Pathological left-handedness revisited: dichotic listening in children with left vs right congenital hemiplegia

Dichotic listening deficits in children with hearing loss

PURPOSE

This correlational study compared dichotic listening among children with significant hearing loss to typically developing children and children clinically assessed for auditory processing disorder.

METHOD

Recorded versions of two dichotic tests were delivered under earphones or in the sound field for children using amplification. Individual ear scores and interaural asymmetry were compared to normative data. Matched deficit patterns from both tests were identified, ranked for severity of deficit, and compared across groups. Relationships between dichotic scores and factors related to amplification were investigated in the children with hearing loss.

RESULTS

Dichotic scores were significantly poorer among children with hearing loss without the large interaural asymmetries seen in children assessed clinically for auditory processing problems. Device type and age of implantation had no effect on scores; non-dominant ear scores on the digits test were significantly correlated to age of device use in the left ear and duration of device use in the right ear. Non-dominant ear scores with digits were also significantly correlated with bilateral word recognition.

CONCLUSIONS

Poor dichotic perception in children with significant hearing losses may be related to the use of recorded test materials, immature skills in attention and working memory, or other factors that contribute to development of vocabulary and language. These weaknesses may interfere with successful mainstream educational placement in these children. Assessment of dichotic performance in this population could lead to deficit-specific interventions that may improve outcomes and enhance educational opportunities for children with hearing loss.

Plasticity of the language system in children and adults

The language system is perhaps the most unique feature of the human brain's cognitive architecture. It has long been a quest of cognitive neuroscience to understand the neural components that contribute to the hierarchical pattern processing and advanced rule learning required for language. The most important goal of this research is to understand how language becomes impaired when these neural components malfunction or are lost to stroke, and ultimately how we might recover language abilities under these circumstances. Additionally, understanding how the language system develops and how it can reorganize in the face of brain injury or dysfunction could help us to understand brain plasticity in cognitive networks more broadly. In this chapter we will discuss the earliest features of language organization in infants, and how deviations in typical development can-but in some cases, do not-lead to disordered language. We will then survey findings from adult stroke and aphasia research on the potential for recovering language processing in both the remaining left hemisphere tissue and in the non-dominant right hemisphere. Altogether, we hope to present a clear picture of what is known about the capacity for plastic change in the neurobiology of the human language system.

Is Psychopathy a Mental Disorder or an Adaptation? Evidence From a Meta-Analysis of the Association Between Psychopathy and Handedness

Psychopathy has historically been conceptualized as a mental disorder, but there is growing evidence that it may instead be an alternative, adaptive life history strategy designed by natural selection. Although the etiology of mental disorders is not fully understood, one likely contributor is perturbations affecting neurodevelopment. Nonright-handedness is a sign of such perturbations, and therefore can be used to test these competing models. If psychopathy is a mental disorder, psychopaths should show elevated rates of nonright-handedness. However, an adaptive strategy perspective expects psychopaths to be neurologically healthy and therefore predicts typical rates of nonright-handedness. We meta-analyzed 16 studies that investigated the association between psychopathy and handedness in various populations. There was no difference in the rates of nonright-handedness between community participants high and low in psychopathy. Furthermore, there was no difference between psychopathic and nonpsychopathic offenders in rates of nonright-handedness, though there was a tendency for offenders scoring higher on the Interpersonal/Affective dimension of psychopathy to have lower rates of nonright-handedness, and for offenders scoring higher on the Behavioral dimension of psychopathy to have higher rates of nonright-handedness. Lastly, there was no difference in rates of nonright-handedness between psychopathic and nonpsychopathic mental health patients. Thus, our results fail to support the mental disorder model and partly support the adaptive strategy model. We discuss limitations of the meta-analysis and implications for theories of the origins of psychopathy.

