Cognitive impairment in neuromuscular diseases: A systematic review

A comparison of peak cough flow and peak expiratory flow in children with neuromuscular disorders

Spirometry and peak cough flow testing (PCF) are commonly used in the respiratory assessment of children with a neuromuscular disorder (NMD). Testing uses two different machines, increases laboratory time, costs and resource utilisation. No studies have assessed the correlation between peak expiratory flow (PEF) obtained from spirometry and PCF in children with NMD using one device. An audit of children with a NMD managed at the Children's Hospital at Westmead in 2022-2024 aged < 20 years who performed spirometry and PCF testing on the same device (Vyaire Body BoxTM, Ultrasonic flow meter-based, or Vyaire PneumotachographTM, Pneumotach flow meter-based; Germany) was conducted to assess the correlation between PCF and PEF. Fifty-one sets of testing were identified, and 40 subjects (9F) had reproducible testing and were included. Median (range) age was 14.95 (7.20-19.00) years. Median PEF (L/min) was 4.05 (1.22-10.26) and median PCF (L/min) was 4.29 (1.69-10.82). PEF and PCF had a strong Pearson's correlation coefficient, (R = 0.97, p = 0.03). The coefficient of determination was 0.93. If laboratory resources permit, spirometry should be the test of choice for children with NMD. On average, spirometry required multiple practices to achieve reproducibility to meet ATS/ERS standards. PCF testing can be utilised for children where performing technically acceptable spirometry is not possible.

Inherited causes of combined vision and hearing loss: clinical features and molecular genetics

Combined vision and hearing loss, also known as dual sensory impairment, can occur in several genetic conditions, including ciliopathies such as Usher and Bardet-Biedl syndrome, mitochondrial DNA disorders and systemic diseases, such as CHARGE, Stickler, Waardenburg, Alport and Alstrom syndrome. The retinal phenotype may point to the diagnosis of such disorders. Herein, we aim to provide a comprehensive review of the molecular genetics and clinical features of the most common non-chromosomal inherited disorders to cause dual sensory impairment.

Connectomic disturbances in Duchenne muscular dystrophy with mild cognitive impairment

Duchenne muscular dystrophy (DMD) is frequently associated with mild cognitive deficits. However, the underlying disrupted brain connectome and the neural basis remain unclear. In our current study, 38 first-episode, treatment-naive patients with DMD and 22 matched healthy controls (HC) were enrolled and received resting-sate functional magnetic resonance imaging scans. Voxel-based degree centrality (DC), seed-based functional connectivity (FC), and clinical correlation were performed. Relative to HC, DMD patients had lower height, full Intellectual Quotients (IQ), and IQ-verbal comprehension. Significant increment of DC of DMD patients were found in the left dorsolateral prefrontal cortex (DLPFC.L) and right dorsomedial prefrontal cortex (DMPFC.R), while decreased DC were found in right cerebellum posterior lobe (CPL.R), right precentral/postcentral gyrus (Pre/Postcentral G.R). DMD patients had stronger FC in CPL.R-bilateral lingual gyrus, Pre/Postcentral G.R-Insular, and DMPFC.R-Precuneus.R, had attenuated FC in DLPFC.L-Insular. These abnormally functional couplings were closely associated with the extent of cognitive impairment, suggested an over-activation of default mode network and executive control network, and a suppression of primary sensorimotor cortex and cerebellum-visual circuit. The findings collectively suggest the distributed brain connectome disturbances maybe a neuroimaging biomarker in DMD patients with mild cognitive impairment.

