Clinical Presentation, Management, and Diagnostic Performance of 2021 Criteria for Paraneoplastic Neurologic Syndromes in Childhood.

BACKGROUND AND OBJECTIVES: Paraneoplastic neurologic syndromes (PNSs) are remote neurologic immune-related effects of tumors. The clinical characteristics of pediatric PNSs remain unclear. We retrospectively examined the clinical characteristics of cases of pediatric PNSs and assessed the performance of the 2021 diagnostic criteria in children. METHODS: Patients hospitalized in the Beijing Children's Hospital between June 2015 and June 2023 and fulfilling the description of definite by 2004 diagnostic criteria of PNSs were included. A retrospective analysis of clinical characteristics was conducted, and the 2021 diagnostic criteria were applied to rediagnostic stratification. RESULTS: Among the 42 patients included, the most common neurologic syndrome was opsoclonus-myoclonus syndrome (OMS) (62%), followed by rapidly progressive cerebellar syndrome (26%). Most tumors were neuroblastomas (88%), with few being ovarian teratomas (10%). Approximately 71% (30/42) of patients were classified as definite and 24% (10/42) as probable according to the 2021 criteria. All cases judged as probable exhibited rapidly progressive cerebellar ataxia with neuroblastoma. For OMS, chemotherapy was administered based on the tumor's risk stage, accompanied by regular infusion of IV gamma globulin and oral steroids following tumor diagnosis. Twenty-one patients underwent regular follow-ups over 4.92 (0.58-7.58) years. The initial hospitalization recorded a median score of 12 (7-14) on the Mitchell and Pike OMS rating scale, decreasing to 0 (0-5) at the final follow-up. In cases of rapidly progressive cerebellar syndrome, a similar therapeutic regimen was used. Nine patients underwent regular follow-ups over 4.42 (1.17-7.50) years. The mean modified Rankin scale score at first hospitalization was 4 (3-4), reducing to 1 (0-4) at the final follow-up. Only 17% (5/30) of patients across both groups exhibited poor response to this regimen. Among these 5 patients, 4 belonged to the low-risk group (without chemotherapy). DISCUSSION: OMS followed by rapidly progressive cerebellar ataxia are the most common forms of PNSs in children and are associated with neuroblastoma. An aggressive approach with multiple immunotherapies may improve the prognosis of neuroblastoma-associated PNSs. The 2021 criteria perform well in pediatric PNSs. However, we propose upgrading the classification of antibody-negative rapidly progressive cerebellar ataxia with neuroblastoma to definite diagnosis. This adjustment aims to further improve the diagnostic efficacy of this diagnostic criterion in childhood.

Encephalitis is an Important Phenotype of Myelin Oligodendrocyte Glycoprotein Antibody-Associated Diseases: A Single-Center Cohort Study.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is considered a demyelinating disease of the central nervous system, but an increasing number of encephalitis cases associated with MOG antibodies have been reported recently. METHODS: This was a single-center, retrospective study. All data for pediatric patients with MOGAD diagnosed at Beijing Children's Hospital from January 2017 to January 2022 were collected. Clinical characteristics and outcomes were analyzed, and treatment responses were compared between the rituximab (RTX) and mycophenolate mofetil (MMF) groups. RESULTS: A total of 190 patients (age range: 5 months to 16 years; median age: 7.2 years; females: 97) were included in this study. The phenotypes of the first attack included acquired demyelinating syndromes (105 [55%]), encephalitis other than acute disseminated encephalomyelitis (82 [43%]), and isolated meningitis (3 [2%]). After a median follow-up of 30.4 months (interquartile range: 14.8-43.7), 64 (34%) patients had relapses. Fifty-one of the 64 (80%) patients who had relapse received maintenance therapy, including MMF (41), RTX (11), maintenance intravenous immunoglobulin (two), and tocilizumab (two). The annualized relapse rates decreased significantly after treatment in both the RTX and MMF cohorts (P < 0.05); however, there were no significant differences between the two groups (P = 0.56). A total of 178 (94%) patients had complete (175 patients) or almost complete (three patients) recovery (modified Rankin scale [mRS] < 2), and 12 had moderate to severe deficits (mRS ≥ 2). CONCLUSIONS: The spectrum of pediatric MOGAD is broader than previously reported and includes demyelinating syndromes and encephalitis. Encephalitis is an important initial phenotype observed in pediatric patients with MOGAD.

