Hypersarcosinemia, resulting from sarcosine dehydrogenase (SARDH) gene mutation, is a rare autosomal recessive disorder with variable, often nonspecific clinical presentations, leading to diagnostic difficulty and low clinical awareness. A 6-year-old boy presented with clinical features suggestive of viral encephalitis, including headache, vomiting, intermittent fever, and lethargy. Initial MRI revealed cytotoxic edema in the subcortical white matter and splenium of the corpus callosum. Although symptoms improved transiently with steroid therapy, persistent imaging abnormalities prompted metabolic and genetic evaluations. Metabolic and genetic investigations confirmed a diagnosis of hypersarcosinemia, with markedly elevating sarcosine levels and compounding heterozygous SARDH mutations. Genetic testing identified compound heterozygous mutations in the SARDH gene (c.293G > C and c.679 C > T), confirming hypersarcosinemia. Following initiation of folic acid and mecobalamin, partial radiological improvement was observed, although a causal relationship could not be established. This case highlights the diagnostic challenge of hypersarcosinemia and its potential mimicry of acquired encephalitis. To our knowledge, this is the first report describing an acute encephalitis-like presentation accompanied by persistent cytotoxic edema on MRI, thereby suggesting a possible expansion of the known clinical and neuroimaging spectrum of this disorder, although this observation requires confirmation in additional cases. However, given the rarity of hypersarcosinemia and the possibility of underreporting, the absence of prior similar reports should be interpreted with caution. In this case, genetic testing was essential for establishing the diagnosis, although the necessity of genetic testing in all cases of unexplained white matter changes cannot be determined from a single report. The temporal association of partial radiological improvement with folic acid and mecobalamin supplementation is hypothesis-generating only and requires further investigation ; no causal or therapeutic conclusion can be drawn from this single case.

AIMS:To characterize the clinical, electrophysiological, and genetic spectrum of pediatric CMS and evaluate genotype-informed outcomes using an integrated phenotype-electrophysiology-genomics approach. METHODS:We retrospectively reviewed 36 pediatric CMS patients evaluated at a single center between 2015 and 2025. Clinical features, RNS, targeted NGS/WES variants, ventilator use, treatments, ACMG/AMP classifications, and MG-ADL outcomes were analyzed. RESULTS:Of 36 patients, 28 (77.8%) developed symptoms in the neonatal period or infancy. Biallelic variants involved 17 CMS genes; postsynaptic CMS was most common (55.6%, 20/36). COLQ and CHRNE were the most frequent genes (13.9%, 5/36 each), followed by CHAT (11.1%, 4/36). VUS were detected in 19 patients (52.8%, 19/36), including 8 with biallelic VUS supported by phenotype, neuromuscular transmission findings, treatment response, and follow-up. RNS showed a ≥ 10% decrement in 16/21 tested patients (76.2%). CHAT-CMS was associated with higher ventilator use (3/4 vs. 6/32; p = 0.041) and early mortality (3/4 vs. 1/32; p = 0.002). Median MG-ADL improved from 5 to 3 after genotype-informed therapy. CONCLUSION:Pediatric CMS shows marked genetic heterogeneity and frequent VUS-related uncertainty. Integrating phenotype, electrophysiology, and genomics supports diagnosis and mechanism-guided therapy. CHAT-CMS is high risk for early respiratory failure and mortality.

