Motor development in children with Dravet syndrome

Natural history of rare diseases using natural language processing of narrative unstructured electronic health records: The example of Dravet syndrome

OBJECTIVE

The increasing implementation of electronic health records allows the use of advanced text-mining methods for establishing new patient phenotypes and stratification, and for revealing outcome correlations. In this study, we aimed to explore the electronic narrative clinical reports of a cohort of patients with Dravet syndrome (DS) longitudinally followed at our center, to identify the capacity of this methodology to retrace natural history of DS during the early years.

METHODS

We used a document-based clinical data warehouse employing natural language processing to recognize the phenotype concepts in the narrative medical reports. We included patients with DS who have a medical report produced before the age of 2 years and a follow-up after the age of 3 years ("DS cohort," 56 individuals). We selected two control populations, a "general control cohort" (275 individuals) and a "neurological control cohort" (281 individuals), with similar characteristics in terms of gender, number of reports, and age at last report. To find concepts specifically associated with DS, we performed a phenome-wide association study using Cox regression, comparing the reports of the three cohorts. We then performed a qualitative analysis of the surviving concepts based on their median age at first appearance.

RESULTS

A total of 76 concepts were prevalent in the reports of children with DS. Concepts appearing during the first 2 years were mostly related with the epilepsy features at the onset of DS (convulsive and prolonged seizures triggered by fever, often requiring in-hospital care). Subsequently, concepts related to new types of seizures and to drug resistance appeared. A series of non-seizure-related concepts emerged after the age of 2-3 years, referring to the nonseizure comorbidities classically associated with DS.

SIGNIFICANCE

The extraction of clinical terms by narrative reports of children with DS allows outlining the known natural history of this rare disease in early childhood. This original model of "longitudinal phenotyping" could be applied to other rare and very rare conditions with poor natural history description.

Clinical and Genetic Features of Dravet Syndrome: A Prime Example of the Role of Precision Medicine in Genetic Epilepsy

Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy, is a rare and drug-resistant form of developmental and epileptic encephalopathies, which is both debilitating and challenging to manage, typically arising during the first year of life, with seizures often triggered by fever, infections, or vaccinations. It is characterized by frequent and prolonged seizures, developmental delays, and various other neurological and behavioral impairments. Most cases result from pathogenic mutations in the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene, which encodes a critical voltage-gated sodium channel subunit involved in neuronal excitability. Precision medicine offers significant potential for improving DS diagnosis and treatment. Early genetic testing enables timely and accurate diagnosis. Advances in our understanding of DS's underlying genetic mechanisms and neurobiology have enabled the development of targeted therapies, such as gene therapy, offering more effective and less invasive treatment options for patients with DS. Targeted and gene therapies provide hope for more effective and personalized treatments. However, research into novel approaches remains in its early stages, and their clinical application remains to be seen. This review addresses the current understanding of clinical DS features, genetic involvement in DS development, and outcomes of novel DS therapies.

Functional mobility in children and young adults with Dravet syndrome

AIM

This cohort study aimed to describe functional mobility in Dravet syndrome, a developmental and epileptic encephalopathy.

METHOD

Functional mobility was assessed in individuals (aged 3-25 years), diagnosed with Dravet syndrome, using the Functional Mobility Scale (FMS), Mobility Questionnaire 28 (MobQues28), and estimated walking distance. Secondary outcome variables were Gait Profile Score (GPS), walking velocity, age at independent walking, intellectual disability, seizure frequency, genetic variant type, and body mass index (BMI).

RESULTS

Forty participants aged 3 years to 24 years 2 months (mean = 12 years 2 months) had a median MobQues28 of 79%, median scores of 5, 5, and 4 for the FMS 5 m, 50 m, and 500 m and a median estimated walking distance of 1 km to 3 km. Most difficulties were seen in walking up and down the stairs, walking over obstacles, kicking a ball, and running. MobQues28 scores showed a significant decrease (-6.6%, p = 0.016) in the age category of young adults (≥18 years). After correcting for age, MobQues28 was correlated to age at independent walking (-0.485, p = 0.002), GPS (-0.460, p = 0.003), and walking velocity (0.334, p = 0.038). Analysis of variance showed a significant effect of intellectual disability and BMI on MobQues28 (p = 0.029, p = 0.049). No effect of seizure frequency or genetic variant was found (p = 0.579, p = 0.337).

