IQ AND ITS PREDICTORS IN CHILDHOOD HEMIPLEGIA

Robert Goodman Carole Yude

We had three reasons for being interested in intelligence and its predictors in a rep- resentative sample of children with hemi- plegia. First, in order to guide parental and educational expectations, paediatri- cians are often asked to predict the intel- ligence of preschool children with hemiplegia. How well can this be done on the basis of a neurological history and examination? A good clinical algorithm for predicting IQ would be useful in its own right and could also act as a ‘bench- mark’ for evaluating whether brain scans or other special investigations add much in predictive value.

Our second reason for studying the cognitive sequelae of hemiplegia was that these offer a window on neuroplasticity. .Previous studies of the cognitive conse- quences of early unilateral lesions have generated conflicting findings and theo- ries (see Vargha-Khadem et a!. 1994). The authors of some early studies argued that the two hemispheres have the same cognitive potential at birth and that lateral specialisation develops only slowly over the course of childhood. The authors of a subsequent wave of studies challenged this idea, proposing that adult-like specialisation was present from birth or earlier. Recent research supports an inter- mediate position. Many studies now sug- gest that after early unilateral damage (particularly in the absence of seizures),

language and verbal intelligence gener- ally develop well, perhaps at some cost to visuospatial intelligence. Early damage may also be more likely to reduce overall intelligence than is comparable later damage. These important conclusions are almost entirely based on clinical studies and need to be examined in studies of representative samples.

Our third reason for studying a repre- sentative sample of children with hemi- -

5 plegia was to clarify the relation between neurological predictors of intelligence - and ‘ordinary’ genetic and psychosocial predictors of intelligence. Genes and F.

family environment both have a substan- 3 tial influence on the intelligence of ordi- nary children (Bouchard and McGue 5 + 1982), and both factors probably con- tribute to the higher IQs of children - z from socially advantaged backgrounds \ 8 (Capron and Duyme 1989). Among chil-

i, dren with neurological disorde s, how do . 2

biological risk factors, such as preterm birth or prenatal viral infections, may $

e z ligence being exaggerated among >

biological risk factors may have a coil-

, X

X X

2‘ c -

z

<

the effects of neurological fictors and social class interact? Exposure to some

- - Y - - - ” .- 2

F ? have an aniplificatio~i effect, with the social class differential in measured intel-

affected children (Sameroff 1986). Other

striction effect. reducing or obliterating the social class differential in IQ. For

g *

5

881

TABLE I The five scales whose subscores were summed Lo constitute the N score

SC& Score

Degree of hemiparesis Mild = good helper hand, low visibility except when stressed Moderate = poor helper hand, awkward gait . Severe = 'paperweight' hand, very awkward gait

Purely unilateral Minor or dubious signs in 'good' arm or leg 'Good' arm or leg definitely involvedl

No seizures have ever occurred Seizures have occurred but ncver complicated' ones complicated^ seizures have occurred, either now or in past

Head Circumference on or above 3rd centile Head circumference below 3rd ccntile

Presumed before 28 days after delivery Between I mth and 5 yrs of age After 5 yrs of age

Bilaterality

Seizures

Microcephaly

Age at onset of hemiplegia

0 2 3

0 2 3

0

4

0 3

0 3 0

7 -

ICould be considered an asymmetrical diplegia or quadriplegia. 'Complicated seizures include infantile spasms, 'stare, jerk, fall' seizures, complex partial seizures, very frequent seizures, seizures some of which are prolonged and seizures resistant to conventional anticonvulsants. Considered to be not complicated were a few seizures at time of initial insult, a few brief generalised seizures with fever at age I to 5 years and infrequent brief hemi- seizures or generalised tonic-clonic seizures.

example. Carr (1988) found that the IQs of individuals with Down syndrome were not affected by parental social class. Finally, neurological factors and social class could have additive effects on IQ, without either amplification or constriction.

