Can spatial deficits in Turner's syndrome be explained by focal CNS dysfunction or atypical speech lateralization?

The speech and language profile of a child with Turner Syndrome- a case study

BACKGROUND

Turner syndrome is a genetic disorder that affects only females. It has specific cognitive characteristics, but speech and language data are scarce.

METHODS AND PROCEDURES

Prospective case report; we report a girl aged seven's cognitive and speech and language profile.

RESULTS

Cognitive assessment shows higher performance IQ (PIQ), and atypical cognitive profile for Turner syndrome. Speech and language assessment show a significant difference between receptive and expressive language levels. Although the girl did comprehend most of the language structure, there was a lack of it in spontaneous speech. She demonstrated inconsistency in the use of language morphology and complex linguistic structures, primarily because of significant inconsistency in her sound production. Although she produced the majority of phonemes correctly in isolation, her spontaneous speech production was incomprehensible.

CONCLUSION

Case studies of speech and language development may reveal a specific characteristic in the cases with Turner syndrome to delineate genetic factors from individual developmental variabilities.

Turner syndrome: language profile of young girls at 12 and 24 months of age

Background

Turner syndrome (TS) is a genetic disorder associated with complete or partial absence of an X chromosome affecting approximately 1/2000 live female births. Available evidence suggests that, in the school-age years, girls with TS often require speech and language services; however, little is known about the language development of infants and toddlers.

Method

This study (N = 31) explored the language profiles of 12- and 24-month-old girls with TS, as well as the percentage of girls who might be “at risk” for language delays. We also followed a subset of 12-month-old girls with TS to 24 months of age to determine the stability of the 12-month findings.

Results

Although all mean scores were within the average range at both time points, results revealed a higher prevalence of 24-month-old girls with TS “at risk” for receptive language difficulties. In addition, expressive language skills significantly exceeded receptive language skills at both time points. We found 12-month-old girls to be “at risk” for social and symbolic difficulties based on clinical assessment; only symbolic difficulties were significant based on caregiver report. At 24 months, clinical assessment indicated greater use of speech sounds and words than normative expectations. Caregivers reported greater use of speech sounds, and also, greater use of gestures. Although some changes occurred over a 1-year time span (12 to 24 months), all mean test scores remained within the average range and the changes in the percentage of girls manifesting “at risk” status on either the PLS-4 or CSBS-DP were non-significant.

Conclusions

Although within normal limits, receptive language skills were found to be significantly lower than expressive language skills at both ages. Social and symbolic communication skills also were in the average range, with both showing significant improvement from 12 to 24 months based on clinical assessment. Caregiver report found that use of gestures and production of speech sounds not only improved from 12 to 24 months, but also exceeded normative expectations. Findings suggest the presence of relatively intact speech and language abilities during the first 2 years of life, with perhaps some emergent concerns for receptive language development. Ongoing developmental surveillance will be important.

Investigation of a Mental Rotation Task with School-Age Children

Mental rotation skills were investigated with a number of pediatric populations. The measure utilized was developed by Thurstone and involves mental rotation of letters/words, objects, and figures. The first study investigated the construct validity of the mental rotation task. The results indicated that the test assessed a distinct construct, which focused on visual integrative functions. The second study examined differences on the mental rotation test between academically average and academically dysfunctional children. The results yielded significant differences on the overall measure. The third study investigated differences among normal, attention deficit disorder, and neurological dysfunction children. Significant results again were obtained; the normals showed higher performance than the attention deficit and neurological dysfunctional children. The overall results of these investigations support the clinical utility of the mental rotation task. Differential patterns within the measure also were noted across the pediatric groups.

Turner syndrome: review of clinical, neuropsychiatric, and EEG status: an experience of tertiary center

We reviewed the clinical, neuropsychiatric, and EEG status of 53 turner syndrome (TS) females, aged 3-16 years, in Assiut university hospitals, Upper Egypt. The diagnosis and care of patients with TS in Egypt is still in the developing stage. Hence this study was undertaken to review the details of patients with TS with respect to the pattern of cognitive, psychiatric, and motor dysfunction. We aimed to provide a comprehensive data about the experience of our center comparable to previous studies, which have been published in this field. This will contribute to a better definition of the neuropsychiatric features that may be specific to TS that allows early and better detection and management of these cases. We found FSIQ and verbal IQ that seem to be at a nearly normal level and a decreased performance IQ. ADHD and autistic symptoms were found in 20.70 and 3.77 % of our cohort, respectively. The motor performance in TS was disturbed, with some neurological deficits present in 17 % (reduced muscle tone and reduced muscle power). In addition, females with TS in our study exhibit social and emotional problems, including anxiety (5.66 %) and depression (11.30 %). The EEG results revealed abnormalities in seven patients (13.20 %). One patient presenting with generalized tonic-clonic seizures showed generalized epileptiform activity, and six patients presenting with intellectual disabilities showed abnormal EEG background activity.