HyperCKemia: An early sign of childhood-onset neutral lipid storage disease with myopathy.

Neutral lipid-storage disease with myopathy (NLSDM) is an autosomal recessive neuromuscular disorder caused by mutations in PNPLA2, and the average age at onset is 30 years. To date, only eight patients with childhood-onset NLSDM have been reported in detail. We investigated 3 unreported patients with NLSDM detected in childhood and reviewed 8 childhood-onset and 82 adult-onset patients with NLSDM documented in the literature. In the childhood-onset cohort, NLSDM presented initially as asymptomatic or paucisymptomatic hyperCKemia in 6/11 patients, and follow-up data showed onset of muscle weakness in 6/11 childhood-onset patients. In the adult-onset cohort, 95.1% (78/82) of patients showed muscle weakness. Cardiac involvement developed in 6/11 childhood-onset patients. Hepatomegaly was observed in 3/11 childhood-onset patients. Serum creatine kinase levels were elevated greater than five-fold of the upper limit of normal (ULN) in most childhood-onset patients and were elevated to less than ten-fold of the ULN in most adult-onset patients. Peripheral blood smears and muscle biopsies showed cytoplasmic lipid droplets in leukocytes and myocytes. NLSDM can present in children with asymptomatic or paucisymptomatic hyperCKemia before the onset of muscle weakness. The presence of lipid droplets in leucocytes (Jordans' anomaly) aids in diagnosing and confirming the pathogenicity of PNPLA2 variants of uncertain significance. There were no clear genotype-phenotype correlations in patients with NLSDM.

The clinical spectrum associated with ATP1A2 variants in Chinese pediatric patients.

PURPOSE: To evaluate the clinical spectrum associated with ATP1A2 variants in Chinese children with hemiplegia, migraines, encephalopathy or seizures. METHODS: Sixteen children (12 males and 4 females), including ten patients with ATP1A2 variants whose cases had been published previously, were identified using next-generation sequencing. RESULTS: Fifteen patients had FHM2 (familial hemiplegic migraine type 2), including three who had AHC (alternating hemiplegia of childhood) and one who had drug-resistant focal epilepsy. Thirteen patients had DD (developmental delay). The onset of febrile seizures, which occurred between 5 months and 2 years 5 months (median 1 year 3 months) was earlier than the onset of HM (hemiplegic migraine), which occurred between 1 year 5 months and 13 years (median 3 years 11 months). Disturbance of consciousness subsided first, at 40 h to 9 days (median 4.5 days); hemiplegia and aphasia were resolved slowly, taking 30 min to 6 months (median 17.5 days) for the former and 24 h to over 1 year (median 14.5 days) for the latter. Cranial MRI showed edema in the cerebral hemispheres, mainly the left hemisphereacute attacks. All thirteen FHM2 patients recovered to baseline in 30 min to 6 months. Fifteen patients had between 1 and 7 (median 2) total attacks between the baseline and follow-up timepoints. We report twelve missense variants, including a novel variant ATP1A2 variant, p.G855E. CONCLUSIONS: The known genotypic and phenotypic spectra of Chinese patients with ATP1A2-related disorders were further expanded. Recurrent febrile seizures and DD combined with paroxysmal hemiplegia and encephalopathy should raise the clinical suspicion of FHM2. The avoidance of triggers and thus the prevention of attacks may be the most effective therapy for FHM2.

Autoimmune cerebellar ataxia associated with anti-Purkinje cells antibodies: the next frontier of neuroimmunology.