Language Cerebro-cerebellar Reorganization in Children After Surgery of Right Cerebellar Astrocytoma: a fMRI Study

Language processing depends on an integrated circuit involving the left supratentorial language areas and the right posterior lateral cerebellar hemisphere (lobule VI, lobule VII, Crus I, and Crus II). Reorganization of the language system after lesions of the cerebral language areas includes also cerebellar relocation. This is the first study assessing functional language reorganization after lesions concerning primarily the cerebellum, using a fMRI paradigm of phonological covert word production task in six children operated for right cerebellar astrocytoma and in 15 typically developing children. We found right cerebellar and left frontal activations in healthy controls and high variability of reorganizational patterns in patients with early right cerebellar lesion. Also lesions not located in the areas typically involved in language tasks (Crus I and Crus II) can cause reorganization between the two hemispheres or hemispheric language reinforcement of the original lateralization. We discuss the role of several variables in determining the reorganizational pattern such as the site, extension, and timing of surgery. No variables revealed as predictors, suggesting that co-occurring influence of other biological and/or pathological factors are not yet demonstrated. Lesions in the postero-lateral cerebellum seem related to less efficient language performances, as an indicator of the system's functioning.

Cortical auditory evoked potentials and hemispheric specialization of speech in individuals with learning disability and healthy controls: A preliminary study

Background: Dichotic listening (DL) technique is a behavioral non-invasive tool which is used in studying hemispheric lateralization. Previous studies using behavioral DL have hypothesized that individuals with learning disabilities (LD) exhibit a lack of cortical specialization for processing speech stimulus. However, there is no event related potential (ERP) evidence, hence the main objective of the study is to explore hemispheric asymmetry using cortical auditory evoked potential (CAEPs) in normal hearing adults and also to compare the same in children with LD and healthy controls.

Methods: CAEPs were recorded in 16 normal hearing young adults, eight right-handed children with LD and their age matched controls. Two stop constants (/Pa/ – voiceless, bilabial, stop: /Ta/ - voiceless, alveolar, stop) were chosen for this experiment and presented in each ear and dichotically in two different orders (/pa-ta/, /ta-pa/). ERPs were processed using a standard pipeline, and electrodes readings over the left and right hemispheres were averaged to create left and right regions of interest (ROI). The CAEPs were analyzed for mean amplitude and peak latency of P1-N1-P2 components.

Results: The current study results suggest no statistically significant difference between the two stimulus in monaural condition and absence of order effect in dichotic condition. In healthy controls the CAEP latencies were shorter over the left hemisphere in both monaural and dichotic conditions in adults and control children. However, it was very evident that such a difference was lacking in children with LD.

Conclusions: Hemispheric asymmetry can be detected using CAEPs for speech stimulus. The measures are consistent and void of stimulus or order effect. Taken together, the findings of current study, both monaural and dichotic condition illustrates the hemispheric differences in processing speech stimuli in normal hearers. Absence of latency differences between hemispheres in children with LD indicate a lack of hemispheric asymmetry.

Interictal and postictal performances on dichotic listening test in children with focal epilepsy

Dichotic listening test (DL) is an important tool to disclose speech dominance in healthy subjects and in clinical cases. The aim of this study was to probe if focal epilepsy in children reveals a corresponding suppression of the ear reports contralateral to seizure onset site. Thus, 15 children and adolescents with clinically and electroencephalographically diagnosed focal epilepsy selected for left-hemisphere speech dominance without mental retardation were compared to matched controls according to age, gender, IQ and handedness. All children were assessed with DL for three times: Interictally (t(0)), postictally 5' (t(1)) and 1h (t(2)). At t(0), all groups revealed a right ear advantage (REA), indicating a left-hemisphere speech dominance. There was a continuous increase in right correct score (REC) over the trials for normal controls. Five minutes postictally, there was an abrupt decrease in REC with a sustained left ear correct score (LEC) for children with epilepsy, independent of which side suffered from seizures. This effect was maintained even after 1h. Thus, in children with left-hemisphere speech dominance the epileptic discharges caused a suppression of REC regardless of origin. The seizures may have a prolonged impact on attention and auditory perception for a considerable time after consciousness has been regained.

