Opsoclonus–myoclonus syndrome

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): current understanding and challenges

New diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) have recently been proposed, distinguishing this syndrome from other inflammatory diseases of the central nervous system. Seropositivity status for MOG-IgG autoantibodies is important for diagnosing MOGAD, but only in the context of robust clinical characterization and cautious interpretation of neuroimaging. Over the last several years, access to cell-based assay (CBA) techniques has improved diagnostic accuracy, yet the positive predictive value of serum MOG-IgG values varies with the prevalence of MOGAD in any given patient population. For this reason, possible alternative diagnoses need to be considered, and low MOG-IgG titers need to be carefully weighted. In this review, cardinal clinical features of MOGAD are discussed. Key challenges to the current understanding of MOGAD are also highlighted, including uncertainty regarding the specificity and pathogenicity of MOG autoantibodies, the need to identify immunopathologic targets for future therapies, the quest to validate biomarkers that facilitate diagnosis and detect disease activity, and the importance of deciphering which patients with MOGAD require long-term immunotherapy.

Opsoclonus Myoclonus Syndrome in a Case of Severe Acute Malnutrition in Children: A Case Report

Opsoclonus myoclonus syndrome (OMS) is a rare (1 in 10 million people per year) but nonfatal autoimmune disorder characterized by involuntary oscillating eye movements, multifocal muscular jerky movements, severe ataxia, and neuropsychological and behavioral changes. It usually manifests as a paraneoplastic condition but has other etiologies also. To the best of our knowledge, this is the first case of OMS seen in a patient with severe acute malnutrition (SAM). Parents brought a three-year-old female child with complaints of being unable to sit, stand, and hold her neck for the past 18 months. The patient has had involuntary eyeball movements for three months and has shown regression in milestones. Our study aimed to understand the pathophysiology, etiology, and clinical course of OMS in a child with SAM. However, relapses and long-term developmental sequelae are common due to the lack of a common consensus regarding therapeutic guidelines.

Clinical features and outcomes of opsoclonus myoclonus ataxia syndrome

OBJECTIVES AND METHODS

Opsoclonus myoclonus ataxia syndrome (OMAS) is a rare neuroinflammatory disorder. We aimed to retrospectively evaluate clinical and laboratory data and outcomes of 23 children diagnosed with OMAS in two children's hospitals between 2010 and 2021.

RESULTS

There were 14 boys and 9 girls aged 4-113 months, median 24 months. Ten (43.5%) children had paraneoplastic causes: neuroblastoma/ganglioneuroblastoma (n = 9), acute lymphoblastic leukemia (n = 1). Three children had a postinfectious cause (upper respiratory tract infection in 2, EBV infection in 1) and two had a history of vaccination (varicella in 1, hepatitis A and meningococcal in 1). No underlying factor was identified in 8 (34.8%) children. Speech disorders were more frequent in patients with neural tumors than in those without (p = 0.017). Intravenous immunoglobulin and steroids were effective as initial treatment in most children. Rituximab resulted in at least mild improvement in all 6 children with persistent or recurrent symptoms. Nine (39%) children experienced at least one relapse. Neurological sequelae were detected in 13 (57%) children. There was no significant correlation between clinical characteristics and outcome, except for higher risk of relapse in case of incomplete recovery after first attack (p = 0.001).

CONCLUSIONS

Acute lymphoblastic leukemia, vaccines against hepatitis A and meningococci can be included among antecedent factors in OMAS. Among clinical symptoms, speech problems might point to the likelihood of an underlying neoplasm in OMAS. Intravenous immunoglobulin and steroids may be chosen for initial treatment while rituximab can increase the chance of recovery in case of persistent or recurrent symptoms. The presence of relapse was associated with poor outcome.

Opsoclonus myoclonus and ataxia syndrome with supraventricular tachycardia

Pediatric opsoclonus-myoclonus and ataxia syndrome (OMAS) is a neurologic disorder characterized by disturbances in eye movement, muscle jerks, ataxia, sleep, and mood. In approximately 50% of cases, it is a paraneoplastic syndrome associated with a neuroblastoma. In the remaining cases, it is believed that the tumor is occult, has involuted, or there is a preceding immune-stimulating event. While neuroblastomas can be associated with other paraneoplastic syndromes, supraventricular tachycardia (SVT) is rarely reported in the literature, and to our knowledge, this is the first case of SVT secondary to idiopathic OMAS. Confounding treatment toxicity, including intravenous immunoglobulin and other immunomodulatory drugs, should be screened for possible cardiovascular side effects in OMAS patients. The development of cardiac arrhythmias during OMAS treatment is not a contraindication to therapy. In these patients, arrhythmias should be controlled with vagal maneuvers or antiarrhythmics as needed while OMAS treatment is completed.