Epilepsy-dyskinesia syndromes (EDS) are a complex group of neurogenetic disorders characterized by the co-occurrence of epilepsy and movement disorders. Despite their increasing clinical recognition, the molecular and clinical spectrum of EDS remains poorly understood. While numerous genetic aetiologies have been implicated, systematic characterization across diverse populations is lacking. This study aimed to delineate the molecular and clinical landscape of EDS in a large, multinational cohort, focusing on movement disorder phenomenologies, genotype-phenotype correlations, and treatment responses. We conducted a multicentre, cross-sectional study involving 609 patients with childhood-onset movement disorders associated with pathogenic variants in 105 predefined genes. Clinical data were collected from over 30 centres across 25 countries using a standardized survey, capturing movement disorder phenomenologies, seizure types, developmental trajectories, motor function and treatment outcomes. We classified EDS-associated genes into biologically meaningful groups by performing unsupervised clustering, which integrated protein-protein interactions and functional data. Genotype-phenotype correlations were assessed using a one-versus-remainder approach to quantify differential enrichment of clinical manifestations and treatment responses. Pathogenic variants were identified in 74 of the 105 predefined genes, with 12 genes accounting for two-thirds of cases. The most frequently reported genes were MECP2, ATP1A3, and GNAO1. Data-driven gene cluster analysis identified 12 functional groups, mapping EDS to relevant biological pathways and informing genotype-phenotype analyses. Dystonia (34.2%), stereotypies (24.6%) and ataxia (16.2%) were the most prevalent movement disorders, with gene- and pathway-specific movement disorder signatures extending beyond previously known associations. Notably, most patients exhibited mixed movement disorders, highlighting the phenotypic complexity of EDS. Epilepsy was diagnosed in only 66.8% of cases, suggesting that some EDS primarily manifest as movement disorders. Developmental trajectories varied by genetic aetiology. Pharmacological responses demonstrated gene- and pathway-specific treatment effects, confirming established therapeutic associations (e.g. PRRT2 variants responding to carbamazepine) and identifying previously unrecognized effects, such as exacerbation of motor symptoms with levodopa/carbidopa in GNAO1 and MECP2 variants. This study provides a detailed characterization of EDS, identifying distinct genetic, phenotypic and therapeutic patterns. The findings underscore the need for early recognition of movement disorders within epilepsy cohorts, offer immediate insights to improve anticipatory guidance and clinical management of EDS, and advocate for personalized treatment strategies. By laying the groundwork for longitudinal studies to refine genotype-phenotype correlations and establish a natural history, this work paves the way for interventional clinical trials and precision medicine approaches.

OBJECTIVE:This study was undertaken to characterize the clinical and genetic spectrum of RHOBTB2-related disorders (RHOBTB2-RDs) in a Chinese population, explore genotype-phenotype correlations, and develop a refined clinical framework to improve diagnosis and management. METHODS:We conducted a comprehensive analysis by integrating data from 12 Chinese patients (five retrospective, seven from literature) with 79 international cases from published studies. Genetic analysis focused on variant classification and hotspot identification. Standardized phenotypic data extraction was performed, followed by systematic classification and correlation analyses. RESULTS:In the Chinese cohort, all variants were de novo missense mutations, with 75% in the Broad-complex, Tramtrack, and Bric-à-brac (BTB) domain and conserved hotspots (e.g., p.Arg483His). Across the combined cohort (N = 91), RHOBTB2-RDs presented a broad phenotypic spectrum. As an exploratory proposal, we introduce paroxysmal encephalopathy with weakness (PEW) as a potential novel clinical phenotypic cluster, strongly associated with BTB domain variants. A practical subtyping framework was proposed: the BTB subtype (severe developmental and epileptic encephalopathy [DEE] with prominent paroxysmal features, often necessitating aggressive seizure management), the truncating/splicing subtype (primarily intellectual disability/developmental delay and movement disorders with epilepsy, requiring focused neurodevelopmental support), the guanosine triphosphatase subtype (a mixed phenotype with a generally more favorable neurodevelopmental course), and the interdomain subtype (frequently associated with PEW alongside DEE or paroxysmal movement disorders). SIGNIFICANCE:This study systematically characterizes RHOBTB2-RDs in Chinese patients, confirming conserved pathogenic hotspots across ethnicities and identifying population-specific features. The proposed clinical subtyping framework and PEW diagnostic criteria provide valuable tools for improving diagnostic accuracy and guiding personalized management of RHOBTB2-RDs.