Autoimmune cerebellar ataxia (ACA) is an important cause of sporadic cerebellar ataxia. Technological innovation promotes the rapid development of cerebellar autoimmunity researches in recent years. More and more new antibodies have been proposed to be associated with ACA. Several autoantibodies against Purkinje cells (PCs) have been identified, which constitute the main components. These autoantigens are mainly located in the cytoplasm and dendrites of PCs, and exhibit a specific morphology in immunohistochemistry (IHC). Although the clinical features are relatively homogeneous, there were still some differences among different antibodies. Due to the lack of understanding of the disease and the limited detection technology, it is really difficult to diagnose and manage at present. However, unlike the most of hereditary ataxias, ACA is treatable, and even the neurological dysfunction of some patients may be reversible. Therefore, promptly identification, diagnosis and treatment may benefit some patients. Thus, this article elaborates on the clinical manifestations and laboratory characteristics of anti-PCs-antibody-associated ACA in order to help neurologists to understand ACA more comprehensively. At the same time, combining our previous exploratory work as well as the technology available, we try to propose a diagnostic strategy for ACA the text and the relevant differential diagnosis was illustrated in detail.

Clinical and Radiologic Features Among Children With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Myelitis.

BACKGROUND: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) often manifests as optic neuritis, transverse myelitis(TM), and acute disseminated encephalomyelitis. Patients with a TM phenotype are at high risk for neurological sequelae, so recognizing the characteristics of MOG-IgG myelitis is essential for early, accurate diagnosis and treatment. METHODS: This was a single-center retrospective study. Pediatric MOG antibody-associated disease patients who had clinical myelitis were recruited for this study. Data on clinical and radiologic features and outcomes were retrospectively collected. RESULTS: Thirty-four patients (age range: 6 months to 13 years; median age, 7 years; female, 16) were enrolled in this study. As one patient had two clinical episodes of myelitis, 35 episodes were included. Isolated transverse myelitis was the initial manifestation in 28 (82%) patients. The most frequent clinical features of MOG-IgG myelitis were weakness and neurogenic bladder, and 80% were better than wheelchair-dependent at the nadir. There was a high presentation of weakness (91%), bowel/bladder dysfunction (63%), and sensory dysfunction (46%), and 80% were better than wheelchair-dependent at the nadir. In addition, seven patients (20%) had radicular pain, and six had flaccid areflexia. Magnetic resonance imaging features were often longitudinally extensive (63%) and prominently involved gray matter (H-sign) (63%), accompanied by leptomeningeal enhancement (4/14.29%) and spinal root enhancement (6/14.43%). At the final follow-up (median, 28 months; range, 8-109 months), 10 patients (29%) had developed one or more relapses, spinal cord lesions resolved entirely in 11 of 22 children (50%), and none had appreciable spinal cord atrophy. At the final follow-up, most patients had favorable outcomes, with median (interquartile range) Expanded Disability Status Scale scores of 0 (range, 0-2), four patients (12%) had sphincter dysfunction, and one patient had gait problems. CONCLUSIONS: Pediatric MOG-IgG myelitis clinically presents with weakness and bowel and bladder dysfunctions. Prominent involvement of the gray matter, leptomeningeal enhancement, and spinal root enhancement are common in pediatric MOG-IgG myelitis.

De novo frameshift variant in MT-ND1 causes a mitochondrial complex I deficiency associated with MELAS syndrome.