Paraneoplastic syndrome in neuroophthalmology

Paraneoplastic syndrome is a group of clinical symptoms that occur in the state of systemic malignant tumors. Paraneoplastic syndrome of the nervous system can affect any part of the central and peripheral nervous system and may also affect the eyes. In neuroophthalmology, paraneoplastic syndrome has a variety of manifestations that can affect both the afferent and efferent visual systems. The afferent system may involve the optic nerve, retina and uvea; the efferent system may involve eye movement, neuromuscular joints or involuntary eye movements and pupil abnormalities and may also have other neurological symptoms outside the visual system. This article discusses the clinical manifestations, pathological mechanisms, detection methods and treatment methods of paraneoplastic syndrome in neuroophthalmology. The performance of paraneoplastic syndrome is diverse, the diagnosis is difficult, and the treatment should be considered systematically. Differential diagnosis, optimal evaluation and management of these manifestations is not only the key to treatment but also a challenge.

Eye Movement Disorders in Movement Disorders

Oculomotor assessment is an essential element of the neurological clinical examination and is particularly important when evaluating patients with movements disorders. Most of the brain is involved in oculomotor control, and thus many neurological conditions present with oculomotor abnormalities. Each of the different classes of eye movements and their features can provide important information that can facilitate differential diagnosis. This educational review presents a clinical approach to eye movement abnormalities that are commonly seen in parkinsonism, ataxia, dystonia, myoclonus, tremor, and chorea. In parkinsonism, subtle signs such as prominent square wave jerks, impaired vertical optokinetic nystagmus, and/or the "round the houses" sign suggest early progressive supranuclear gaze palsy before vertical gaze is restricted. In ataxia, nystagmus is common, but other findings such as oculomotor apraxia, supranuclear gaze palsy, impaired fixation, or saccadic pursuit can contribute to diagnoses such as ataxia with oculomotor apraxia, Niemann-Pick type C, or ataxia telangiectasia. Opsoclonus myoclonus and oculopalatal myoclonus present with characteristic phenomenology and are usually easy to identify. The oculomotor exam is usually unremarkable in isolated dystonia, but oculogyric crisis is a medical emergency and should be recognized and treated in a timely manner. Gaze impersistence in a patient with chorea suggests Huntington's disease, but in a patient with dystonia or tremor, Wilson's disease is more likely. Finally, functional eye movements can reinforce the clinical impression of a functional movement disorder.

Neuroblastoma With Opsoclonus-Myoclonus-Ataxia Syndrome: Role of Chemotherapy in the Management: Experience From a Tertiary Care Center in a Resource-limited Setting

Children with neuroblastoma (NB) and opsoclonus-myoclonus-ataxia syndrome (OMAS) have a favorable oncologic outcome and overall survival. In contrast, despite intensive multidrug immunomodulation, the neurologic outcome is complicated by the relapsing nature of the neurologic symptoms and long-term neurobehavioral sequelae. Being associated with low-risk NB, there exists an ambiguity in the current literature regarding the administration of chemotherapy in these children. We reviewed our archives for children with NB-OMAS over a 22-year (January 1996 to January 2018) period. Eighteen children (10 female) with a median age at diagnosis of 23 months had NB-OMAS and were included. They had stage 1 (9/18; 50%), 2 (1/18; 5.5%), 3 (7/18; 39%), and 4 (1/18; 5.5%) disease according to the International Neuroblastoma Staging System. Multimodality therapy included surgery (16/18; 89%), chemotherapy (11/18; 61%), and immunomodulatory therapy (10/18; 55%). Complete oncologic remission was achieved in all children. Relapse of OMAS and presence of neurologic sequelae were observed in 1 (5.5%) and 5 (28%) cases, respectively. Presence of neurologic sequelae was significantly associated with low-tumor stage (P=0.036) and treatment without chemotherapy (P=0.003). Chemotherapy administration was the only variable significantly predicting a favorable neurologic outcome (95% confidence interval: 0.26-1.40, P=0.01). To conclude, our study including a limited cohort of patients highlights a favorable neurologic outcome associated with chemotherapy administration in children with NB-OMAS. However, further studies with larger sample size need to be conducted before drawing any definite conclusions.

De Novo Movement Disorders and COVID-19: Exploring the Interface

Background

Neurological manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being widely documented. However, movement disorders in the setting of 2019 coronavirus infectious disease (COVID-19) have been a strikingly less discussed topic.

Objectives

To summarize available pieces of evidence documenting de novo movement disorders in COVID-19.

Methods

We used the existing PRISMA consensus statement. Data were collected from PubMed, EMBASE, Web of Science, and Scopus databases up to the 29th January, 2021, using pre-specified searching strategies.

Results

Twenty-two articles were selected for the qualitative synthesis. Among these, a total of 52 patients with de novo movement disorders were reported. Most of these had myoclonus, ataxia, tremor or a combination of these, while three had parkinsonism and one a functional disorder. In general, they were managed successfully by intravenous immunoglobulin or steroids. Some cases, primarily with myoclonus, could be ascribed to medication exposures, metabolic disturbances or severe hypoxia, meanwhile others to a post-or para-infectious immune-mediated mechanism. SARS-CoV-2 could also invade the central nervous system, through vascular or retrograde axonal pathways, and cause movement disorders by two primary mechanisms. Firstly, through the downregulation of angiotensin-converting enzyme 2 receptors, resulting in the imbalance of dopamine and norepinephrine; and secondly, the virus could cause cellular vacuolation, demyelination and gliosis, leading to encephalitis and associated movement disorders.

