Hemispatial neglect in young children with early unilateral brain damage

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1 Hemispatial neglect in young children with early unilateral brain damage Doris A Trauner MD, Departments of Neurosciences and Pediatrics, University of California, San Diego School of Medicine, La Jolla, CA, USA. Correspondence to author at Department of Neurosciences, UCSD School of Medicine 0935, 9500 Gilman Drive, La Jolla, CA , USA. dtrauner@ucsd.edu Hemispatial neglect is commonly observed in adults following right-hemisphere brain lesions. Given the potential for reorganization in the developing brain, spatial neglect may not be apparent following early unilateral damage. This study aimed to determine whether infants who experienced pre- or perinatal focal brain lesions showed evidence of spatial neglect. Study participants were 33 infants/toddlers (22 males, 11 females; age range 6 to 48 months); 27 preschool children (14 males, 13 females; age range 28 to 75 months) with either left hemisphere (LH) or right hemisphere (RH) damage of pre- or perinatal onset (total 60), and 36 control individuals (15 females, 21 males; age range 28 to 75 months). Participants were assessed using two objectremoval preference tasks. Control children showed no lateralized preference for object removal. Those with LH or RH damage preferentially removed objects from the side of the board ipsilateral to the lesion first and the contralateral side last. These results suggest that spatial neglect may be found in young children even after very early unilateral brain damage. Further, in contrast to the adult pattern, contralateral neglect is present for up to 6 years after either LH or RH damage. This pattern suggests that there may be a different distribution of attention to space in the developing brain as compared with the mature brain. The persistence of spatial neglect suggests that there are some limitations on plasticity in the developing human brain. A common sequel to unilateral brain injury in adults is hemispatial neglect, or inattention to the contralateral half of the individual s extrapersonal space. Evidence for such neglect can be found after either right hemisphere (RH) or left hemisphere (LH) damage in adults (Heilman and Van Den Abell 1980, Denes et al. 1982, DeRenzi et al. 1982, Ogden 1985, Gainotti et al. 1986, Weintraub and Mesulam 1987, Karnath 1988, Petersen et al. 1989). However, lesions of the RH often produce more severe and lasting neglect (Heilman and Van Den Abell 1980, Weintraub and Mesulam 1987). This has led to the hypothesis that the RH may be dominant for the distribution of attention within extra-personal space (Heilman and Van Den Abell 1980, Mesulam 1981, Weintraub and Mesulam 1987). Except for isolated case reports (Ferro et al. 1982, 1984; Johnston and Shapiro 1986; Thompson et al. 1991), similar studies have not been conducted in children after early focal brain injury. The potential for reorganization after very early brain damage, as has been demonstrated in the case of language development (Thal et al. 1991, Bates et al. 1999), may mean that other cognitive functions such as hemispatial neglect may not be a significant problem in children with early-onset focal brain lesions. Global intellectual function, for example, is in the normal range for most children with early focal brain damage, although mean IQ for these groups tends to be lower than that for control participants matched according to socioeconomic status (Ballantyne et al. 1994). However, there is some evidence suggesting that there may be limitations to plasticity in the developing nervous system. For example, spatial skills may be impaired in children albeit subtly, well into the school years after perinatal focal brain lesions (Stiles-Davis 1988, Stiles et al. 1997, Vicari et al. 1998, Schatz et al. 2000). In addition, children with early RH damage may have persistent deficits in social interaction, attention, and prosody (Weintraub and Mesulam 1983; Voeller 1986; Tranel et al. 1987; Trauner et al. 1996a, b). Studies by Heilman and colleagues (1978) and Heilman and Van Den Abell (1979) suggested that adults with RH lesions who demonstrate the neglect syndrome have disturbances in bilateral arousal, and that this disorder of arousal may be responsible in part for the flattened affect observed in the same individuals. Similarly, if children with early RH damage demonstrate an analogous neglect syndrome, then this might explain some of their difficulty in attending to the emotional nuances of others and help to explain their reported