 6-year-oldchildren, the second set, age band 2 for 7- and 8-

year-old children, the third for 9- and 10-year-oldsand the fourth for children 11 years old and above.Within each age band, the structure of the test isidentical. All children complete three itemsdesigned to assess mental dexterity, two itemsdesigned to assess the ability to propel or intercepta moving object, and three items which assess staticand dynamic balance (see Table 1 for examples of tasks within each category).

The Movement ABC test can be administered ina number of ways. When all that is required is a

8 Original article: M Spano Á et al.

Table 1 Movement ABC: description of items

Domain Description Item (examples)

Manual dexterity 1. Speed and accuracy of unimanualmovements

. Peg insertion

2. Bimanual coordination . Threading beads3. Accuracy (preferred hand) . Drawing between two lines which form a

simple shapeBall skills 1. Receiving a moving object . Bouncing and catching a ball in one-hand

2. Aiming an object at a fixed target . Throwing a bean bag into a boxStatic/dynamic balance 3. Dynamic balance (control of slow

movements). Walking heel-to-toe along a line



measure of how a child compares with hischronological age peers, he/she need only betested on one age band i.e. that appropriate forhis/her age. Raw scores on each of the eight itemsare converted to scaled scores ranging from 0 to 5,with higher scores indicating poorer performance.Item scores are then summed to produce total

scores (ranging from 0 to 40). Finally, percentiletables are consulted to determine how an indivi-dual compares with his/her age peers. In thisstudy, we report each child's total score on the testsupplemented by performance data on each of theeight items individually.

Although a simple norm-referenced statementabout a child is adequate for some purposes, it isoften necessary to go beyond this level of assess-ment. Since in the present study, our objective wasto determine whether the perceptuomotor devel-opment of children with DS was even across alltasks or varied systematically in some way, a moredetailed profile of the strengths and weaknesses of each child was required. To achieve this theMovement ABC test was used as recommended by the authors in the section on `clinical/educa-tional' uses of the test (p.118 of the manual). Thisinvolved starting at the appropriate age band asusual then continuing testing at lower levels until(a) the child passed the item or (b) no furthertesting was possible because the child had failed allitems in that category. Using a downwards step-ping procedure, performance was then scored asfollows: if a child obtained a score of 4 or 5 on an

item at the appropriate age band (i.e. below the 5thpercentile), he/she was tested on the same item atthe next lowest age band. This procedure wasrepeated until a score of 3 or less was obtained orthe child failed completely. (NB This procedure, of course, could be only applied to children olderthan 6 years as for children below that age no lowerage bands were available.)

In order to obtain a measure of the degree of failure in each category of item, the followingscoring system was then applied. One point wasgiven each time a child failed the item at his/her

own age level then additional points were given forfailure on the lower age bands. A child passing anitem in his/her appropriate age band wouldtherefore have a score of 0 while progressivelyhigher scores indicate that the child had failed oneor more of the lower age bands.

Using this scoring system, we were able toobtain:

a) a detailed profile of test performance for eachchild in the study. Expressed in terms of `ageequivalent' scores, we might find, for example,

that a child of chronological age 12 had`passed' on all three manual dexterity itemsin the test at the 9-year level (i.e. was able toachieve a score of 3 or less on that particularitem), managed to pass the balance tasks at the7-year level but failed to achieve even the 4-year level on the tasks involving throwing and

catching moving objects. b) more information on the level of performance

achieved by the group as a whole on thedifferent kinds of items in the test. Thismeasure was obtained by summing the scoresobtained by all children on each category of item.

Developmental Test of Visual±Motor Integration (VMI)

This is a paper-and-pencil task11 in which a childcopies a series of geometric shapes of increasingdifficulty. The standard score reflects the accuracyof the copies and can range from 0 to 19; the lowerthe score, the less competent the performance.

Results

Clinical assessment

Karyotype information was available for 14 of the 22

children: this showed trisomy 21 in 13 children anda translocation in the other. No information wasavailable for the other 8 children. All 22 childrenwere born at term from uncomplicated pregnanciesand all had a history of global neurodevelopmentaldelay. When they were referred to our rehabilita-tion centre, the children varied in age from 2 to 9years. The duration and type of therapy received before referral was very varied and often discon-tinuous. Only 6 of the 24 children received early(i.e. started before 2 years) and continuous therapy.