Method As described more fully elsewhere (Goodman and Yude 1996), the London Hemiplegia Register used multiple sources to ascertain a representative sam- ple of London children with a clinical diagnosis of hemiplegia. The full sample comprised 458 London children (plus three children who lived just outside the Greater London boundary). This study is primarily concerned with the representa- tive sample of 149 of these children who were neurologically and psychometri- cally assessed by the authors (Goodman and Yude 1996). All 149 were aged between 6 and 10 years, and all but one lived in Greater London. The IQ of 130 children was assessed by administering a full version of the Wechsler Intelligence

882

ScaIe for Children - Revised (WISC-R; Wechster 1974). The remaining 19 chil- dren were near or below the floor of this test (with IQs under 50); on the basis of an independent assessment of their men- tal age, they were categorised as having profound, severe or moderate mental retardation and assigned IQs of 20, 30 and 40 respectively. Verbal-performance (VP) discrepancies were calculated by subtracting performance IQ (PIQ) from verbal IQ (VIQ) for those subjects with a full-scale IQ of 50 or more.

As summarised in Table I, a composite neurological score (N score) was gener- ated from subscores on five items: age at onset of hemiplegia, degree of hemipare- sis (following Ingram 1966). seizure his- tory, bilateral involvement and head circumference. Bilateral involvement in hemiplegia may seem a contradiction in

. terms, but the presence of bilateral signs in a substantial minority of children with a clinical diagnosis of hemiplegia is well recognised (e.g. Uvebrant 1988); one paediatrician's hemiplegia is another

paediatrician's asymmetrical diplegia or quadriplegia. Congenital hemiplegia was operationally defined to exclude subjects with causal lesions acquired after the end of the neonatal period (Goodman 1994). Acquired hemiplegia was classified as being of early or late onset. depending on whether onset was before or after 60 months of age. For simplicity, the N score was generated from global ratings rather than from a much larger number of ratings of individual symptoms and signs. Global ratings of visual or somatosensory deficits were not included, since thcse are hard to assess routinely in young children. This difficulty might preclude the use of the N score in future studies of preschool chil- dren. Item weightings for the N score were derived from the univariate and multivariate analyses reported below.

The Registrar General's classification of paternal occupation (Office of Population Censuscs and Surveys 1980) formed the basis for dichotomising social class into 'non-manual' and 'other' (with the latter including households headed by single mothers). This definition was cho- sen in preference to one based on both parents' occupations, because it resulted in greater group differences in housing tenure, car ownership and neighbourhood disadvantage.

Though most analyses were restricted to the 149 intensively studied children, late- acquired hemiplegia was so rare that its impact on IQ could only be studied by extending the analyses to a larger sample consisting of the 265 schoolchildren on the London Hemiplegia Register whose par- ents had completed questionnaire items on age at onset of hemiplegia and mental age. Ratio IQs derived from these parental esti- mates of mental age were highly corre- lated with psychometrically assessed 1Qs in our sample (Goodman and Yude 1996). The larger sample comprised 141 children who had not been individually assessed plus 124 of the 149 intensively studied children, (Twenty-five children from the intensively studied group could not be included in the larger group because their parents had not completed the question- naire item on mental age).

120

110

100

Bo

70

60

50

MMR

SMR

PMR

Results The IQ distribution of the 124 individu-

R L

L

R L R RR

-RR U

R

R L ~ R R

L L

Fig. 1. Relatiori between IQ. iige (it oriset of herriiplegia arid it it era lit^ og hetriiplegicr iii 25 iridividiriilly assessed childreri with ircyrrired herriiplegin. PMR. SMR, MMR = profowid. sewre arid riioilertrte riieiitol remrddoi i . respectively; L = left-sided Iierriiplegiti (N = 10); R = right-siiled hemiplegiii (N = I S ) .

ally assessed children with congenital hemiplegia was normally distributed around a mean of 81 points (median 83 points), with a standard deviation of 23 points. This standard deviation is sub- stantially larger than the normative stan- dard deviation of 15 - representing just over twice the variance that would be found in a normal population sample. There were no significant differences in IQ between the 73 children with right hemiplegia and the 51 children with left hemiplegia ( r test for mean: r=1.6. df=122. ris; F test for variance: F=1.5. df=72,50, 11s).