ENT characteristics and therapeutic results in multisystemic disorders of mitochondrial encephalomyopathy

Here we report the evaluation of the frequency of subjective and objective otolaryngologic findings and therapeutic results in 32 patients with mitochondrial encephalomyopathy (MEM) from September 2001 to June 2021. Our analysis included studying the patients’ family histories, the clinical manifestations of MEM, and the therapeutic effects of treatments. The patients’ ages ranged from 2 to 77 years, with a median age of 12.3 years. We found that MEM ENT symptoms were characterized by hearing loss, dysphagia, and facial weakness. Most cases of sensorineural hearing loss were bilateral symmetrical progressive or sudden deafness since adolescence, which were often underestimated. Associated neuromuscular symptoms required mtDNA testing. Dysphagia and facial weakness occurred preferentially in middle-aged patients, and muscle biopsies were advised. Distortion product otoacoustic emissions and auditory brainstem responsetesting were more sensitive and reliable than pure tone averages for objective monitoring of pathogenesis. Administration of the mitochondrial synthase complex benefited patients with acute episodes. If patients did not fully recover and exhibitedresidual language deficits, hearing aids or cochlear implants were recommended. Counsel was given regarding synthetical treatments for facial weakness, endoscopic circopharyngealmyotomy for dysphagia, and surgical correction of ptosis. This study demonstrates that increased awareness of these symptoms is important to address appropriate interventions and avoid complications such as ablepsia, aphasia, social isolation, malnutrition, aspiration pneumonia, and heart failure in the setting of MEM.

A Systematic Study into the Effects of Long-Term Multicomponent Training on the Cognitive Abilities of Older Adults with Neurodegenerative Disorders

Cognition includes all processes through which a person becomes aware of their situation, needs, goals, and necessary actions. Regular specialized cognitive and neuromotor simulation exercises have improved various cognitive processes, including memory, speed of reasoning, and problem-solving skills. This review focuses on understanding the efficacy of long-term multicomponent exercise interventions to mitigate and delay the effects on cognitive abilities in older adults with neurodegenerative disorders. The main criteria for final studies were randomised controlled trials with a minimum of a 24-week intervention. The Cochrane Central Register of Controlled Trials, Web of Science, SCOPUS, B-On, Sport Discus, Scielo, APA PsycINFO, Psychology and Behavioural Sciences, Academic Search Complete, Medline (PubMed), ERIC, and Google Scholar databases were checked. The search occurred between April 2022 and July 2022. A total of 19 studies were used in this review. The initial search identified 6.835 studies. In the first screening, a total of 6474 studies were excluded. After this, 361 studies were analysed by co-authors and did not meet the specific final criteria and were excluded. In total, 19 studies were included in the final analysis, and 14 papers met all requirements previously defined.

The Hidden Disease: Delayed Diagnosis in Duchenne Muscular Dystrophy and Co-Occurring Conditions

OBJECTIVE

Early diagnosis of Duchenne muscular dystrophy (DMD) is important for timely intervention to prolong function and preserve quality of life. The prevalence of various neurocognitive disorders is known to be higher in patients with DMD than the general population. In this study, we highlight cases of delayed DMD diagnosis that resulted from misattribution of early motor symptoms to co-occurring neurocognitive conditions. We also investigate the difference in age at DMD diagnosis in the setting of specific co-occurring neurocognitive conditions.

METHOD

In this study, we reviewed 40 consecutive patients seen at a Certified Duchenne Care Center, excluding siblings of already-diagnosed patients. We highlight cases of significant delay in DMD diagnosis in the setting of co-occurring neurocognitive diagnoses. We also investigate the association of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), intellectual disability, and speech/language delay on age of DMD diagnosis.

RESULTS

The prevalence of co-occurring neurocognitive diagnoses was 73.1% in patients diagnosed at or after age 5 years vs. 35.7% in those diagnosed before age 5 years. The average age of DMD diagnosis was 6.6 years in patients with any co-occurring neurocognitive diagnoses and 4.9 years in patients without ( p = 0.09). Individual analysis of ASD and ADHD showed significant differences. A greater number of co-occurring conditions were associated with an increased age at DMD diagnosis ( R2 = 0.87, p < 0.001).

CONCLUSION

The data suggest an association between the presence of co-occurring neurocognitive conditions and a later age of DMD diagnosis. One cost-effective diagnostic step that can be implemented by all pediatric practitioners is testing serum creatinine kinase (CK) in any child with motor delays or hypotonia, even in the context of other behavioral or cognitive disabilities.

