A Critical Evaluation of Current Concepts in Cerebral Palsy

Neurobiological Insights Into Cerebral Palsy: A Review of the Mechanisms and Therapeutic Strategies

BACKGROUND

Cerebral palsy (CP) is a common neurodevelopmental disorder characterized by impaired mobility and posture caused by brain injury or abnormal development. CP relates to a variety of neurological mechanisms and pathways that impact the type and severity of motor disability, as well as comorbidities. The heterogeneity in clinical phenotype, pathogenesis, and etiology poses significant challenges for effective therapeutic intervention.

OBJECTIVES

The review aims to provide a comprehensive analysis of the neurobiological mechanisms underlying CP and evaluate current and prospective therapeutic strategies, highlighting the necessity for targeted interventions to address the disorder's multifaceted nature.

METHODS

A thorough literature review was conducted, focusing on studies published in peer-reviewed journals that explore the pathophysiological mechanisms, clinical interventions, and therapeutic strategies for CP.

RESULTS

The pathogenesis of CP involves a complex interplay of genetic, environmental, and perinatal factors leading to brain injury. Inflammatory processes, oxidative stress, and excitotoxicity are critical in CP development. Current therapeutic approaches primarily focus on symptom management through physical and occupational therapy, as well as pharmacological interventions. Emerging therapies, including anti-inflammatory agents, antioxidants, and neuroprotective and neurotrophic agents, show potential but require further validation. Notably, although steroids provide anti-inflammatory benefits, their use in pediatric patients raises concerns regarding long-term adverse effects such as osteoporosis.

CONCLUSION

Despite advances in understanding CP's neurobiological underpinnings, effective therapeutic targets remain elusive. A comprehensive approach addressing CP's heterogeneity is essential. Future research should emphasize in-depth evaluations of the efficacy and safety of therapeutic agents, particularly in pediatric populations, to develop targeted and effective treatments for CP.

The RhoB p.S73F mutation leads to cerebral palsy through dysregulation of lipid homeostasis

Cerebral palsy (CP) is a prevalent neurological disorder that imposes a significant burden on children, families, and society worldwide. Recently, the RhoB p.S73F mutation was identified as a de novo mutation associated with CP. However, the mechanism by which the RhoB p.S73F mutation causes CP is currently unclear. In this study, rabbit models were generated to mimic the human RhoB p.S73F mutation using the SpG-BE4max system, and exhibited the typical symptoms of human CP, such as periventricular leukomalacia and spastic-dystonic diplegia. Further investigation revealed that the RhoB p.S73F mutation could activate ACAT1 through the LYN pathway, and the subsequently altered lipid levels may lead to neuronal and white matter damage resulting in the development of CP. This study presented the first mammalian model of genetic CP that accurately replicates the RhoB p.S73F mutation in humans, provided further insights between RhoB and lipid metabolism, and novel therapeutic targets for human CP.

Cerebral Palsy: A Narrative Review on Childhood Disorder

Cerebral palsy, one of the most common reasons for infirmity in children and young people in developed countries, refers to several neurological diseases that impact movement and coordination. Central nervous system damage received during the first stages of brain development can cause cerebral palsy, a non-progressive condition that manifests as impairments of movement and posture. Two cases per 1000 are reported, and the causes include those mentioned for high-risk infants. Mental retardation, sensory deficiencies, failure to thrive, seizures, and behavioral or emotional issues are some of the associated difficulties. To enable interdisciplinary intervention, early identification is crucial. The result varies depending on the topography, severity, and presence of concomitant abnormalities in cerebral palsy. Cerebral palsy is caused by a static injury to the cerebral motor cortex that happens before, during, or within five years after birth. Various circumstances can influence the disease, including cerebral anoxia, cerebral hemorrhage, infection, and hereditary disorders. Interventions for children are typically provided as part of multidisciplinary rehabilitation programs. Musculoskeletal complaints are common, and pain is a significant underreported symptom.

Physiotherapy management of children with cerebral palsy in low- and middle-income countries: a scoping review protocol

INTRODUCTION

Cerebral Palsy (CP) is the most common childhood physical disability worldwide. Approximately 1.5 to 4 children per live births live with CP, globally. There have been no specific treatments that can reverse the brain damage responsible for the complex clinical dysfunctions of CP. There are, however, several interventions that are currently being used by physiotherapists, most of which are deemed to be ineffective and unnecessary. We will conduct a scoping review aimed at mapping evidence on the physiotherapy management of children living with CP in low- and middle-income countries (LMICs).