BACKGROUND:Febrile infection‑related epilepsy syndrome (FIRES) is a severe acute inflammation‑associated encephalopathy in children, characterized by high mortality and poor long‑term outcomes. FIRES with claustrum lesions (FIRES‑C) represents a distinct subtype. However, the relationship between its neuroimaging heterogeneity and electrophysiological phenotype remains unclear, and the association between sleep spindles and acute‑phase severity has not been systematically investigated. This study aimed to characterize the electroclinical features of FIRES‑C to facilitate improvements in diagnosis, treatment, and prognostic evaluation. METHODS:This retrospective study enrolled pediatric patients from our previously reported large cohort. We evaluated dynamic electroencephalographic changes across the acute and chronic phases, examined the correlation between sleep spindles and disease severity, and compared differences between isolated claustrum lesions and those with concurrent thalamic/temporal lobe involvement. All statistical analyses were performed using SPSS 26.0. RESULTS:Twenty-one patients with FIRES-C were included, with a median age of onset of 8.33 years. All presented with focal motor seizures and impaired consciousness. Claustrum lesions appeared >10 days after onset in 90.5% of patients, and 76.2% had additional brain involvement. Among the 19 patients who were followed up, 63.2% achieved favorable long-term outcomes. Acute-phase electroencephalography (EEG) revealed absent occipital rhythm, diffuse delta slowing, disrupted sleep architecture, and migratory focal discharges; EEG abnormalities improved markedly during the chronic phase. Patients without sleep spindles exhibited more severe acute clinical manifestations; however, this finding did not correlate significantly with long-term neurological outcomes. Univariate analyses showed that children with isolated bilateral claustrum lesions had milder acute symptoms and better long-term functional prognosis. In contrast, patients with concomitant thalamic and temporal lobe involvement tended to have impaired consciousness, significantly lower detection rates of sleep spindles on EEG, and poorer long-term functional outcomes. CONCLUSION:FIRES-C exhibits characteristic dynamic EEG evolution. The absence of sleep spindles merely indicates a trend toward more severe acute clinical manifestations and cannot serve as a predictor of long‑term functional prognosis. Univariate intergroup comparisons demonstrated that the extent of imaging lesions was correlated with acute disease severity, EEG findings, and long‑term prognosis.

PRRT2 is associated with autosomal dominant paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE) and other diseases. To explore the phenotypic spectrum associated with PRRT2 mutations, we analyzed a patient carrying a 16p11.2 deletion including PRRT2. A retrospective analysis was conducted on the clinical and genetic characteristics of a patient with a 16p11.2 deletion containing PRRT2. A literature search was performed in CNKI, Wanfang, and PubMed from the establishment of the databases to December 2025, using the keywords "acute encephalopathy", "PRRT2", "paroxysmal non-kinesigenic dyskinesia", "ataxia", "copy number variation of chromosome 16", and "16p11.2 deletion", to identify case reports similar to the present case. This patient presented with infection-induced acute encephalopathy, acute-onset non-motor-induced movement disorders and ataxia phenotype. Genetic testing indicated a 16p11.2 deletion involving PRRT2, de novo. After immunotherapy and rehabilitation treatment, the patient achieved a favorable prognosis. Literature review identified only two complete international case reports similar to this case (specifically regarding ataxia), and genetic analysis showed that they were respectively a 16p11.2 deletion containing PRRT2 and a PRRT2 gene variation. The 16p11.2 deletion containing PRRT2 has been reported for the first time to present as an acute encephalopathy phenotype. Rare cases of paroxysmal non-motor-induced movement disorder (PNKD) and ataxia have also been reported. These findings underscore the importance of timely genetic testing and appropriate genetic counseling for patients presenting with unexplained acute encephalopathy and/or acute episodic non-motor-induced movement disorders, as well as those with ataxia symptoms.