Impact and predictors of quality of life in adults diagnosed with a genetic muscle disorder: a nationwide population-based study

OBJECTIVES

To determine the impact of genetic muscle disorders and identify the sociodemographic, illness, and symptom factors influencing quality of life.

METHODS

Adults (aged 16-90 years) with a confirmed clinical or molecular diagnosis of a genetic muscle disorder identified as part of a nationwide prevalence study were invited to complete an assessment of the impact of their condition. Quality of life was measured using the World Health Organization Quality of Life questionnaire. Impact was measured via the prevalence of symptoms and comparisons of quality of life against New Zealand norms. Multivariate regression models were used to identify the most significant predictors of quality of life domains.

RESULTS

490/596 participants completed the assessment (82.2% consent rate). Quality of life was lower than the general population on physical (t = 9.37 p < 0.0001, d = 0.54) social (t = 2.27 p = 0.02, d = 0.13) and environmental domains (t = 2.28 p = 0.02, d = 0.13), although effect sizes were small. No difference was found on the psychological domain (t = - 1.17 p = 0.24, d = 0.07). Multivariate regression models (predicting 42%-64% of the variance) revealed personal factors (younger age, being in employment and in a relationship), symptoms (lower pain, fatigue, and sleep difficulties), physical health (no need for ventilation support, fewer activity limitations and no comorbidities), and psychosocial factors (lower depression, anxiety, behavioural dyscontrol and higher self-efficacy, satisfaction with health care and social support) contributed to improved quality of life.

CONCLUSIONS

A range of factors influence the quality of life in adults diagnosed with a genetic muscle disorder and some may serve as targets for multi-faceted intervention.

Assessing Cognitive Function in Neuromuscular Diseases: A Pilot Study in a Sample of Children and Adolescents

Central nervous system (CNS) involvement has been variously studied in pediatric neuromuscular disorders (NMDs). The primary goal of this study was to assess cognitive functioning in NMDs, and secondary aims were to investigate possible associations of cognitive impairment with motor impairment, neurodevelopmental delay, and genotype. This was a cross-sectional study of 43 pediatric patients, affected by six NMDs. Myotonic dystrophy type 1 (DM1) and glycogen storage disease type 2 (GSD2) patients had a delay on the Bayley-III scales. On Wechsler scales, DMD and DM1 patients showed lower FSIQ scores, with an intellectual disability (ID) in 27% and 50%, respectively. FSIQ was normal in Becker muscular dystrophy (BMD), GSD2, and hereditary motor sensory neuropathy (HMSN) patients, while higher individual scores were found in the spinal muscular atrophy (SMA) group. In the DM1 cohort, lower FSIQ correlated with worse motor performance (ρ = 0.84, p < 0.05), and delayed speech acquisition was associated with ID (p = 0.048), with worse cognitive impairment in the congenital than in the infantile form (p = 0.04). This study provides further evidence of CNS in some NMDs and reinforces the need to include cognitive assessment in protocols of care of selected pediatric NMDs.

Disrupted structural connectome and neurocognitive functions in Duchenne muscular dystrophy: classifying and subtyping based on Dp140 dystrophin isoform

OBJECTIVE

Neurocognitive disabilities in Duchenne muscular dystrophy (DMD) children beginning in early childhood and distal DMD gene deletions involving disruption of Dp140 isoform are more likely to manifest significant neurocognitive impairments. MRI data analysis techniques like brain-network metrics can provide information on microstructural integrity and underlying pathophysiology.

METHODS

A prospective study on 95 participants [DMD = 57, and healthy controls (HC) = 38]. The muscular dystrophy functional rating scale (MDFRS) scores, neuropsychology batteries, and multiplex ligand-dependent probe amplification (MLPA) testing were used for clinical assessment, IQ estimation, and genotypic classification. Diffusion MRI and network-based statistics were used to analyze structural connectomes at various levels and correlate with clinical markers.