METHODS

The scoping review will be guided by the Arksey and O'Malley and Levac et al. frameworks. The databases that will be used to search for literature include PubMed, MEDLINE, CINAHL, EBSCOhost, Web of Science, and ProQuest One Academic and Scopus. Gray literature articles will also be included in this review, provided they meet our inclusion criteria. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis: Extension for Scoping Reviews (PRIMSA-ScR) guideline will be used to report the results of the scoping review. The screened results will be reported using the PRISMA flow diagram guidelines, and the results will be charted using an electronic data charting form and analyzed using thematic analysis.

DISCUSSION

Understanding how physiotherapists manage children with CP in LMICs is essential for the development of internationally sound, yet locally relevant, intervention strategy for physiotherapists. It is anticipated that the results of the scoping review will inform the thinking geared towards the development of a contextualised evidence-based framework for physiotherapists to effectively manage CP in children.

SYSTEMATIC REVIEW REGISTRATION

Open Science Framework. https://doi.org/10.17605/OSF.IO/VTJ84.

Spasticity Interventions: Decision-Making and Management

Spasticity results from an abnormality of the central nervous system and is characterized by a velocity-dependent increase in muscle tone or stiffness. In children, it can cause functional impairments, delays in achieving developmental or motor milestones, participation restrictions, discomfort, and musculoskeletal differences. Unique to children is the ongoing process of a maturing central nervous system and body, which can create the appearance of worsening or changing spasticity. Treatment options include physical interventions such as stretching, serial casting, and bracing; oral and injectable medications; and neurosurgical procedures such as selective dorsal rhizotomy and intrathecal baclofen pump.

Inhibitory Synaptic Influences on Developmental Motor Disorders

During development, GABA and glycine play major trophic and synaptic roles in the establishment of the neuromotor system. In this review, we summarise the formation, function and maturation of GABAergic and glycinergic synapses within neuromotor circuits during development. We take special care to discuss the differences in limb and respiratory neuromotor control. We then investigate the influences that GABAergic and glycinergic neurotransmission has on two major developmental neuromotor disorders: Rett syndrome and spastic cerebral palsy. We present these two syndromes in order to contrast the approaches to disease mechanism and therapy. While both conditions have motor dysfunctions at their core, one condition Rett syndrome, despite having myriad symptoms, has scientists focused on the breathing abnormalities and their alleviation-to great clinical advances. By contrast, cerebral palsy remains a scientific quagmire or poor definitions, no widely adopted model and a lack of therapeutic focus. We conclude that the sheer abundance of diversity of inhibitory neurotransmitter targets should provide hope for intractable conditions, particularly those that exhibit broad spectra of dysfunction-such as spastic cerebral palsy and Rett syndrome.

Is baclofen the least worst option for spasticity management in children?

Baclofen is often considered a first-line treatment option for spasticity management in children. However, adverse effects, administration, and dosing can be barriers to effectiveness. In my practice, other medications for spasticity management are often used prior to initiating baclofen. In this article, baclofen use for spasticity management in children is briefly reviewed along with discussion of approaches using other medications as first-line treatment options. I will present a rationale for medication selection for spasticity management and discuss the approaches I take in medication selection that incorporate spasticity severity, patient goals, and medication side effect profiles.

The Effects of Virtual Reality Training on Balance, Gross Motor Function, and Daily Living Ability in Children With Cerebral Palsy: Systematic Review and Meta-analysis

Background

The increasing number of children with cerebral palsy (CP) has a serious impact on individuals, families, and society. As a new technology, virtual reality (VR) has been used in the rehabilitation of children with CP.

Objective

This study aimed to systematically evaluate the effect of VR training on balance, gross motor function, and daily living ability in children with CP.

Methods

PubMed, Embase, The Cochrane Library, Web of Science, and China National Knowledge Infrastructure databases were searched by computer, with the search period being from the establishment of each database to December 25, 2021, to collect randomized controlled trials (RCTs) on the effects of VR training on balance, gross motor function, and daily living ability in children with CP. The Cochrane risk of bias assessment tool was used to conduct quality assessment on the included literature, and RevMan software (version 5.3) was used to analyze data.