This real-world study evaluated the effectiveness and safety of pitolisant, a histamine H₃ receptor inverse agonist, in Chinese pediatric patients with narcolepsy. This retrospective, observational, single-center study enrolled 40 pediatric patients treated with pitolisant between May and August 2024. Data collection encompassed demographic profiles, sleep questionnaires (Pediatric Epworth Sleepiness Scale [PESS] and Ullanlinna Narcolepsy Scale [UNS]), polysomnographic parameters, concomitant medications, and laboratory evaluations. Efficacy endpoints included changes in PESS and UNS scores from baseline, and caregiver-reported improvement in core narcolepsy manifestations other than excessive daytime sleepiness (EDS). Safety was assessed through adverse event monitoring. The cohort had a mean age at onset of 9.1 ± 1.9 years, a median disease duration of 6 (IQR: 2, 24)months and a mean follow-up period of 5.6 months (range:4.5–7months). Patients received either pitolisant monotherapy (n = 20, mean dose: 12.8 mg) or add-on therapy (n = 20, mean dose: 9.4 mg). Post-treatment, significant reductions were observed in both PESS (14.3 ± 2.8 vs. 10.7 ± 2.6, P < 0.001) and UNS scores (22.8 ± 5.8 vs. 17.0 ± 3.4, P < 0.001). Subgroup analysis demonstrated a greater PESS improvement in patients with baseline scores > 13 compared to those with scores ≤ 13 (P < 0.005). Additionally, 73.7

BACKGROUND:ATP1A3-related disorders are characterized by genetic heterogeneity and phenotypic pleiotropy, posing significant challenges for classification. Although canonical phenotypes have traditionally guided decision-making, increasing evidence highlights their limitations in capturing the clinical complexity. OBJECTIVE:The aims of this study were to characterize movement disorders, paroxysmal features, and genotype-phenotype relationships; to build a curated video archive; and to assess alignment with canonical phenotypes. METHODS:This is an observational study of 88 individuals with pathogenic or likely pathogenic variants in ATP1A3 who were evaluated in specialized movement disorders programs. RESULTS:Age at last clinical follow-up ranged from 0.1 to 63 years; 80.7% were pediatric patients. Chronic movement disorders were present in 68 of 88 individuals (75%); most had two or more coexisting phenomenologies. Dystonia was most common (47/88, 53%), followed by spasticity (28/88, 32%) and ataxia (28/92, 32%). Paroxysmal events occurred in 78 of 88 (88%) patients, including dystonic spells (45/78, 58%), abnormal eye movements (39/78, 50%), and hemiplegic episodes (37/78, 47%). Common comorbidities included epilepsy (21/88, 24%), cognitive impairment (41/88, 47%), and neuropsychiatric disorders. Only 22 of 88 (25%) fulfilled criteria for a single canonical phenotype; 28 of 88 (32%) met canonical criteria plus additional features, 18 of 88 (20%) satisfied criteria for ≥2 canonical phenotypes, and 20 of 88 (23%) fit no canonical category. We identified 43 distinct ATP1A3 variants; recurrent variants (eg, p.Arg756His, p.Asp801Asn, p.Glu818Lys) showed variable expressivity across categories. CONCLUSIONS:The extensive clinical heterogeneity in ATP1A3-related disorders challenges rigid phenotypic classifications. The predominance of patients with overlapping or atypical features supports a shift toward flexible, symptom-based clinical approaches rather than strict reliance on canonical phenotype recognition. © 2026 International Parkinson and Movement Disorder Society.

Objective To evaluate the association between early postoperative neuroimaging findings, clinical characteristics, and long-term clinical outcomes in pediatric post-pump chorea (PPC). Methods We conducted a retrospective, combined cohort study incorporating two institutional PPC cases and 24 literature-derived cases (total n = 26). PPC was defined as chorea onset within one month of cardiac surgery using cardiopulmonary bypass. Outcomes were categorized as good (resolution within 6 months), poor (persistence >6 months), or death. Clinical features and acute-phase neuroimaging (CT/MRI within one month of symptom onset) were compared between outcome groups. Results Only five patients (19.2%) achieved complete neurological recovery. Persistent chorea occurred in 15 patients (57.7%), and six deaths were recorded. Older age at onset (10.1 ± 4.0 vs. 2.8 ± 4.3 years; P = 0.002) and longer surgery-to-chorea latency (11.4 ± 6.3 vs. 4.9 ± 3.3 days; P = 0.029) were associated with good outcomes. Cyanotic heart disease was more frequent in the poor-outcome group (100% (15/15) vs. 40.0% (2/5); χ2 = 10.6, P = 0.009). Acute-phase neuroimaging abnormalities were also more prevalent in the poor-outcome group (86.7% (13/15) vs. 20.0% (1/5); χ2 = 12.9, P = 0.048), with basal ganglia lesions (40.0%) and cortical involvement (predominantly atrophy/reduced volume, 46.7%). Conclusion Younger age at onset, shorter symptom latency, the presence of cyanotic heart disease, and acute neuroimaging abnormalities involving the basal ganglia and cortex are associated with persistent neurological deficits in pediatric PPC and may aid in early risk stratification, although study limitations prevent causal inference.