Exceptional lexical skills but executive language deficits in school starters and young adults with Turners syndrome: implications for X chromosome effects on brain function

TS school starters had enhanced receptive and expressive language on standardised assessment (CELF-P) and enhanced rhyme judgements, spoonerisms, and lexical decision, indicating enhanced phonological skills and word representations. There was marginal but consistent advantage across lexico-semantic tasks. On executive tasks, speeded naming of numbers was impaired but not pictures. Young TS adults had enhanced naming and receptive vocabulary, indicating enhanced semantic skills. There were consistent deficits in executive language: phonemic oral fluency, rhyme fluency, speeded naming of pictures, numbers and colours; sentence completion requiring supression of prepotent responses. Haploinsufficiency of X-chromosome drives mechanisms that affect the anatomical and neurochemical development of the brain, resulting in enhanced temporal lobe aspects of language. These strengths co-exist with impaired development of frontal lobe executive language systems. This means not only that these elements of language can decouple in development but that their very independence is driven by mechanisms linked to the X-chromosome.

Cerebral laterality in Turner syndrome: a critical review of the literature

Turner syndrome (TS) is a genetic disorder in females characterized by the complete or partial absence of one X chromosome. Its most consistent physical features include short stature and ovarian dysgenesis. TS individuals demonstrate a characteristic neurocognitive profile involving weaknesses in visuospatial processing. The hypothesis of defective right hemisphere specialization has been offered to explain the visuospatial deficits in TS. In contrast, an alternative explanation proposes a more uniform dysfunction of the left and right hemispheres, based on findings of symmetrical abnormalities. This article presents an overview of the two hypotheses, along with relevant findings on hemispheric specialization with respect to TS. The impact of the genetic and hormonal mechanisms on the neurocognitive profile of TS is also discussed and directions for further empirical research are identified.

Ocular motor indicators of executive dysfunction in fragile X and Turner syndromes

Fragile X and Turner syndromes are two X-chromosome-related disorders associated with executive function and visual spatial deficits. In the present study, we used ocular motor paradigms to examine evidence that disruption to different neurological pathways underlies these deficits. We tested 17 females with fragile X, 19 females with Turner syndrome, and 40 females with neither disorder who comprised the comparison group. Group differences emerged for both the fragile X and Turner syndrome groups, each relative to the comparison group: Females with fragile X had deficits in generating memory-guided saccades, predictive saccades, and saccades made in the overlap condition of a gap/overlap task. Females with Turner syndrome showed deficits in generating memory-guided saccades, but not during either the predictive saccade or gap/overlap task. Females with Turner syndrome, but not females with fragile X, showed deficits in visually guided saccades and anti-saccades. These findings indicate that different brain regions are affected in the two disorders, and suggest that different pathways lead to the similar cognitive phenotypes described for fragile X and Turner syndromes.

Knox’s cube imitation test: A historical review and an experimental analysis

The cube imitation test was developed by as a nonverbal test of intelligence. Many variants show satisfactory reliability, but performance is correlated both with Verbal IQ and with Performance IQ. Performance is impaired by cerebral lesions but unrelated to the side of lesion. Examinees describe both verbal and visuospatial strategies. In a new experiment, performance was disrupted by concurrent random generation, manual tapping, and articulatory suppression. The cube imitation test is not simply a measure of the ability to retain visuospatial information but also depends on verbal representations as well as attentional capacity. Even so, the test was central to the modern appreciation that any adequate measure of intelligence must incorporate both verbal tests and performance tests.

A review of neuropsychological and motor studies in Turner Syndrome

We reviewed the literature on Turner Syndrome (TS) from 1962 until March 2003 with respect to the following questions: Is there a consistent pattern of cognitive and/or motor dysfunction in TS girls and if so, is there an explanation for the disturbance? Many studies indicate that girls with TS have a disharmonic IQ profile: a verbal IQ that seems to be at a (nearly) normal level and a decreased PIQ. This profile remains into adulthood. Visual-spatial problems are mentioned most frequently and there is some evidence for a relationship to particular neuro-anatomical structures, hormonal dysfunction, and genotype. Although much less research has been done on motor performance in TS, there is clear evidence that it is disturbed too in TS. Many authors emphasize the interaction between somatic, psychological and social factors, but we did not find a clear theoretical framework explaining this relationship. We argue that there may be two independent problems: a visuospatial and a motor deficit possible related to specific genotypes and both have implications for functioning in daily life.