BACKGROUND: The variant m.3571_3572insC/MT-ND1 thus far only reported in oncocytic tumors of different tissues. However, the role of m.3571_3572insC in inherited mitochondrial diseases has yet to be elucidated. METHODS: A patient diagnosed with MELAS syndrome was recruited, and detailed medical records were collected and reviewed. The muscle was biopsied for mitochondrial respiratory chain enzyme activity. Series of fibroblast clones bearing different m.3571_3572insC variant loads were generated from patient-derived fibroblasts and subjected to functional assays. RESULTS: Complex I deficiency was confirmed in the patient's muscle via mitochondrial respiratory chain enzyme activity assay. The m.3571_3572insC was filtered for the candidate variant of the patient according to the guidelines for mitochondrial mRNA variants interpretation. Three cell clones with different m.3571_3572insC variant loads were generated to evaluate mitochondrial function. Blue native PAGE analysis revealed that m.3571_3572insC caused a deficiency in the mitochondrial complex I. Oxygen consumption rate, ATP production, and lactate assays found an impairment of cellular bioenergetic capacity due to m.3571_3572insC. Mitochondrial membrane potential was decreased, and mitochondrial reactive oxygen species production was increased with the variant of m.3571_3572insC. According to the competitive cell growth assay, the mutant cells had impaired cell growth capacity compared to wild type. CONCLUSIONS: A novel variant m.3571_3572insC was identified in a patient diagnosed with MELAS syndrome, and the variant impaired mitochondrial respiration by decreasing the activity of complex I. In conclusion, the genetic spectrum of mitochondrial diseases was expanded by including m.3571_3572insC/MT-ND1.

Clinical and genetic spectrum of hereditary spastic paraplegia in Chinese children.

AIM: To explore the clinical and genetic spectrum of hereditary spastic paraplegia (HSP) in Chinese children. METHOD: This retrospective study was conducted between January 2014 and October 2021 in children clinically diagnosed with either pure HSP (pHSP) or complex HSP (cHSP). RESULTS: We investigated 45 children (32 males, 13 females; mean age [SD] at symptom onset 4 years [7 months]). clinically diagnosed with HSP and identified genetic causes in 35 patients. Most patients with autosomal dominant HSP had pHSP (16/18), whereas most patients with autosomal recessive HSP tended to have cHSP (14/16). SPG11 was the most common autosomal recessive subtype, followed by FA2H/SPG35, whereas SPAST/SPG4 was the most frequent cause of autosomal dominant HSP. Two patients with CPT1C mutations presented with a complex phenotype. Meanwhile, 10 patients were found to have likely pathogenic variants/variants of uncertain clinical significance in six genes related to HSP. INTERPRETATION: SPG11 and SPG4 were the most frequent subtypes in Chinese children with autosomal recessive HSP and autosomal dominant HSP. However, the prevalence of SPG4 was much lower than that in adults, which might be explained by the late onset of the disease. On the other hand, FA2H/SPG35 was common in our cohort, while it contributed to only a small proportion of adult cases, which might be explained by its rapid progression and early death in some patients. We also expanded the genetic and clinical spectra of SPG73.

High levels of cerebrospinal fluid soluble triggering receptor expressed on myeloid cells 2 might be a biomarker of activity in pediatric patients with MOG-AD.

Myelin oligodendrocyte glycoprotein antibody disease (MOG-AD) is characterized by its monophasic or relapsing course and inflammatory demyelinating condition which is unable to be classified in typical multiple sclerosis (MS) or other known neuroinflammatory conditions. In the condition of neuroinflammatory, activated microglia are essential for demyelination. The secreted ectodomain of soluble triggering receptor expressed on myeloid cells 2 (sTREM2), expressed by microglial cells, is associated with abnormal biological pathways. It is known that the cerebrospinal fluid (CSF) sTREM2 concentration is much higher in neuroinflammatory and neurodegeneration diseases. However, the role of activated microglia has not been reported in MOG-AD pediatric patients. For the first time, the increased CSF and serum sTREM2 concentration in pediatric patients with MOG-AD is investigated in this work, showing evidence of microglia activation in MOG-AD. CSF sTREM2 levels significantly correlated with clinical inflammatory indexes and adapted modified Rankin Scale score, indicating the potential value of sTREM2 as a severity biomarker.

Mycophenolate mofetil: An alternative disease-modifying agent for MOG-IgG-associated disorders in childhood: A single-center bidirectional cohort study.