Results

A total of 16 articles were included, involving 513 children with CP. VR training can improve the balance function (Pediatric Balance Scale: mean difference 2.06, 95% CI 1.15-2.97; P<.001; Berg Balance Scale: mean difference 3.66, 95% CI 0.29-7.02; P=.03) and gross motor function (standardized mean difference [SMD] 0.60, 95% CI 0.34-0.87; P<.001) of children with CP. However, there is still certain disagreement on the impact on daily living ability (SMD 0.37, 95% CI –0.04 to 0.78; P=.08); after removing the source literature with heterogeneity, VR training can improve the daily living ability of children with CP (SMD 0.55, 95% CI 0.30-0.81; P<.001).

Conclusions

VR training can significantly improve the balance function and gross motor function of children with CP, but the effect on the daily living ability of children with CP remains controversial.

An association study of IL2RA polymorphisms with cerebral palsy in a Chinese population

Background

Cerebral palsy (CP), the most common physical disability of childhood, is a nonprogressive movement disorder syndrome. Eighty percent of cases are considered idiopathic without a clear cause. Evidence has shown that cytokine abnormalities are widely thought to contribute to CP.

Methods

An association between 6 SNPs (rs12244380, rs2025345, rs12722561, rs4749926, rs2104286 and rs706778) in IL2RA (interleukin 2 receptor subunit alpha) and CP was investigated using a case–control method based on 782 CP cases and 778 controls. The allele, genotype and haplotype frequencies of SNPs were assessed using the SHEsis program. Subgroup analyses based on complications and clinical subtypes were also conducted.

Results

Globally, no differences in genotype or allele frequencies for any SNPs remained significant after Bonferroni correction between patients and controls, except rs706778, which deviated from Hardy–Weinberg equilibrium and was excluded from further analyses. However, subgroup analysis revealed a significant association of rs2025345 with spastic tetraplegia (P genotype = 0.048 after correction) and rs12722561 with CP accompanied by global developmental delay (P allele = 0.045 after correction), even after Bonferroni correction.

Conclusions

These findings indicated that genetic variations in IL2RA are significantly associated with CP susceptibility in the Chinese Han population, suggesting that IL2RA is likely involved in the pathogenesis of CP. Further investigation with a larger sample size in a multiethnic population is needed to confirm the association.

A Review on Recent Advances of Cerebral Palsy

This narrative review summarizes the latest advances in cerebral palsy and identifies where more research is required. Several studies on cerebral palsy were analyzed to generate a general idea of the prevalence of, risk factors associated with, and classification of cerebral palsy (CP). Different classification systems used for the classification of CP on a functional basis were also analyzed. Diagnosis systems used along with the prevention techniques were discussed. State-of-the-art treatment strategies for CP were also analyzed. Statistical distribution was performed based on the selected studies. Prevalence was found to be 2-3/1000 lives; the factors that can be correlated are gestational age and birth weight. The risk factors identified were preconception, prenatal, perinatal, and postnatal categories. According to the evidence, CP is classified into spastic (80%), dyskinetic (15%), and ataxic (5%) forms. Diagnosis approaches were based on clinical investigation and neurological examinations that include magnetic resonance imaging (MRI), biomarkers, and cranial ultrasound. The treatment procedures found were medical and surgical interventions, physiotherapy, occupational therapy, umbilical milking, nanomedicine, and stem cell therapy. Technological advancements in CP were also discussed. CP is the most common neuromotor disability with a prevalence of 2-3/1000 lives. The highest contributing risk factor is prematurity and being underweight. Several preventions and diagnostic techniques like MRI and ultrasound were being used. Treatment like cord blood treatment nanomedicine and stem cell therapy needs to be investigated further in the future to apply in clinical practice. Future studies are indicated in the context of technological advancements among cerebral palsy children.