The importance of head growth patterns in predicting the cognitive abilities and literacy skills of small-for-gestational-age children

This study evaluated the effects of head growth compromise beginning in utero and continuing, in some cases, through the first 9 months of life on the cognitive and literacy skills of school-age small-for-gestational-age (SGA) children. Seventy-one SGA children, aged 7 to 9 years (gestational ages, 24-41 weeks) and 16 full-term appropriate-for-gestational-age control children of comparable socioeconomic backgrounds and age at testing completed tests assessing intelligence, receptive language, working memory, problem solving, visual-motor integration, phonological awareness, reading, and spelling. SGA children were subdivided into head-growth pattern groups based on their head circumference at birth and at 9 months postterm. Analyses showed that SGA children with poor prenatal and postnatal head growth had the worst outcomes, followed by those with prenatal brain compromise, but good postnatal head growth. SGA children with preserved head growth in utero as well as good head growth after birth demonstrated the best outcomes, although spelling skills were deficient relative to full-term peers. The Verbal and Full Scale IQ ratings of the SGA children who had experienced brain compromise in utero declined significantly from 5 to 8 years of age. We conclude that mild intrauterine growth retardation (IUGR) has a minimal effect on the development of cognitive or academic abilities, providing that brain growth in utero is not affected. IUGR that slows brain growth in utero impairs the acquisition of some cognitive and academic abilities, even when followed by good catch-up head growth after birth, whereas poor brain growth in utero followed by little or no catch-up head growth results in widespread impairments. Findings highlight the limits to brain plasticity and emphasize the importance of optimal prenatal and postnatal brain growth.

Slow Motor Performance in Girls with Turner Syndrome Is Not Related to Increased Neuromotor Noise

This study examined the relationship between decreased speed-accuracy trade-off and increased neuromotor noise in girls with Turner Syndrome (TS). Fifteen girls with TS and 15 age-matched controls performed isometric force contractions with both index fingers separately at 5 force levels, based on their maximum voluntary contraction. The results revealed that (a) groups did not differ in speed-accuracy tradeoff or neuromotor noise, (b) output-variability increased linearly with force level, (c) signal-to-noise ratio changed according to an inverted U-shaped function, (d) broadening in the frequency profile is highest at the lower force levels, (e) with increasing force level, the power peak in the 0-4 Hz domain dominates, (f) frequency profile broadens more in the dominant hand. These findings suggest that, in girls with TS, motor performance is not diminished in an isometric force task, that motor recruitment is intact, and that neuromotor noise is not increased. The findings are discussed with respect to motor control and neuromotor noise.

Oral fluency and narrative production in children with Turner's syndrome

Despite good verbal skills, children with Turner's syndrome (TS) have been found to perform poorly on oral fluency tasks. Explanations for this impairment were explored in a study of 9-12-year-old children with TS. The children with TS were found, as expected, to have impaired levels of retrieval on initial letter fluency tasks, in comparison to their peers. Children with TS were also found to have receptive vocabularies which were significantly better than controls, indicating that the weak performance on oral fluency cannot be attributed to lower vocabulary levels. Naming skills were normal for children with TS, indicating that oral fluency scores cannot be attributed to generalised problems with lexical access. Analysis of the content of fluency performance indicated clusters of words within sub-categories which were of normal size but there were fewer switches between clusters than for controls and fewer returns to previously successful clusters. Additionally, a significantly larger proportion of the words generated were of low frequency (e.g. Assyrian, antediluvian) and the children with TS did not thereby show a normal frequency effect in word retrieval. One explanation is that these reflect abnormal action of executive language retrieval processes. Within narrative production, picture description was normal. However, in relation to narrative tasks, hypothesised to place greater executive demands, there was impairment which was significantly greater for narratives of yesterday than narratives of organising a party. This impairment within the narrative generation tasks could be attributable to a selective impairment within executive retrieval skills, or could represent an impairment in episodic memory or the executive processes involved in its retrieval.

Syntactic processing in Turner's syndrome

A significant controversy concerning language development in Turner's syndrome has been found. Whereas some authors have observed that girls with Turner's syndrome maintain their verbal abilities intact, others have reported significant differences in Wechsler Verbal IQ when compared with normal controls. However, little has been studied about the linguistic characteristics of these patients when using tests to evaluate different linguistic levels. With the aim of assessing syntactic processes, 15 patients with Turner's syndrome (aged 8 to 19 years) were compared with 15 healthy girls, matched by age, Wechsler Full-Scale IQ range, type of school (private or public), and school grade. A syntactic processing battery including 11 different subtests was developed. Compared with controls, the participants with Turner's syndrome obtained a fewer number of correct answers in most of the subtests and shorter latencies in some of them. We concluded that the subjects with Turner's syndrome have difficulties in using syntactic structures. It is suggested that some of these language difficulties are related to disturbances in using spatial-language relationships.