social and interpersonal difficulties (Weintraub and Mesulam 1983; Voeller 1986; Tranel et al. 1987; Nass and Koch 1987, 1991; Reilly et al. 1995; Trauner et al. 1996a, b; Goodman and Yude 1997). The purpose of the present study was to determine whether young children who had experienced very early (preor perinatal) acute, focal brain damage demonstrated evidence of hemispatial neglect. Because of evidence for limitations on plasticity in non-verbal cognitive domains after early RH damage (Stiles-Davis 1988, Stiles et al. 1997, Vicari et al. 1998, Schatz et al. 2000), our hypothesis was that children who had experienced early, unilateral brain lesions would have similar indications of hemispatial neglect as those in adults. In other words, children with RH lesions would demonstrate neglect of left hemispace, whereas children with LH lesions would demonstrate little or no evidence of contralateral neglect. In order to test this hypothesis, two novel tasks were developed in our laboratory. 160 Developmental Medicine & Child Neurology 2003, 45:

2 Method PARTICIPANTS Two groups of children participated in separate segments of the study: the infant/toddler-age group comprised 22 participants with LH lesions (16 males, six females), 11 with RH lesions (six males, five females) and 36 control children (21 males, 15 females) between the ages of 6 and 48 months. The preschool-age group comprised 14 children with LH lesions (11 males, three females), 13 with RH lesions (seven males, six females), and 36 control participants (21 males, 15 females) between the ages of 28 and 75 months. There was some overlap in the ages between the two groups because some of the children were unable to perform the preschool task at the expected age and were thus given the infant task. Those children who could not perform the preschool-age task typically began reaching for the toys spontaneously, without waiting for instructions. Each child in the focal brain lesion groups had a single, unilateral lesion documented by a neuroimaging procedure (either CT or MRI). Lesion occurrence was believed to be pre- or perinatal in every child, based on medical history and hospital records. Lesion etiologies included ischemic or hemorrhagic infarcts or intraparenchymal hemorrhages, except for one child with a ganglioneuroma involving the entire right temporal lobe. This child was included in the study because the lesion was believed to be present from birth. Exclusionary criteria were the presence of multiple lesions, history of exposure to illicit drugs in utero, severe closed head trauma, history of bacterial meningitis or anoxia, or any condition that might have produced more global brain damage. Control participants were recruited primarily from advertisements in parent magazines, from fliers placed in pediatricians offices, and by word of mouth. All control participants had a history of normal development without evidence of neurodevelopmental or significant medical problems. Children were excluded if there was a history of exposure to illicit drugs in utero, severe closed head trauma, history of bacterial meningitis or anoxia, or any condition that might have resulted in cognitive dysfunction. Control children were group-matched to the experimental groups on the basis of socioeconomic status. Informed consent was obtained before participant enrollment in the study, in accordance with the procedures of the University of California, San Diego Institutional Review Board, which gave ethical consent. NEUROLOGICAL EXAMINATION Each participant in the focal lesion groups underwent a detailed neurological examination as part of the study. Data from this examination were used to identify those children with hemiparesis or a visual field defect. TESTS OF GENERAL COGNITIVE FUNCTION Most of the infants and young children in the focal lesion groups were assessed using the Bayley Scales of Infant Development (BSID, BSID-II; Bayley 1969, 1993) as a general measure of developmental function. The Bayley scales are standardized measures that assess the motor and cognitive abilities of children from 1 to 42 months of age. The test yields a Mental and a Psychomotor Developmental Index (MDI and PDI respectively), which have a mean value of 100 with a standard deviation of 15. The Wechsler Preschool and Primary Scale of Intelligence Revised (WPPSI-R; Wechsler 1989) was administered to the children aged between 3 years 6 months and 6 years. It is a widely used, standardized test of young children s intellectual ability. It comprises 12 subtests that are divided into a Verbal Scale (Information, Comprehension, Arithmetic, Vocabulary, Similarities, Sentences) and a Performance Scale (Object Assembly, Geometric Design, Block Design, Mazes, Picture Completion, Animal Pegs). The test yields scaled scores for the subtests, and standard scores for Verbal IQ (VIQ), Performance IQ (PIQ), and Full-Scale IQ (FSIQ). NEGLECT TASKS Two neglect tasks were employed. The same stimuli were used for each task. A corkboard (30 45cm) was placed directly in front of the child. On the corkboard were 20 small toys in four categories (cars, cows, boats, and dinosaurs), arranged in a fixed random array such that each item was represented on both sides of the board. For the infant/toddler group, the child was seated on the parent s lap, body centered in relation to the board and at a comfortable level facing the board. The examiner sat directly across the table from the child. There was no attempt to hold the head in a fixed position during the task. The child was allowed to remove toys from the board without specific directions. As soon as the child touched or picked up an object, the object was removed from the child s hand and they were encouraged to pick up another toy until all of the toys had been removed from the board. The order in which the child removed the toys from the board was recorded, as well as the total time taken to remove all of the objects from the board. As the children did not remove all toys from one side of the board first, the time taken to remove toys from each side of the board separately could not be determined. Children were videotaped during the task so that analyses could be performed later by viewing the videotape. For the preschool-age group, a slightly different method was used. The same board with the same stimuli was placed in front of the seated child and centered. The child was then asked to hand the examiner all of the cars he or she could find on the board. The order of removal of the cars was recorded. This procedure was repeated with a request for removal of all of the cows that the child could find on the board, and a third trial requested the removal of all of the boats the child could find. The mean order of object removal from the left and right sides of the board was calculated from the results of the three trials. The individuals conducting these tests were blinded to the neurological status of the participants at the time of testing and during the reviews of the videotaped sessions. STATISTICAL ANALYSIS For the standardized tests of developmental or cognitive function, independent t-tests were used to compare group means. Mann Whitney U tests were used to compare differences between the LH lesion group and control children, and the RH lesion group and control children on the neglect tasks. Variables tested for both tasks were the preference for object removal from the left side of the board and the right side of the board. For the infant task, the time taken to remove of all of the objects was also compared among the three groups. Preference for object removal was also compared within each Spatial Neglect in Children Doris A Trauner 161

3 lesion group between those individuals with hemiparesis and those without hemiparesis, and between those children with or without a visual field deficit, as identified using confrontation techniques during the neurological examination. Preference for object removal was determined as follows: the order in which the child removed each toy was recorded. The order of removal for the toys in the left- and right-most column was totalled and divided by the number of toys in the column (4 toys). Thus for the left-most column, for example, if the child picked up the boat first, the cow fifth, the boat eighth, and the dinosaur fifteenth, the mean score for object removal in the left-most column would be =29 (4=7.25). Results Tables I and II summarize the relevant clinical, neurological, developmental, and cognitive information on infants/toddlers who were given the infant neglect task (see Table I) and the preschool neglect task (see Table II). Table III summarizes relevant group information on age, BSID scores, and WPPSI-R scores for the infant and preschool neglect groups. There were no significant differences in ages, BSID scores, or WPPSI-R scores for the LH, RH, or control groups in either infant or preschool studies, with one exception. The mean age of children with RH lesions in the infant study was significantly higher than that of the control children in the infant study. Mean ages of RH and LH lesion groups were not significantly different from each other. NEUROLOGICAL EXAMINATION