RESULTS

Motor and executive sub-networks were extracted and analyzed. Out of 57 DMD children, 23 belong to Dp140 + and 34 to Dp140- subgroup. Motor disabilities are pronounced in Dp140- subgroup as reflected by lower MDFRS scores. IQ parameters are significantly low in all-DMD cases; however, the Dp140- has specifically lowest scores. Significant differences were observed in global efficiency, transitivity, and characteristic path length between HC and DMD. Subgroup analysis demonstrates that the significance is mainly driven by participants with Dp140- than Dp140 + isoform. Finally, a random forest classifier model illustrated an accuracy of 79% between HC and DMD and 90% between DMD- subgroups.

CONCLUSIONS

Current findings demonstrate structural network-based characterization of abnormalities in DMD, especially prominent in Dp140-. Our observations suggest that participants with Dp140 + have relatively intact connectivity while Dp140- show widespread connectivity alterations at global, nodal, and edge levels. This study provides valuable insights supporting the genotype-phenotype correlation of brain-behavior involvement in DMD children.

Gene targeting techniques for Huntington's disease

Huntington's disease (HD) is an autosomal neurodegenerative disorder caused by extended trinucleotide CAG repetition in the HTT gene. Wild-type huntingtin protein (HTT) is essential, involved in a variety of crucial cellular functions such as vesicle transportation, cell division, transcription regulation, autophagy, and tissue maintenance. The mutant HTT (mHTT) proteins in the body interfere with HTT's normal cellular functions and cause additional detrimental effects. In this review, we discuss multiple approaches targeting DNA and RNA to reduce mHTT expression. These approaches are categorized into non-allele-specific silencing and allele-specific-silencing using Single Nucleotide Polymorphisms (SNPs) and haplogroup analysis. Additionally, this review discusses a potential application of recent CRISPR prime editing technology in targeting HD.

Differences in Societal Participation Across Diagnostic Groups: Secondary Analyses of 8 Studies Using the Utrecht Scale for Evaluation of Rehabilitation-Participation

OBJECTIVE

To determine differences in participation problems between diagnostic groups and to examine diagnosis as a determinant of participation with and without statistically accounting for confounders.

DESIGN

Secondary analyses of data from 8 studies.

SETTING

Community, the Netherlands.

PARTICIPANTS

Participants (N=1735) in diagnostic groups: stroke (n=534), subarachnoid hemorrhage (n=104), other acquired brain injury (n=163), progressive neurologic diseases (n=112), acute coronary syndrome (n=536), and spinal cord injury (n=286).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participation was measured with the Utrecht Scale for Evaluation of Rehabilitation-Participation. This measure has 3 scales: Restrictions, Satisfaction, and Frequency. In this study, scores were also computed for 3 domains across these scales: Productivity, Leisure, and Social. Scores ranged from 0 (worst) up to 100 (best). Possible confounders were age, sex, level of education, marital status, and time since onset of the condition.

RESULTS

Significant differences were found in levels of participation between diagnostic groups. Individuals with acute coronary syndrome showed better participation scores in all scales and domains compared with most or all other diagnostic groups, except for the Social domain. Individuals with progressive neurologic diseases showed the lowest (worst) Restriction and Satisfaction scores, whereas those with stroke showed the lowest Frequency scores. After correcting for confounders, diagnosis explained significant proportions of the variance of participation (Frequency, 6.4%; Restrictions, 15.1%; Satisfaction, 5.1%; Productivity, 13.2%; Leisure, 13.8%; Social, 6.9%).

CONCLUSIONS

Participation problems occurred in all 6 diagnostic groups within this study. Differences were found in participation between diagnostic groups, demonstrating diagnosis-specific participation profiles, including after correcting for confounders.