Background Haploinsufficient deletions of GABA transporter 1 (GAT-1)- encoding SLC6A1, and GABA transporter 3 (GAT-3)-encoding SLC6A11 are implicated in epileptic syndromes. Despite their significance, the impact of these deletions has not been characterized. Our previous work on SLC6A1 missense mutations prompted a clinical trial for Ravicti (NCT04937062), a glycerol formulation of 4-phenylbutyrate (PBA), for treatment-resistant epilepsy. We observed phenotypic overlap between trial-eligible SLC6A1 mutation patients and 3p- syndrome patients carrying deletions of SLC6A1 and SLC6A11. This study characterizes the functional impact of these deletions and assesses the urgent question of whether 3p- syndrome patients could benefit from this treatment. Methods Chromosomal microarray analysis identified a deletion affecting one allele of both SLC6A1 and SLC6A11 in two pediatric patients with 3p- syndrome. Clinical phenotyping included electroencephalogram (EEG) recordings and neurodevelopmental assessments. Functional characterization was conducted using 3H-labeled GABA uptake assays and Western blotting in HEK293T cells, comparing haploinsufficient and missense variant models. Results The haploinsufficient GAT-1 and GAT-3 conditions demonstrated reduced GABA uptake and protein expression, comparable to known SLC6A1 missense variants. Post-treatment EEGs showed a moderate reduction in epileptiform discharges following PBA administration, and patients exhibited improved motor function. However, varying degrees of cognitive impairments persisted. Conclusions Haploinsufficiency of SLC6A1 and SLC6A11 contributes to the epileptic phenotypes observed in 3p- syndrome, marking this as the first study to biochemically characterize the functional impact of these deletions. Treatment with PBA may provide therapeutic benefits, particularly for addressing seizures and motor deficits, though further exploration of PBA’s long-term effects in patients with 3p- syndrome is warranted.

OBJECTIVE:This study aimed to assess the diagnostic value of symmetrical claustrum sign (SCS) in children with febrile infection-related epilepsy syndrome (FIRES), and describe the clinical features, treatment responses, and prognosis of children with FIRES accompanied by symmetrical claustrum lesions (FIRES-C). METHODS:A retrospective cohort study conducted at Beijing Children's Hospital from January 2015 to April 2024 included children with "fever and convulsions" who met the inclusion criteria. The diagnostic efficacy of SCS was calculated by analyzing the sensitivity and specificity. RESULTS:The study enrolled 1105 patients, including 129 with FIRES, 35 of whom were diagnosed with FIRES-C (median onset age: 8.3 years; 18 male). In the cohort of patients with status epilepticus (n = 347), the sensitivity of SCS was 27.1% (95% confidence interval [CI], 19.8%-35.9%), and the specificity was 95.4% (95% CI, 91.8%-97.4%). The median time to develop bilateral claustrum lesions was 15.8 days (interquartile range [IQR] 11-19). The results of the magnetic resonance imaging (MRI) scans revealed that 7 patients (20%) had isolated claustrum lesions, whereas 28 patients (80%) had extra-claustrum lesions. After a median follow-up of 42 months, 14 of the 29 patients (48.3%) who survived exhibited moderate to severe deficits (modified Rankin scale [mRS] ≥3) and 2 patients died. When compared to FIRES patients without claustrum lesions (n = 94), those with FIRES-C (n = 35) demonstrated a tendency toward milder disease severity, characterized by higher Glasgow Coma Scale (GCS) scores and lower incidence of non-midazolam anesthetic use and respiratory support requirements (p < .001). However, no significant differences in prognosis were observed between the two groups (p = .322). SIGNIFICANCE:SCS exhibit high specificity but limited sensitivity in the diagnosis of FIRES in pediatric patients. SCS may serve as a biomarker to assist in the diagnostic process and is typically associated with a less severe clinical progression.