In the infant/toddler group, 15 of the 22 children in the LH group, and six of 11 children in the RH group had detectable Table I: Background information on infants/toddlers with unilateral brain lesions who performed infant neglect task Sex, age Side of Lobes involved Lesion Hemiparesis BSID BSID Seizure history Evidence (mo) lesion size MDI PDI of neglect M, 6 L T-P 5 No Seizures Yes F, 37 L F-T-P-O 5 Yes Seizures No F, 19 L F-T-P-O 5 Yes None No M, 7 L F-T-P-O 5 No None Yes M, 6 L F-T-P-O 5 Yes Neonatal No M, 6 L T-O 5 No Neonatal No F, 26 L Basal ganglia 2 Yes None No M, 9 L F 4 No Neonatal Yes M, 9 L F-T-P-O 5 Yes Seizures Yes M, 20 L F-T 5 No None No M, 18 L F-T-P-O 5 Yes Seizures Yes M, 24 L T 4 Yes Febrile Yes F, 6 L F-T-P-O 5 Yes None No M, 25 L F-T-P 5 Yes None No M, 32 L F-T-P 5 Yes 139 Seizures Yes M, 15 L P 4 Yes None Yes M, 12 L O 4 No Neonatal No F, 19 L F-T-P-O 5 Yes Neonatal Yes M, 38 L P 4 Yes None Yes F, 21 L F 4 Yes None Yes M, 24 L F 4 Yes None Yes M, 18 L P 4 No Neonatal Yes M, 30 R Frontal horn dilation 3 No None Yes F, 18 R F-P-O 5 Yes Seizures Yes M, 12 R F-T-P-O 5 Yes None Yes M, 13 R P 4 No Neonatal Yes F, 39 R F-T-P-O 5 Yes Seizures Yes M, 12 R Frontal horn dilation 3 No None Yes M, 37 R F 3 No None No F, 30 R T 4 No Seizures Yes M, 48 R F-T-P-O 5 Yes Seizures Yes M, 26 R F-T-P-O 5 Yes Seizures Yes F, 24 R F-T-P-O 5 Yes None No L, left hemisphere; R, right hemisphere; T, temporal lobe; P, parietal lobe; F, frontal lobe; O, occipital lobe. Lesion size: (1) minimal ventricular dilatation or atrophy, seen on <3 cuts on CT or MRI; (2) moderate ventricular dilatation or atrophy, seen on >3 cuts on CT or MRI; (3) focal porencephaly involving only one lobe, seen on <3 cuts on CT or MRI; (4) focal porencephaly involving only one lobe, seen on >3 cuts on CT or MRI; (5) large porencephaly, involving multiple lobes. BSID MDI, Bayley Scales of Infant Development Mental Index; BSID PDI, Bayley Scales of Infant Development Psychomotor Index (Bayley 1969, 1993). Seizures, presence of seizures beyond the neonatal period; Neonatal, seizures in the neonatal period only. Evidence of neglect: determined by subtracting order of object removal on left side from that on right side of board for left hemisphere lesions, and by subtracting order of object removal on right side from that on left side of board for right hemisphere lesions. If difference was >3, participant was assumed to have hemispatial neglect for purposes of analyses. 162 Developmental Medicine & Child Neurology 2003, 45:

4 hemiparesis on neurological examination. In the preschool group, 10 of 14 children with LH lesions and eight of 13 with RH lesions had evidence of at least mild hemiparesis. Visual fields were examined by confrontation. In the infant/toddler group, seven of 22 children in the LH group, and four of 11 children in the RH group had at least a suggestion of a visual field deficit contralateral to the side of the lesion. In the preschool-age group, four of 14 children with LH lesions and two of 13 with RH lesions had indications of a contralateral visual field deficit. INFANT/TODDLER TASK Control infants and toddlers showed no lateralized preference for object removal from the board. The typical pattern of toy removal for control children was to remove the objects in the middle of the board first, and then to move outward to the left and right to remove the remaining objects, with no obvious preference for either side of the board. Those with LH lesions, in contrast, preferentially removed objects from the left side of the board first, and the right side last (Table IV). Those with RH lesions demonstrated the opposite pattern, preferentially choosing objects from the right side of the board before removing toys from the left side. Significant group differences emerged for object removal from both the left and right sides of the board (see Table IV). Those children with LH lesions demonstrated a significant preference for removing objects from the left side of the board compared with control individuals, while children with RH lesions demonstrated a significant preference for object removal from the right side of the board compared with control children. Neither the RH nor the LH group differed significantly from control children in the time required to remove the objects from the board (see Table IV). No significant difference was found in object removal preference for either the LH or RH group when children with hemiparesis were compared with children without hemiparesis (LH group, left side of board Mann Whitney U=28.5, right side of board, Mann Whitney