The Dog Model in the Spotlight: Legacy of a Trustful Cooperation

Dogs have long been used as a biomedical model system and in particular as a preclinical proof of concept for innovative therapies before translation to humans. A recent example of the utility of this animal model is the promising myotubularin gene delivery in boys affected by X-linked centronuclear myopathy after successful systemic, long-term efficient gene therapy in Labrador retrievers. Mostly, this is due to unique features that make dogs an optimal system. The continuous emergence of spontaneous inherited disorders enables the identification of reliable complementary molecular models for human neuromuscular disorders (NMDs). Dogs’ characteristics including size, lifespan and unprecedented medical care level allow a comprehensive longitudinal description of diseases. Moreover, the highly similar pathogenic mechanisms with human patients yield to translational robustness. Finally, interindividual phenotypic heterogeneity between dogs helps identifying modifiers and anticipates precision medicine issues.

This review article summarizes the present list of molecularly characterized dog models for NMDs and provides an exhaustive list of the clinical and paraclinical assays that have been developed. This toolbox offers scientists a sensitive and reliable system to thoroughly evaluate neuromuscular function, as well as efficiency and safety of innovative therapies targeting these NMDs. This review also contextualizes the model by highlighting its unique genetic value, shaped by the long-term coevolution of humans and domesticated dogs. Because the dog is one of the most protected research animal models, there is considerable opposition to include it in preclinical projects, posing a threat to the use of this model. We thus discuss ethical issues, emphasizing that unlike many other models, the dog also benefits from its contribution to comparative biomedical research with a drastic reduction in the prevalence of morbid alleles in the breeding stock and an improvement in medical care.

Dystrophin deficiency leads to dysfunctional glutamate clearance in iPSC derived astrocytes

Duchenne muscular dystrophy (DMD) results, beside muscle degeneration in cognitive defects. As neuronal function is supported by astrocytes, which express dystrophin, we hypothesized that loss of dystrophin from DMD astrocytes might contribute to these cognitive defects. We generated cortical neuronal and astrocytic progeny from induced pluripotent stem cells (PSC) from six DMD subjects carrying different mutations and several unaffected PSC lines. DMD astrocytes displayed cytoskeletal abnormalities, defects in Ca⁺² homeostasis and nitric oxide signaling. In addition, defects in glutamate clearance were identified in DMD PSC-derived astrocytes; these deficits were related to a decreased neurite outgrowth and hyperexcitability of neurons derived from healthy PSC. Read-through molecule restored dystrophin expression in DMD PSC-derived astrocytes harboring a premature stop codon mutation, corrected the defective astrocyte glutamate clearance and prevented associated neurotoxicity. We propose a role for dystrophin deficiency in defective astroglial glutamate homeostasis which initiates defects in neuronal development.

Rehabilitation management of Pompe disease, from childhood trough adulthood: A systematic review of the literature

Pompe disease (PD) is a rare neuromuscular disorder caused by a deficiency of the enzyme acid alpha-glucosidase. There are three forms of PD depending on the age at onset and clinical severity. PD causes involvement of different organ systems, such as the heart, musculoskeletal system, and respiratory system. As of today, enzyme replacement therapy represents the main therapeutic tool for PD. Rehabilitation is an integral part of a multidisciplinary approach to this pathology. The goal of the present review is to find scientific evidence for the rehabilitative approach to PD, with respect to both the infantile- and adult-onset forms. A systematic literature review was made using the following databases: Pubmed, Pedro, Cochrane Library, EDS Base Index, Trip, and Cinhal. Randomized controlled trials or cohort studies with a sample population of at least six subjects were retrieved. The PICO method was used to formulate the clinical query. The search resulted in 1665 articles. Of these, four cohort studies were subjected to the final phase of the review. Three studies regarded inspiratory muscle training with a threshold, while the fourth study analyzed the effectiveness of therapeutic, aerobic, and reinforcement exercises. Inspiratory muscle training with a threshold increases the pressures generated during inhalation. Aerobic exercise is capable of increasing patients' muscular endurance and performance. To date, however, rehabilitative treatment for patients with PD has no validation in evidencebased medicine. Further studies, possibly with a larger sample size and higher quality are necessary to confirm the effectiveness of rehabilitation in patients with PD.