Movement disorders in patients with Rett syndrome: A systematic review of evidence and associated clinical considerations

Repetitive active and passive cognitive stimulations induce EEG changes in patients with Rett syndrome

BACKGROUND

Despite being considered a rare disease, Rett syndrome is a leading cause of profound cognitive impairment in females. This study explores game-based cognitive stimulation to enhance attention during learning tasks, offering an alternative treatment perspective.

METHODS

Fifteen diagnosed Rett syndrome girls participated in four 24-minute sessions, including a 5-minute initial resting state recording. Primary indicators for analysis included relative power and spectral entropy.

RESULTS

Significant findings indicated variations among conditions (resting state, active task, passive task) in response to stimulation. Notably, over four days, evolution occurred, characterized by decreasing delta power and increasing theta and beta power. Topographic maps confirmed these shifts, highlighting affected brain areas. Linear regression emphasized the most significant impact on the first day, with subsequent shifts towards higher frequencies, particularly during the resting state. By the fourth day, resting-state patterns resembled those during cognitive activities.

CONCLUSION

Findings suggest cognitive stimulation induces substantial EEG spectral changes, potentially linked to cognitive enhancements in Rett syndrome. The shift towards higher frequency bands and increased spectral entropy align with enhanced brain activation during cognitive sessions, underscoring the potential of cognitive stimulation therapies and calling for further research to optimize abilities in individuals with Rett syndrome.

IMPACT

Game-based cognitive stimulation induces substantial EEG changes in individuals with Rett syndrome, enhancing cognitive functions, notably attention during learning. This study conducts a distinctive examination, assessing the habituation paradigm through the combination of game-based cognitive stimulation and learning, providing valuable insights into enhancing attention in Rett syndrome. Impacting understanding of cognitive processes in Rett syndrome, this research reveals significant EEG variations during tasks, emphasizing the potential of cognitive stimulation for attention enhancement and the need for further research in tailored interventions.

Psychological aspects of being a parent of an individual with Rett syndrome: A scoping review

BACKGROUND

Rett syndrome (RTT) causes multiple disabilities with a lifelong need for substantial care, placing a tremendous lifelong responsibility on the parents. Parenting an individual with RTT can therefore be challenging. Research on the psychological aspects of parenting individuals with RTT is limited and unclear. We aimed to identify and map the existing literature on this subject.

METHOD

A scoping review was conducted with systematic searches in PubMed, PsycINFO and CINAHL.

RESULTS

Eighteen studies were included. Negative and positive psychological aspects were described with the majority focusing on the negative. Three factors seemed to especially affect the parents: severity of the diagnosis, time (increasing age of parents or individual with RTT; years of caretaking), work-status of the mother.

CONCLUSIONS

Seemingly, parents are highly affected; however, the literature is scarce and has several gaps. Future research should include older parents, fathers, parents of individuals living in group homes, and positive aspects.

Therapeutic effects of extracorporeal shock wave therapy on patients with spastic cerebral palsy and Rett syndrome: clinical and ultrasonographic findings

BACKGROUND

Extracorporeal shock wave therapy (ESWT) is reportedly effective for improving spasticity and motor function in children with cerebral palsy (CP). Because late-stage Rett syndrome has a similar presentation, this study aimed to investigate the effects of ESWT on these two diseases.

MATERIAL AND METHODS

Patients diagnosed with spastic CP and Rett syndrome received 1500 impulses of ESWT at 4 Hz and 0.1 mJ/mm2, on their spastic legsonce weekly for a total of 12 weeks. Outcomes were assessed before and 4 and 12 weeks after ESWT. Clinical assessments included the Modified Ashworth Scale (MAS), passive range of motion (PROM), and Gross Motor Function Measure 88 (GMFM-88). Ultrasonographic assessments included muscle thickness, acoustic radiation force impulse (ARFI), and strain elastography.