Conclusion

De novo movement disorders are scantly reported in COVID-19. The links between SARS-CoV-2 and movement disorders are not yet established. However, we should closely monitor COVID-19 survivors for the possibility of post-COVID movement disorders.

Inflammatory Diseases of the Central Nervous System

Pediatric neuroinflammatory conditions are a complex group of disorders with a wide range of clinical presentations. Patients can present with a combination of focal neurologic deficits, encephalopathy, seizures, movement disorders, or psychiatric manifestations. There are several ways that pediatric neuroinflammatory conditions can be classified, including clinical presentation, pathophysiologic mechanism, and imaging and laboratory findings. In this article, we group these conditions into acquired demyelinating diseases, immune-mediated epilepsies/encephalopathies, primary rheumatologic conditions with central nervous system (CNS) manifestations, CNS vasculitis, and neurodegenerative/genetic conditions with immune-mediated pathophysiology and discuss epidemiology, pathophysiology, clinical presentation, treatment, and prognosis of each disorder.

Pathogenesis, diagnosis and treatment of paraneoplastic neurologic syndromes

Introduction: Paraneoplastic neurological syndromes (PNS) are a rare heterogeneous group of neurological diseases associated with tumors. These syndromes are the result of a cross-reactive immune response against antigens shared by the tumor and the nervous system. The discovery of an increasing number of autoantigens and the identification of tumoral factors leading to a substantial antitumoral immune response makes this topic highly innovative.Areas covered: This review covers the clinical, oncological, pathophysiological aspects of both immunological PNS groups. One is associated with autoantibodies against intracellular onconeural antibodies, which are highly specific for an underlying tumor, although the disease is mainly T-cell mediated. In contrast, PNS associated with pathogenic surface-binding/receptor autoantibodies, which are often responsive to immunosuppressive treatment, may manifest as paraneoplastic and non-paraneoplastic diseases. The most frequent tumors associated with PNS are (small cell) lung cancer, gynecological tumors, thymoma, lymphoma, and, in children, neuroblastoma. A special interest is given to PNS, induced by immune checkpoint-inhibitors (ICIs).Expert opinion: Research in PNS, including the group of ICI-induced PNS provide new insights in both the pathophysiology of PNS and tumor immune interactions and offers new treatment options for this group of severe neurological diseases.

Opsoclonus-myoclonus syndrome associated with anti Kelch-like protein-11 antibodies in a young female patient without cancer

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder. The pathogenesis is thought to be immune-mediated. In adults, it may be idiopathic or paraneoplastic in origin. However, most cases of paraneoplastic OMS in adults are not associated with well-characterized antibodies, except for a small subgroup who have anti-Ri antibodies. Herein, we provide the first detailed description of a case of OMS associated with a Kelch-like protein-11 antibody, a newly discovered biomarker for paraneoplastic neurological syndromes associated with germ-cell tumors. This was a young female patient in whom no tumor was ever detected and who had an excellent response to rituximab.

Opsoclonus-myoclonus-ataxia syndrome in children

Opsoclonus-myoclonus-ataxia syndrome is a rare neuroimmunologic disorder typically presenting in previously healthy infants and toddlers. It is characterized by a clinical triad of (1) erratic saccadic intrusions; (2) myoclonus and/or ataxia; (3) behavioral features, typified by developmental plateauing, irritability and insomnia. About half of cases are associated with an underlying neuroblastoma and diagnostic imaging is essential once OMAS is suspected. A thorough workup, including serum, urine, and cerebrospinal fluid studies is critical to identify underlying biomarkers of OMAS itself or neuroblastoma. Historically, many children had relatively poor long-term outcomes, with residual neurologic and/or neuropsychiatry sequelae typical. More recent concepts have emphasized combined immunotherapy regimens that offer hope for better outcomes in children with this remarkable, challenging disease.

Tics, tremors and other movement disorders in childhood

Movement disorders presenting in childhood include tics, dystonia, chorea, tremor, stereotypy, myoclonus, and parkinsonism, each of which can be part of various clinical syndromes with distinct etiologies.  Some of these conditions are benign and require only reassurance; others are bothersome and require treatment, or may be clues that herald underlying pathology.  Answers lie in the inherent characteristics of the movements themselves, together with the clinical context provided in the history obtained by the examiner.  The aim of this review is to present an overview of the categories of involuntary movements, along with examples of common acquired and genetic causes, and an approach to history-taking, examination, and treatment.

