Opsoclonus-myoclonus syndrome is a rare neurological condition characterized by opsoclonus, myoclonus, ataxia, irritability, and sleep disturbances. In pediatric patients, symptoms usually start between 16 and 18 months of age; opsoclonus-myoclonus syndrome presentation in children under 6 months is rare. Approximately 50% of cases are associated with neuroblastoma. We report an early onset presentation of opsoclonus-myoclonus syndrome in a previously healthy, 3-month-old female infant. The diagnostic workup revealed no abnormalities. The patient underwent monthly cycles of dexamethasone pulses and intravenous immunoglobulin with a favorable response. After a few months, the patient presented intermittent opsoclonus before the next scheduled pulse so from the 9th cycle onwards, the intravenous immunoglobulin dose was increased to 2 g/kg. After 9 months of treatment, she was diagnosed with a latent Mycobacterium tuberculosis infection. Due to this infection, dexamethasone pulses were discontinued, and intravenous immunoglobulin treatment was maintained with clinical improvement The patient received 18 intravenous immunoglobulin cycles, leaving her with a score of one on the Mitchell-Pike scale. Developmental milestones have been attained according to age. Despite the range of therapeutic options for managing opsoclonus-myoclonus syndrome described in the literature, the efficacy of these available therapies needs to be better established. A modified upfront approach with dexamethasone and intravenous immunoglobulin could be an option in settings where rituximab is unavailable.

OBJECTIVE: To describe a case of post-immune checkpoint inhibitor (ICI) opsoclonus-myoclonus-ataxia syndrome (OMAS), with complete clinical remission after treatment.
METHODS: A 52-year-old man was admitted because of subacute-onset vertigo, dysarthria, vomiting, and weight loss. He was under atezolizumab (anti-PD-L1) monotherapy (23 cycles) for metastatic small-cell lung cancer, with excellent response.
RESULTS: On examination (1 month after symptom onset), the patient had opsoclonus, dysarthria, severe truncal and gait ataxia, and mild appendicular ataxia without myoclonus (SARA score 26/40). Brain MRI showed mild cerebellar atrophy, and CSF analysis disclosed pleocytosis and oligoclonal bands. Anti-SOX1 antibodies were detected in serum and CSF. Atezolizumab was stopped, and corticosteroids and monthly IV immunoglobulins were administered. Chemotherapy (carboplatin and etoposide) was also started because of cancer progression. Three months later, examination showed regression of the opsoclonus, truncal ataxia, and dysarthria and persistence of very mild gait ataxia (SARA score 3.5/40), which completely regressed at last examination (20 months after onset).
CONCLUSIONS: The clinical pattern and reversibility bring the present case close to a few patients with paraneoplastic OMAS described before the ICI era. More research is needed to clarify the pathogenesis and outcomes of OMAS in the context of ICI.

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UNASSIGNED: Opsoclonus is a rare disorder characterized by conjugate multidirectional, horizontal, vertical, and torsional saccadic oscillations, without intersaccadic interval, resulting from dysfunction within complex neuronal pathways in the brainstem and cerebellum. While most cases of opsoclonus are associated with autoimmune or paraneoplastic disorders, infectious agents, trauma, or remain idiopathic, opsoclonus can also be caused by medications affecting neurotransmission. This review was prompted by a case of opsoclonus occurring in a patient with Multiple System Atrophy, where amantadine, an NMDA-receptor antagonist, appeared to induce opsoclonus.
UNASSIGNED: Case report of a single patient and systematized review of toxic/drug-induced opsoclonus, selecting articles based on predefined criteria and assessing the quality of included studies.
UNASSIGNED: The review included 30 articles encompassing 158 cases of toxic/drug-induced opsoclonus. 74% of cases were attributed to bark scorpion poisoning, followed by 9% of cases associated with chlordecone intoxication. The remaining cases were due to various toxics/drugs, highlighting the involvement of various neurotransmitters, including acetylcholine, glutamate, GABA, dopamine, glycine, and sodium channels, in the development of opsoclonus.
UNASSIGNED: Toxic/drug-induced opsoclonus is very rare. The diversity of toxics/drugs impacting different neurotransmitter systems makes it challenging to define a unifying mechanism, given the intricate neuronal pathways underlying eye movement physiology and opsoclonus pathophysiology.