Measuring familial sinistrality: Problems with dichotomous classification

Familial sinistrality (FS), or familial left-handedness, is usually measured as a presence/absence dichotomy (FS+/FS-). Measuring FS as a dichotomy is problematic in at least two ways: (1) magnitude data are discarded and (2) there is an increased risk of violating statistical assumptions. We hypothesised that using a non-dichotomised FS measure would allow more sensitive statistical tests than using a dichotomised measure. The non-dichotomised measure examined was proportion of family that is left-handed, or Proportional FS (FSP). FS measures of 60 healthy adults were consistent with our hypothesis: (1) The effect size was 2.3 times larger when FSP was used than when Dichotomised FS (FSD) was used; (2) the observed relationship was statistically significant when FSP was used but not when FSD was used; and (3) statistical assumptions were violated when FSD was used but not when FSP was used. When cases were weighted to account for an increased likelihood of FS in large families, results were similar. Next, bootstrapping methods were used to estimate empirically the long-term differences in power between analyses incorporating FSP and those incorporating FSD. Using FSP was associated with long-term increases in both power and effect size of over 50% relative to using FSD. We conclude that using a proportional rather than a dichotomous measure of FS will enhance the accuracy of observed effect sizes, increase the sensitivity of statistical tests, and reduce the likelihood of violating statistical assumptions.

Rapid recovery of motor and cognitive functions after resection of a right frontal lobe meningioma in a child

PURPOSE

The purpose of this study is to provide longitudinal data on neurological and neuropsychological restitution following resection of an extra-axial space-occupying lesion.

CASE REPORT

A comprehensive neuropsychological test battery was utilised preoperatively and 1, 4, 11, and 24 months, respectively, after removal of a parasagittal meningioma compressing the right frontal lobe in a right-handed 6-year-old boy with average intelligence.

RESULTS

Symptoms related to brain compression (left-sided hemiparesis, diplopia) resolved shortly after surgery. Recovery of specific cognitive functions (short- and long-term memory, attention, and dichotic listening performance) was more protracted.

CONCLUSION

Here, we illustrate the potential of a structured follow-up analysis, based on neuropsychological testing. We were able to distinguish separate time-courses for neurological functions but even more distinct within complex neuropsychological processes. This time-dependent recovery should be considered when designing longitudinal follow-up studies.

Increased Frequency of Left-Handedness in Patients with Unilateral Coronal Synostosis

Objective:

Left-handedness reportedly has been more common in persons with neurological afflictions (e.g., stroke) and malformations (e.g., cleft lip with or without cleft palate) that demonstrate marked unilateral involvement. Coronal synostosis is also more frequently unilateral, affecting the right side more commonly than the left. We sought to compare left-handedness in patients with unilateral coronal synostosis versus healthy controls.

Subjects:

All patients aged 3 years or older with nonsyndromic unilateral coronal synostosis and healthy controls recruited by pediatricians blinded to the study.

Main Outcome Measures:

Prospective data obtained for all participants included age, gender, and handedness. In patients with unilateral coronal synostosis, the side of synostosis and age at surgery were documented. Left-handedness in the study and control groups was compared using chi-square analysis. Left-handedness also was analyzed in the study group according to side of fusion.

Results:

Eighty-six patients with nonsyndromic unilateral coronal synostosis comprised the study group; there were 96 controls. The mean ages of the study (8.8 years) and control groups (9.8 years) were not statistically different (p > .05). There were more girls in the study group (67%) than in the control group (56%), but this difference was not statistically significant (p > .05). Left-handedness was documented in 30.2% of the study group and 11.4% of the control group (p < .005). Left-handedness was twice as common in patients with left versus right unilateral coronal synostosis (44.4% versus 20.4%; p < .05).