OBJECTIVE: To evaluate the efficacy of mycophenolate mofetil (MMF) in the treatment of childhood MOG-IgG-associated disorder (MOGAD). METHODS: Thirty patients diagnosed with relapsing MOGAD and treated with MMF for >1 year from a childhood MOGAD ambispective cohort were included in the study. The clinical characteristics, therapeutic regimen, side effects, annualized relapse rate (ARR), and Expanded Disability Status Scale (EDSS) scores of these patients were evaluated. RESULTS: The median age of disease onset was 7.05 (2.50-12.75) years. The male to female ratio was 1:1.31. All patients used MMF as first-line maintenance treatment. The median time to add MMF from disease onset was 1.08 (0.25-5.00) year. The median number of attacks before MMF initiation was 2 (2 - 8). The median duration of MMF therapy was 2.13 (1.00-3.58) years. Twenty (66.67%) patients did not experience further attacks during MMF therapy. The Kaplan-Meier curves showed a 3-year relapse-free rate of 59.8% (95% CI, 36.62-76.88%). ARR decreased during MMF therapy (0 (0 - 1.72) vs. 1.25 (0.60-4.00); P < 0.05). EDSS stabilized during MMF therapy (1.0 (0 - 2.0) vs. 0 (0 - 2.0); P = 0.206). None of the patients stopped the use of MMF due to intolerable side effects. Onset age, sex, phenotype of the first attack, ARR before MMF, MOG-IgG titers, and combined long-term prednisone (prednisone <10 mg daily for patients >40 kg or <5 mg daily for patients ≤40 kg longer than 6 months) did not predict recurrence during MMF therapy in univariate analysis. CONCLUSIONS: MMF was effective and safe for treating childhood MOGAD. No clinical feature that could predict efficacy of MMF was found in pediatric patients with MOGAD.

Oculogyric crisis mimicked epilepsy in a Chinese aromatic L-amino acid decarboxylase-deficiency patient: A case report.

Background: Aromatic amino acid decarboxylase (AADC) deficiency is a rare, autosomal recessive neurometabolic disorder with heterogeneous phenotype, including hypotonia, movement disorders, autonomic dysfunction, and developmental delay. Here, we reported a Chinese patient with AADCD who was initially misdiagnosed with epilepsy. Case presentation: The proband was a 4-month-old Chinese girl, representing hypotonia, episodes of oculogyric crises with dystonia, and delayed developmental milestones. The patient was first misdiagnosed with epilepsy because of the similarity between episodes of oculogyric crisis and epileptic seizure. The accurate diagnosis of AADCD was established through analysis of neurotransmitters in cerebrospinal fluid (CSF). The genetic test confirmed the patient carried novel compound heterozygous mutations in the DDC gene:c.419G>A and c.1375C>T. Conclusion: This study reported a patient with AADCD who was initially misdiagnosed as epilepsy. Two novel missense mutations in the DDC gene were identified from the patient and her family. Little infants with epileptic-like attacks should consider AADCD. An accurate diagnosis of AADCD is essential for drug choice and patient management.

Functional connectivity differences in speech production networks in Chinese children with Rolandic epilepsy.

Previous studies have demonstrated that language impairments are frequently observed in patients with benign epilepsy with centrotemporal spikes (BECTS). However, how BECTS affects language processing in the Chinese population remains unclear. With the use of functional magnetic resonance imaging (fMRI) in an overt picture-naming task, the present study examined functional connectivity in 27 children with BECTS and 26 healthy controls. The results indicated that children with BECTS showed altered functional connectivity associated with speech production between the left precuneus and the right cerebellum, between the right precuneus and the bilateral thalamus and the left superior temporal gyrus, between the right cuneus and the right postcentral gyrus and the right inferior parietal lobule, and between the right cerebellum and right middle frontal gyrus. Collectively, the findings in this study demonstrate the abnormal functional connectivity basis of speech production in Chinese children with BECTS, providing clues to understanding the brain mechanisms of language-related network in patients with BECTS.

Novel Loss-of-Function Variants in CHD2 Cause Childhood-Onset Epileptic Encephalopathy in Chinese Patients.