NK Cell-mediated Neuroblastoma Cell Lysis is Enhanced by IgG From Patients With Pediatric Opsoclonus-Myoclonus Syndrome

Pediatric opsoclonus-myoclonussyndrome (OMS) is a rare autoimmune disorder of which 50% are associated with neuroblastoma (NB). We investigated whether surface-binding autoantibodies in OMS can enhance natural killer (NK) cell-mediated cytotoxicity in these patients. OMS immunoglobulin G (IgG) bound to NB cell lines and NK cell-mediated cytotoxicity to NB cells was enhanced after preincubation with OMS-IgG, but not IgG from NB without OMS or healthy controls. Activation of NK cells by surface-binding autoantibodies may be an additional mechanism of antitumor immunity in children with NB and OMS.

Eye oscilations with neurological implications in pediatric age

INTRODUCTION

Eye oscillations, both nystagmic and non-nystagic, can occur from birth. Most correspond to infantile nystagmus that dubates in the first six months of life, which include idiopathic, sensory, latent, or overt latent motor nystagmus. Those associated with neurological diseases or syndromes correspond to approximately 33%, their identification and correct evaluation being important given the potential visual and vital complications.

MATERIAL AND METHODS

We made a systematic review of the literature on supranuclear gaze control mechanisms and the main ocular oscillations with possible neurological implications, both in childhood. With this, we intend to assess if there are already established clinical-anatomical associations, and to propose a protocol on the complementary studies to be carried out in these cases.

RESULTS

There are still anatomical pathways involved in supranuclear gaze control that are not fully clarified and understood. Besides, except in the case of nystagmus in seesaw and upbeat, we did not find anatomical explanations for their pathogenesis. The need for complete neuro-ophthalmological physical examinations and the request for additional tests in children who present ocular oscillations with neurological characteristics are clear.

CONCLUSIONS

Supranuclear gaze control follows a complex neurological network that still needs to be studied better. With a better dissection of the same we could try to understand why the ocular oscillations that we studied have these specific forms of presentation. As for the complementary requests, the request for neuroimaging tests is practically constant, making the others according to the specific case before which we find ourselves.

Diagnostic values of 68Ga-labelled DOTANOC PET/CT imaging in pediatric patients presenting with paraneoplastic opsoclonus myoclonus ataxia syndrome

OBJECTIVES

Opsoclonus myoclonus ataxia (OMA) syndrome, also known as "Kinsbourne syndrome" or "dancing eye syndrome," is a rare, paraneoplastic entity which may be associated with pediatric neuroblastic tumors and carry a grave prognosis. We aimed to evaluate the role of ⁶⁸Ga DOTANOC PET/CT for detecting neuroblastic tumors in patients with OMA syndrome.

METHODS

We retrospectively evaluated the ⁶⁸Ga-DOTANOC PET/CT data of pediatric patients presenting with OMA syndrome from March 2012 to November 2018. A somatostatin receptor (SSTR)-expressing lesion with corresponding morphological change on CT image was considered PET-positive, while no abnormal SSTR expression or lesion was noticed in PET-negative patients. Histopathology and/or clinical/imaging follow-up (minimum one year) was considered a reference standard for comparing the PET/CT findings. The results of ⁶⁸Ga-DOTANOC PET/CT were also compared with ¹³¹I MIBG whole-body scintigraphy, which was available in five patients.

RESULTS

Of 38 patients (13 males, 25 females, aged 3-96 months), 18 (47.3%) had SSTR-expressing lesions (PET-positive), and histopathology revealed neuroblastic tumors in 17/18 lesions (neuroblastoma 14, ganglioneuroblastoma 2, and ganglioneuroma 1) and reactive hyperplasia in 1/18. The remaining 20/38 (52.6%) patients did not demonstrate SSTR-expressing lesions (PET-negative) and had an uneventful follow-up. The average SUVmax of the PET-positive lesions was 10.3 (range 2.8-34.5). The PET/CT results revealed 17 true-positive, one false-positive, 20 true-negative, and zero false-negative. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 100%, 95.2%, 94.4%, 100%, and 97.3% respectively.

CONCLUSIONS

⁶⁸Ga-DOTANOC PET/CT identified neuroblastic tumors with a high diagnostic accuracy in our cohort compared to histology and follow-up.

KEY POINTS

• Opsoclonus myoclonus ataxia (OMA) syndrome or "dancing eye syndrome" is a rare paraneoplastic entity which may be associated with pediatric neuroblastic tumors with a grave prognosis. • ¹²³I/¹³¹I MIBG imaging has a proven role for functional imaging in neuroblastoma or patients with OMA, but the role of ⁶⁸Ga-DOTANOC PET/CT is not yet studied. • 68Ga-labelled DOTANOC PET/CT (SSTR) imaging, in our cohort, was able to positively identify neuroblastic tumors with high diagnostic accuracy when compared with histology.

Treatment and revaccination of children with paraneoplastic opsoclonus-myoclonus-ataxia syndrome and neuroblastoma: The Memorial Sloan Kettering experience

OBJECTIVE

To review the treatment and revaccination of neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome (OMAS) patients at Memorial Sloan Kettering Cancer Center (MSK).

