Understanding the role of AMPA receptors in autism: insights from circuit and synapse dysfunction.

Autism spectrum disorders represent a diverse etiological spectrum that converge on a syndrome characterized by discrepant deficits in developmental domains often highlighted by concerns in socialization, sensory integration, and autonomic functioning. Importantly, the incidence and prevalence of autism spectrum disorders have seen sharp increases since the syndrome was first described in the 1940s. The wide etiological spectrum and rising number of individuals being diagnosed with the condition lend urgency to capturing a more nuanced understanding of the pathogenic mechanisms underlying the autism spectrum disorders. The current review seeks to understand how the disruption of AMPA receptor (AMPAr)-mediated neurotransmission in the cerebro-cerebellar circuit, particularly in genetic autism related to SHANK3 or SYNGAP1 protein dysfunction function and autism associated with in utero exposure to the anti-seizure medications valproic acid and topiramate, may contribute to the disease presentation. Initially, a discussion contextualizing AMPAr signaling in the cerebro-cerebellar circuitry and microstructural circuit considerations is offered. Subsequently, a detailed review of the literature implicating mutations or deletions of SHANK3 and SYNGAP1 in disrupted AMPAr signaling reveals how bidirectional pathogenic modulation of this key circuit may contribute to autism. Finally, how pharmacological exposure may interact with this pathway, via increased risk of autism diagnosis with valproic acid and topiramate exposure and potential treatment of autism using AMPAr modulator perampanel, is discussed. Through the lens of the review, we will offer speculation on how neuromodulation may be used as a rational adjunct to therapy. Together, the present review seeks to synthesize the disparate considerations of circuit understanding, genetic etiology, and pharmacological modulation to understand the mechanistic interaction of this important and complex disorder.

Gastrointestinal Dysfunction in Genetically Defined Neurodevelopmental Disorders.

Gastrointestinal symptoms are common in most forms of neurodevelopment disorders (NDDs) such as in autism spectrum disorders (ASD). The current patient-reported outcome measures with validated questionnaires used in the general population of children without NDDS cannot be used in the autistic individuals. We explore here the multifactorial pathophysiology of ASD and the role of genetics and the environment in this disease spectrum and focus instead on possible diagnostics that could provide future objective insight into the connection of the gut-brain-microbiome in this disease entity. We provide our own data from both humans and a zebrafish model of ASD called Phelan-McDermid Syndrome. We hope that this review highlights the gaps in our current knowledge on many of these profound NDDs and that it provides a future framework upon which clinicians and researchers can build and network with other interested multidisciplinary specialties.

Updated consensus guidelines on the management of Phelan-McDermid syndrome.

Phelan-McDermid syndrome (PMS) is a genetic condition caused by SHANK3 haploinsufficiency and characterized by a wide range of neurodevelopmental and systemic manifestations. The first practice parameters for assessment and monitoring in individuals with PMS were published in 2014; recently, knowledge about PMS has grown significantly based on data from longitudinal phenotyping studies and large-scale genotype-phenotype investigations. The objective of these updated clinical management guidelines was to: (1) reflect the latest in knowledge in PMS and (2) provide guidance for clinicians, researchers, and the general community. A taskforce was established with clinical experts in PMS and representatives from the parent community. Experts joined subgroups based on their areas of specialty, including genetics, neurology, neurodevelopment, gastroenterology, primary care, physiatry, nephrology, endocrinology, cardiology, gynecology, and dentistry. Taskforce members convened regularly between 2021 and 2022 and produced specialty-specific guidelines based on iterative feedback and discussion. Taskforce leaders then established consensus within their respective specialty group and harmonized the guidelines. The knowledge gained over the past decade allows for improved guidelines to assess and monitor individuals with PMS. Since there is limited evidence specific to PMS, intervention mostly follows general guidelines for treating individuals with developmental disorders. Significant evidence has been amassed to guide the management of comorbid neuropsychiatric conditions in PMS, albeit mainly from caregiver report and the experience of clinical experts. These updated consensus guidelines on the management of PMS represent an advance for the field and will improve care in the community. Several areas for future research are also highlighted and will contribute to subsequent updates with more refined and specific recommendations as new knowledge accumulates.