Cognitive abilities

Full scale IQ ranged from 41 to 54, the verbal IQfrom 45 to 55 and the performance IQ from 45 to 61.Table 2 shows details of the results of the cognitiveassessment.

Movement ABC

On the Movement ABC all children obtained totalscores below the 5th percentile for their age.

Original article: Motor and perceptual±motor competence in children with Down syndrome 9



Figures 1, 2, and 3 show individual details of thelevel of performance. Here we plot each child's ageequivalent score on each item in the MovementABC.

Table 3 shows the results of the within-groupvariation. To determine whether there was anyevidence of systematic variation as a function of the

type of task being performed, the results on the

individual items were scored with a global impair-ment score. The scores in the whole group rangedfrom 25 (ball skills 2) to 56 (manual dexterity 2).

Developmental Test of Visual±Motor Integration

All the subjects obtained low scores for theirchronological age with their performance rangingfrom an age equivalent of 2 years to a maximum of 4 years, 2 months. None of the children was able to


Table 2 Full scale, verbal and performance IQ: individualresults

Age Age band Full scale IQ VIQ PIQ

4.9 1 52 54 584.6 1 54 55 614.11 1 45 51 515.4 1 49 54 536.3 1 45 52 486.9 1 51 64 47

7.9 2 44 46 517.8 2 48 47 588.6 2 41 46 458.10 2 41 46 479.5 3 44 47 509.2 3 46 50 5110.6 3 41 46 4510.2 3 43 49 4811.11 4 49 51 5411.6 4 41 45 4512.4 4 46 47 5012.5 4 44 49 4913.6 4 42 46 4713.10 4 45 50 5014.3 4 42 45 4514.7 4 44 50 46

Table 3 Global impairments scores

Global impairment score

Manual dexterity 38Manual dexterity 56Manual dexterity 45Ball skills 44Ball skills 25

Balance 1 39Balance 2 35Balance 3 44

A global impairment score was developed to produce a detailedprofile of the strengths and weaknesses of each item in thewhole group. For each item one point was given each time thechild failed the item at his/her own age level then additionalpoints were given for each failure on the lower age bands. Themaximum score possible depended on the number of lower age bands available, with a minimum of 1 for age band 1 and amaximum score of 4 for age band 4 (the child fails the items onall 4 age bands). The global impairment score was produced byadding the individual results of all the children on thatparticular item.

Fig. 1. Level of performance (expressed as age equivalent)on the three items assessing manual dexterity.



copy any of the three-dimensional figures showingintersections.

Figure 4 shows individual details of the level of performance.

Discussion

Many studies have reported motor impairment inchildren with DS which extends across the entire

range of functioning, including both fine and grossmotor skills.2±9,12,13 In agreement with these studies,our results also indicate that children with DSperform poorly in most areas of motor functioning.Although there was some variability in the level of performance, none of our children had scoresadequate for their chronological age on either theMovement ABC or the VMI. The aim of this study,however, was not simply to replicate other studies but to try to determine whether all aspects of motordevelopment at school age progressed evenly orwhether there was systematic variation as a

function of task and/or age. Since the study wascross-sectional, our results must be treated withcaution.

Nevertheless, using the Movement ABC, wehave been able to show distinct variations inperformance that seem to be related to both ageand type of task. For example, on some tasks, not asingle child achieved age appropriate levels of motor competence and the gap between motorperformance and chronological age appeared to become progressively wider. In contrast, for other


Fig. 2. Level of performance (expressed as age equivalent)on the two items assessing ball skills.

Fig. 3. Level of performance (expressed as age equivalent)on the three items assessing balance.



aspects of motor functioning, delays were clearlypresent but the amount of discrepancy betweenlevel of performance and chronological ageremained relatively stable, irrespective of thechild's age at assessment.

We were also able to demonstrate the task-dependent variation in performance in anotherway. By averaging scores across all subjects, it wasclear that some skills were consistently worse thanothers irrespective of age. Unlike previous studieswhich have suggested that fine motor skills might be less affected than gross motor skills,13,14 ourresults have shown that all the aspects of fine

motor skills we assessed were severely impaired inall the children examined, irrespective of their age.