The professional network underlying cerebral palsy intervention research based on systematic reviews and meta-analyses published in international journals: authors' communities, institutional networks, and international collaboration

Cerebral palsy (CP) is a well-researched area of medical science, health science and special education. The growing number of publications every year makes difficult to monitor the progress of this research domain, therefore there is a broad interest for conducting systematic reviews and meta-analyses of interventions in international peer-reviewed scientific journals. Our goal is to analyze the scientific activity of authors who published systematic reviews and meta-analyses of CP intervention studies. To identify the active researchers, institutions, and countries, we used scientometric and bibliometric indicators that assess their productivity, collaborations, and the citations (utilization/usefulness of their studies), also paying attention to the institutional background and the network structure of national and international collaboration. We used Scopus to search for articles and included systematic reviews and meta-analyses of intervention studies, a total of 180 works, in our sample. Our results showed active and large communities of prolific authors and groups of authors with diverse institutional background. Most institutions are universities, hospitals, but we found various other organizations among them. Most of the universities are leading educational institutions according to international rankings; some of them are among the top-ranking ones. In geographical terms, the North American, Australian, and European regions are the most active and most interconnected ones. We assume organizations other than scientific collaboration networks also play a major role in the productivity and dissemination of scientific knowledge in this research area. As an example, we could mention the network, including the US, Australian and European registers. Authors living and working in the Far East, the Middle East or in South America also started to publish relevant articles in the 2010s. The research network structuring scientific knowledge in this area is flourishing.

Diaphragm Muscle Function in a Mouse Model of Early Onset Spasticity

Spasticity is a common symptom in many developmental motor disorders, including spastic cerebral palsy (sCP). In sCP, respiratory dysfunction is a major contributor to morbidity and mortality, yet it is unknown how spasticity influences respiratory physiology or diaphragm muscle (DIAm) function. To investigate the influence of spasticity on DIAm function, we assessed in vivo transdiaphragmatic pressure (Pdi - measured using intra-esophageal and intragastric pressure catheters under conditions of eupnea, hypoxia/hypercapnia and occlusion) including maximum Pdi (Pdimax via bilateral phrenic nerve stimulation), ex vivo DIAm specific force and fatigue (using muscle strips stimulated with platinum plate electrodes) and type-specific characteristics of DIAm fiber cross-sections (using immunoreactivity against myosin heavy chain slow and 2A) in spa and wildtype mice. Spa mice show reduced Pdimax, reduced DIAm specific force, altered fatigability and atrophy of type IIx/IIb fibers. These findings suggest marked DIAm dysfunction may underlie the respiratory phenotype of sCP.

Physical therapy in children with cerebral palsy in Brazil: a scoping review

AIM

To identify and assess published studies concerning physical therapy in Brazilian children and adolescents with cerebral palsy (CP) using the International Classification of Functioning, Disability and Health (ICF) framework.

METHOD

Articles in English and Portuguese published until October 2020, with no date restrictions, were searched in several different databases. Study characteristics, journal metrics, sample characteristics, and ICF domains explored intervention components and outcomes were extracted. Studies were classified according to the Oxford Centre for Evidence-Based Medicine hierarchy levels to characterize the evidence.

RESULTS

Ninety-four studies were included. Spastic CP with fewer limitations in gross motor abilities was the most reported; 67% of the studies had low levels of evidence and were published in journals without an impact factor. The three most frequent interventions were neurodevelopmental treatment, suit therapy, and transcranial direct current stimulation. Intervention components explored body functions and structures (73.4%), activity (59.6%), environment (2.1%). They did not explore participation (0%). The outcomes investigated addressed activity (79.8%), body functions and structures (67.0%), and participation (1.1%), but not environment (0%).

INTERPRETATION

Studies of physical therapy for Brazilian children and adolescents with CP focused on reducing impairments and activity limitations. Studies with higher levels of evidence and an expanded focus on participation and environmental factors are necessary.

Fisioterapia em crianças com paralisia cerebral no Brasil: uma revisão de escopo

OBJETIVO

Identificar e avaliar os estudos publicados sobre fisioterapia em crianças e adolescentes brasileiros com paralisia cerebral (PC), usando o modelo da Classificação Internacional de Funcionalidade, Incapacidade e Saúde (CIF). MÉTODO: Artigos em inglês e português publicados até outubro de 2020, sem restrição de data, foram pesquisados em diferentes bases bibliográficas. Foram extraídos dados sobre as características do estudo, métricas do periódico, características da amostra, domínios da CIF explorados a partir dos componentes e desfechos das intervenções. Para caracterizar as evidências, os estudos foram classificados de acordo com os níveis de evidência do Centro de Medicina Baseada em Evidência de Oxford.