Child clinical/pediatric neuropsychology: some recent advances

The neuropsychological assets and deficits of several types of pediatric neurological disease, disorder, and dysfunction are described. These are examined from the perspective of the syndrome of nonverbal learning disabilities (NLD) and the "white matter model" designed to explain its complex manifestations. It is concluded that children with some of these diseases exhibit the NLD phenotype, whereas others do not. For the most part, the diseases in which the NLD phenotype is particularly evident are those wherein it has been demonstrated that perturbations of white matter (long myelinated fibers) are particularly prominent.

Reading skills in children with Turner's syndrome: an analysis of hyperplexia

Most neuropsychological studies of cases of chromosomal abnormalities report associations with disorders or disabilities. Studies of Turner's Syndrome (TS), in which their is functional absence of the information carried on the short arm of the second X chromosome, have emphasised disorders of spatial skill and potential abnormality of the parietal lobes or right hemisphere. In contrast, language skills have received little investigation despite suggestions by Shaffer (1962) of considerable verbal skill. This paper reports on an analysis of reading skill, in girls with TS. The girls with TS attained reading levels higher than those predicted on the basis of their age and intelligence. Moreover, they attained significantly higher reading levels than controls. Unlike many previous studies of hyperlexia, reading comprehension was also better than controls. The hyperlexia of the girls with TS was characterised by strength in both lexical reading systems, as assessed by the ability to read irregular words, and strength in alphabetical or phonological reading skills, as assessed by the ability to read long unfamiliar regular words. Hyperlexia need not therefore co-occur with comprehension difficulties nor need it reflect strength in only part of the reading system. In TS it appears to represent a genuine hyperdevelopment of a skill. The strength of reading skill counterbalances the spatial difficulties of a comparable sample of girls with TS (Temple and Carney, 1995), and with other verbal skills may potentially be exploited in remedial enterprises.

Patterns of spatial functioning in Turner's syndrome

This paper presents results from a study of task performance on a variety of spatial tasks in 9-11 year-old children with Turner's Syndrome (T.S.), divided into those with genotype 45XO and those with Mixed genotypes, including isochromosomes of X and mosaicism. There was a significant overall effect of group reflecting impaired spatial cognition in T.S. with greater decrement in the 45XO group. Further investigation of the significant group by task interaction indicated that the group effects appeared on a visuo-perceptual task and on three visuo-constructional tasks but that there were no specific deficits in the T.S. groups on visuo-spatial or tactile-spatial tasks. In T.S., visuo-perceptual and visuo-constructive sub-systems of spatial skill may be more vulnerable than other components of spatial cognition, to the neuro-biological influences which contribute to the disorder. Such dissociation supports theories of modularity in the development of spatial skill. The spatial tasks which create difficulty overlap only partially with those for which there are sex differences amongst normal children and do not represent a simple exaggeration of normal male-female differences.

Specific arithmetic calculation deficits in children with Turner syndrome

Study 1 compared arithmetic processing skills on the WRAT-R in 45 girls with Turner syndrome (TS) and 92 age-matched female controls. Results revealed significant underachievement by subjects with TS, which reflected their poorer performance on problems requiring the retrieval of addition and multiplication facts and procedural knowledge for addition and division operations. TS subjects did not differ qualitatively from controls in type of procedural error committed. Study 2, which compared the performance of 10 subjects with TS and 31 controls on the Keymath Diagnostic Arithmetic Test, showed that the TS group had less adequate knowledge of arithmetic, subtraction, and multiplication procedures but did not differ from controls on Fact items. Error analyses revealed that TS subjects were more likely to confuse component steps or fail to separate intermediate steps or to complete problems. TS subjects relied to a greater degree on verbal than visual-spatial abilities in arithmetic processing while their visual-spatial abilities were associated with retrieval of simple multidigit addition facts and knowledge of subtraction, multiplication, and division procedures. Differences between the TS and control groups increased with age for Keymath, but not WRAT-R, procedures. Discrepant findings are related to the different task constraints (timed vs. untimed, single vs. alternate versions, size of item pool) and the use of different strategies (counting vs. fact retrieval). It is concluded that arithmetic difficulties in females with TS are due to less adequate procedural skills, combined with poorer fact retrieval in timed testing situations, rather than to inadequate visual-spatial abilities.