PROCEDURE

Institutional Review Board approval was obtained for this retrospective study of patients with neuroblastoma-associated OMAS followed at MSK from 2000 to 2016.

RESULTS

Fourteen patients (nine female) were 9-21 (median 17) months old at diagnosis of neuroblastoma and OMAS syndrome. They had stage 1 (n = 12), stage 2B, or intermediate-risk stage 4. Tumor histology was favorable in 11 patients, unfavorable in two, and unknown in one patient. No patient had amplified MYCN. All patients underwent tumor resection at diagnosis. Anti-neuroblastoma treatment was limited to chemotherapy in one patient. Overall survival is 100% at 3-16 (median 10) years. For OMAS, 13 patients received intravenous immune globulin (IVIg), adrenocorticotropic hormone (ACTH), and rituximab, and one received ACTH and IVIg. Seven patients experienced OMAS relapse. For these relapses, five patients received low-dose cyclophosphamide and two received rituximab. The mean total OMAS treatment was 20-96 (median 48) months. Seven patients started rituximab ≤3 months from diagnosis and did not relapse. The other six experienced OMAS relapse. To date, six patients have been revaccinated at a minimum of 2 years after completion of OMAS therapy without OMAS recurrence.

CONCLUSIONS

Patients with neuroblastoma-associated OMAS had excellent overall survival. Early initiation of rituximab, IVIg, and ACTH may reduce risks of OMAS relapse. Revaccination can be resumed without exacerbation of OMAS. Further investigation with a larger cohort of patients is needed.

Opsoclonus-myoclonus syndrome: clinical characteristics, therapeutic considerations, and prognostic factors in a Spanish paediatric cohort

INTRODUCTION

Opsoclonus-myoclonus-ataxia syndrome is a rare neuroinflammatory disorder with onset during childhood; aetiology may be paraneoplastic, para-infectious, or idiopathic. No biomarkers have yet been identified, and diagnosis is clinical. Better cognitive prognosis appears to be related to early onset of immunomodulatory therapy.

METHODS

We describe the epidemiological, clinical, therapeutic, and long-term prognostic characteristics of a cohort of 20 Spanish patients.

RESULTS

The mean age of onset was 21 months (range, 2-59). Ataxia and opsoclonus were the most frequent symptoms both at disease onset and throughout disease progression. The mean time from onset to diagnosis was 1.1 months. Neuroblast lineage tumours were detected in 45% of patients; these were treated with surgical resection in 7 cases and chemotherapy in 2. Cerebrospinal fluid analysis revealed pleocytosis in 4 cases (25%) and neither antineuronal antibodies nor oligoclonal bands were detected in any patient. Immunomodulatory drugs were used in all cases. Nine patients started combined immunomodulatory treatment at the time of diagnosis, and 5 patients after a mean of 2.2 months. In the long term, 6 of the 10 patients followed up for more than 5 years presented mild or moderate cognitive sequelae. Four patients presented relapses, generally coinciding with the decrease of corticosteroid doses.

CONCLUSIONS

Early initiation of immunotherapy, as well as triple combination therapy, where needed, was associated with a lower frequency of cognitive impairment 2 years after onset.

Paraneoplastic opsoclonus-myoclonus syndrome secondary to melanoma metastasis form occult primary cancer

Introduction

Opsoclonus-myoclonus syndrome (OMS) is an inflammatory neurological disorder, often requiring a prompt medical evaluation. Among the diverse etiologies associated with OMS are autoimmune, infectious, paraneoplastic, and systemic diseases, and drug intoxication.

Clinical Summary

The case of a 36-year-old female with a disabling holocranial headache, sudden loss of consciousness, aggressive behavior, vertigo, and a personal history of somatoform disorder and major depression is presented here. After hospital admission, the patient developed sudden stereotyped movements in all four extremities and oculogyric crises compatible with OMS. Cerebrospinal fluid analysis, viral and autoimmune assays, as well as blood, urine, and bronchial secretion cultures, drug metabolite urinalysis, and tumor markers were all negative. Furthermore, brain computed tomography (CT) and brain magnetic resonance imaging, along with thoraco-abdominopelvic CT and electroencephalography, were also all negative. The patient suffered type one respiratory insufficiency after 72 h of hospitalization, requiring an endotracheal tube. After 13 days the patient suffered cardiac arrest. Necropsy was performed reporting lymph nodes with a poorly differentiated malignant neoplastic lesion, HMB-45, melan-A, vimentin, and S-100 positive, compatible with melanoma metastasis from an occult primary cancer.

Discussion

While the incidence of melanoma of unknown primary is between 2.6 and 3.2%, with a median overall survival ranging between 24 and 127 months, when melanoma patients develop OMS their survival is markedly decreased. Although only 5 cases of paraneoplastic OMS secondary to melanoma have been reported in the literature, all had a poor prognosis, dying within 8 months of OMS onset.

Glutamate receptor δ2 serum antibodies in pediatric opsoclonus myoclonus ataxia syndrome

Objective

To identify neuronal surface antibodies in opsoclonus myoclonus ataxia syndrome (OMAS) using contemporary antigen discovery methodology.