The VP discrepancies in congenital hemiplegia were also normally distrib- uted, with a mean of 13 points (VIQ higher than PIQ) and a standard deviation of 16 points. The VP discrepancy did not differ significantly according to the later- ality of hemiplegia (f=0.5, df= 1 10. 11s).

The relation between IQ. age at onset of hemiplegia and laterality of hemiplegia is shown in Figure 1 for the 25 individu- ally assessed children who had acquired hemiplegia as a result of insults after the neonatal period. The correlation between 1Q and age at onset was 0.58 for the whole sample ( ~ ~ 0 . 0 I ). but this fell markedl) to 0.13 and was no longer significant once 883

884

TABLE I1 Relation between age at onset of hemipfe- gia and IQ as judged from parental esti- mate of mental age

Age ot oiisei N Mem IQ (Sn)

< I mth

1-60 mths

>60 mths

(‘congenital’) 22 1 87 (21)

(acquired ‘early’) 37 68” (25)

(acquired ‘late‘) 7 92 ( 1 1 ) .

*ANOVA for difference in means: F(2262) = 12.7, pc0.001. On Duncan’s multiple range test, the group with h e m i p l e ~ i ~ acquired early differed significantly from the other two groups but the other two groups did not differ from one anothcr.

the two children with late-acquired hemi- plegia had been excluded from the analy- sis. For the remaining 23 children, with early-acquired hemiplegia, multiple regression analyses showed that IQ was not significantly predicted by age at onset, laterality or an interaction of the two. The mean IQ of children with earIy-acquired hemiplegia was significantly lower than that of children with congenital hemiple- gia (52 compared with 8 I; f=5.8, df= 145, p<O.OOl). The mean VIQ in acquired hemiplegia was I2 points higher than PIQ (SD 16 points) and multiple regression analyses showed that the VP discrepancy was not predicted by age at onset, lateral- ity or an interaction of the two.

The hint that children with late- acquired hemiplegia have relatively well- preserved IQs was investigated further by analysing questionnaire data on the 265 schoolchildr~n from the London Hemiplegia Register for whom there was complete information from parents on age at onset and current level of functioning. In this larger sample, the mean IQ of the 7 children with late- acquired hemiplegia was comparable with that of children with congenital hemiplegia and was significantly higher than that of children with early-acquired hemiplegia (Table 11).

Table 111 shows group differences in IQ and VP discrepancy when the 149 inten- sively studied subjects were subdivided

according to the presence or absence of putative predictors. Sex, laterality and preterm birth (c37 weeks) had no signifi- cant effect on IQ or VP discrepancy. Neither were there any significant lateral- ity effects when males and females were analysed separately, or when individuals with and without seizures were analysed separately.

IQ was signi~cantiy related to five neurological variables, namely, age at onset, severity, bilateral involvement, seizure history and head circumference. ’ All five continued to have independent predictive value when entered simultane- ously in multiple regression analyses with IQ as the dependent measure. These five predictors were used to generate the N score (see Table 1). using the effect sizes from the multiple regression analy- ses to guide the weighting of the five components. N score and IQ were lin- early related (Fig. 2). There was a nega- tive correlation (r;.-0.73) between N score and IQ across the whole range, with this correlation falling slightly to -0.59 when children with IQs under 50 were excluded (p<O.OOI for both correlations). The N score predicted 53% of the vari- ance in IQ, while stepwise multiple regression involving a11 five neurological factors individually, plus all interaction and quadratic terms, did only fractionally better, predicting 54% of the variance. After allowing for the predictive effect of the i4 score, the standard deviation of the IQ distribution fell to 17 (i.e. close to the value in a normal population sample).