Conclusions:

Left-handedness is nearly three times more common in patients with unilateral coronal synostosis than in controls and four times more likely in patients with left-sided fusion.

Increased prevalence of left-handedness in hemifacial microsomia

Ten percent of people are left handed, but a higher frequency has been associated with certain craniofacial malformations, such as cleft lip and unilateral coronal synostosis. The purpose of this study was to determine the frequency of left-handedness in patients with hemifacial microsomia (HFM). Patients with HFM were identified in our craniofacial database. Normal controls were recruited by local pediatricians. Data gathered included age, sex, and handedness (determined by writing and/or drawing); the orbit, mandible, ear, nerve, and soft tissue (OMENS)-plus score and side of involvement were tabulated for patients with HFM. Hand preference was compared between the groups using chi analysis; possible correlations were analyzed between handedness and age, sex, the OMENS score, extracraniofacial findings, and side of involvement. One hundred seventy-eight patients with HFM were identified; 92 (51%) were excluded. Of the 86 included, 48% were boys (n = 47) and the mean age at inquiry was 13.5 years. Predominant side of involvement was right in 49% (n = 42) and left in 38% (n = 33). Eleven patients (13%) had severe involvement of both sides. Expanded-spectrum HFM was documented in 41% of patients. Ninety-six children were in the control group; 44% were boys (n = 42), and the mean age was 10 years. The difference in age between the groups was significant (P < 0.05), but sex differences were not. Patients with HFM were more likely to be left handed for writing compared with the control group (26% vs. 11%; P < 0.05). The frequency was higher, 36%, in those with bilateral involvement (P > 0.05). There was no correlation with predominant side or OMENS score. This study confirms that this disorder affects cerebral lateralization.

Neurocognitive sequelae of a giant arachnoid cyst: case study

We conducted a comprehensive neuropsychological evaluation of a normally functioning man with a giant arachnoid cyst encompassing much of the space normally occupied by the left hemisphere. Although of solidly average intellectual ability, the patient demonstrated neurocognitive deficits only revealed upon neuropsychological assessment. Despite the remarkable left hemisphere lesion, the pattern of cognitive dysfunction suggested right hemisphere pathology. We review the arachnoid cyst literature and discuss the possibility of a crowding phenomenon by which language function relocates to the more viable hemisphere. This case illustrates striking preservation of higher cognition in the presence of substantial structural abnormality.

Increased occurrence of left-handedness after severe childhood bacterial meningitis: Support for the pathological left-handedness hypothesis

The hypothesis that brain damage during infancy causes pathological left-handedness was tested by assessing handedness in 182 survivors of childhood non-Hemophilus influenza type b bacterial meningitis in the Netherlands (mean age of 9.7 years). These children were selected randomly after clustering them into those with or without parental report on academic and behavioural problems. Medical records were obtained from the hospitals, while handedness and neurodevelopmental outcome were assessed at school age. Logistic regression analysis was used to study the relationship between a severity score of bacterial meningitis and handedness. Fifteen percent were left-handed. Severity of childhood bacterial meningitis was related to left-handedness (Odds ratio (OR) 6.2, 95% confidence interval (CI) 2.0-18.6 for those with a total severity score above the median as compared to those below). Compared to non-left-handed children, left-handed children had lower IQ (mean difference -6.6, 95% CI -12 to -1.2), tended to have lower vocabulary scores on WISC-r (-1.0, -2.1 to 0), and lower Beery scores on visual-motor integration (-4.9, -10.1 to 0.4). Left-handed children also tended to have more combined academic and behavioural limitations (OR 2.7, 95% CI 0.9-8.6), lower manual speed of the dominant hand (mean difference -9 taps, p < 0.05) and better manual steadiness in the non-dominant hand (mean difference of contact's time -2.7 s, p < 0.05). Left-handed post-meningitic children generally have worse neurodevelopmental outcome than non-left-handed survivors. Our results support the role of early life brain damage in left-handedness.