INTERPRETATION

Functional mobility limitations were observed mainly in dual tasks and activities requiring stability, with limitations increasing from the age of 18 years. Age at independent walking, gait impairments, intellectual disability, and BMI can impact functional mobility in Dravet syndrome.

WHAT THIS PAPER ADDS

Most limitations were seen in dual task activities and activities that required more stability. Deterioration in functional mobility occurred in young adults. The more gait impairments, the more functional mobility limitations. Age at independent walking, intellectual disability, and body mass index can impact functional mobility.

Intellectual functioning and adaptive behaviour in children with Dravet syndrome: A population-based study

AIM

To identify, on a population basis, the prevalence of intellectual disability in children with Dravet syndrome, profiles on a measure of adaptive behaviour, and factors associated with intellectual functioning and adaptive behaviour.

METHOD

Forty-two out of 48 children with Dravet syndrome living in Sweden, born between 1st January 2000 and 31st December 2018, underwent assessment of intellectual functioning and adaptive behaviour. Factors associated with level of intellectual functioning and adaptive behaviour were analysed.

RESULTS

Eight-six per cent (n = 36) of the children fulfilled DSM-5 criteria for intellectual disability (29% [n = 12] mild intellectual disability, 24% [n = 10] moderate intellectual disability, 33% [n = 14] severe intellectual disability, 0% profound intellectual disability) and 93% (n = 39) had an adaptive behaviour composite more than two standard deviations below the mean. Communication was a significant weakness compared with daily living skills (p < 0.001; mean difference 95% confidence interval [CI] -8.193 to -4.092) and socialization (p = 0.001; mean difference 95% CI 6.511 to -1.775) on the Vineland Adaptive Behavior Scales, Second Edition. The only factors significantly associated with both decreased adaptive behaviour and presence of severe intellectual disability was the presence of increased autistic symptoms and younger age.

INTERPRETATION

Children with Dravet syndrome have a very high level of intellectual disability and almost all have significant deficits in adaptive behaviour. Greater deficits in adaptive behaviour and greater severity of intellectual disability are associated with the presence of increased autistic symptoms, highlighting the need for comprehensive neurodevelopmental assessment for all affected children.

WHAT THIS PAPER ADDS

Eighty-six per cent (n = 36) of children with Dravet syndrome fulfilled criteria for intellectual disability. Ninety-three per cent (n = 39) of children with Dravet syndrome had significant deficits in adaptive behaviour. Communication was a significant weakness on a measure of adaptive behaviour. Increased autistic symptoms were associated with greater deficits in cognition/adaptive behaviour. Older age and earlier status epilepticus were associated with decreased adaptive behaviour.

The clinical, economic, and humanistic burden of Dravet syndrome - A systematic literature review

Dravet syndrome (DS) is a developmental and epileptic encephalopathy with evolving disease course as individuals age. In recent years, the treatment landscape of DS has changed considerably, and a comprehensive systematic review of the contemporary literature is lacking. Here we synthesized published evidence on the occurrence of clinical impacts by age, the economic and humanistic (health-related quality-of-life [HRQoL]) burden, and health state utility. We provide an evidence-based, contemporary visualization of the clinical manifestations, highlighting that DS is not limited to seizures; non-seizure manifestations appear early in life and increase over time, contributing significantly to the economic and humanistic burden of disease. The primary drivers of HRQoL in DS include seizure severity, cognition, and motor and behavioral problems; in turn, these directly affect caregivers through the extent of assistance required and consequent impact on activities of daily living. Unsurprisingly, costs are driven by seizure-related events, hospitalizations, and in-home medical care visits. This systematic review highlights a paucity of longitudinal data; most studies meeting inclusion criteria were cross-sectional or had short follow-up. Nonetheless, available data illustrate the substantial impact on individuals, their families, and healthcare systems and establish the need for novel therapies to address the complex spectrum of DS manifestations.