There was a trend for children from non-manual backgrounds to have lower N scores (3.5 compared with 4.6: I = 1.83, df= 147, p=O.07). Although this partly explained why children from non-~anua l backgrounds had an average IQ some 18 points higher than other children, there was still it social class difference of 12 points after allowing for the N score (see Fig. 2). In multiple regression analyses with IQ as the dependent variable, N score and social class both had main effects (pc0.001 for both) without a sig- ni fican t interact ion. Simi larl y , with VIQ as the dependent variable, both N score and social class had main effects @<0.001 for both) without any interac- tion; the social class differential in VIQ

- TABLE I11 E

VIQ-PIQ' I-.

X

X P

- IQ and verbal-performance discrepancy for entire and subdivided sample

x N c/o with lQ<SO Metrri FSIQI

Entire sample Sex

Male Female

Side of heriiiplegicr Right Left

Olmr Congenital (preterm) Congenital (term) Acquired

Sever-iiy of keniipleyid Mild Moderatelsevere

Purely unilateral 'Partly bilateral

Seixres Ncver Current or resolved

<3rd centile Other

Socid clrss Non-manual Other

Bittirerotit$

Hend circirrnfereiice

149

91 58

88 61

38 86 25

65 84

I10 39

88 61

23 19-6

74 75

84( 19)

86(20) 82( 19)

85( 19) 83(21)

83(20) 87( 19) 73( 19)"

92( 19) 77( 17)"*'*

87(20) 72( 13)*:w

90( 18) 73( 16)**+

72( 15) 86( ]9)*.*

89(20) 79( I7)**

+13(16)

+13(14) +12( 18)

+12(15) +13(18)

+16(17) + I l(16) +12(16)

+13(17) +12(15)

+ I l(17) +20( 13):y

+12( 16) +15(17)

+16(12) +12(17)

+16(16) +8( l5)*?

FSIQ = Full Scale 10. VlQ = Verbal IQ, PIQ = Performance IQ. Significance of group difference (x ' . r test or ANOVA): '>p<0.05; *:3/~<0.01; ""'p<O.OOI. I Analvses restricted to subiects with 10250. ?See Table I for definition:

-

was 14 points after allowing for the N score. With PIQ as the dependent vari- able, however, the main effect of social class was only marginally significant (p=0.054), though. as before, the main effect of the N score was highly signifi- cant ( ~ ~ 0 . 0 0 1 ) without a significant interaction; the social class differential in PIQ after allowing for the N score was only 5 points. This sample's class differ- entials in VlQ and PIQ are compared (Table IV) with those found in two other studies of London children assessed with the WISC-R.

As shown in Table 111. VIQ was higher than PIQ for all subgroups of the sample. This difference reflected a consistent pat- tern of subscale scores, shown separately for children with left and right hemiple- gia in Figure 3. There were no significant laterality differences for mean scale score on any of the 1 I administered subtests of

the WISC-R. The magnitude of the VP discrepancy

was predicted by just two factors, namely, bilateral involvement and social class. The non-significant association between preterm birth and a greater VP discrepancy reflected the association between preterm birth and bilateral involvement. In multiple regression analyses with V P discrepancy as the dependent variable, both bilateral involvement and social class had main effects (p<O.OOI for both) without a sig- nificant intera+-on.

Discussion A summary rating of neurological impair- ment - our N score - was a good predic- tor of IQ in our subjects with hemiplegia. explaining just over half of the total vari- ance in IQ. It would be premature, how- ever. to conclude that the N score is a

I

.