Verbal dichotic listening and manual performance in children with congenital unilateral brain lesions

The authors assessed manual performance and verbal dichotic listening performance in 16 epilepsy-free children with congenital unilateral brain lesions and normal IQ to investigate cerebral reorganization. In all children, the paretic hand had fair grip function, but reaction times were impaired, and cerebral reorganization of hand function in those with right hemiplegia was shown by the high incidence of pathological left-handedness. The dichotic listening results showed that most children with left lesions had a left ear advantage significantly related to the extent of brain damage. This finding suggests that extent of cortical damage and presence of thalamic involvement, irrespective of neuropathology, are the primary factors inducing rightward cerebral language reorganization in children with unilateral congenital brain lesions.

Hippocampal gray matter reduction associates with memory deficits in adolescents with history of prematurity

Using optimized voxel-based morphometry (VBM), we compared the relationship between hippocampal and thalamic gray matter loss and memory impairment in 22 adolescents with history of prematurity (HP) and 22 normal controls. We observed significant differences between groups in verbal learning and verbal recognition, but not in visual memory. VBM analysis showed significant left hippocampal and bilateral thalamic reductions in HP subjects. Using stereological methods, we also observed a reduction in hippocampal volume, with left posterior predominance. We found correlations between left hippocampal gray matter reductions (assessed by VBM) and verbal memory (learning and percentage of memory loss) in the premature group. The stereological analysis showed a correlation between verbal learning and the left posterior hippocampus. Our results suggest that left hippocampal tissue loss may be responsible for memory impairment and is probably related to the learning disabilities that HP subjects present during schooling.

Eye-Hand Preference in Schizophrenia: Sex Differences and Significance for Hand Function

Hand preference and eye dominance were investigated in 73 (30 women, 43 men) schizophrenic patients and 71 (30 women, 41 men) healthy controls. There were significantly more schizophrenic patients and normal controls who were significantly right-hand dominant. However, schizophrenic patients showed a significant excess of left-eye dominance relative to controls (65.8% vs 29.6%; Odds Ratio = 4.75, p < .001). In addition, female schizophrenic patients showed a higher rate of non-right (either left or inconsistent) eye dominance (80%) than male schizophrenic patients (55.8%) and controls (33.3%). Analysis of hand performance on the Purdue Pegboard Test indicated that schizophrenic patients who showed crossed eye-hand dominance scored higher than did patients without crossed eye-hand dominance.

Age effects in dichotic listening to consonant-vowel syllables: interactions with attention

A relatively large sample of individuals (N = 240) ranging from 7 to 70 years were studied with the dichotic listening (DL) technique as a measure of language lateralization. Two questions were asked: (a) Is there a developmental effect for the right-ear advantage (REA) with age? (b) Is there a developmental effect for attentional modulation of the REA? The participants were all right-handed, healthy individuals tested in Sweden and Norway. The stimuli were dichotic presentations of consonant-vowel (CV) syllable pairs. There were 3 different attentional conditions: nonforced (NF) attention, with no specific instructions about focusing of attention; forced-right (FR) attention, with instructions to focus attention on the right-ear stimulus; and forced-left (FL) attention, with instructions to focus attention on the left-ear stimulus. The results showed a REA in all age groups, except for the 9-year-olds, in the NF condition. In the FR condition, all age groups showed a REA. The youngest age groups did not, however, increase the REA to the same degree as the older age groups, as indicated by the significant age x ear interaction. In the FL condition, all age groups, with the exception of the youngest groups, showed a left-ear advantage (LEA). It is concluded that the REA effect in DL is subject to developmental effects and that attentional effects on laterality also develop with increasing age.