Longitudinal neurological analysis of moderate and severe pediatric cerebral visual impairment.

Introduction: Cerebral visual impairment (CVI) results from damage to cerebral visual processing structures. It is the most common cause of pediatric visual impairment in developed countries and rising in prevalence in developing nations. There is currently limited understanding on how neurologic, developmental, and ophthalmic factors predict outcome for pediatric CVI. Method: A retrospective manual chart review of pediatric CVI patients seen at the tertiary pediatric hospital neurology and neuro-ophthalmology service between 2010 and 2019 was conducted. Patients were stratified into severity groups (based on a custom CVI grading score), and followed over time to identify outcome predictors. Collected baseline characteristics included perinatal, genetic, developmental, and neurologic history, along with neuroimaging and fundoscopic findings on examination. Longitudinal data collected included age, seizure control, and type of therapy received. Linear mixed-effect models were used for longitudinal CVI grade outcome analysis. Results: A total of 249 individuals spanning 779 patient visits were identified. Mean age at diagnosis was 18.8 ± 16.8 months (2-108 months). About 64.3% were born at term age. Perinatal history revealed hypoxic ischemic encephalopathy (HIE) in 16.5%, intraventricular hemorrhage (IVH) in 11.6%, and seizures in 21.7%. At presentation, 60.3% had a diagnosis of cerebral palsy and 84.7% had developmental delay. Among all subjects, 78.6% had epilepsy; 33.8% had an epileptic encephalopathy, with spasms/hypsarrhythmia being most common. Abnormal neuroimaging was present in 93.8%. Genetic anomalies were present in 26.9%. Baseline visual examination revealed no blink-to-light (BTL) in 24.5%; only BTL in 34.5%, fixation/tracking in 26.5%, and optokinetic drum follow in 14.4%. Longitudinal data analysis showed that perinatal history of HIE, a positive epilepsy history, using multiple (≥3) epilepsy medications, cerebral palsy, and abnormal fundoscopic findings were all negatively associated with CVI grade change over time. After controlling for significant confounders, receiving any type of therapy [early childhood intervention (ECI), physical and occupational therapy (PT/OT), refractive error correction or glasses] was significantly associated with longitudinal improvement in CVI grade compared to patients who did not receive any therapy, with glasses yielding the largest benefit. Conclusion: This study offers extensive insights into neurologic, developmental and ophthalmologic features in patients with moderate to severe CVI. In concordance with previous findings, aspects of perinatal history and epilepsy/seizure control may help inform severity and prognosis in the general neurology or ophthalmology clinic. Conversely, these aspects, as well as genetic and specific epilepsy traits may alert vision health care providers in the clinic to pursue visual evaluation in at-risk individuals. Longitudinal follow-up of CVI patients showed that interventional therapies demonstrated vision function improvement greater than no therapy and maturational development.

Trends in Body Mass Index and Association With Outcomes in Pediatric Patients on Continuous Flow Ventricular Assist Device Support.

Data are limited regarding body mass index (BMI) in pediatric patients supported by ventricular assist devices (VAD) and associated clinical outcomes and complications. We performed a retrospective single-center cohort study including patients aged ≤21 years on durable continuous-flow VAD support for ≥30 days from 2009 to 2020. Patients were classified based on BMI percentile at implant using the US Centers for Disease Control and Prevention criteria: underweight (<5th percentile), healthy weight (5th-<85th percentile, reference group), overweight (85th-<95th percentile), and obese (≥95th percentile). Primary outcomes were hospital mortality and length of stay (LOS) after implant. Secondary outcomes included infectious complications and pump thrombosis. Seventy-two patients (58 HeartWare, 13 HeartMateII, 1 HeartMate3) were included. At implant, the study cohort comprised 13% underweight, 53% healthy weight, 18% overweight, and 17% obese. BMI increased across all categories during support, with 29% gaining BMI categories. No patients with obesity reduced their BMI category. At explant, the study cohort comprised 1% underweight, 54% healthy weight, 22% overweight, and 22% obese. There was no significant difference in hospital mortality, postoperative LOS, or pump thrombosis. Patients who were overweight had more frequent non-VAD infections. Patients with obesity required longer duration on VAD support and were less likely to be transplanted. We concluded that pediatric patients on VAD support who are overweight or have obesity do not improve their BMI and instead have significant increase. Larger studies are needed to assess the impact of abnormal BMI on VAD complications in pediatric patients.