885

886

140

120

100

: 80 P

60

40

20

0

- - -Other

\ \ 0 8 '

8

0

0 2 4 6 8 10 12 14 16 N score

Fig. 2. ~ e ~ a t i ~ ~ i betweeit /Q arid N score iti I49 ~ ~ i ~ l d r e n with ~ ~ ~ ~ ~ ~ i p ~ e g ~ a .

useful innovation. Any predictor index is likely to perform best-on the population from which i t was derived; independent replication is essential. In addition. from the age of roughly 3 or 4 years, it will almost certainly be more accurate to pre- dict a child's future IQ from their current. IQ or developmental quotient than from their N score. The key question is

whether the N score is a useful alternative or adjunct to developmental tests when predicting eventual IQ in very young children with hemiplegia,

There is conflicting evidence about whether neuroradiological appearances predict eventual cognitive outcome in hemiplegia (e.g. Cohen and Duffner 1981, ~ o l t e n i et al. 1987, Wiklund and

- TABLE IV F

X I

X P

- Social class difference in VIQ and PIQ (non-manual minus other)

2' *5

0 51 s

Sociul class difference VIQ PIQ

- Current sample 14 5 s. 2 Normal twins' 13 7 Child psychiatric outpatients? 10 8

2 'Data on 460 13-year-old London twins (J Stcvenson, personal communi- cation. 1993). 5 'Data on 362 children aged 5 to 16 seen at a children's psychiatric clinic

severe learning difficulties (Goodman. unpublished data).

z - - - - z .-

h other than for psychotic disorders. pervasive developmental disorders or - -

- " .> z - -

10

8

6

4

2

0 , In

a 0 Left hemipbgii Right herniplegla M O k77

Si Ar Vo Cm DS PC PA BD OA Cd Subtest of WISC-R

Fig. 3. Menri scores 011 siibtesrs of W S C - R . riccordirig to side of lesiorl (lQ2-50). Iri = linforrnariori. Si = Siiriilnriries, Ar = Arithtrreric, Vo = Vocabitlar?, Cni = Conipreherision. DS = Digit Span. PC = Pictiire Cornpletiori. PA = Pictiire Arrarigerrierit, BD = Block Design. OA = Object Asseriihly, Cd = Cotlirig. All differelices left vs right riori-sigriificatit ( t rest).

Uvebrant 1991). It should not be assumed that high-technology measures are neces- sarily better than ordinary clinical mea- sures. Thus, in studies of the cognitive outcome of hemiplegia carried out by Vargha-Khadem and colleagues. rela- tively crude neuroradiological measures of the extent of the underlying lesion were much weaker predictors than clinical fac- tors (Vargha-Khadem er a/. 1985, 1992). In keeping with this finding, Kornhuber et nl. (1985) found no correlation between IQ and the neuroradiologically deter- mined extent of localised forebrain lesions sustained before the age of 5 years (though the extent of lesion and IQ were

linearly related after that age). If the pre- dictive power of the N score is confirmed for very young children, this will provide a useful benchmark for evaluating whether qualitative or quantitative analy- ses of early brain scans or other special investigations add extra predictive power.

Our findings on a representative sam- ple of children with hemiplegia largely support previous conclusions about neu- roplasticity. In keeping with Teuber's (1975) original suggestion. it does seem that verbal reasoning is relatively well preserved after early damage to either hemisphere, though there is some dam- age to visuospatial skills. Thus the mean 887

verbal IQ was greater than the mean per- formance IQ in all subgroups of this sam- ple. Before concluding that hemiplegia does indeed selectively impair visuospa- tial reasoning, it is important to consider the alternative that lower performance IQ may simply reflect the physical difficulty children with hemiplegia have in manipu- lating blocks or puzzle pieces. In other words, is performance IQ artificially depressed in hemiplegia because the chil- dren are disadvanta~ed by their motor dis- ability rather than by a selective deficit in visuospatial intelligence? The case is plausible. but the pattern of subtest scores argues against it. Children with hemiple- gia did as badly on the picture completion subtest (which involves a verbal answer or one-handed pointing) as they did on the other visuospatial subtests that would have been more dependent on bimanual skill. It seems likely. therefore, that the lower performance IQ in hemiplegia docs reflect selective visuospatial deficits.