RESULTADOS

Noventa e quatro estudos foram incluídos. Crianças com PC espástica e com menores limitações nas habilidades motoras grossas foram as mais reportadas; 67% dos estudos apresentaram baixos níveis de evidência e foram publicados em periódicos sem fator de impacto. As três intervenções mais frequentes foram o conceito neuroevolutivo Bobath/terapia do neurodesenvolvimento, a terapia com vestes e a estimulação transcraniana por corrente contínua. Os componentes das intervenções exploraram estruturas e funções do corpo (73,4%), atividade (59,6%) e ambiente (2,1%). Entretanto não exploraram a participação (0%). Os desfechos investigados abordaram atividade (79,8%), estruturas e funções do corpo (67,0%), participação (1%) e ambiente (0%). INTERPRETAÇÃO: Os estudos de intervenções fisioterapêuticas para crianças e adolescentes brasileiros com PC, apresentam maior foco em minimizar deficiências em estruturas e funções do corpo e limitações de atividades. São necessários mais estudos, com melhor nível de evidência e foco ampliado para a participação e os fatores ambientais.

Saccharomyces boulardii improves the behaviour and emotions of spastic cerebral palsy rats through the gut-brain axis pathway

BACKGROUND

Cerebral palsy (CP) is a kind of disability that influences motion, and children with CP also exhibit depression-like behaviour. Inflammation has been recognized as a contributor to CP and depression, and some studies suggest that the gut-brain axis may be a contributing factor. Our team observed that Saccharomyces boulardii (S. boulardii) could reduce the inflammatory level of rats with hyperbilirubinemia and improve abnormal behaviour. Both CP and depression are related to inflammation, and probiotics can improve depression by reducing inflammation. Therefore, we hypothesize that S. boulardii may improve the behaviour and emotions of spastic CP rats through the gut-brain axis pathway.

METHODS

Our new rat model was produced by resecting the cortex and subcortical white matter. Seventeen-day-old CP rats were exposed to S. boulardii or vehicle control by gastric gavage for 9 days, and different behavioural domains and general conditions were tested. Inflammation was assessed by measuring the inflammatory markers IL-6 and TNF-α. Hypothalamic-pituitary-adrenal (HPA) axis activity was assessed by measuring adrenocorticotropic hormone and corticosterone in the serum. Changes in the gut microbiome were detected by 16S rRNA.

RESULTS

The hemiplegic spastic CP rats we made with typical spastic paralysis exhibited depression-like behaviour. S. boulardii treatment of hemiplegic spastic CP rats improves behaviour and general conditions and significantly reduces the level of inflammation, decreases HPA axis activity, and increases gut microbiota diversity.

CONCLUSIONS

The model developed in this study mimics a hemiplegic spastic cerebral palsy. Damage to the cortex and subcortical white matter of 17-day-old Sprague-Dawley (SD) rats led to spastic CP-like behaviour, and the rats exhibited symptoms of depression-like behaviour. Our results indicate that S. boulardii might have potential in treating hemiplegic spastic CP rat models or as an add-on therapy via the gut-brain axis pathway.

Effects of TNFα on Dynamic Cytosolic Ca2 + and Force Responses to Muscarinic Stimulation in Airway Smooth Muscle

Previously, we reported that in airway smooth muscle (ASM), the cytosolic Ca²⁺ ([Ca²⁺]_cyt) and force response induced by acetyl choline (ACh) are increased by exposure to the pro-inflammatory cytokine tumor necrosis factor α (TNFα). The increase in ASM force induced by TNFα was not associated with an increase in regulatory myosin light chain (rMLC₂₀) phosphorylation but was associated with an increase in contractile protein (actin and myosin) concentration and an enhancement of Ca²⁺ dependent actin polymerization. The sensitivity of ASM force generation to elevated [Ca²⁺]_cyt (Ca²⁺ sensitivity) is dynamic involving both the shorter-term canonical calmodulin-myosin light chain kinase (MLCK) signaling cascade that regulates rMLC₂₀ phosphorylation and cross-bridge recruitment as well as the longer-term regulation of actin polymerization that regulates contractile unit recruitment and actin tethering to the cortical cytoskeleton. In this study, we simultaneously measured [Ca²⁺]_cyt and force responses to ACh and explored the impact of 24-h TNFα on the dynamic relationship between [Ca²⁺]_cyt and force responses. The temporal delay between the onset of [Ca²⁺]_cyt and force responses was not affected by TNFα. Similarly, the rates of rise of [Ca²⁺]_cyt and force responses were not affected by TNFα. The absence of an impact of TNFα on the short delay relationships between [Ca²⁺]_cyt and force was consistent with the absence of an effect of [Ca²⁺]_cyt and force on rMLC₂₀ phosphorylation. However, the integral of the phase-loop plot of [Ca²⁺]_cyt and force increased with TNFα, consistent with an impact on actin polymerization and, contractile unit recruitment and actin tethering to the cortical cytoskeleton.