RESULTS

Fifteen patients with CP and six with Rett syndrome were enrolled in this study. After ESWT, patients with CP showed significant clinical improvement in the MAS (P = 0.011), ankle PROM (P = 0.002), walking/running/jumping function (P = 0.003), and total function (P < 0.001) of the GMFM-88. The patients with Rett syndrome showed improved MAS scores (P = 0.061) and significantly improved total gross motor function (P = 0.030). Under ARFI, patients with CP demonstrated decreased shear wave speed in the gastrocnemius medial head (P = 0.038). Conversely, patients with Rett syndrome show increased shear-wave speeds after ESWT.

CONCLUSION

Our study provides evidence that a weekly course of low-dose ESWT for 12 weeks is beneficial for children with both CP and Rett syndrome, with the clinical effects of reducing spasticity and improving the gross motor function of the lower limbs. The ARFI sonoelastography reveals improvement of muscle stiffness in patients with CP after ESWT, but deteriorated in patients with Rett syndrome. The diverse therapeutic response to ESWT may be caused by the MECP2 mutation in Rett syndrome, having a continuous impact and driving the pathophysiology differently as compared to CP, which is secondary to a static insult. Trial registration IRB 201700462A3. Registered 22March 2017, https://cghhrpms.cgmh.org.tw/HRPMS/Default.aspx .

Mitochondrial modulation with leriglitazone as a potential treatment for Rett syndrome

BACKGROUND

Rett syndrome is a neuropediatric disease occurring due to mutations in MECP2 and characterized by a regression in the neuronal development following a normal postnatal growth, which results in the loss of acquired capabilities such as speech or purposeful usage of hands. While altered neurotransmission and brain development are the center of its pathophysiology, alterations in mitochondrial performance have been previously outlined, shaping it as an attractive target for the disease treatment.

METHODS

We have thoroughly described mitochondrial performance in two Rett models, patients' primary fibroblasts and female Mecp2tm1.1Bird-/+ mice brain, discriminating between different brain areas. The characterization was made according to their bioenergetics function, oxidative stress, network dynamics or ultrastructure. Building on that, we have studied the effect of leriglitazone, a PPARγ agonist, in the modulation of mitochondrial performance. For that, we treated Rett female mice with 75 mg/kg/day leriglitazone from weaning until sacrifice at 7 months, studying both the mitochondrial performance changes and their consequences on the mice phenotype. Finally, we studied its effect on neuroinflammation based on the presence of reactive glia by immunohistochemistry and through a cytokine panel.

RESULTS

We have described mitochondrial alterations in Rett fibroblasts regarding both shape and bioenergetic functions, as they displayed less interconnected and shorter mitochondria and reduced ATP production along with increased oxidative stress. The bioenergetic alterations were recalled in Rett mice models, being especially significant in cerebellum, already detectable in pre-symptomatic stages. Treatment with leriglitazone recovered the bioenergetic alterations both in Rett fibroblasts and female mice and exerted an anti-inflammatory effect in the latest, resulting in the amelioration of the mice phenotype both in general condition and exploratory activity.

CONCLUSIONS

Our studies confirm the mitochondrial dysfunction in Rett syndrome, setting the differences through brain areas and disease stages. Its modulation through leriglitazone is a potential treatment for this disorder, along with other diseases with mitochondrial involvement. This work constitutes the preclinical necessary evidence to lead to a clinical trial.

Relationship between hand stereotypies and purposeful hand use and factors causing skin injuries and joint contractures in individuals with Rett syndrome

BACKGROUND

Skin injuries and joint contractures in the upper limbs are observed in approximately 50 % of individuals with Rett syndrome, respectively.

AIMS

To investigate the relationship between stereotypic hand movements and purposeful hand skills, items related to these, and factors that cause upper extremity skin injuries and joint contractures in individuals with Rett syndrome.

STUDY DESIGN

We conducted a cross-sectional observational study in 2020 with families belonging to either of the two largest Rett syndrome organizations in Japan.

SUBJECTS

In 2020, we sent a questionnaire to 194 Japanese families.

