Longitudinal multi-modal neuroimaging in opsoclonus–myoclonus syndrome

Paraneoplastic Cerebellar Degeneration Associated with Breast Cancer: A Case Report and a Narrative Review

Paraneoplastic neurological syndromes (PNSs) are an uncommon complication of cancer, affecting nearby 1/10,000 subjects with a tumour. PNSs can involve all the central and peripheral nervous systems, the muscular system, and the neuromuscular junction, causing extremely variable symptomatology. The diagnosis of the paraneoplastic disease usually precedes the clinical manifestations of cancer, making an immediate recognition of the pathology crucial to obtain a better prognosis. PNSs are autoimmune diseases caused by the expression of common antigens by the tumour and the nervous system. Specific antibodies can help clinicians diagnose them, but unfortunately, they are not always detectable. Immunosuppressive therapy and the treatment of cancer are the cornerstones of therapy for PNSs. This paper reports a case of PNSs associated with breast tumours and focuses on the most common paraneoplastic neurological syndromes. We report a case of a young female with a clinical syndrome of the occurrence of rigidity in the right lower limb with postural instability with walking supported and diplopia, with a final diagnosis of paraneoplastic cerebellar degeneration and seronegative rigid human syndrome associated with infiltrating ductal carcinoma of the breast.

Temporal Changes in Brain Perfusion in a Patient with Myoclonus and Ataxia Syndrome Associated with COVID-19

Myoclonus and ataxia, with or without opsoclonus, have recently been recognized as a central nervous system syndrome associated with coronavirus disease-2019 (COVID-19). A 52-year-old Japanese man developed myoclonus and ataxia 16 days after the onset of COVID-19. Brain single-photon emission computed tomography (SPECT) revealed hyperperfusion in the cerebellum and hypoperfusion in the cerebral cortices with frontal predominance during the acute stage, which improved over two months. This study indicates that brain perfusion SPECT can be effective in detecting functional alterations in COVID-19-related myoclonus and ataxia.

Autoimmune cerebellar hypermetabolism: Report of three cases and literature overview

We report three cases of vermian cerebellar hypermetabolism in patients with autoimmune encephalitis. One of our patients was positive for anti-Ma2 antibodies and one for anti-Zic4 antibodies while the remaining patient did not present any known antibodies. The seronegative patient deteriorated after immune checkpoint inhibitor treatment for a pulmonary adenocarcinoma and improved with immunosuppressive drugs, which is in favour of an underlying autoimmune mechanism. They all presented with subacute neurological symptoms. Brain magnetic resonance imaging was normal except in one patient, where hyperintensities were present on FLAIR sequence around the third ventricle and the cerebral aqueduct. ¹⁸F-FDG brain positron emission tomography with computed tomography (¹⁸F-FDG PET-CT) demonstrated an unusual vermian cerebellar hypermetabolism in the three cases. While cerebellar hypermetabolism on ¹⁸F-FDG PET-CT has been described in various neurological diseases, such vermian - and more broadly cerebellar - hypermetabolism was seldom described in previous studies on autoimmune encephalitis. When differential diagnoses have been ruled out, this pattern may be of interest for the positive diagnosis of autoimmune encephalitis in difficult diagnostic cases.

Opsoclonus-myoclonus syndrome with severe clinical course and beneficial outcome: A case report

RATIONALE

Opsoclonus-myoclonus syndrome (OMS) is a rare immune-mediated movement disorder, mostly of paraneoplastic or idiopathic origin. The disease usually has an acute onset, serious course and leads rapidly to disability in adult patients. To the best of our knowledge, this is the fourth presented case of OMS with a severe course and complete reversibility of neurological symptoms in a pregnant woman. This report includes videos and a literature review.

PATIENT CONCERNS

A 30-year-old woman in the 12th week of pregnancy developed severe nausea and vomiting, after several days balance and gait disorders appeared. On admission to hospital, neurological examination revealed opsoclonus, dysarthria, myoclonic jerks with ataxia of the trunk and limbs with inability to sit, stand or walk.