Timing and type of congenital brain lesion determine different patterns of language lateralization in hemiplegic children

Cerebral lateralization for language has been assessed by means of the Fused Dichotic Words Test in 26 hemiplegic children (mean age 7 years 2 months) with congenital focal brain damage (ten with left, seven with right and nine with bilateral lesions). The specific aim of the study was to investigate the relation between lesion characteristics (side, size and localization) at high field, multiple plane MRI and the pattern of language lateralization at the dichotic test. Significant side and site effects were found at group level; in children with lesions of the left hemisphere a left ear advantage (LEA) was found, while children with right lesions had the expected right ear advantage (REA). Analysis of individual data, however, revealed that type of lesion, cortical-subcortical or periventricular, occurring at term or preterm age, respectively, may be the primary factor responsible for inter versus intrahemispheric organization of language after congenital brain lesions. Only when the left lesions involved cortical-subcortical regions encroaching the temporal lobe and occurred at term age, was language reorganized in the right hemisphere; when lesions (whether left or right) involved only the periventricular white matter and occurred at preterm age, language was lateralized in the left hemisphere. Our results provide evidence that within 'congenital hemiplegias', strictly defined as hemiplegias whose causal lesion occurs before the end of the neonatal period, different recovery mechanisms are at work, depending on the type of brain lesion (neuropathology) which largely depends on the timing of insult (preterm vs. term period).

Sinistrality--a side-effect of prenatal sonography: a comparative study of young men

Although ultrasound during pregnancy is used extensively, there is little published on adverse fetal effects. We undertook a cohort study including men born in Sweden from 1973 to 1978 who enrolled for military service. We estimated relative risks for being born left-handed according to ultrasound exposure in fetal life using logistic regression analysis. Eligible for the study were 6,858 men born at a hospital that included ultrasound scanning in standard antenatal care (exposed) and 172,537 men born in hospitals without ultrasound scanning programs (unexposed). During the introduction phase (1973 to 1975) there was no difference in left-handedness between ultrasound exposed and unexposed (odds ratio = 1.03, 95% confidence interval (CI) = 0.91 to 1.17). When ultrasonography was offered more widely (1976 to 1978), the risk of left-handedness was higher among those exposed to ultrasound compared with those unexposed (odds ratio = 1.32, 95% CI = 1.16 to 1.51). We conclude that ultrasound exposure in fetal life increases the risk of left-handedness in men, suggesting that prenatal ultrasound affects the fetal brain.

Cognitive outcome of children with early-onset hemiparesis

The aim of this study was to examine the cognitive outcome of children with congenital and acquired early-onset unilateral brain lesions associated with hemiparesis. The neuropsychologic evaluation was done using the NEPSY test battery on 37 children with hemiparesis and 13 sex- and age-matched healthy controls. Compared to the controls, children with left-sided brain lesions had significant delay in phonologic and language functions, while children with right-sided brain lesions performed more poorly in visual and spatial skills and in somatosensory functions. There were more left-handed children in the former (6 of 23) than in the latter (1 of 14) group. There was no significant difference in cognitive outcome between children with congenital and acquired lesions. The cognitive outcome of boys and that of children with active epilepsy was more affected. Overall, the patients showed impairment in many cortical functions and diffuse cognitive delay compared to controls and the side of lesion, active epilepsy, and male gender were significant factors in predicting cognitive outcome.

Speech Lateralisation in Callosal Agenesis Assessed by the Dichotic Fused Words Test

Child patients with left-hemisphere damage (n = 2), with total callosal agenesis (n = 2), and with partial callosal agenesis or hypotrophy (n = 3) were submitted to dichotic verbal stimulation by the Fused Words Test. The controls were nine normal children, right-, left-, and mixed-handed. As expected, the left-injured patients presented a massive advantage of the ear contralateral to the intact hemisphere. Among the controls the right-handers showed a significant right-ear prevalence, whereas left-and mixed-handers exhibited rather inconsistent earasymmetries. The major finding of this study is the striking difference in perceptual asymmetry between partial and total acallosals. Based on the notion that the dichotic verbal asymmetry is an effect of the underlying functional asymmetry for language, these findings are interpreted as an indication that development of the unilateral speech control is influenced by the presence, during ontogenesis, of callosal connections.