OUTCOME MEASURES

We used descriptive statistics to indicate frequency in each question. We analysed the association between hand stereotypies and purposeful hand use, their associations with each questionnaire item, and the relationship between the occurrence of skin injuries and joint contractures.

RESULTS

We acquired information from 72 cases. We found correlations between stereotypy frequency with reaching and between purposeful hand use with intellectual development grade and hand function. Hand and finger skin injuries and elbow and finger joint contractures were associated with wringing/washing, grasping, locomotion, reaching, and intellectual development grade. We identified cut-off points for the occurrence of elbow and finger joint contractures of 10 years 6 months, ability to roll over, finger feeds only, and understanding of simple words.

CONCLUSIONS

Direct interventions can reduce hand stereotypies and increase purposeful hand use, while related items can be addressed with indirect interventions. Evaluations of factors that cause skin injuries and joint contractures can prevent their occurrence.

Evidence Synthesis of Gene Therapy and Gene Editing from Different Disorders-Implications for Individuals with Rett Syndrome: A Systematic Review

This systematic review and thematic analysis critically evaluated gene therapy trials in amyotrophic lateral sclerosis, haemoglobinopathies, immunodeficiencies, leukodystrophies, lysosomal storage disorders and retinal dystrophies and extrapolated the key clinical findings to individuals with Rett syndrome (RTT). The PRISMA guidelines were used to search six databases during the last decade, followed by a thematic analysis to identify the emerging themes. Thematic analysis across the different disorders revealed four themes: (I) Therapeutic time window of gene therapy; (II) Administration and dosing strategies for gene therapy; (III) Methods of gene therapeutics and (IV) Future areas of clinical interest. Our synthesis of information has further enriched the current clinical evidence base and can assist in optimising gene therapy and gene editing studies in individuals with RTT, but it would also benefit when applied to other disorders. The findings suggest that gene therapies have better outcomes when the brain is not the primary target. Across different disorders, early intervention appears to be more critical, and targeting the pre-symptomatic stage might prevent symptom pathology. Intervention at later stages of disease progression may benefit by helping to clinically stabilise patients and preventing disease-related symptoms from worsening. If gene therapy or editing has the desired outcome, older patients would need concerted rehabilitation efforts to reverse their impairments. The timing of intervention and the administration route would be critical parameters for successful outcomes of gene therapy/editing trials in individuals with RTT. Current approaches also need to overcome the challenges of MeCP2 dosing, genotoxicity, transduction efficiencies and biodistribution.

Dystonia genes and their biological pathways

High-throughput sequencing has been instrumental in uncovering the spectrum of pathogenic genetic alterations that contribute to the etiology of dystonia. Despite the immense heterogeneity in monogenic causes, studies performed during the past few years have highlighted that many rare deleterious variants associated with dystonic presentations affect genes that have roles in certain conserved pathways in neural physiology. These various gene mutations that appear to converge towards the disruption of interconnected cellular networks were shown to produce a wide range of different dystonic disease phenotypes, including isolated and combined dystonias as well as numerous clinically complex, often neurodevelopmental disorder-related conditions that can manifest with dystonic features in the context of multisystem disturbances. In this chapter, we summarize the manifold dystonia-gene relationships based on their association with a discrete number of unifying pathophysiological mechanisms and molecular cascade abnormalities. The themes on which we focus comprise dopamine signaling, heavy metal accumulation and calcifications in the brain, nuclear envelope function and stress response, gene transcription control, energy homeostasis, lysosomal trafficking, calcium and ion channel-mediated signaling, synaptic transmission beyond dopamine pathways, extra- and intracellular structural organization, and protein synthesis and degradation. Enhancing knowledge about the concept of shared etiological pathways in the pathogenesis of dystonia will motivate clinicians and researchers to find more efficacious treatments that allow to reverse pathologies in patient-specific core molecular networks and connected multipathway loops.