Our finding that side of lesion in con- genital hemiplegia does not affect IQ or VP discrepancy is in keeping with the conclusions of Vargha-Khadem ef a/. (1992). We did not find the interaction between sex and laterality reported by Carlsson ef al. ( 1994) in their epidemio- logical sample of children with hemiple- gia. Among children with acquired hemiplegia. we found no evidence that lesions had side-specific effects on ver- bal and visuospatial skills. However, since most of the acquired lesions dated back to the first three years of life - in line with findings in previous studies (Aicardi and Bax 1992) - we cannot rule out an adult pattern of side-specificity for lesions acquired in later childhood. Two previous studies have reported that right-sided lesions acquired after the age of 1 year selectively lower performance IQ while comparable left-sided lesions do not (Woods 1980. Riva and Cazzaniga 1986). In both of these clinic- based studies, however, the mean age at onset was over 6 years, so the absence of a Iaterality effect among children who acquired their lesion in the preschool years could have been masked by com- bining them with a larger number of subjects who acquired their lesion later in development.

If the relative preservation of language irrespective of the side of the lesion is an advantage of having a lesion early rather than late, then the loss of overall intel- lectual ‘power’ may be a correspond in^ cost (Hebb 1942). For example, cranial irradiation leads to greater overall cogni- tive impairment when given before the age of 4 or 5 years than when given later in childhood (Cousens ef nl. 1988). The findings of this study suggest that in hemiplegia the curve describing the refa- tion between age at insult and eventual IQ may be U-shaped rather than linear. with the lowest mean IQs being found among children who acquired their lesions between I and 60 months of age, rather than earlier or later. This age effect was evident even in multivariate analyses that allowed for the possible confounding effects of seizures, severity, bilaterality and microcephaly. The period between I and 60 months is a peak period for synaptic production and elimination ( ~ u t t e n ~ o c h e r 1979. Huttenlocher ef 01. 1982); perhaps lesions sustained in this period are par- ticularly likely to evoke maladaptive neuroplastic responses that result in dif- fuse misconnections or over-connections that impair the brain’s ‘power’ (Goodman 1989, 1991).

For both IQ and VP discrepancy, the effects of neurological factors and social class appeared to be additive rather than interactive. Thus the class differential in predicted IQ was constant across the entire range of N scores, without any evi- dence for an amplification effect (which wouId have led to a greater class differ- ential at high N scores) or for a constric- tion effect (which would have led to the narrowing or obliteration of the class dif- ferential at high N scores), Similarly, the sizes of the class differentials for verbal and performance 1Qs were roughly in line with those for neurolo~icalIy intact children. The most straightforward explanation is that the genetic and psy- chosocial factors that influence the IQ of ordinary children have similar effects on children with hemiplegia - with- the effects of these ‘ordinary’ influences simply summing with the effects of neurological influences. If this is so. then the N score appears to account for nearIy

all of the neurologically determined IQ variation i n our sample, since the resid- ual IQ variance not explained by the N score was hardly greater than the vari- ance one would expect in any population. The relation between neurological and ordinary influences on cognitive devel- opment could be further clarified by studies of childhood hemiplegia that also examined the IQs of unaffected relatives. Indeed, the most informative design might be an epidemiological twin study that looked both at ordinary twin pairs and at twin pairs discordant for hemiplegia.

Arcepred for pirblicrtlioii I9lli Se[)ruiiiber 1995.

A ~ k r i o ~ ~ l c d ~ e i i i r i r r s We arc very grateful to, the many professionals who helped us find our sample; to the children. parents and teachers who participated in the study; to Bob Adak and Suzanne Pembcrton, who provided essen- tial administrative support and to Faraneh Vargha- Khadem and Philip Graham. who gave invaluable supervision and encouragement. The study was gen- erously funded by the Wellcome Trust and Scope (formerly The Spastics Society).