Developmental and epileptic encephalopathy-94 (DEE94) is a severe form of epilepsy characterized by a broad spectrum of neurodevelopmental disorders. It is caused by pathogenic CHD2 variants. While only a few pathogenic CHD2 variants have been reported with detailed clinical phenotypes, most of which lack molecular analysis. In this study, next-generation sequencing (NGS) was performed to identify likely pathogenic CHD2 variants in patients with epilepsy. Three likely pathogenic variants were finally identified in different patients. The seizure onset ages were from two years to six years. Patients 1 and 2 had developmental delays before epilepsy, while patient 3 had intellectual regression after the first seizure onset. The observed seizures were myoclonic, febrile, and generalized tonic-clonic, which had been controlled by different combinations of antiepileptic drugs. Two de novo (c.1809_1809+1delGGinsTT, p.? and c.3455+2_3455+3insTG, p.?) and one maternal (c.3783G>A, p.W1261*) variant were identified, which were all predicted to be pathogenic/likely pathogenic. Molecular analysis was performed in patient 1, and we detected aberrantly spliced products, proving the pathogenicity of this CHD2 variant. New cases with novel variants, along with a detailed clinical and molecular analysis, are important for a better understanding of CHD2-related epileptic encephalopathy.

Chinese patients with p.Arg756 mutations of ATP1A3: Clinical manifestations, treatment, and follow-up.

Importance: The phenotypes of ATP1A3 gene mutations are diverse. Relapsing encephalopathy with cerebellar ataxia and fever-induced paroxysmal weakness and encephalopathy (FIPWE) are considered non-classical phenotypes caused by p.Arg756 mutations of ATP1A3. Objective: To summarize the clinical manifestations, treatment, and follow-up of Chinese patients with p.Arg756 mutations of ATP1A3. Methods: We analyzed the clinical features, treatment, and genotypes of eight children with p.Arg756 mutations of ATP1A3 who were treated in Beijing Children's Hospital from January 2014 to December 2019. Results: Eight patients (six boys and two girls) were included; seven had been misdiagnosed with encephalitis. The age of onset ranged from 0.8 to 4.5 years. All patients had encephalopathy and had at least one episode of FIPWE. Cerebellar ataxia was present in nine episodes. Reversible splenial lesions of the corpus callosum were found in two patients in the acute phase. Three types of heterozygous ATP1A3 mutations were found: c.2267G > T (p.R756L) (patient 3 [P3]), c.2266C > T (p.R756C) (P2 and P4), and c.2267G > A (p.R756H) (P1, P5, P6, P7, and P8). Six mutations were de novo; two mutations were inherited. Both patients with p.R756C and one patient (P7) with p.R756H had four episodes of severe ataxia as the main manifestations. However, in the other three episodes, limb weakness was more prominent than ataxia. P5 with p.R756H exhibited overlap with FIPWE and rapid-onset dystonia-parkinsonism. Interpretation: Acute encephalopathy followed by febrile disease was characteristic of the disease in patients with p.Arg756 mutations of ATP1A3. However, the weakness and ataxia were variable. Phenotypic crossover and overlap were observed among these patients.

Phenotypes and genotypes of mitochondrial diseases with mtDNA variations in Chinese children: A multi-center study.

Mitochondrial DNA (mtDNA) associated mitochondrial diseases hold a crucial position but comprehensive and systematic studies are relatively rare. Among the 262 patients of four children's hospitals in China, 96%-point mutations (30 alleles in 11 genes encoding tRNA, rRNA, Complex I and V) and 4%-deletions (seven of ten had not been reported before) were identified as the cause of 14 phenotypes. MILS presented the highest genetic heterogeneity, while the m.3243A > G mutation was the only "hotspot" mutation with a wide range of phenotypes. The degrees of heteroplasmy in the leukocytes of MM were higher than MELAS. The heteroplasmy level of patients was higher than that in mild and carrier group, while we found low-level heteroplasmy pathogenic mutations as well. Some homoplasmic variations (e.g., m.9176 T > C mutation) are having high incomplete penetrance. For a suspected MELAS, m.3243A > G mutation was recommended to detect first; while for a suspected LS, trios-WES and mtDNA genome sequencing by NGS were recommended first in both blood and urine.

