Cerebellum Atrophy and Development of a Peripheral Dysgraphia: A Paediatric Case

Handedness in autism spectrum disorders and intellectually disabled children and adolescents - Contrasting caregivers' reports with assessments of hand preference

Background

A higher rate of atypical handedness prevalence (non-right-handedness or left-, mixed-hand dominance) has been recurrently reported in individuals diagnosed with autism spectrum disorder (ASD) compared to individuals with other types of developmental disabilities. However, the exact magnitude of this difference as well as the presence of possible contributing factors remained unknown. The main aim of this study was to understand caregivers' impression of the handedness of their child with developmental disabilities and its relationship with assessments of the child using a hand preference scale.

Methods and procedures

The sample of the present study was 1116 individuals with developmental disabilities from two countries, 541 (51.5%) individuals from Iran and 575 (48.5%) individuals from the Kurdistan Region of Iraq (KRI). The handedness of the sample was evaluated based on the parental report and utilizing a standardized scale (The Hand-Preference Demonstration Test "HPDT").

Outcomes and results

There was a statistically significant difference between caregivers' reports on their dependents' handedness and the application of a valid hand preference scale and they do not necessarily overlap. There was a statistically significant relationship between handedness and type of developmental disabilities based on caregivers' reports and individuals with ASD were more non-right-handed compared to individuals with ID based on the caregivers' report. Hence similar difference was not seen between the ASD and ID groups when HDTP was applied as a diagnostic scale. While left-handedness in the ASD and ID group was similar (23-24%), mixed-handedness in the ASD group was 38% compared to 33% in the ID group.

Conclusions and implications

The Hand-Preference Demonstration Test (HPDT) was a valid way to determine the hand preference of individuals with ASD and ID. It is concluded that parental reports on their offspring with ASD's hand preference need to be approved through the application of a scale and caregivers and professionals need to be more aware of early motor symptoms such as handedness. Further research should focus on the role of handedness in the development of fine motor skills and eye-hand coordination in children with differing developmental disabilities and variations among those differing impairments.

The Modularity of Dysgraphia

Research regarding dysgraphia, an impairment in writing, is attaining more attention in recent times. The existing studies on dysgraphia draw insights from cognitive, behavioural, neurological, and genetic fields of knowledge. However, these multiple studies on dysgraphia fail to illustrate how these cognitive, behavioural, neurological, and genetic systems interact and intersect in dysgraphia. Therefore, the studies could not offer a comprehensive understanding of dysgraphia. In order to fill this gap, the review attempts to study dysgraphia using the notion of modularity by accommodating insights from cognitive, behavioural, neurological, and genetic aspects of dysgraphia. Such a profound understanding could facilitate an early diagnosis and holistic intervention towards dysgraphia.

Cerebellar contributions to orthographic working memory: A single case cognitive neuropsychological investigation

Single case cognitive neuropsychological investigations involve the precise characterization of cognitive impairment at the level of an individual participant. This deep data precision affords a more fine-grained understanding of the cognitive and neural underpinnings of complex tasks, and continues to provide unique insights that inform theory in cognitive neuroscience. Here, we present a single case study of an individual, F.R., who suffered a stroke that led to chronic reading and writing problems that include an impairment to the orthographic working memory system proposed to be involved in both written language production and comprehension. Individuals who have been previously reported with a similar cognitive impairment commonly have left parietal lesions. However, F.R.'s orthographic working memory deficit resulted from damage to the right cerebellum, specifically to a region that is both structurally and functionally connected to the left parietal lobe and has been identified as part of the spelling network in previous meta-analyses of writing fMRI studies. From this lesion-symptom association, we argue that orthographic working memory is subserved by a cortical-cerebellar circuit, with damage at any point in the circuit resulting in an impairment to this function. Such a conclusion is warranted by observations from this single case approach, and we argue that these observations would likely have been missed if F.R. had been included in a larger, shallower group study. In addition to elucidating our understanding of the neural basis of spelling, this case study demonstrates the value that single case neuropsychology can continue to bring to cognitive neuroscience.

Disorder of written expression and dysgraphia: definition, diagnosis, and management

Writing is a complex task that is vital to learning and is usually acquired in the early years of life. 'Dysgraphia' and 'specific learning disorder in written expression' are terms used to describe those individuals who, despite exposure to adequate instruction, demonstrate writing ability discordant with their cognitive level and age. Dysgraphia can present with different symptoms at different ages. Different theories have been proposed regarding the mechanisms of dysgraphia. Dysgraphia is poorly understood and is often undiagnosed. It has a high rate of co-morbidity with other learning and psychiatric disorders. The diagnosis and treatment of dysgraphia and specific learning disorders typically centers around the educational system; however, the pediatrician can play an important role in surveillance and evaluation of co-morbidity as well as provision of guidance and support.

Language and the cerebellum

During the past decades neuroanatomic, neuroimaging, and clinical studies have substantially changed the long-standing view of the role of the cerebellum as a sole coordinator of sensorimotor function. Currently, the cerebellum is considered to be crucially implicated in a variety of cognitive, affective, social, and behavioral processes as well. In this chapter we aim to summarize a number of critical insights from different research areas (neuroanatomy, functional neuroimaging, clinical practice) that provide evidence for a role of the cerebellum in motor speech and nonmotor language processing in both adults and children. Neuroanatomic studies have provided a robust basis for the development of new insights in the modulatory role of the cerebellum in neurocognition, including nonmotor language processing by means of identifying a dense network of crossed reciprocal connections between the cerebellum and the supratentorial association areas. A topologic distinction has been established between the "motor" cerebellum, projecting to the cortical motor areas, and the "cognitive/affective" cerebellum, connected with the cortical and limbic association areas. Neuroimaging studies have demonstrated cerebellar involvement in several different language tasks, even after controlling for motor aspects. In addition, several clinical studies have identified a variety of nonmotor linguistic deficits after cerebellar disease in both children and adults, implying a prominent role for the cerebellum in linguistic processes. Functional neuroimaging has confirmed the functional impact of cerebellar lesions on remote, structurally intact cortical regions via crossed cerebellocerebral diaschisis. Overall, evidence from neuroanatomic, neuroimaging, and clinical studies shows a (strongly lateralized) involvement of the cerebellum in a broad spectrum of nonmotor language functions through a dense network of crossed and reciprocal cerebellocerebral connections. It is argued that the cerebellum is involved in language in a similar manner as it is involved in motor functions: through monitoring/coordinating cortical functions via timing and sequencing mechanisms.