A 14-year-old boy was admitted to the hospital due to a single episode of afebrile seizure and four hours of impaired consciousness.Three months prior to admission,he had a history of bilateral uveitis.Cerebrospinal fluid analysis revealed a mild elevation in white blood cell count.Cranial magnetic resonance imaging and contrast-enhanced scans showed multiple abnormal signals in both cerebral hemispheres,with punctate and nodular enhancement.Susceptibility-weighted imaging revealed multiple punctate hemorrhages within lesions in the bilateral frontal and left parietal lobes,suggestive of vasculitis.Brain biopsy demonstrated inflammatory granulomatous lesions.No secondary causes were identified,and the final diagnosis was granulomatous primary central nervous system vasculitis.The patient's condition improved after treatment with methylprednisolone sodium succinate and mycophenolate mofetil.This report describes a rare case of granulomatous central nervous system vasculitis in a child and provides valuable insights for the diagnosis and treatment of this disease.

Background:Hemiplegic migraine (HM) is a rare monogenic subtype of migraine characterized by a broad spectrum of symptoms, ranging from transient hemiplegic episodes to recurrent coma. Imaging documentation of cerebral vasospasm during acute HM attacks is exceedingly rare. We present a pediatric case of familial HM (FHM) with cerebral vasospasm and acute encephalopathy caused by an ATP1A2 gene variant to enhance clinical recognition of this condition. Case Description:An 11-year-old Asian female with a 2-year history of recurrent HM presented with fever, headache, altered consciousness, and right-sided weakness for 48 hours. The current acute episode occurred without identifiable triggers and was characterized by fever, prolonged headache, acute encephalopathy, and persistent hemiplegia. Acute-phase magnetic resonance imaging revealed left cerebral cortical swelling with mild diffusion restriction. Magnetic resonance angiography demonstrated dynamic cerebral vasospasm, with spontaneous resolution observed on follow-up imaging. A heterozygous c.2464G>A (p.Glu822Lys) missense variant in the ATP1A2 gene was identified; this variant was inherited from her mother, who has a history of recurrent headaches. Conclusions:This report describes a unique case of internal carotid artery vasospasm occurring in HM, which, to our knowledge, has not been previously reported in the literature. Investigating alterations in the cerebrovascular system contributes significantly to understanding the clinical manifestations and underlying mechanisms of HM.

OBJECTIVE:The KCNMA1 gene encodes the BK K⁺ channel, which modulates neuronal and muscular excitability. Variants in this gene are associated with heterogeneous or overlapping clinical features, including movement disorders, epilepsy, and developmental delays. This study aimed to analyze the genotype-phenotype correlations of KCNMA1-related disorders in China. METHODS:Clinical and genetic datas were collected from patients diagnosed with KCNMA1-related disoreders at Beijing Children's Hospital between January 2017 and December 2024. Literature reviews were conducted using the China National Knowledge Infrastructure (CNKI) and Wanfang databases with "KCNMA1″ as the keyword (from database establishment to December 2024) to summarize reported Chinese cases. Data on clinical phenotypes, genetic variant types, imaging findings, and prognosis were analyzed. RESULTS:Twenty-seven patients (20 males, 7 females) with KCNMA1 variants were included. Six presented with epilepsy and paroxysmal movement disorders, 6 with movement disorders alone, and 12 with epilepsy alone. Movement disorder types included paroxysmal nonkinesigenic dyskinesia (PNKD), ataxia, and episodic limb weakness. Seizure types encompassed generalized tonic-clonic, tonic, epileptic spasms, absence, focal, myoclonic, and atonic seizures. Twenty-six patients exhibited developmental delays, including 3 with delays alone (no seizures or movement disorders). A total of 25 distinct variants were identified, including 19 missense, 2 frameshift, 2 splice-site, 1 nonsense, and 1 deletion variant, of which 16 were novel. About genotype-phenotype correlations, among the 12 epilepsy-only cases, 8 (66.7%, 8/12) had variants located in transmembrane domains (S0-S6). Of the 12 cases with movement disorders (with or without epilepsy; 10 variants), 8 (80%, 8/10) had variants in intracellular domains, predominantly the RCK-2 region. CONCLUSIONS:This study summarized the primary clinical features of KCNMA1 variants, including movement disorders, epilepsy, and developmental delays. Additionally, 16 novel variants were reported. Genotype-phenotype correlations analysis suggested that variants in transmembrane domains are more likely to cause epilepsy, while those in intracellular domains, especially RCK-2, are primarily associated with movement disorders, with or without epilepsy. However, further studies with larger sample sizes are needed for validation.