Of the three tests assessing manual dexterity, theone which focuses on accuracy and timing in bimanual coordination yielded the highest impair-ment score in the whole test with the degree of impairment much more evident in the olderchildren. With one exception, no child over theage of 11 achieved the level expected of a normal 7-year-old. Considerable impairment was also evi-dent in both the manual dexterity task whichassesses timing and accuracy in both hands tested

separately and in that evaluating visuomotorintegration by testing the accuracy in tracing aline between boundaries. A deficit in visuomotorskills was further demonstrated in our cohort bythe VMI test which showed progressively lowscores with age. In these children the lack of accuracy in drawing the line was only part of theproblem as even the oldest children had majorproblems with the more complex three-dimen-sional figures showing intersections. As the figuresto be copied increased in complexity, it was clearthat the DS children had no strategies for working

out the demands of the task and planning anappropriate motor output.

The results on the items assessing gross motorabilities, in contrast, showed a wider variability.The two items assessing ball skills showed differentresults illustrating clearly the difference in thefunctions tested. While the ability to direct an

object in space, such as hitting a target, wasrelatively maintained, the ability to adjust the body in space to receive a moving object and toanticipate the event was very poor and showedlittle improvement with age. Both static anddynamic balance were also affected, though awider variability could be observed in these items.

Attempts to explain the pattern of perceptuomo-tor impairment in DS are many and varied.15±23 Inthe general population of individuals with mentalretardation, the relationship between level of cognitive impairment, as measured by IQ, andmotor competence has been explored in numerousstudies. Since reported correlations rarely exceed0.5 (leaving 75% of the variance in motor perfor-mance to be accounted for), there is now very littleinterest in pursuing this relationship further. In anexclusively DS sample, a slightly higher correlation between mental age and motor performance has been reported3 but this finding has not beenreplicated. In our study, the range of IQs obtained by the DS children was rather narrow (41±45) withmany of the children performing a floor level. Thelack of variance associated with this floor effectprevented us from exploring the relationship

between IQ and performance on our two percep-tuomotor tests. However, in the light of previousfindings, we consider it much more fruitful to lookfor other kinds of explanation for the variousperceptuomotor difficulties experienced by DSchildren.

Some of the earlier studies of children with DSfocused on the presence of physical featuresassociated with the syndrome which might affectperformance.3,16,17 Poor results in manual dexterityfor example, were attributed to the short fingers,flabby hands and lax ligaments which are a feature

of DS. Similarly, hypotonia and lax ligaments in thehips were thought to be responsible for abnormal balance and gross motor difficulties. More recently,experimental studies have identified specific defi-cits in aspects of visuomotor integration, eye±handcoordination, and balance ± all of which point toimpairment in much higher levels of motor con-trol.3,12,13,21 Neuropathological studies,18 and morerecently magnetic resonance imaging studies20,21

have clearly demonstrated that in individualswith DS both the cerebellum and the brainstemlook smaller. The incomplete development of these


Fig. 4. Level of performance (expressed as age equivalent)on the Developmental Test of Visual±Motor Integration.



structures might therefore play a role in theintegration of the sensory input and in the dexterityand coordination of movement.

In conclusion, our results suggest that thedelayed perceptuomotor development exhibited by all children with DS is not evenly distributedacross all tasks. Although we have used only a

small number of the vast range of motor tasks wemight have used, our results suggest that thedegree of impairment in gross motor abilitiesseems to remain relatively similar irrespective of the age when the test was performed. In contrast,fine motor skills, especially bimanual skills andskills requiring fast responses to moving objects donot seem to progress at the same rate. This seems to be especially true when the perceptual demands of the task are high and there are tight timeconstraints.

As we have already noted, the fact that this was across-section, rather than longitudinal study meansthat our findings must be interpreted with caution.Moreover, since few of the children in this studyhad received early and regular intervention pro-grammes, we must consider the possibility that thepattern of results we have obtained might not begeneralizable to all DS populations as we cannotexclude that children who receive early and regularintervention programmes might show better devel-opment, as previously shown.14,23,24 Nevertheless,our results clearly indicate that some areas of motor abilities, especially in absence of rehabilita-tion seem to be more affected than others,

suggesting that these might be the target for earlyintervention.

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