Consensus paper: Language and the cerebellum: an ongoing enigma

In less than three decades, the concept "cerebellar neurocognition" has evolved from a mere afterthought to an entirely new and multifaceted area of neuroscientific research. A close interplay between three main strands of contemporary neuroscience induced a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Indeed, the wealth of current evidence derived from detailed neuroanatomical investigations, functional neuroimaging studies with healthy subjects and patients and in-depth neuropsychological assessment of patients with cerebellar disorders shows that the cerebellum has a cardinal role to play in affective regulation, cognitive processing, and linguistic function. Although considerable progress has been made in models of cerebellar function, controversy remains regarding the exact role of the "linguistic cerebellum" in a broad variety of nonmotor language processes. This consensus paper brings together a range of different viewpoints and opinions regarding the contribution of the cerebellum to language function. Recent developments and insights in the nonmotor modulatory role of the cerebellum in language and some related disorders will be discussed. The role of the cerebellum in speech and language perception, in motor speech planning including apraxia of speech, in verbal working memory, in phonological and semantic verbal fluency, in syntax processing, in the dynamics of language production, in reading and in writing will be addressed. In addition, the functional topography of the linguistic cerebellum and the contribution of the deep nuclei to linguistic function will be briefly discussed. As such, a framework for debate and discussion will be offered in this consensus paper.

Brainstem arteriovenous malformation presenting with dyspraxic handwriting in a young girl

We report the case of a 11-year-old girl who developed an isolated hand-writing disorder with dysgraphia at the beginning of the school year in the sixth grade. A brain magnetic resonance angiography showed a round arteriovenous malformation sited in the left side of the midbrain extending to the ipsilateral medio-basal thalamus. Child neurologists should never neglect a thorough neurological evaluation in case of isolated worsening of handwriting, to rule out possible underlying organic causes.

Hemicerebellitis: Report of three paediatric cases and review of the literature

Acute inflammation of a single cerebellar hemisphere (hemicerebellitis) is a rare disorder of unknown origin. The clinical presentation is mainly characterized by headache, ataxia, dysmetria, and vomiting. In addition, some children may develop severe intracranial hypertension. The neuroimaging of hemicerebellitis raises a challenging differential diagnosis, particularly with posterior fossa tumours. Although there is no standard treatment for hemicerebellitis, its outcome is usually favourable. However, ipsilateral hemicerebellar atrophy develops in up to half of cases, and a minority of children may show persisting fine motor and/or neurocognitive sequelae. In this article, we contribute with three new reports and review a total of 35 cases of hemicerebellitis.

Neural correlates of paediatric dysgraphia

Writing is an important skill that is related both to school performance and to psychosocial outcomes such as the child's self-esteem. Deficits in handwriting performance are frequently encountered in children with developmental coordination disorder. This review focuses on what is known about the neural correlates of atypical handwriting in children. Knowledge of the neural correlates is derived from studies using clinical case designs (e.g. lesion studies), studies using neuroimaging, and assessment of minor neurological dysfunction. The two functional imaging studies suggest a contribution of cortical areas and the cerebellum. The largest study indicated that cortical areas in all regions of the brain are involved (frontal, temporal, parietal, and occipital). The two lesion studies confirmed cerebellar involvement. The findings of the study on minor neurological dysfunction in children with writing problems correspond to the imaging results. The limited data on the neural substrate of paediatric dysgraphia suggest that at least a subset of the children with dysgraphia have dysfunctions in extensive supraspinal networks. In others, dysfunction may be restricted to either the cerebellum or specific cortical sites.

Examining the central and peripheral processes of written word production through meta-analysis

Producing written words requires “central” cognitive processes (such as orthographic long-term and working memory) as well as more peripheral processes responsible for generating the motor actions needed for producing written words in a variety of formats (handwriting, typing, etc.). In recent years, various functional neuroimaging studies have examined the neural substrates underlying the central and peripheral processes of written word production. This study provides the first quantitative meta-analysis of these studies by applying activation likelihood estimation (ALE) methods (Turkeltaub et al., 2002). For alphabet languages, we identified 11 studies (with a total of 17 experimental contrasts) that had been designed to isolate central and/or peripheral processes of word spelling (total number of participants = 146). Three ALE meta-analyses were carried out. One involved the complete set of 17 contrasts; two others were applied to subsets of contrasts to distinguish the neural substrates of central from peripheral processes. These analyses identified a network of brain regions reliably associated with the central and peripheral processes of word spelling. Among the many significant results, is the finding that the regions with the greatest correspondence across studies were in the left inferior temporal/fusiform gyri and left inferior frontal gyrus. Furthermore, although the angular gyrus (AG) has traditionally been identified as a key site within the written word production network, none of the meta-analyses found it to be a consistent site of activation, identifying instead a region just superior/medial to the left AG in the left posterior intraparietal sulcus. These meta-analyses and the discussion of results provide a valuable foundation upon which future studies that examine the neural basis of written word production can build.