U=43.5, ns). Similarly, no significant difference was found in side preference when children with visual field deficits were compared with those who had no evidence of visual field defects. PRESCHOOL TASK A similar pattern was observed for the preschool task. Both Table II: Background information on children with unilateral brain lesions who performed preschool neglect task Sex, age Side of Lobes involved Lesion size Hemiparesis WPPSI FSIQ WPPSI VIQ/PIQ Seizures Evidence of (mo) lesion (age mo) neglect M, 36 L Periventricular 1 Yes 134 (53) 142/118 None No M, 48 L T-P 5 No 115 (49) 107/120 Neonatal Yes M,55 L T-P 5 No 110 (54) 109/109 Seizures No F, 61 L Basal ganglia 2 Yes 108 (63) 111/112 None Yes F, 41 L F-T-P-O 5 Yes 93 (42) 100/86 None Yes M, 65 L T 3 No (66) /68 Seizures No M, 29 L F-T-P-O 5 Yes 94 (53) 97/93 Seizures No M, 75 L T 4 Yes 93 (51) 94/93 1 Febrile Yes M, 66 L Periventricular cyst 3 No 99 (65) 102/97 Neonatal Yes M, 45 L T-P-O 5 Yes 63 (51) 75/57 Seizures No M, 63 L F-T-P 5 Yes 81 (62) 85/80 Seizures No M, 65 L P 4 Yes None Yes F, 53 L F-T-P-O 5 Yes 80 (53) 83/80 Seizures Yes M, 45 R P 4 No 133 (83) 124/133 Neonatal Yes M, 48 R T-O 5 No (47) /71 Neonatal Yes F, 53 R F-P-O 5 Yes Seizures Yes M, 37 R F 4 Minimal None No F, 54 R T-P 5 No 110 (53) 114/105 None No M, 44 R F-T-P-O 5 Yes None Yes M, 49 R P 4 Yes 94 (47) 98/91 None Yes M, 62 R F-T-P-O 5 Yes 74 (70) 83/69 Seizures Yes M, 66 R F-T-P 5 Yes Seizures No F, 30 R T 4 No Seizures No F, 33 R F-T-P 5 Yes None No M, 52 R F-T-P-O 5 Yes 86 (72) 93/80 Seizures Yes F, 60 R F-T-P-O 5 Yes 66 (61) 74/65 Seizures Yes L, left hemisphere; R, right hemisphere; T, temporal lobe; P, parietal lobe; F, frontal lobe; O, occipital lobe. Lesion size: (1) minimal ventricular dilatation or atrophy, seen on <3 cuts on CT or MRI; (2) moderate ventricular dilatation or atrophy, seen on >3 cuts on CT or MRI; (3) focal porencephaly involving only one lobe, seen on <3 cuts on CT or MRI; (4) focal porencephaly involving only one lobe, seen on >3 cuts on CT or MRI; (5) large porencephaly, involving multiple lobes. WPPSI, Wechsler Preschool and Primary Scales of Intelligence (Wechsler 1989; FSIQ, Full-scale IQ; VIQ, Verbal IQ; PIQ, Performance IQ. Seizures, presence of seizures beyond the neonatal period; Neonatal, seizures in the neonatal period only. Evidence of neglect: determined by subtracting order of object removal on left side from that on right side of board for left hemisphere lesions, and by subtracting order of object removal on right side from that on left side of board for right hemisphere lesions. If difference was >1.2, child was assumed to have hemispatial neglect for purposes of analyses. Spatial Neglect in Children Doris A Trauner 163

5 RH and LH groups preferentially removed objects from the side ipsilateral to the lesion, whereas control children demonstrated no preference for one side of the board or the other. Removal preference was significantly lower on the right side of the board when comparing the LH group with control individuals (i.e. LH children showed a low preference for object removal from the side of the board contralateral to the lesion; Table V). The RH group had a significantly lower preference for object removal on the left side of the board (the side contralateral to the lesion) when compared with control children (see Table V). As was found in the infant task, there was no significant difference in object removal preference for either the LH or RH group when children with hemiparesis were compared with children without hemiparesis (LH group, left side of board Mann Whitney U=18.5, right side of board Mann Whitney U=11.5, ns; RH group, left side of board Mann Whitney U=17, right side of board Mann Whitney U=16, ns), or when children with visual field defects were compared with children without visual field deficits (LH group, left side of board Mann Whitney U=10, right side of board, Mann Whitney U=15, ns). Although there was no clear quantitative difference between the LH and RH groups in the magnitude of the neglect observed, there were qualitative differences that could be identified during the testing and on later review of the videotapes. Although children with either LH or RH lesions began their search on the ipsilateral side of the board, the LH children tended to complete the task by going from Table III: Mean (SD) ages, BSID and WPPSI-R IQ scores for focal lesion and control groups in infant and preschool neglect tasks Group Age, y BSID MDI BSID PDI FSIQ VIQ PIQ Infant LH 1.55 (0.86) 95.1 (21.4) 88.7 (21.7) Infant RH 2.20 (1.01) a 86.1 (15.2) 75.7 (16.4) Infant