Genetics of autism spectrum disorders and future direction

Autism spectrum disorders (ASDs) have been increasing in prevalence. ASD is a complex human genetic disorder with high heredity and involves interactions between genes and the environment. A significant inheritance pattern in ASD involves a rare genetic mutation; common copy number variants refer to duplication or deletion of stretches of chromosomal loci or protein-disrupting single-nucleotide variants. Haploinsufficiency is one of the more common single-gene causes of ASD, explaining at least 0.5% of cases. Epigenetic mechanisms, such as DNA methylation, act at an interface of genetic and environmental risk and protective factors. Advances in genome-wide sequencing have broadened the view of the human methylome and have revealed the organization of the human genome into large-scale methylation domains with a footprint over neurologically important genes involved in embryonic development. Psychiatric disorders, including ASD, are expected to be diagnosed based on their genetically regulated pathophysiology and to be linked to their treatment.

Pathological gait in Rett syndrome: Quantitative evaluation using three-dimensional gait analysis

OBJECTIVES

Ataxic-rigid gait is a characteristic gait pathology in patients with Rett syndrome (RTT). In the present study, we aimed to quantitatively evaluate gait pathology in patients with RTT using three-dimensional gait analysis (3DGA).

METHODS

We performed 3DGA in 11 patients with RTT ranging from 5 to 18 years (median age, 9 years) and in 33 age-matched healthy female controls. We compared the results of 3DGA, including spatiotemporal gait parameters and comprehensive indices of gait kinematics, such as the Gait Deviation Index (GDI) and Gait Profile Score (GPS), between the two groups. The GPS consists of nine sub-indices called Gait Variable Scores (GVSs). Decline in GDI or elevation of GPS and GVS indicated greater abnormal gait pathology.

RESULTS

The patients demonstrated significantly slower walking speed, lower step length/length of the lower extremities, lower cadence, wider step width, and higher coefficient of variation of step length than the controls. Moreover, the patients had a lower GDI and higher GPS than the controls. The patients also exhibited higher GVSs for eight out of nine gait kinematics, particularly the sagittal plane in the pelvis, hip, knee, and ankle joint; coronal plane in the pelvis and hip joint; and horizontal plane in the pelvis than the controls.

CONCLUSIONS

Quantitative evaluation of gait pathology in patients with RTT is possible using 3DGA. We found that in addition to ataxic-rigid gait, abnormalities in the coronal plane of the pelvis and hip joint and the horizontal plane of the pelvis were prominent.

Paroxysmal limb dystonias associated with GABBR2 pathogenic variant: A case-based literature review

BACKGROUND

De novo mutations in the GABBR2 (Gamma-Aminobutyric acid Type B Receptor Subunit 2) gene have recently been reported to be associated with a form of early-infantile epileptic encephalopathy (EIEE59; OMIM# 617904), as well as a Rett syndrome (RTT)-like disorder defined as a neurodevelopmental disorder with poor language and loss of hand skills (NDPLHS; OMIM# 617903).

METHODS

We describe a pediatric case carrying a de novo GABBR2 pathogenic variant and showing a phenotype encompassing RTT, epilepsy, generalized hypotonia with a paroxysmal limb dystonia.

RESULTS

A 11-year-old girl, born to non-consanguineous parents after an uneventful pregnancy, had developmental delay and generalized hypotonia. At age 3.5 months she presented with infantile spasms with an electroencephalographic pattern of hypsarrhythmia. After treatment with clonazepam and prednisolone, she became seizure-free with a slow background electrical activity. Brain magnetic resonance imaging was normal. Paroxysmal dystonic posturing of the extremities, especially the upper limbs, have been observed since the age of 3 years. Motor stereotypies, non-epileptic episodes of hyperventilation and breath-holding were also reported. The girl suffered from feeding difficulties requiring gastrostomy at the age of 8. Exome sequencing (ES) revealed a de novo GABBR2 pathogenic variant (NM_005458:c.G2077T:p.G693W).

CONCLUSION

Paroxysmal limb dystonias, especially in the context of neurodevelopmental disorder featuring epilepsy, generalized hypotonia and RTT-like features should lead to the suspect of GABBR2 mutations.