Progressive Worsening of Gait and Motor Abnormalities in Older Adults With Dravet Syndrome

BACKGROUND AND OBJECTIVES

Relative to the pediatric population, there is very limited information about Dravet Syndrome (DS) in adults. In addition to some of the gait abnormalities reported in children with DS (such as crouch gait and ataxia), adults with this condition have other gait and motor disturbances. Our primary objective was to examine gait and motor manifestations in older adults with DS.

METHODS

This study has a prospective arm where 6 patients (mean age 32-years-old) were examined through a modified version of the Unified Parkinson's Disease Rating Scale (mUPDRS) in 2014 and again in 2019. mUPDRS scores were assigned to gait, resting tremors, facial expression, arising from a chair, posture, and body bradykinesia. The cross-sectional arm includes mUPDRS testing in patients that were not evaluated in 2014, and an instrumental gait analysis (IGA). These cross-sectional tests were done in the 2019-2020 period. The IGA was performed using the ProtoKinetics software with a gait mat built with sensors and two cameras capturing the sagittal and coronal planes. The IGA was performed in a group of 17 patients with DS (mean age: 31-years-old), the control group consisted of 81 healthy individuals, whose mean age was 62-years-old. Regression analyses were performed for the IGA and mUPDRS data.

RESULTS

Five out of six participants evaluated prospectively over 5 years experienced worsening of their parkinsonian manifestations, including gait. Two patients (47 and 51 years old) who were initially ambulatory, could no longer walk 5 years later. The cross-sectional analysis of mUPDRS in a larger group of adults showed that worse scores for arising from a chair (p= 0.04), body bradykinesia (p= 0.01), and gait (p= 0.0003) were positively associated with age. The IGA cross-sectional arm revealed that all 17 adults with DS had abnormal gait parameters in all domains tested. This group of patients performed worse than the healthy and older control group.

DISCUSSION

Although seizures may decrease in older adults with DS, this prospective and cross-sectional study showed that their motor symptoms and gait become progressively worse as they age.

Fine motor impairment in children with epilepsy: Relations with seizure severity and lateralizing value

Motor skill deficits are common in epilepsy. The Grooved Pegboard Test (GPT) is the most commonly used fine motor task and is included in the NIH Common Data Elements Battery for the assessment of epilepsy. However, there are limited data on its utility in children and adolescents. The present study investigated the effectiveness of this task in children and adolescents with epilepsy clinically referred for neuropsychological evaluation in a tertiary medical center. Two hundred and two children and adolescents (ages 6-16, 104 males, 98 females) completed the GPT. Base rates of impairment were calculated, correlational analyses determined relations with clinical variables, and ANOVAs and t-tests assessed for differences by seizure type, gender, and lateralized deficits in those with lateralized focal epilepsy. The GPT was sensitive to fine motor impairment in these children and adolescents, with over 60% having impaired performances. Further, performance was significantly correlated with IQ, age of epilepsy onset, number of medications, and seizure frequency. At the group level, those with lateralized focal epilepsy did not show significant differences between left and right hands, though the GPT correctly lateralized 63% of those with large between-hand performance disparities (i.e., one standard deviation or greater). In sum, the GPT is sensitive to fine motor deficits in pediatric epilepsy and is related to known epilepsy severity factors. However, the ability of the task to lateralize epilepsy onset is not robust.

Strength measurements in patients with Dravet Syndrome

BACKGROUND

Dravet Syndrome (DS) is a developmental and epileptic encephalopathy, characterized by drug resistant infantile onset seizures and cognitive and motor impairment. Walking problems progressively occur and crouch gait is frequently observed. Muscle weakness is hypothesized as contributing impairment. Yet, so far, no studies have performed strength measurements in patients with DS, most likely due to cognitive impairment.