Methods

OMAS patient serum immunoglobulin G immunohistochemistry using age-equivalent rat cerebellar tissue was followed by immunoprecipitation, gel electrophoresis, and mass spectrometry. Data are available via ProteomeXchange (identifier PXD009578). This generated a list of potential neuronal surface cerebellar autoantigens. Live cell-based assays were used to confirm membrane-surface antigens and adsorb antigen-specific immunoglobulin Gs. The serologic results were compared to the clinical data.

Results

Four of the 6 OMAS sera tested bound rat cerebellar sections. Two of these sera with similar immunoreactivities were used in immunoprecipitation experiments using cerebellum from postnatal rat pups (P18). Mass spectrometry identified 12 cell-surface proteins, of which glutamate receptor δ2 (GluD2), a predominately cerebellar-expressed protein, was found at a 3-fold-higher concentration than the other 11 proteins. Antibodies to GluD2 were identified in 14/16 (87%) OMAS samples, compared with 5/139 (5%) pediatric and 1/38 (2.6%) adult serum controls (p < 0.0001), and in 2/4 sera from patients with neuroblastoma without neurologic features. Adsorption of positive OMAS sera against GluD2-transfected cells substantially reduced but did not eliminate reactivity toward cerebellar sections.

Conclusion

Autoantibodies to GluD2 are common in patients with OMAS, bind to surface determinants, and are potentially pathogenic.

Neuroblastoma

Neuroblastoma is one of the most common solid tumors in children and has a diverse clinical behavior that largely depends on the tumor biology. Neuroblastoma exhibits unique features, such as early age of onset, high frequency of metastatic disease at diagnosis in patients over 1 year of age and the tendency for spontaneous regression of tumors in infants. The high-risk tumors frequently have amplification of the MYCN oncogene as well as segmental chromosome alterations with poor survival. Recent advanced genomic sequencing technology has revealed that mutation of ALK, which is present in ~10% of primary tumors, often causes familial neuroblastoma with germline mutation. However, the frequency of gene mutations is relatively small and other aberrations, such as epigenetic abnormalities, have also been proposed. The risk-stratified therapy was introduced by the Japan Neuroblastoma Study Group (JNBSG), which is now moving to the Neuroblastoma Committee of Japan Children's Cancer Group (JCCG). Several clinical studies have facilitated the reduction of therapy for children with low-risk neuroblastoma disease and the significant improvement of cure rates for patients with intermediate-risk as well as high-risk disease. Therapy for patients with high-risk disease includes intensive induction chemotherapy and myeloablative chemotherapy, followed by the treatment of minimal residual disease using differentiation therapy and immunotherapy. The JCCG aims for better cures and long-term quality of life for children with cancer by facilitating new approaches targeting novel driver proteins, genetic pathways and the tumor microenvironment.

Childhood opsoclonus-myoclonus syndrome: A case series from Tunisia

INTRODUCTION

Opsoclonus myoclonus syndrome (OMS) is a rare immune-mediated disorder characterized by opsoclonus, myoclonus, ataxia and behavioral changes. The aim of our study was to investigate the epidemiology, clinical features, etiological aspects and outcome of OMS in Tunisian children.

METHODS

We conducted a retrospective study over 11years (2005-2016) including all patients aged under 18years who were managed for newly diagnosed OMS in a tertiary care research centre for children with neurological symptoms. Epidemiological and clinical data were analyzed.

RESULTS

Fifteen patients were included. The male-female ratio was 7:8. Median age of onset was 4.32years (range: 14months-16years). Time to diagnosis ranged between 2days and 10months. Median follow-up period was 3.8years (range: 2-6years). Acute ataxia was the preponderant inaugural feature. Mean severity score was 9 (range: 3-14). In "Tumor group" (n=7), the main underlying malignancy was neuroblastoma identified in 5 patient. In "No tumor group" (n=8), parainfectious and idiopathic OMS were identified in 5 and 3 patients, respectively. All patients received immunomodulatory treatment. Complete recovery of OMS symptoms was obtained in 12 children. Comparing the "Tumor group" and the "No tumor group", there were no differences in age of onset, sex ratio, main presenting symptom, median OMS severity score or responsiveness to treatment. However, sleep and behavioral disturbances were more frequent in the "No tumor group" (p=0.04). Neurological sequelae were equally found in both groups.

CONCLUSION

Annual incidence of OMS in Tunisia could be estimated as 0.6 patients in children per million per year. Diagnosis may be challenging especially when the triad is incomplete. Although behavioral disturbances seem to be more frequent in the "No tumor group", our study suggests that there is no specific features differentiating paraneoplastic OMS from non paraneoplastic OMS. Acute symptoms are responsive to immunomodulatory treatment but long term follow up can reveal neurological (mainly cognitive) sequelae.