Unilateral brain injury to pregnant rats induces asymmetric neurological deficits in the offspring

Effects of environmental factors may be transmitted to the following generation, and cause neuropsychiatric disorders including depression, anxiety, and posttraumatic stress disorder in the offspring. Enhanced synaptic plasticity induced by environmental enrichment may be also transmitted. We here test the hypothesis that the effects of brain injury in pregnant animals may produce neurological deficits in the offspring. Unilateral brain injury (UBI) by ablation of the hindlimb sensorimotor cortex in pregnant rats resulted in the development of hindlimb postural asymmetry (HL-PA), and impairment of balance and coordination in beam walking test in the offspring. The offspring of rats with the left UBI exhibited HL-PA before and after spinal cord transection with the contralesional (i.e., right) hindlimb flexion. The right UBI caused the offspring to develop HL-PA that however was cryptic and not-lateralized; it was evident only after spinalization, and was characterized by similar occurrence of the ipsi- and contralesional hindlimb flexion. The HL-PA persisted after spinalization suggesting that the asymmetry was encoded in lumbar spinal neurocircuits that control hindlimb muscles. Balance and coordination were affected by the right UBI but not the left UBI. Thus, the effects of a unilateral brain lesion in pregnant animals may be intergenerationally transmitted, and this process may depend on the side of brain injury. The results suggest the existence of left-right side-specific mechanisms that mediate transmission of the lateralized effects of brain trauma from mother to fetus.

Progress in clinical trials of stem cell therapy for cerebral palsy

Cerebral palsy is the most common disease in children associated with lifelong disability in many countries. Clinical research has demonstrated that traditional physiotherapy and rehabilitation therapies cannot alone cure cerebral palsy. Stem cell transplantation is an emerging therapy that has been applied in clinical trials for a variety of neurological diseases because of the regenerative and unlimited proliferative capacity of stem cells. In this review, we summarize the design schemes and results of these clinical trials. Our findings reveal great differences in population characteristics, stem cell types and doses, administration methods, and evaluation methods among the included clinical trials. Furthermore, we also assess the safety and efficacy of these clinical trials. We anticipate that our findings will advance the rational development of clinical trials of stem cell therapy for cerebral palsy and contribute to the clinical application of stem cells.

Diaphragm neuromuscular transmission failure in a mouse model of an early-onset neuromotor disorder

The spa transgenic mouse displays spasticity and hypertonia that develops during the early postnatal period, with motor impairments that are remarkably similar to symptoms of human cerebral palsy. Previously, we observed that spa mice have fewer phrenic motor neurons innervating the diaphragm muscle (DIAm). We hypothesize that spa mice exhibit increased susceptibility to neuromuscular transmission failure (NMTF) due to an expanded innervation ratio. We retrogradely labeled phrenic motor neurons with rhodamine and imaged them in horizontal sections (70 µm) using confocal microscopy. Phrenic nerve-DIAm strip preparations from wild type and spa mice were stretched to optimal length, and force was evoked by phrenic nerve stimulation at 10, 40, or 75 Hz in 330-ms duration trains repeated each second (33% duty cycle) across a 120-s period. To assess NMTF, force evoked by phrenic nerve stimulation was compared to force evoked by direct DIAm stimulation superimposed every 15 s. Total DIAm fiber number was estimated in hematoxylin and eosin-stained strips. Compared to wild type, spa mice had over twofold greater NMTF during the first stimulus train that persisted throughout the 120 s period of repetitive activation. In both wild type and spa mice, NMTF was stimulation-frequency dependent. There was no difference in neuromuscular junction morphology or the total number of DIAm fibers between wild type and spa mice, however, there was an increase innervation ratio (39%) in spa mice. We conclude that early-onset developmental neuromotor disorders impair the efficacy of DIAm neuromuscular transmission, likely to contribute to respiratory complications.NEW & NOTEWORTHY Individuals with motor control deficits, including cerebral palsy (CP) often have respiratory impairments. Glycine-receptor mutant spa mice have early-onset hypertonia, and limb motor impairments, similar to individuals with CP. We hypothesized that in the diaphragm of spa mice, disruption of glycinergic inputs to MNs would result in increased phrenic-DIAm neuromuscular transmission failure. Pathophysiologic abnormalities in neuromuscular transmission may contribute to respiratory dysfunction in conditions where early developmental MN loss or motor control deficits are apparent.