Routine ultrasound screening in pregnancy and the children's subsequent handedness

OBJECTIVE

To study a possible association between ultrasound screening in early pregnancy and altered cerebral dominance measured by the prevalence of non-right handedness among children, particularly boys.

METHODS

Follow-up of 8 to 9 year old children to women who participated in a randomised controlled trial on ultrasound screening during pregnancy in 1985-87. The children were followed up through a questionnaire sent to their mothers. The dominant hand of the child was assessed by eleven questions. The dominant foot by one question.

RESULTS

No differences were found in non-right handedness between children in the screening and non-screening group. In separate analyses on ultrasound exposure and non-right handedness among boys a significant difference was found (odds ratio 1.33; 95% confidence interval 1.02-1.74).

CONCLUSION

This study could not rule out a possible association between non-right handedness among boys and ultrasound exposure in early fetal life. The association was, however, confined to analyses comparing exposed and non-exposed boys and no associations were found when the comparisons were performed according to the randomised groups.

Evidence of altered dominance in children with congenital spastic hemiplegia

The study aimed at investigating lateralization effects and signs of transfer and crowding in children with congenital lateralized brain damage with the aid of a dichotic listening test, a chimeric test, and verbal and nonverbal neuropsychological tests. Thirty-three children with spastic hemiplegia and 86 control children (age 5.0-12.0 yr) were assessed. Children with left-hemisphere damage (n = 17) were found to have a pathological left-ear advantage for verbal material, and children with right-hemisphere damage (n = 16) were found to have a pathological right visual half-field advantage for visual material. Children with left-hemisphere damage and a left-ear advantage on the dichotic test were also found to have a right visual half-field advantage on the chimeric test, which was regarded as a sign of reversed dominance. No verbal or nonverbal differences emerged between the left-hemisphere and the right-hemisphere damage groups, nor did differences emerge when the children were reclassified by considering children with left hemisphere damage and signs of reversed dominance as having damage to the nondominant hemisphere. It was concluded that although lateralized brain damage may alter the dominance for verbal and visual functions, there is still considerable inter-individual variability with respect to inter- and intrahemispheric neural adjustment to damage. The dichotic and the chimeric tests did not indicate the presence of brain damage accurately, but they indicated the lateralization of damage in children with stated abnormality with a high degree (91.3%) of accuracy.

Verbal and non-verbal function of children with right- versus left-hemiplegic cerebral palsy of pre- and perinatal origin

Eighteen children with right- and 13 with left-sided congenital hemiplegia were compared with 19 normal age-matched controls for verbal and non-verbal function. CT scans were obtained from 27 of the 31 hemiplegic children. The two hemiplegic groups were impaired in non-verbal function compared with controls. The right-hemiplegic group was more impaired in verbal function than the left-hemiplegic group and controls; however, impairments were restricted to the girls in the right-hemiplegic group. The results are discussed in terms of cerebral plasticity and functional reorganisation of cognitive functions after an early unilateral injury. It is argued that girls with left-hemisphere lesions may be more limited in cerebral plasticity than boys.

Dichotic listening and focused attention in children with hemiplegic cerebral palsy

Dichotic listening data are reported from children with left and right hemiplegia, compared with a normal, age-matched, control group. The dichotic listening test was performed under two different attentional instructions. The aim of the study was to investigate whether lateral injury to one hemisphere also affects the capacity to direct attention in a laterality task because of inattention. The dichotic task consisted of consonant-vowel syllables that were presented with two different instructions, to attend to the left- or right-ear stimulus. The results showed that the control children had a right-ear advantage during the forced-right attention instruction, and a small left-ear advantage during the forced-left instruction. The two hemiplegia groups, however, showed the same ear advantage irrespective of attentional instruction. The results are discussed in terms of hemi-inattention and hypoarousal of the lesioned hemisphere in children with hemiplegia.