BACKGROUND: Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare autoimmune disorder of the nervous system presenting with abnormal eye and limb movements, altered gait, and increased irritability. Two to four percent of children diagnosed with neuroblastoma have neuroblastoma-associated OMAS (NA-OMAS). These children typically present with non-high-risk neuroblastoma that is cured with surgery, with or without chemotherapy. Despite excellent overall survival, patients with NA-OMAS can have significant persistent neurological and developmental issues.
OBJECTIVE: This study aimed to describe long-term neurocognitive and adaptive functioning of patients with NA-OMAS treated with multimodal therapy, including intravenous immunoglobulin (IVIG) on Children\'s Oncology Group (COG) protocol ANBL00P3.
METHODS: Of 53 children enrolled on ANBL00P3, 25 submitted evaluable neurocognitive data at diagnosis and at least one additional time point within 2 years and were included in the analyses. Adaptive development was assessed via the Vineland Adaptive Behavior Scale, and validated, age-appropriate measures of intellectual function were also administered.
RESULTS: Twenty-one of the 25 patients in this cohort ultimately received IVIG. Descriptive spaghetti plots suggest that this cohort demonstrated stable long-term cognitive functioning and adaptive development over time. This cohort also demonstrated decreased OMAS scores over time consistent with improved OMAS symptoms.
CONCLUSIONS: While statistical significance is limited by small sample size and loss to follow-up over 10 years, findings suggest stable long-term cognitive and adaptive functioning over time in this treated cohort.

OBJECTIVE: 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).
CONCLUSIONS: 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.

BACKGROUND: Little is known about the longitudinal trajectory of brain growth in children with opsoclonus-myoclonus ataxia syndrome. We performed a longitudinal evaluation of brain volumes in pediatric opsoclonus-myoclonus ataxia syndrome patients compared with age- and sex-matched healthy children.
METHODS: This longitudinal case-control study included brain magnetic resonance imaging (MRI) scans from consecutive pediatric opsoclonus-myoclonus ataxia syndrome patients (2009-2020) and age- and sex-matched healthy control children. FreeSurfer analysis provided automatic volumetry of the brain. Paired t tests were performed on the curvature of growth trajectories, with Bonferroni correction.
RESULTS: A total of 14 opsoclonus-myoclonus ataxia syndrome patients (12 female) and 474 healthy control children (406 female) were included. Curvature of the growth trajectories of the cerebral white and gray matter, cerebellar white and gray matter, and brainstem differed significantly between opsoclonus-myoclonus ataxia syndrome patients and healthy control children (cerebral white matter, P = .01; cerebral gray matter, P = .01; cerebellar white matter, P < .001; cerebellar gray matter, P = .049; brainstem, P < .01).
CONCLUSIONS: We found abnormal brain maturation in the supratentorial brain, brainstem, and cerebellum in children with opsoclonus-myoclonus ataxia syndrome.

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare immune-mediated movement disorder occurring as a paraneoplastic manifestation of neuroblastic tumours (NTs), especially neuroblastoma in infancy. Ganglioneuroma (GN), the benign tumour in the spectrum, is rarely associated with OMAS. We report the case of a child in her second year of life presenting with acute onset of progressive paraplegia and OMAS. MRI showed diffuse and infiltrating left paraspinal mass from T3-T9 levels with differentials of neuroblastoma or ganglioneuroblastoma. Histopathological and immunohistochemistry examination of the excised tumour showed maturing GN. The OMAS was managed with intravenous immunoglobulin and steroids. In the 6-month follow-up, the child has a residual motor weakness with myelomalacia in neuroimaging. The case report substantiates the occurrence of OMAS as paraneoplastic manifestation in NTs, including benign, in children younger than 2 years with a female predilection.

暂无摘要。

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder characterized by myoclonus, ataxia, and tremors. It can be classified as neoplastic or idiopathic, with small cell lung cancer being commonly associated. Herein, we present a rare case of refractory paraneoplastic neurological syndrome (PNS) caused by large cell neuroendocrine carcinoma (LCNEC), a rare form of non-small cell lung cancer (NSCLC). A 60-year-old otherwise healthy man presented with acute-onset dysarthria, gait instability, and numbness on the right side of his body. According to the clinical symptoms and neurological examination, we initially suspected cerebellar infarction; however, brain imaging revealed no abnormal findings. After a few days, the patient developed worsening horizontal nystagmus, irregular ocular rhythms, and generalized involuntary movements, indicative of OMS. A systemic evaluation revealed a solitary nodule in the lower lobe of the right lung, leading to a clinical diagnosis of PNS. The patient underwent segmentectomy to treat an early-stage LCNEC nodule after one month from onset. Despite all therapeutic interventions, OMS was refractory, and after consulting with the person himself and the family, palliative care was selected. However, the patient showed a clinical response belatedly five months after surgery. This case highlights the importance of considering PNS, and that it may be associated with a rare malignancy when cerebellar symptoms are observed, and the challenges in managing refractory PNS associated with rare forms of NSCLC.