AIMS

To determine the feasibility and validity of strength measurements in the framework of gait analysis and to outline strength problems in patients with DS.

METHODS

Manual muscle testing, dynamometry (hand grip strength and handheld dynamometry) and functional tests (underarm throwing, standing long jump, sit-to-stand, stair climbing) were performed in 46 patients with DS. Results were compared to age-related reference values from literature.

RESULTS

Forty one percent (19/46) of the patients (aged 5.2-24.8 years, median: 15.8 years) accomplished all measurements and scored generally below the fifth percentile of norm values. The remaining 59% (27/46) was not able to complete all strength assessment due to cognitive, behavioural and motor difficulties. Handheld dynamometry seemed most sensitive and specific to detect isolated muscle strength. Validity of the functional tests was controversial, as motor proficiency, balance and coordination may interfere.

CONCLUSION

Although measuring strength in patients with DS was challenging in the context of gait analysis, decreased muscle strength was observed in patients that could perform strength measurements. Handheld dynamometry is preferred over functional tests for future investigations of muscle strength and its interference with gait are required for better understanding of walking problems.

Improving early diagnosis of rare diseases using Natural Language Processing in unstructured medical records: an illustration from Dravet syndrome

Background

The growing use of Electronic Health Records (EHRs) is promoting the application of data mining in health-care. A promising use of big data in this field is to develop models to support early diagnosis and to establish natural history. Dravet Syndrome (DS) is a rare developmental and epileptic encephalopathy that commonly initiates in the first year of life with febrile seizures (FS). Age at diagnosis is often delayed after 2 years, as it is difficult to differentiate DS at onset from FS. We aimed to explore if some clinical terms (concepts) are significantly more used in the electronic narrative medical reports of individuals with DS before the age of 2 years compared to those of individuals with FS. These concepts would allow an earlier detection of patients with DS resulting in an earlier orientation toward expert centers that can provide early diagnosis and care.

Methods

Data were collected from the Necker Enfants Malades Hospital using a document-based data warehouse, Dr Warehouse, which employs Natural Language Processing, a computer technology consisting in processing written information. Using Unified Medical Language System Meta-thesaurus, phenotype concepts can be recognized in medical reports. We selected individuals with DS (DS Cohort) and individuals with FS (FS Cohort) with confirmed diagnosis after the age of 4 years. A phenome-wide analysis was performed evaluating the statistical associations between the phenotypes of DS and FS, based on concepts found in the reports produced before 2 years and using a series of logistic regressions.

Results

We found significative higher representation of concepts related to seizures’ phenotypes distinguishing DS from FS in the first phases, namely the major recurrence of complex febrile convulsions (long-lasting and/or with focal signs) and other seizure-types. Some typical early onset non-seizure concepts also emerged, in relation to neurodevelopment and gait disorders.

Conclusions

Narrative medical reports of individuals younger than 2 years with FS contain specific concepts linked to DS diagnosis, which can be automatically detected by software exploiting NLP. This approach could represent an innovative and sustainable methodology to decrease time of diagnosis of DS and could be transposed to other rare diseases.

Independent walking and cognitive development in preschool children with Dravet syndrome

AIM

To investigate the relation between cognitive and motor development in preschool aged children with Dravet syndrome, in particular between the age of independent walking and cognitive development.

METHOD

Results of cognitive and motor developmental assessments and the age of independent walking were retrieved retrospectively from the medical records of 33 children (17 males, 16 females; mean age at last evaluation 33.2mo, SD 8.2mo, range 9-48mo) diagnosed with Dravet syndrome. Cognitive and motor developmental age, derived from the Bayley Scales of Infant Development or through standardized neurodevelopmental assessment, were converted into cognitive and motor developmental quotients. Multiple test scores per child were included.