To the editor: Myoclonus-dystonia syndrome(MDS)(OMIM15990)is a heritable disorder characterized by early onset subcortical myoclonic jerks and/or less prominent dystonia.This leads to disability and is often refractory to medical treatment.1 Deep brain stimulation(DBS)for the treatment of refrac-tory MDS has been proven effective in adults for reducing both myoclonic jerks and dystonia.1-3 Here,we describe the application of bilateral globus pallidus internus(GPi)DBS in a 5-year-old boy diagnosed with MDS.

Objective: To summarize the clinical and prognostic features of children with opsoclonus-myoclonus-ataxia syndrome (OMAS). Methods: A total of 46 patients who met the diagnostic criteria of OMAS in the Department of Neurology, Beijing Children's Hospital from June 2015 to June 2023 were retrospectively analyzed. Centralized online consultations or telephone visits were conducted between June and August 2023. The data of the children during hospitalization and follow-up were collected, including clinical manifestations, assistant examination, treatment and prognosis. According to the presence or absence of tumor, the patients were divided into two groups. The chi-square test or Mann-Whitney U test was used to compare the differences between the two groups. Univariate Logistic regression was used to analyze the factors related to OMAS recurrence and prognosis. Results: There were 46 patients, with 25 males and the onset age of 1.5 (1.2, 2.4) years. Twenty-six (57%) patients were diagnosed with neuroblastoma during the course of the disease, and no patients were categorized into the high-risk group. A total of 36 patients (78%) were followed up for≥6 months, and all of them were treated with first-line therapy with glucocorticoids, gammaglobulin and (or) adrenocorticotrophic hormone. Among the 36 patients, 9 patients (25%) were treated with second-line therapy for ≥3 months, including rituximab or cyclophosphamide, and 17 patients (47%) received chemotherapy related to neuroblastoma. At the follow-up time of 4.2 (2.2, 5.5) years, 10 patients (28%) had relapsed of OMAS. The Mitchell and Pike OMS rating scale score at the final follow-up was 0.5 (0, 2.0). Seven patients (19%) were mildly cognitively behind their peers and 6 patients (17%) were severely behind. Only 1 patient had tumor recurrence during follow-up. The history of vaccination or infection before onset was more common in the non-tumor group than in the tumor group (55%(11/20) vs. 23%(6/26), χ²=4.95, P=0.026). Myoclonus occurred more frequently in the non-tumor group (40%(8/20) vs. 4%(1/26), χ²=7.23, P=0.007) as the onset symptom. Univariate Logistic regression analysis showed that the tumor group had less recurrence (OR=0.19 (0.04-0.93), P=0.041). The use of second-line therapy or chemotherapy within 6 months of the disease course had a better prognosis (OR=11.64 (1.27-106.72), P=0.030). Conclusions: OMAS in children mostly starts in early childhood, and about half are combined with neuroblastoma. Neuroblastoma in combination with OMAS usually has a low risk classification and good prognosis. When comparing patients with OMAS with and without tumors, the latter have a more common infection or vaccination triggers, and myoclonus, as the onset symptom, is more common. Early addition of second-line therapy is associated with better prognosis in OMAS.