Generation of an iPSC line from a patient with early-onset epileptic encephalopathy carrying CARS2 (p.G476R) mutation.

Mutations in CARS2 gene, encoding for the mitochondrial cysteinyl-tRNA synthetase, has been reported to be associated with early-onset epileptic encephalopathy (EOEE). Here, we generated an induced pluripotent stem cell (iPSC) line from the human dermal fibroblasts (HDFs) of an one-year-old boy with EOEE carrying homozygous c.1426G > A mutation in CARS2 gene. These iPSCs exhibited stable amplification, expressed pluripotent markers, and differentiated spontaneously into three germ layers in vitro.

Age-dependent characteristics and prognostic factors of pediatric anti-N-methyl-d-aspartate receptor encephalitis in a Chinese single-center study.

OBJECTIVE: To describe the clinical features and prognosis of pediatric anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis from a single center in northern China. METHODS: The clinical and laboratory characteristics of hospitalized patients with anti-NMDAR encephalitis, stratified by age, were retrospectively studied. Risk factors including relapse and long-term (follow-up ≥1 year) outcomes were analyzed. RESULTS: A total of 273 patients were included between November 2011 and December 2019, and the average age of onset was 7.5 ± 4.0 years (0.5-15.8 years). Of them, 159（58.2%） were female, and the proportion of females increased with age. Seizures were the most common initial symptom. Movement disorders（86.1%） and psychiatric（82.4%） symptoms were most frequent in the acute phase. In the acute stage, the incidence of movement disorders decreased with age (χ2 = 10.676, p = 0.011), while the proportion of psychiatric symptoms increased with age (χ2 = 21.85, p < 0.001) The recurrence rate was 9.6% (24/250). Demyelination was an independent risk factor for relapse (p = 0.006, OR = 5.877, 95% CI: 1.658-20.835). Among the 210 patients who were followed up for more than one year, 28 patients had a poor prognosis (mRS ≥3). Onset age (p = 0.038，OR = 0.844, 95% CI: 0.720-0.991), precursor of viral encephalitis (p = 0.007，OR = 9.876, 95% CI: 1.878-51.940), and ICU admission (p = 0.023，OR = 5.924, 95% CI: 1.280-27.064) significantly affected the prognosis. The mortality rate was 2.9%. CONCLUSIONS: The characteristics of anti-NMDAR encephalitis in children are age-dependent. Early-onset, the precursor of viral encephalitis, and ICU admission may indicate poor prognosis. Demyelination may be a risk factor for recurrence.

Immunotherapies for Anti-N-M-methyl-D-aspartate Receptor Encephalitis: Multicenter Retrospective Pediatric Cohort Study in China.

Background: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis has been discovered for more than a decade, but the establishment of standardized immunotherapy protocol for pediatric patients still needs more clinical evidence. Methods: A multicenter, retrospective study was conducted on pediatric patients diagnosed with anti-NMDAR encephalitis between November 2011 and December 2018. The clinical records including clinical manifestations, immunotherapy strategies, and outcomes were collected and analyzed. Results: A total of 386 patients were included in our study and the median onset age was 8.00 (IQR 4.83-10.90) years. All patients received first-line immunotherapy and the majority (341, 88.3%) used the standard combination of methylprednisolone pulses (MEP) and intravenous immunoglobulins (IVIG), but 211 patients did not show satisfactory improvement (mRS ≥ 3). Mainly three treatment strategies were applied after first-line immunotherapy: second-line immunotherapy, repetitive first-line immunotherapy, and maintaining oral prednisolone. For patients with mRS ≥ 4 after first-line immunotherapy, the incidence of poor outcome (mRS ≥ 3) in oral prednisolone group was higher than that in other treatment groups (p = 0.039). No difference in complete recovery rate (mRS = 0) was found between patients receiving second-line and repetitive first-line immunotherapy, or patients using long-term and short-term prednisolone. Out of 149 patients who received anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) test, 27 (18.12%) were positive. Patients with concomitantly positive MOG-Ab showed milder conditions compared to patients with typical anti-NMDAR encephalitis and were more inclined to relapses. We also identified female, MOG-Ab positive, and not receiving second-line and/or repetitive first-line immunotherapy were risk factors for relapses. Conclusions: For patients with mRS ≥ 4 after first-line immunotherapy and patients with concomitantly positive MOG-Ab, second-line immunotherapy is recommended. When second-line immunotherapy is not applicable, repetitive first-line immunotherapy can be considered as an option. Both second-line and repetitive first-line immunotherapy are beneficial to reduce relapse rate. The duration of sequential oral prednisolone can be shortened after fully evaluating patients' conditions.