A irrhorz ’ Appoirirrric~rirs .*Robert Goodman. MRCP. MRCPsych. Reader in Brain and Behavioural Mcdiciqe. Institute of Psychiatry. London. UK. Carole Yude. BA, Research Psychologist: Institute of Child Health.

.“iiiie.cpoiir/rii~e 10 Jirsr crirrlior at Department of Child and Adolescent Psychiatry. Institute of Psychiatry. De Crcspigny Park. London SE5 8AF. UK.

SUMMARY In a population-based sample of 149 children with hemiplegia, IQ was highly correlated with a simple-to-calculate indcx of neurological scverity. Performance IQ was an average of I3 points lower then verbal IQ - a difference that seemed to reflect specific visuospatial difficulties rather than an effect of the motor disability itself. Side of lesion was not significantly related to either IQ or vcrbal-performance discrcpancy. Neurological factors and social class had additive effects on IQ, suggesting that neurological damage neither amplified nor obliterated the impact of ordinary psychosocial and genetic factors on IQ.

RESUME Le QI et sn wileiir prgdictive dms l*liCinipl&jr inJkrtilr Sur un echantillon de population de 149 enfants hCmiplegiques, le Q1 etait hautement correle avcc un index de simple calcul de la gravite neurologique. Le QI de performance etait en moyenne de 13 points inferieur au QI verbal. une diffhence qui semblait traduire des diffcultes visuo-spatiales spkifiques plutBt que I’incapacite motrice par elle-mtme. Le c6te de la ICsion n’etait relie significativement. ni aux QI verbal ou performance. ni h la diffkrence verbal-performance. Les facteurs ncurologiqucs et la classe sociale avaient des effcts additionnels sur le QI. suggennt que le dommage neurologique n’amplifie ni masque I’impact des facteurs psychosociaux et ginCtiques habituels sur le QI:

ZUSAMMENFASSUNG IQ iirid seine progriostischeir Fnktoreri Dei Kiritlerii iiiit Hrrriiplrgie Bei einer Gruppe von 149 Kindern mit Hemiplegie bestand eine deutliche Korrelation zwischen IQ und einem cmfach zu berechnenden Index fur den neurologischen Schweregrad. Der Handlungs-IQ war im Durchschnitt 13 Punkte niedriger als der verbale IQ - ein Unterschied. dcr cher Ausdruck speziellcr visuell-rhumlicher Storungen als der motorischcn Storung selbst war. Die Seite der Lasion spielte keine signifikante Rolle. weder fur den IQ noch fur die Diskrcpanz zwischen verbalem - und Handlungs-IQ. Neurologische Faktoren und sozialer Status hatten einen additiven Effeckt auf den 1Q. was vcrmuten IhBt, daB die neurologische Schhdigung das Gewicht der allgemeinen psychosozialen und genetischen Faktoren auf den IQ weder versthrkt noch vermindert.

RESUMEN CI y siis predictores en la Irerriiplegin irlforitil En una poblaci6n dc 149 niiios con hemiplegia. el CI estaba altamente correlacionado con el indice de gravedad neurologica, ficilmente calculable. El CI de realizacion era de un promedio de 13 puntos por debajo del verbal. Esta’ diferencia parecc reflejar dificultades visuo-espaciales especificas. mis que un efecto de la disfunci6n motora en si. El lado de la lesi6n no estaba significativarncnte en relacion con el CI o con la discrepancia entre el CI verbal y el de realizacion. Los factores neurologicos y la clase social tenian efectos aditivos sobre el CI. lo que sugiere que el daiio neurol6gico ni amplificaba ni obliteraba el impact0 de 10s faciores ordinarios psicosociales y genkticos sobre el CI.

889

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