Myoclonic Disorders

Few movement disorders seem to make a straightforward approach to diagnosis and treatment more difficult and frustrating than myoclonus, due to its plethora of causes and its variable classifications. Nevertheless, in recent years, exciting advances have been made in the elucidation of the pathophysiology and genetic basis of many disorders presenting with myoclonus. Here, we provide a review of all of the important types of myoclonus encountered in pediatric and adult neurology, with an emphasis on the recent developments that have led to a deeper understanding of this intriguing phenomenon. An up-to-date list of the genetic basis of all major myoclonic disorders is presented. Randomized studies are scarce in myoclonus therapy, but helpful pragmatic approaches at diagnosis as well as treatment have been recently suggested.

Postintervention acute opsoclonus myoclonus syndrome

Opsoclonus myoclonus syndrome (OMS) is a rare, neurological condition affecting 1 in 10 000 000 people annually. Opsoclonus, defined as involuntary rapid, multivectorial oscillations of the eyes, together with ataxia and myoclonus are usually present. OMS may be paraneoplastic: often associated with occult neuroblastoma in childhood and with breast carcinoma or small cell lung carcinoma in adults. Other aetiologies include viral or toxic agents. The pathogenesis is thought to be immune mediated. A 37-year-old woman with previous inflammatory cranial mononeuropathies was admitted for elective dilatation and curettage (D&C). Immediately after she complained of left-sided paraesthesia and later became disoriented, with incoherent speech, inability to obey commands, opsoclonus of the eyes and myoclonic jerks. Investigations including onconeuronal antibodies, cerebrospinal fluid analysis, and imaging were normal. She was treated with intravenous methylprednisolone with rapid improvement. Previous surgeries with anaesthesia were uncomplicated. The anaesthetic agents used for the D&C were fentanyl and propofol.

Neuroimaging of Infectious and Inflammatory Diseases of the Pediatric Cerebellum and Brainstem

Cerebellar involvement by infectious-inflammatory conditions is rare in children. Most patients present with acute ataxia, and are typically previously healthy, young (often preschool) children. Viral involvement is the most common cause and ranges from acute postinfectious ataxia to acute cerebellitis MR imaging plays a crucial role in the evaluation of patients suspected of harboring inflammatory-infectious involvement of the cerebellum and brainstem. Knowledge of the imaging features of these disorders and technical competence on pediatric MR imaging are necessary for a correct interpretation of findings, which in turn prompts further management.

Altered functional brain connectivity in children and young people with opsoclonus-myoclonus syndrome

AIM

Opsoclonus-myoclonus syndrome (OMS) is a rare, poorly understood condition that can result in long-term cognitive, behavioural, and motor sequelae. Several studies have investigated structural brain changes associated with this condition, but little is known about changes in function. This study aimed to investigate changes in brain functional connectivity in patients with OMS.

METHOD

Seven patients with OMS and 10 age-matched comparison participants underwent 3T magnetic resonance imaging (MRI) to acquire resting-state functional MRI data (whole-brain echo-planar images; 2mm isotropic voxels; multiband factor ×2) for a cross-sectional study. A seed-based analysis identified brain regions in which signal changes over time correlated with the cerebellum. Model-free analysis was used to determine brain networks showing altered connectivity.

RESULTS

In patients with OMS, the motor cortex showed significantly reduced connectivity, and the occipito-parietal region significantly increased connectivity with the cerebellum relative to the comparison group. A model-free analysis also showed extensive connectivity within a visual network, including the cerebellum and basal ganglia, not present in the comparison group. No other networks showed any differences between groups.

INTERPRETATION

Patients with OMS showed reduced connectivity between the cerebellum and motor cortex, but increased connectivity with occipito-parietal regions. This pattern of change supports widespread brain involvement in OMS.

Clinical and Immunological Features of Opsoclonus-Myoclonus Syndrome in the Era of Neuronal Cell Surface Antibodies

IMPORTANCE

Most studies on opsoclonus-myoclonus syndrome (OMS) in adults are based on small case series before the era of neuronal cell surface antibody discovery.

OBJECTIVE

To report the clinical and immunological features of idiopathic OMS (I-OMS) and paraneoplastic OMS (P-OMS), the occurrence of antibodies to cell surface antigens, and the discovery of a novel cell surface epitope.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study and laboratory investigations of 114 adult patients with OMS at a center for autoimmune neurological disorders done between January 2013 and September 2015.

MAIN OUTCOMES AND MEASURES

Review of clinical records. Immunohistochemistry on rat brain and cultured neurons as well as cell-based assays were used to identify known autoantibodies. Immunoprecipitation and mass spectrometry were used to characterize novel antigens.