Growth and survival characteristics of spa mice

Characterization of growth and survival of mice displaying early onset hypertonic symptoms is critical as these animals are important for research investigating mechanisms and treatments of pediatric conditions associated with hypertonia, such as cerebral palsy. Currently, most animal models of cerebral palsy reproduce risk factors for developing this condition, with most failing to develop the physical symptoms or failing to survive in the postnatal period. The B6.Cg-Glrbspa /J (Gly receptor mutation) transgenic mouse (spa mouse), displays symptoms of early onset hypertonia, though little has been reported on growth and survival, with no reports of growth and survival since genotyping became available. We found that the majority of spa mice display symptoms by P14-P16. Of mice surviving to weaning, only ~9% were spa mice. By weaning age, spa mice had significantly lower weights than their heterozygote and wild-type littermates. Of mice that died after weaning and prior to use in experiments or being culled, 48% were spa mice. The poor growth and decreased survival of spa mice across multiple developmental and adult ages resembled the varied survival rates observed in humans with mild or severe cerebral palsy. The understanding of the expected survival of these mice is helpful for planning breeding and animal numbers for experiments. Due to the symptoms and timing of symptom onset, spa mice will be valuable in uncovering mechanisms and long-term effects of early onset hypertonia in order to move toward interventions for these conditions.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

Unmasking the Enigma of Cerebral Palsy: A Traditional Review

Cerebral palsy is a group of neuromuscular diseases that is primarily common in the pediatric population and is the most common cause of neurological and motor disability in children. Cerebral palsy is comprised of various subtypes with the most common type being spastic cerebral palsy. It is highly associated with prematurity and affects nerve function, motor function, and intellectual capacity. It is also associated with nutritional deficiencies and gastrointestinal dysfunction. Cerebral palsy is diagnosed via clinical evaluation and does not have specific laboratory or image findings, but certain imaging findings are positively correlated with it. There are numerous interventions and treatment modalities that are aimed at ensuring the highest quality of life for the patient and their families. This article was compiled with peer-reviewed publications from the PubMed database in which various keywords were utilized in the search engine. These peer-reviewed articles were selected without geographical restrictions and selected based on the use of the English language. These articles were also selected on the restriction of publication within the last 10 years. This review article on cerebral palsy will serve as a medium of education for the physician, healthcare team, and family involved in the management of children or adults with cerebral palsy. It is important because it discusses the possible etiologies, diagnostic and assessment techniques, prevention methods, and possible rehabilitation interventions. This article aims to broaden the reader's understanding of cerebral palsy and answer any questions that may arise during the management of this disease. The management of cerebral palsy is often plagued with frustration, depression, and anxiety. The main goal of treatment is to attain the highest quality of life for the family and the child.

Impaired neuromuscular transmission of the tibialis anterior in a rodent model of hypertonia

Early-onset hypertonia is characteristic of developmental neuromotor disorders, including cerebral palsy (CP). The spa transgenic mouse displays early-onset spasticity, abnormal gait, and motor impairments that are remarkably similar to symptoms of human CP. Previously, we showed that spa mice have fewer motor neurons innervating the tibialis anterior (TA). An expanded innervation ratio may result in increased susceptibility to neuromuscular transmission failure (NMTF). We assessed NMTF in an ex vivo TA muscle nerve preparation from spa and wild-type (WT) mice by comparing forces elicited by nerve versus muscle stimulation. TA muscle innervation ratio was assessed by counting the number of muscle fibers and dividing by the number of TA motor neurons. Muscle fiber cross-sectional areas were also assessed in the TA muscle. We observed that NMTF was immediately present in spa mice, increased with repetitive stimulation, and associated with increased innervation ratio. These changes were concomitant with reduced TA muscle fiber cross-sectional area in spa mice compared with WT. Early-onset hypertonia is associated with increased innervation ratio and impaired neuromuscular transmission. These disturbances may exacerbate the underlying gait abnormalities present in individuals with hypertonia.NEW & NOTEWORTHY Nerve-muscle interaction is poorly understood in the context of early-onset spasticity and hypertonia. In an animal model of early-onset spasticity, spa mice, we found a marked impairment of tibialis anterior neuromuscular transmission. This impairment is associated with an increased innervation ratio (mean number of muscle fibers innervated by a single motor neuron). These disturbances may underlie weakness and gait disturbances observed in individual with developmental hypertonia and spasticity.