RESULTS

A strong positive relation was found between cognitive and motor developmental quotient (Pearson r=0.854; p<0.001) in 20 children (slope=0.75; 95% CI: 0.54-0.95). A later age of independent walking was associated with a lower cognitive developmental quotient (28 children; p<0.001; slope=-1.01; 95% CI: -1.53 to -0.49). A higher cognitive developmental quotient was seen in children with an age at testing younger than 24 months. The cognitive developmental quotient of children with a delay in independent walking (>17.6mo) was significantly lower than those without a delay (p=0.006).

INTERPRETATION

A strong relation exists between cognitive and motor development. Furthermore, the age of independent walking might be an important indicator of the development of children with Dravet syndrome.

WHAT THIS PAPER ADDS

Cognitive and motor development are strongly related in children with Dravet syndrome. Later age of independent walking is associated with worse cognitive development in children with Dravet syndrome.

Deconstructing Dravet syndrome neurocognitive development: A scoping review

Dravet syndrome (DS) is a rare severe epilepsy syndrome associated with slowed psychomotor development and behavioral disorders from the second year onward in a previously seemingly normal child. Among cognitive impairments, visuospatial, sensorimotor integration, and expressive language deficits are consistently reported. There have been independent hypotheses to deconstruct the typical cognitive development in DS (dorsal stream vulnerability, cerebellar-like pattern, sensorimotor integration deficit), but an encompassing framework is still lacking. We performed a scoping review of existing evidence to map the current understanding of DS cognitive and behavioral developmental profiles and to summarize the evidence on suggested frameworks. We searched PubMed, Scopus, PsycInfo, and MEDLINE to identify reports focusing on cognitive deficits and/or behavioral abnormalities in DS published between 1978 and March 15, 2020. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Twenty-one reports were selected and tabulated by three independent reviewers based on predefined data extraction and eligibility forms. Eighteen reports provided assessments of global intelligence quotients with variable degrees of cognitive impairment. Eleven reports analyzed single subitems contribution to global cognitive scores: these reports showed consistently larger impairment in performance scales compared to verbal ones. Studies assessing specific cognitive functions demonstrated deterioration of early visual processing, fine and gross motor abilities, visuomotor and auditory-motor integration, spatial processing, visuo-attentive abilities, executive functions, and expressive language. Behavioral abnormalities, reported from 14 studies, highlighted autistic-like traits and attention and hyperactivity disorders, slightly improving with age. The cognitive profile in DS and some behavioral and motor abnormalities may be enclosed within a unified theoretical framework of the three main hypotheses advanced: a pervasive sensorimotor integration deficit, encompassing an occipito-parietofrontal circuit (dorsal stream) dysfunction and a coexistent cerebellar deficit.

Foot-floor contact pattern in children and adults with Dravet Syndrome

BACKGROUND

Dravet Syndrome (DS) is a developmental and epileptic encephalopathy characterized by severe drug-resistant seizures and associated with cognitive and motor impairments. Walking problems are frequently observed. As the foot plays a key role during walking, compromised foot function can be a feature of deviant gait.

AIM

To investigate foot function in DS by characterizing foot-floor contact patterns using pedobarography.

METHODS

A total of 31 children and adults were included in the DS group (aged 5.2-32.8 years, 17 female, 174 steps) and 30 in the control group (aged 6.0-32.9, 16 female, 180 steps). The foot-floor contact pattern was evaluated based on progression, length and smoothness (spectral arc length) of the center of pressure (CoP). Linear mixed models were used to identify differences between non-heel strikes and heel strikes and between the DS and control group.

RESULTS

Fifteen participants with DS showed inconsistency in the type of foot-floor contact (heel strikes and non-heel strikes). Heel strikes of participants with DS had significantly reduced time of CoP under the hindfoot and increased time under the midfoot region compared to the control group. Significant time and age effects were detected.

CONCLUSIONS AND IMPLICATIONS

Deviant foot-floor contact patterns were observed in DS. Possible gait immaturity and instability as well as implications for interventions are discussed.