The effects of sex steroids, and the X chromosome, on female brain function: a study of the neuropsychology of adult Turner syndrome

Sex steroids and the X chromosome can independently affect cognitive abilities. Because subjects with Turner syndrome (TS) have gonadal aplasia, and various alterations in X chromosome structure and number, they provide a model to study the effects of sex steroids and of the X chromosome on human brain function. We used neuropsychological tests to study the cognitive abilities of 18 TS adults and 19 age/sex matched healthy controls. Nine TS subjects were mosaic for the 45,X karyotype, and 9 were non-mosaic 45,X (full TS). The TS group as a whole, compared to controls, had (i) significantly lower scores in tests of language and visual-spatial function, attention and memory, and (ii) a significantly greater discrepancy between verbal and performance scores. Mosaic TS subjects were intermediate between full TS and controls in some tests of verbal ability, but did not differ significantly from controls in others. Visuospatial ability was significantly lower than controls in both mosaic and full TS. Within the mosaic TS group, there was a significant negative correlation between visuospatial ability and % lymphocytes having a 45,X karyotype. Memory test scores were reduced independently of "X chromosome dosage" in all TS subjects. We conclude that in humans, the X chromosome is involved in development of both cerebral hemispheres, but moreso of the association neocortices. Also, sex steroids may modulate this effect--particularly in hippocampus.

Intellectual functioning of children with Turner syndrome: a comparison of behavioural phenotypes

This study reports the results of 19 girls with Turner syndrome (TS), aged between nine and 12 years, in relation to intellectual profile and genotypic variation. The results were consistent with the notion that the behavioural phenotype of mixed TS involving predominantly mosaic karyotypes is less deviant from the normal pattern than that of pure 45XO. The results for the pure TS girls were consistent with an exaggeration of a normal sex difference, but for mixed TS girls this effect was task-dependent. There was no evidence of generalised deficiency or immaturity, and the task-specific effects support modularity in the development of components of cognitive skill and spatial ability. They also support a specific overall intellectual profile in TS, but with considerable inter-individual variation in its expression.

The effects of X monosomy on brain development: monozygotic twins discordant for Turner's syndrome

Monosomy for the X chromosome is the most frequent cause of Turner's syndrome, a common clinical syndrome associated with particular physical and neurobehavioral features. The results from comprehensive assessment of prepubertal monozygotic female twins discordant for X monosomy are presented. Zygosity was established with DNA Fingerprinting and no evidence of chromosomal mosaicism was seen in either child. Physical features in the affected twin were relatively mild with respect to the full spectrum of physical malformations and disabilities associated with Turner's syndrome. The neurobehavioral phenotypes of the twins were compared. Although both sisters scored in the superior range of intelligence, the affected twin's Performance IQ was 18 points less than her sister, whereas Verbal IQ showed only a 3-point difference between the sisters. Other relative differences were noted within the executive, visuospatial, and visuomotor domains of function. Behavioral evaluation indicated greater problems with attention, hyperactivity, and anxiety in the affected twin. Quantitative analysis of brain anatomy revealed evidence of both general and regional effects of X monosomy on neurodevelopment. Cerebrospinal fluid volume was increased by 25% in the affected twin compared with her sister with a corresponding decrease in gray matter volume. The right frontal, right parietal-occipital, and left parietal-perisylvian regions showed the greatest discrepancy between the sisters with respect to increased cerebrospinal fluid and decreased gray matter volumes in twin with X monosomy. Differences in the posterior fossa were also noted with a 50% relative increase in the volumes of the fourth ventricle and cisterna magna and a 10 to 15% relative reduction in size of the cerebellar vermis, pons, and medulla in the affected twin. The association between the neurobehavioral and neuroanatomical findings in the affected twin is discussed. The unique nature of the naturally occurring genetic phenomenon seen in this twin pair provides an opportunity to more fully elucidate the neurobehavioral phenotype associated with X monosomy and Turner's syndrome.

Regional cerebral glucose metabolism in Turner syndrome

Regional cerebral glucose metabolism was examined in females with Turner syndrome, a sex chromosome abnormality. Previous studies have found a visual/spatial cognitive anomaly in these women but, to date, no abnormalities in brain structure or function have been associated with the condition. In the present study, decreases in regional metabolism were found in the occipital and parietal cortex. The involvement of the occipital cortex, although consistent with the observed cognitive anomalies, has not been suggested previously as an area dysfunction. Because the occipital cortex is a primary sensory cortex, the reduction of glucose metabolism in the parietal cortex may reflect a lack of innervation from the occipital cortex. Besides insight into the functional specialization of the brain, these findings are also consistent with previous reports on animals regarding the effects of estrogen in brain maturation.