Phenotypic characterization of individuals with SYNGAP1 pathogenic variants reveals a potential correlation between posterior dominant rhythm and developmental progression.

BACKGROUND: The SYNGAP1 gene encodes for a small GTPase-regulating protein critical to dendritic spine maturation and synaptic plasticity. Mutations have recently been identified to cause a breadth of neurodevelopmental disorders including autism, intellectual disability, and epilepsy. The purpose of this work is to define the phenotypic spectrum of SYNGAP1 gene mutations and identify potential biomarkers of clinical severity and developmental progression. METHODS: A retrospective clinical data analysis of individuals with SYNGAP1 mutations was conducted. Data included genetic diagnosis, clinical history and examinations, neurophysiologic data, neuroimaging, and serial neurodevelopmental/behavioral assessments. All patients were seen longitudinally within a 6-year period; data analysis was completed on June 30, 2018. Records for all individuals diagnosed with deleterious SYNGAP1 variants (by clinical sequencing or exome sequencing panels) were reviewed. RESULTS: Fifteen individuals (53% male) with seventeen unique SYNGAP1 mutations are reported. Mean age at genetic diagnosis was 65.9 months (28-174 months). All individuals had epilepsy, with atypical absence seizures being the most common semiology (60%). EEG abnormalities included intermittent rhythmic delta activity (60%), slow or absent posterior dominant rhythm (87%), and epileptiform activity (93%), with generalized discharges being more common than focal. Neuroimaging revealed nonspecific abnormalities (53%). Neurodevelopmental evaluation revealed impairment in all individuals, with gross motor function being the least affected. Autism spectrum disorder was diagnosed in 73% and aggression in 60% of cases. Analysis of biomarkers revealed a trend toward a moderate positive correlation between visual-perceptual/fine motor/adaptive skills and language development, with posterior dominant rhythm on electroencephalogram (EEG), independent of age. No other neurophysiology-development associations or correlations were identified. CONCLUSIONS: A broad spectrum of neurologic and neurodevelopmental features are found with pathogenic variants of SYNGAP1. An abnormal posterior dominant rhythm on EEG correlated with abnormal developmental progression, providing a possible prognostic biomarker.

Re-expression of SynGAP protein in adulthood improves translatable measures of brain function and behavior.

It remains unclear to what extent neurodevelopmental disorder (NDD) risk genes retain functions into adulthood and how they may influence disease phenotypes. SYNGAP1 haploinsufficiency causes a severe NDD defined by autistic traits, cognitive impairment, and epilepsy. To determine if this gene retains therapeutically-relevant biological functions into adulthood, we performed a gene restoration technique in a mouse model for SYNGAP1 haploinsufficiency. Adult restoration of SynGAP protein improved behavioral and electrophysiological measures of memory and seizure. This included the elimination of interictal events that worsened during sleep. These events may be a biomarker for generalized cortical dysfunction in SYNGAP1 disorders because they also worsened during sleep in the human patient population. We conclude that SynGAP protein retains biological functions throughout adulthood and that non-developmental functions may contribute to disease phenotypes. Thus, treatments that target debilitating aspects of severe NDDs, such as medically-refractory seizures and cognitive impairment, may be effective in adult patients.

Global Health Education in Child Neurology and Neurodevelopmental Disabilities Training Programs in the United States: A National Survey.