control 1.35 (0.63) Preschool LH 4.44 (1.17) 97.7 (20.3) (18.9) 93.4 (20.6) Preschool RH 4.06 (0.91) 93.8 (24.6) 97.7 (18.7) 87.7 (24.4) Preschool control 4.53 (1.06) a p=0.002 compared with control children. LH, left hemisphere lesions; RH, right hemisphere lesions; Preschool, Preschool Neglect task; MDI, Bayley Scales of Infant Development, Mental Index; BSID PDI, Bayley Scales of Infant Development, Psychomotor Index; FSIQ, Full Scale IQ; VIQ, Verbal IQ; PIQ, Performance IQ (Wechsler Preschool and Primary Scale of Intelligence Revised; Wechsler 1989). Table IV: Infant/toddler task. Mean (SD) order of object removal from board for LH lesion, RH lesion, and control children. Mann Whitney U test was used for statistical analyses; lower scores reflect greater preference for that side of board Control children (n=36) LH Lesions (n=22) RH Lesions (n=11) Mean order of object removal from left side of board 12.2 (2.4) 10.7 (2.3) c 14.5 (2.5) b p=0.019 a p=0.005 a Mean order of object removal from right side of board 12.1 (2) 13.4 (2.5) c 9.3 (3.6) b p=0.068, ns a p values are for lesion vs control comparison. b p< for LH vs RH on left side, p=0.001 for LH vs RH on right side of board. c Within-group comparisons of LH lesions on left vs right side of board p=0.006; of RH lesions, left vs right side of board, p= p=0.021 a Table V: Preschool task. Mean (SD) order of object removal from board for LH lesion, RH lesion, and control children. Mann Whitney U test was used for statistical analyses; lower scores reflect greater preference for that side of board Control children (n=36) LH Lesions (n=14) RH Lesions (n=13) Mean order of object removal from left side of board 3.4 (0.9) 3.0 (0.96) c 4.1 (0.5) b p=0.154, ns p=0.002 a Mean order of object removal from right side of board 3.4 (0.9) 4.1 (±0.8) c 2.8 (0.9) b p=0.023 a a p values are for lesion vs control comparison. b p=0.001 for LH vs RH on left side, p=0.001 for LH vs RH on right side of board. c Within-group comparisons of LH lesions on left vs right side of board p=0.017; of RH lesions, left vs right side of board, p= p=0.051, ns 164 Developmental Medicine & Child Neurology 2003, 45:

6 left to right. The RH children, in contrast, often were observed to stop after removing the toys from the right side of the board, and to look at the examiner as though they were finished. Their attention often had to be brought back to the board by the examiner tapping the top edge of the board and verbally prompting the child to pick up more toys in order to get the child to complete the toy removal. This suggests that they had less awareness of the contralateral side of the board than did the LH lesion children. Discussion Results of the present study demonstrate that a relative inattention to contralateral space is present in infants, toddlers, and preschoolers following very early (pre- or perinatal) unilateral brain damage. Unlike the pattern observed in adults, however, the young children in this study with LH lesions demonstrated evidence of contralateral neglect, as did the individuals with RH lesions. The neglect was subtle in that, eventually, all of the objects were noticed and removed from the board, but there was clearly a preference for removing objects from the side of the board ipsilateral to the lesion in both lesion groups. Approximately two-thirds of the children with early focal brain lesions demonstrated some degree of hemiparesis on the side contralateral to the lesion. This raised the possibility that the preference for the ipsilateral side might be related to a motor impairment, such as not using the contralateral hand to reach for the toys, rather than indicating a true neglect. However, even children with no hemiparesis and bilateral hand use preferentially chose toys on the side ipsilateral to the lesion first, and no significant difference in performance was found between children with and without hemiparesis in any of the lesion groups. A similar absence of effect of visual-field defects on lateral preference was observed, suggesting that the ipsilateral preference observed in this study was most likely to be caused by a spatial neglect as opposed to a visual-field impairment. The side of preference for object removal persisted through the preschool age group, suggesting that this ipsilateral preference is not transient. This is in contrast to the observations on adults after stroke, where there is often a transient contralateral neglect with either LH or RH lesions. Evidence of neglect disappears in the LH lesion adults after a few weeks, but is more likely to persist in the adults