Case Report: Clinical Features of Childhood Leukoencephalopathy With Cerebral Calcifications and Cysts Due to SNORD118 Variants.

Background: Leukoencephalopathy with cerebral calcifications and cysts (LCC) is a rare autosomal recessive cerebral microangiopathy. Recently, biallelic variants in a non-protein-coding gene SNORD118 have been discovered to cause LCC. Case Presentation: We here report a genetically confirmed childhood case of LCC. The patient was a 4-year-and-1-month-old boy with focal seizures. The age at onset of his seizure was 10 days after birth. The seizures were well-controlled by antiepileptic treatment but reoccurred twice due to a head impact accident and a fever, respectively. He suffered from a self-limited esotropia and unsteady running gait during the seizure onset. He had the typical neuroimaging triad of multifocal intracranial calcifications, cysts, and leukoencephalopathy. Genetic analysis indicated that he carried compound heterozygous variants of n.*9C>T and n.3C>T in SNORD118, which were inherited from his parents. Conclusion: We report a childhood LCC case with compound heterozygous variants in SNORD118. To the best of our knowledge, the patient reported in our case had the youngest onset age of LCC with a determined genotype. The triad cerebral-imaging findings of calcifications, cysts, and leukoencephalopathy provide a crucial diagnostic basis. Moreover, the gene assessment, together with the clinical investigations, should be considered for the diagnosis of LCC.

Clinical Features and Outcomes of Anti-N-Methyl-d-Aspartate Receptor Encephalitis in Infants and Toddlers.

OBJECTIVE: We describe the clinical features and outcomes of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in infants and toddlers. METHODS: This was a single-center retrospective study. Infants and toddlers who met the diagnostic criteria for anti-NMDAR encephalitis were recruited for the study. Data on clinical features, treatment, and long-term outcomes were collected retrospectively. RESULTS: A total of 41 patients (age range: six to 34 months; median age: 23 months; female: 19) were enrolled in this study. Nineteen (46%) patients exhibited classical anti-NMDAR encephalitis, whereas 22 (54%) patients exhibited anti-NMDAR encephalitis after viral encephalitis. There was a high presentation of movement disorders (100%), developmental regression (90%), abnormal behaviors (90%). All patients were administered first-line therapy, with only 17% of them being administered second-line immunotherapy. Two patients succumbed to the disease, whereas none of them relapsed. At the long-term follow-up (more than one year), 20 of 35 (57%) exhibited satisfactory outcomes (modified Rankin Scale ≤2). Compared with patients with classical anti-NMDAR encephalitis (n = 18), patients after viral encephalitis (n = 17) were more likely to have worse clinical outcomes. They exhibited a higher modified Rankin Scale/Pediatric Cerebral Performance Category score and more frequent seizures. A predictor of poor outcome was presentation after viral encephalitis (odds ratio 35.7, 95% confidence interval 4.64 to 275.03, P = 0.001). CONCLUSION: Anti-NMDAR encephalitis in infants and toddlers clinically presents with movement disorders, developmental regression, and abnormal behaviors. Interestingly, this group had a higher proportion of patients after viral encephalitis, which is regarded as the only risk factor for poor outcomes.