DIAGNOSIS

Well-known causes of OMS were excluded. Although in our patient the idiopathic origin of the disorder was taken under consideration, diagnosis of opsoclonus-myoclonus related to the pregnancy was highly likely.

INTERVENTIONS

After administration of steroids and benzodiazepines the patient improved.

OUTCOMES

In the 6th month of pregnancy, after termination of immunotherapy, she recovered completely and was able to sit, stand and walk independently. In the 39th week of pregnancy, she delivered a healthy child.

LESSONS

We confirm that understanding of clinical symptoms and rare causes of OMS contributes to early diagnosis and therapy, which ensures an optimal outcome. One probable cause of OMS could be a physiological change to immune system regulation during pregnancy. The relationship between OMS and pregnancy remains uncertain and needs further investigation.

Myoclonus and cerebellar ataxia associated with COVID-19: a case report and systematic review

Background

Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic in December 2019, neurological manifestations have been recognized as potential complications. Relatively rare movement disorders associated with COVID-19 are increasingly reported in case reports or case series. Here, we present a case and systematic review of myoclonus and cerebellar ataxia associated with COVID-19.

Methods

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline using the PubMed and Ovid MEDLINE databases, from November 1, 2019 to December 6, 2020.

Results

51 cases of myoclonus or ataxia associated with COVID-19, including our case, were identified from 32 publications. The mean age was 59.6 years, ranging from 26 to 88 years, and 21.6% were female. Myoclonus was multifocal or generalized and had an acute onset, usually within 1 month of COVID-19 symptoms. Myoclonus occurred in isolation (46.7%), or with ataxia (40.0%) or cognitive changes (30.0%). Most cases improved within 2 months, and treatment included anti-epileptic medications or immunotherapy. Ataxia had an acute onset, usually within 1 month of COVID-19 symptoms, but could be an initial symptom. Concurrent neurological symptoms included cognitive changes (45.5%), myoclonus (36.4%), or a Miller Fisher syndrome variant (21.2%). Most cases improved within 2 months, either spontaneously or with immunotherapy.

Conclusions

This systematic review highlights myoclonus and ataxia as rare and treatable post-infectious or para-infectious, immune-mediated phenomena associated with COVID-19. The natural history is unknown and future investigation is needed to further characterize these movement disorders and COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10458-0.

Serum IgG-induced microglial activation enhances neuronal cytolysis via the NO/sGC/PKG pathway in children with opsoclonus-myoclonus syndrome and neuroblastoma

Background

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disease. Some children with OMS also have neuroblastoma (NB). We and others have previously documented that serum IgG from children with OMS and NB induces neuronal cytolysis and activates several signaling pathways. However, the mechanisms underlying OMS remain unclear. Here, we investigated whether nitric oxide (NO) from activated microglias and its cascade contribute to neuronal cytolysis in pediatric OMS.

Methods

The activation of cultured cerebral cortical and cerebellar microglias incubated with sera or IgG isolated from sera of children with OMS and NB was measured by the expression of the activation marker, cytokines, and NO. Neuronal cytolysis was determined after exposing to IgG-treated microglia-conditioned media. Using inhibitors and activators, the effects of NO synthesis and its intracellular cascade, namely soluble guanylyl cyclase (sGC) and protein kinase G (PKG), on neuronal cytolysis were evaluated.

Results

Incubation with sera or IgG from children with OMS and NB increased the activation of cerebral cortical and cerebellar microglias, but not the activation of astrocytes or the cytolysis of glial cells. Moreover, the cytolysis of neurons was elevated by conditioned media from microglias incubated with IgG from children with OMS and NB. Furthermore, the expression of NO, sGC, and PKG was increased. Neuronal cytolysis was relieved by the inhibitors of NO signaling, while neuronal cytolysis was exacerbated by the activators of NO signaling but not proinflammatory cytokines. The cytolysis of neurons was suppressed by pretreatment with the microglial inhibitor minocycline, a clinically tested drug. Finally, increased microglial activation did not depend on the Fab fragment of serum IgG.