Phrenic motor neuron loss in an animal model of early onset hypertonia

Phrenic motor neuron (PhMN) development in early onset hypertonia is poorly understood. Respiratory disorders are one of the leading causes of morbidity and mortality in individuals with early onset hypertonia, such as cerebral palsy (CP), but they are largely overshadowed by a focus on physical function in this condition. Furthermore, while the brain is the focus of CP research, motor neurons, via the motor unit and neurotransmitter signaling, are the targets in clinical interventions for hypertonia. Furthermore, critical periods of spinal cord and motor unit development also coincide with the timing that the supposed brain injury occurs in CP. Using an animal model of early-onset spasticity (spa mouse [B6.Cg-Glrbspa/J] with a glycine receptor mutation), we hypothesized that removal of effective glycinergic neurotransmitter inputs to PhMNs during development will result in fewer PhMNs and reduced PhMN somal size at maturity. Adult spa (Glrb-/-), and wild-type (Glrb+/+) mice underwent unilateral retrograde labeling of PhMNs via phrenic nerve dip in tetramethylrhodamine. After three days, mice were euthanized, perfused with 4% paraformaldehyde, and the spinal cord excised and processed for confocal imaging. Spa mice had ~30% fewer PhMNs (P = 0.005), disproportionately affecting larger PhMNs. Additionally, a ~22% reduction in PhMN somal surface area (P = 0.019), an 18% increase in primary dendrites (P < 0.0001), and 24% decrease in dendritic surface area (P = 0.014) were observed. Thus, there are fewer larger PhMNs in spa mice. Fewer and smaller PhMNs may contribute to impaired diaphragm neuromotor control and contribute to respiratory morbidity and mortality in conditions of early onset hypertonia.NEW & NOTEWORTHY Phrenic motor neuron (PhMN) development in early-onset hypertonia is poorly understood. Yet, respiratory disorders are a common cause of morbidity and mortality. In spa mice, an animal model of early-onset hypertonia, we found ~30% fewer PhMNs, compared with controls. This PhMN loss disproportionately affected larger PhMNs. Thus, the number and heterogeneity of the PhMN pool are decreased in spa mice, likely contributing to the hypertonia, impaired neuromotor control, and respiratory disorders.

Why individuals with cerebral palsy are at higher risk for respiratory complications from COVID-19

Respiratory dysfunction is a leading cause of morbidity and mortality in individuals with cerebral palsy (CP). In children and adults with CP, movement and physical function is always affected. Yet, many clinicians overlook potential for impaired movement and function of the diaphragm muscle (DIAm) in individuals with CP. Since individuals with pre-existing respiratory disorders are at greater risk for respiratory complications if they contract COVID-19, understanding potential risks to individuals with CP is important. In this review we present research on respiratory function and DIAm force generation in children with CP. We compare this clinical work to basic science research investigating phrenic motor neuron and DIAm motor unit dysfunction in an animal model with CP symptoms, the spa mouse. Finally, we integrate the clinical and basic science work in respiratory function in CP, discussing potential for individuals with CP to have severe respiratory symptoms from COVID-19.

Animal models of developmental motor disorders: parallels to human motor dysfunction in cerebral palsy

Cerebral palsy (CP) is the most common motor disability in children. Much of the previous research on CP has focused on reducing the severity of brain injuries, whereas very few researchers have investigated the cause and amelioration of motor symptoms. This research focus has had an impact on the choice of animal models. Many of the commonly used animal models do not display a prominent CP-like motor phenotype. In general, rodent models show anatomically severe injuries in the central nervous system (CNS) in response to insults associated with CP, including hypoxia, ischemia, and neuroinflammation. Unfortunately, most rodent models do not display a prominent motor phenotype that includes the hallmarks of spasticity (muscle stiffness and hyperreflexia) and weakness. To study motor dysfunction related to developmental injuries, a larger animal model is needed, such as rabbit, pig, or nonhuman primate. In this work, we describe and compare various animal models of CP and their potential for translation to the human condition.