Neuropathological Characterization of a Dravet Syndrome Knock-In Mouse Model Useful for Investigating Cannabinoid Treatments

Dravet syndrome (DS) is an epileptic syndrome caused by mutations in the Scn1a gene encoding the α1 subunit of the sodium channel Nav1.1, which is associated with febrile seizures that progress to severe tonic-clonic seizures and associated comorbidities. Treatment with cannabidiol has been approved to reduce seizures in DS, but it may also be active against these comorbidities. The aim of this study was to validate a new mouse model of DS having lower mortality than previous models, which may serve to further evaluate therapies for the long-term comorbidities. This new model consists of heterozygous conditional knock-in mice carrying a missense mutation (A1783V) in Scn1a gene expressed exclusively in neurons of the CNS (Syn-Cre/Scn1a^WT/A1783V). These mice have been used here to determine the extent and persistence of the behavioral deterioration in different postnatal days (PND), as well as to investigate the alterations that the disease produces in the endocannabinoid system and the contribution of inflammatory events and impaired neurogenesis in the pathology. Syn-Cre/Scn1a^WT/A1783V mice showed a strong reduction in hindlimb grasp reflex at PND10, whereas at PND25, they presented spontaneous convulsions and a greater susceptibility to pentylenetetrazole-induced seizures, marked hyperactivity, deficient spatial working memory, lower levels of anxiety, and altered social interaction behavior. These differences disappeared at PND40 and PND60, except the changes in social interaction and anxiety. The analysis of CNS structures associated with these behavioral alterations revealed an elevated glial reactivity in the prefrontal cortex and the dentate gyrus. This was associated in the dentate gyrus with a greater cell proliferation detected with Ki67 immunostaining, whereas double-labeling analyses identified that proliferating cells were GFAP-positive suggesting failed neurogenesis but astrocyte proliferation. The analysis of the endocannabinoid system of Syn-Cre/Scn1a^WT/A1783V mice confirmed reductions in CB₁ receptors and MAGL and FAAH enzymes, mainly in the cerebellum but also in other areas, whereas CB₂ receptors became upregulated in the hippocampus. In conclusion, Syn-Cre/Scn1a^WT/A1783V mice showed seizuring susceptibility and several comorbidities (hyperactivity, memory impairment, less anxiety, and altered social behavior), which exhibited a pattern of age expression similar to DS patients. Syn-Cre/Scn1a^WT/A1783V mice also exhibited greater glial reactivity and a reactive response in the neurogenic niche, and regional changes in the status of the endocannabinoid signaling, events that could contribute in behavioral impairment.

Gait deviations in patients with dravet syndrome: A systematic review

BACKGROUND

Dravet Syndrome is a rare developmental and epileptic encephalopathy characterised by epileptic seizures, cognitive impairment and motor disorders. Gait is markedly impaired and could benefit from targeted intervention to improve quality of life for patient and caregivers.

OBJECTIVE

To establish the state of the art regarding gait deviations in patients with Dravet Syndrome.

METHODS

A systematic search was performed in Pubmed, Web of Science, Science Direct and Embase. Studies that assessed gait deviations in patients diagnosed with Dravet Syndrome using clinical observation, video gait analysis or three dimensional (3D) gait analysis and reported gait characteristics, spatiotemporal or kinematic outcomes were included. Screening, quality assessment and data extraction were performed by independent reviewers.

RESULTS

Out of a total of 478 citations, nine articles were included. The total study population had an age range from 2.5 to 47 years. Three studies used clinical observation, three studies video analysis and three studies 3D gait analysis. Crouch gait was observed in about half of the population next to a variety of other gait deviations such as parkinsonian and cerebellar gait. Other findings included abnormalities in spatiotemporal parameters and kinematics, passive knee extension deficits, skeletal malalignment and neurological signs.

CONCLUSIONS

A variety of gait characteristics was observed with crouch gait being the most reported gait pattern. Inconsistency in methods and findings from clinical and instrumented evaluation impede thorough understanding of the causal mechanism and evolution behind these deviations.

PROSPERO REGISTRATION NUMBER

CRD42017070370.