with RH lesions (Heilman and Van Den Abell 1980, Mesulam 1981, Weintraub and Mesulam 1987). In our children with earlyonset LH or RH lesions, the relative inattention to contralateral hemispace appeared to persist, at least throughout the preschool years. We did observe qualitative differences between the LH and RH groups that suggested a more severe neglect in children with RH lesions. It is possible that over a longer period of time, differences between the LH and RH groups will become more obvious. Such differences in functional localization between the developing and mature brain have been found in other cognitive domains, most notably in the domain of language, in which children with either LH or RH damage show initial delays in language development. Thal and coworkers (1991) found that children with LH damage were more impaired in expressive language than those with RH damage, while children with RH damage had more receptive delays than did the LH group. Their study suggests that the early neural substrates for language are more widely distributed within the developing brain and are not identical to those of the adult brain. Other studies further demonstrated functional recovery, in that the initial language delays appeared to resolve by school age (Aram and Ekelman 1988, Bates et al. 1999). Further studies are in progress to determine whether the relative inattention to contralateral space observed in the present study will also be reduced or disappear as these children move into the school-age years. Although reorganization and recovery may occur in some domains (e.g. language), other studies suggest that different cognitive domains may show persistence of deficits into the school-age years (Stiles-Davis 1988, Stiles et al. 1997, Vicari et al. 1998, Schatz et al. 2000). In particular, deficits in spatial analysis, albeit subtle, can be demonstrated in school-age children after very early unilateral brain damage, and the type of deficit is reminiscent of that found in adults after lateonset stroke (Delis et al. 1986). The persistence of contralateral neglect found in the current study, coupled with the findings of persistent spatial analytic deficits, implies that there may be limitations to the plasticity of the developing brain. The fact that the pattern of deficits observed in children with early unilateral brain damage does not follow the pattern observed in adults after late-onset lesions also suggests that there may be a difference in the localization of spatial awareness in the developing brain as contrasted with the mature brain. The results may also reflect the possibility that spatial attention may be determined at an early stage in brain development than other functions such as language, making spatial recovery from early unilateral insults more difficult to achieve than linguistic recovery. The fact that spatial analytic skills are impaired well into school age in children with early focal brain damage(stiles-davis 1988, Stiles et al. 1997, Vicari et al. 1998, Schatz et al. 2000) and that prosodic deficits persist in children with early unilateral damage (Trauner et al. 1996a) lend support to this hypothesis. In addition to the theoretical implications of the current study with respect to plasticity during brain development, these findings also have implications for the management of children with early focal brain injury. It may be important, for example, to seat these children on the side of the classroom contralateral to their lesion side, so that a child with a RH lesion would be seated on the left side of the class. In this way, the child s attentive side will be exposed to the teacher, chalkboard, and other classroom stimuli. Similarly, when such a child is in rehabilitative therapy, awareness of spatial neglect will be important in the therapist s strategies for remediation. With such awareness of the child s cognitive strengths and deficiencies, a more rational approach to rehabilitation can be undertaken. DOI: /S Accepted for publication 22nd October Acknowledgments This research was supported by the March of Dimes Birth Defects Foundation Social and Behavioral Sciences Grant no and by NINCDS grant no. NS22343 for the Center for the Study of the Neurological Basis of Language. We thank Drs Richard Haas and Jill Trice for conducting the neurological examinations; Ms Amy Schatz, Ms Kathleen Scarvie, and Ms Jan Panyard for assisting with the testing; and Dr Angela Ballantyne for her careful review of the manuscript. Spatial Neglect in Children Doris A Trauner 165

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