Conclusions

Serum IgG from children with OMS and NB potentiates microglial activation, which induces neuronal cytolysis through the NO/sGC/PKG pathway, suggesting an applicability of microglial inhibitor as a therapeutic candidate.

IGF-1 alleviates serum IgG-induced neuronal cytolysis through PI3K signaling in children with opsoclonus-myoclonus syndrome and neuroblastoma

BACKGROUND

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder, usually accompanied by neuroblastoma (NB). There is no targeted treatment and animal model of OMS. We aimed to investigate whether insulin-like growth factor 1 (IGF-1)/phosphoinositide 3-kinase (PI3K) signaling alleviates neuronal cytolysis in pediatric OMS.

METHODS

Cultured rat cerebral cortical neurons and cerebellar neurons were incubated with sera or IgG isolated from sera of children with OMS and NB. Cytolysis and PI3K expression were measured by the lactate dehydrogenase assay and enzyme-linked immunosorbent assay, respectively. Using inhibitors and activators, the effects of IGF-1 and PI3K on cytolysis were investigated.

RESULTS

The incubation of sera or IgG from children with OMS and NB increased cytolysis in not only cerebellar neurons, but also cerebral cortical neurons. Furthermore, the IGF-1 receptor antagonist NVP-AEW541 exaggerated cytolysis in children with OMS and NB. IGF-1 alleviated cytolysis, which was blocked by the PI3K inhibitor LY294002. Additionally, sera or IgG from children with OMS and NB compensatively elevated PI3K expression. LY294002 exacerbated cytolysis; whereas, the PI3K activator 740 Y-P suppressed cytolysis.

CONCLUSION

IGF-1/PI3K signaling alleviates the cytolysis of cultured neurons induced by serum IgG from children with OMS and NB, which may be innovation therapy targets.

Update on opsoclonus-myoclonus syndrome in adults

Opsoclonus-myoclonus syndrome in adults is a rare and heterogeneous disorder with the clinical features of opsoclonus, myoclonus, ataxia, and behavioral and sleep disturbances. The pathophysiology is thought to be immunological on the basis of paraneoplastic or infectious etiologies. Immunomodulatory therapies should be performed although the response may be incomplete. A number of autoantibodies have been identified against a variety of antigens, but no diagnostic immunological marker has yet been identified. This review focuses on underlying mechanisms of opsoclonus-myoclonus syndrome, including findings that have been identified recently, and provides an update on the clinical features and treatments of this condition.

Immune-mediated ataxias

Immune-mediated cerebellar ataxia (CA) comprises a group of rare diseases that are still incompletely described, and are probably underdiagnosed. Both acute and progressive progressions are possible. Different syndromes have been identified, including CA associated with anti-GAD antibodies, the cerebellar type of Hashimoto encephalopathy, primary autoimmune CA, gluten ataxia, opsoclonus-myoclonus syndrome, and paraneoplastic cerebellar degenerations. Most of these syndromes are associated with autoantibodies targeting neuronal antigens. Additionally, autoimmune CA can be triggered by infections, especially in children, and in rare cases occur in the context of an autoimmune multisystem disease, such as systemic lupus erythematosus, sarcoidosis, or Behçet disease. A careful workup is needed to distinguish autoimmune CA from other causes. In adults, a paraneoplastic origin must be ruled out, especially in cases with subacute onset. Neurologic outcome in adults is frequently poor, and optimal therapeutic strategies remain ill defined. The outcome in children is in general good, but children with a poor recovery are on record. The precise pathophysiologic mechanisms even in the presence of detectable autoantibodies are still largely unknown. Further research is needed on both the clinical and mechanistic aspects of immune-mediated CA, and to determine optimal therapeutic strategies.