OBJECTIVES: To describe the current landscape of opportunities and education in global health among child neurology and neurodevelopmental disabilities training programs and provide a framework for future development of global health education. METHODS: Authors surveyed Trainee and Program Director groups, obtaining information regarding global health interest, participation and obstacles (trainees); and collaborations in global health, academic yield and obstacles, and global health educational development within the training program (program directors). RESULTS: Of identified trainees and program directors, 35% and 48% responded, respectively. Among trainees, 82% reported interest in global health, with 25% reporting influence in program selection. Among program directors, 34% reported global health collaborations, most frequently clinical. Academic yield (conference participation or publications) was described by 46% of programs. Major obstacles described by both groups included administrative issues and funding; however, the latter was most important for program directors but not for trainees. Among program directors, 16% reported global health curricula, with lectures (100%), orientation courses (50%), and pre/post-travel sessions (50%) being commonest elements. The main content included education in public health, resourcefulness, and epidemiology. Half of responding programs offered a formal global health training track, including opportunities in language education (67%) and advanced degrees (33%). CONCLUSIONS: Similar to other specialties, growing interest in global health among trainees corresponds to growing availability of said opportunities; however, most display significant logistic obstacles and lack curricular development. Potential areas for intervention, including an interdisciplinary approach, and potential benefits to stakeholders are identified for programs wishing to expand in global health education.

Performance of International Medical Graduates in Pediatric Residency: A Study of Peer and Faculty Perceptions.

BACKGROUND: International medical graduates (IMGs) constitute approximately 25% of the US pediatric workforce. Their recruitment into US residency training raises concerns regarding their competence, although this has not been formally studied. Cincinnati Children's Hospital has systematically recruited IMGs over the past 16 years. This study evaluates perceptions of IMG performance by faculty and US graduate (USG) peers. METHODS: We surveyed IMG, USG, and faculty groups, including current and former trainees, assessing perceived IMG performance compared with that of USGs in terms of clinical knowledge/skills, resource utilization, communication, public health knowledge and efficiency, and overall impact on the program. RESULTS: Overall perceived performance was within 1 standard deviation of expected USG performance. IMGs outperformed USGs in clinical knowledge/skills and resource utilization but underperformed in communication, public health knowledge, and efficiency. Significant differences were noted in communication with patients and public health knowledge; IMGs ranked their performance significantly lower than USGs/faculty ranked their performance. Overall impact was perceived positively, including an increased interest in global health in among USGs. CONCLUSIONS: Carefully recruited IMGs are perceived to perform nearly equal to their USG peers, and their presence is perceived as positive to a major pediatric residency program. Specific domains for educational interventions are identified for programs wishing to expand IMG recruitment.

Endoscopic Third Ventriculostomy to address hydrocephalus in Africa: A call for education and community-based rehabilitation.

PURPOSE: Endoscopic Third Ventriculostomy (ETV) and Choroid Plexus Cautery (CPC) are low-cost, safe, and promising interventions for spina bifida-associated hydrocephalus (SBHCP). The purpose of this review was to explore and describe these efforts in Africa in order to upscale surgical training and rehabilitation services. METHODS: A PubMed search for articles on ETV and CPC as management of SBHCP in Africa was performed. Two authors appraised the results for key themes in content: indications, technique, outcomes, complications, education, and rehabilitation. RESULTS: Twenty of 47 articles identified were included for appraisal. Twelve described indications, ten and seven outlined technique and complications, respectively, and four described predictors of operative success. Fourteen studies describe outcomes, including operative and neurodevelopmental outcomes. Only two outlined educational efforts. Half of the literature stems from a single site in Uganda; in total, only six countries were represented. No articles described significant post-operative rehabilitation services or related training. CONCLUSION: The experience of ETV and CPC in Africa is promising, however, efforts to train and empower local staff in surgical technique and methods to upscale post-operative community-based rehabilitation services remain as a key to long-term success.

A refined approach to evaluating global developmental delay for the international medical community.

BACKGROUND: Global developmental delay is usually defined as significant delay in two or more domains of development. Etiologic diagnosis generally proves difficult and the etiology remains undetermined in up to 62% of these children. Those in whom an etiology is established generally undergo an exhaustive and costly diagnostic evaluation, even though this may not change the medical or therapeutic management of the delay. The history and physical examination may provide up to 40% of etiologic diagnoses if adequately conducted. METHODS: We performed a critical review of the literature on global developmental delay via PubMed. RESULTS: Five major etiologic categories for global developmental delay were identified and traits of the history and physical examination suggestive for their diagnosis were described. Additionally, current diagnostic tools and their benefits and limitations were appraised. CONCLUSIONS: We propose an improved approach to enhance clinical diagnosis in both resource-rich and resource-limited settings favoring early intervention and management.