RESULTS

Of the 114 patients (62 [54%] female; median age, 45 years; interquartile range, 32-60 years), 45 (39%) had P-OMS and 69 (61%) had I-OMS. In patients with P-OMS, the associated tumors included lung cancer (n = 19), breast cancer (n = 10), other cancers (n = 5), and ovarian teratoma (n = 8); 3 additional patients without detectable cancer were considered to have P-OMS because they had positive results for onconeuronal antibodies. Patients with I-OMS, compared with those who had P-OMS, were younger (median age, 38 [interquartile range, 31-50] vs 54 [interquartile range, 45-65] years; P < .001), presented more often with prodromal symptoms or active infection (33% vs 13%; P = .02), less frequently had encephalopathy (10% vs 29%; P = .01), and had better outcome (defined by a modified Rankin Scale score ≤ 2 at last visit; 84% vs 39%; P < .001) with fewer relapses (7% vs 24%; P= .04). Onconeuronal antibodies occurred in 13 patients (11%), mostly Ri/ANNA2 antibodies, which were detected in 7 of 10 patients (70%) with breast cancer. Neuronal surface antibodies were identified in 12 patients (11%), mainly glycine receptor antibodies (9 cases), which predominated in P-OMS with lung cancer (21% vs 5% in patients with OMS without lung cancer; P = .02); however, a similar frequency of glycine receptor antibodies was found in patients with lung cancer without OMS (13 of 65 patients [20%]). A novel cell surface epitope, human natural killer 1 (HNK-1), was the target of the antibodies in 3 patients with lung cancer and P-OMS.

CONCLUSIONS AND RELEVANCE

Patients with I-OMS responded better to treatment and had fewer relapses than those with P-OMS. Older age and encephalopathy, significantly associated with P-OMS, are clinical clues suggesting an underlying tumor. Glycine receptor antibodies occur frequently in P-OMS with lung cancer, but the sensitivity and specificity are low. The HNK-1 epitope is a novel epitope in a subset of patients with P-OMS and lung cancer.

Segregation of Incomplete Achromatopsia and Alopecia Due to PDE6H and LPAR6 Variants in a Consanguineous Family from Pakistan

We report on two brothers with visual impairment, and non-syndromic alopecia in the elder proband. The parents were first-degree Pakistani cousins. Whole exome sequencing of the elder brother and parents, followed by Sanger sequencing of all four family members, led to the identification of the variants responsible for the two phenotypes. One variant was a homozygous nonsense variant in the inhibitory subunit of the cone-specific cGMP phosphodiesterase gene, PDE6H:c.35C>G (p.Ser12*). PDE6H is expressed in the cones of the retina, which are involved in perception of color vision. This is the second report of a homozygous PDE6H:c.35C>G variant causing incomplete achromatopsia (OMIM 610024), thus strongly supporting the hypothesis that loss-of-function variants in PDE6H cause this visual deficiency phenotype. The second variant was a homozygous missense substitution in the lysophosphatidic acid receptor 6, LPAR6:c.188A>T (p.Asp63Val). LPAR6 acts as a G-protein-coupled receptor involved in hair growth. Biallelic loss-of-function variants in LPAR6 cause hypotrichosis type 8 (OMIM 278150), with or without woolly hair, a form of non-syndromic alopecia. Biallelic LPAR6:c.188A>T was previously described in five families from Pakistan.

Trends and tenets in relapsing and progressive opsoclonus-myoclonus syndrome

Despite advances in inducing remission in pediatric opsoclonus-myoclonus syndrome (OMS), relapse remains a challenge. By definition, relapse is not a characteristic of monophasic OMS, but occurs at any time in the course of multiphasic OMS. Due to variability and heterogeneity, patients are best approached and treated on a case-by-case basis, using precepts derived from clinical and scientific studies. Treatment of provocations, such as infection or immunotherapy tapering, is the short-term goal, but discovering unresolved neuroinflammation and re-configuring disease-modifying agents is crucial in the long-term. The working hypothesis is that much of the injury in OMS results from neuroinflammation involving dysregulated B cells, which may cause loss of tolerance and autoantibody production. Biomarkers of disease activity include cerebrospinal fluid (CSF) B cell frequency, oligoclonal bands (OCB), B cell attractants (CXCL13) and activating factors (BAFF). Measuring these markers comprises modern detection and characterization of neuroinflammation or verifies 'no evidence of disease activity'. The decision making process is three-tiered: deciding if the relapse is bone fide, identifying its etiology, and formulating a therapeutic plan. Relapsing-remitting OMS is treatable, and combination multimodal/multi-mechanistic immunotherapy is improving the outcome. However, some patients progress to a refractory state with cognitive impairment and disability from failure to go into remission, multiple relapses, or more aggressive disease. This report provides new insights on underappreciated risks and pitfalls inherent in relapse, pro-active efforts to avoid progression, the need for early and sufficient treatment beyond corticosteroids and immunoglobulins, and utilization of disease activity biomarkers to identify high-risk patients and safely withdraw immunotherapy.

Myoclonus: Pathophysiology and Treatment Options

OPINION STATEMENT

Treatment of myoclonus requires an understanding of the physiopathology of the condition. The first step in treatment is to determine if there is an epileptic component to the myoclonus and treat accordingly. Secondly, a review of medications (e.g., opiates) and comorbidities (e.g., hepatic or renal failure) is required to establish the possibility of iatrogenic and reversible conditions. Once those are eliminated, delineation between cortical, cortico-subcortical, subcortical, brainstem, and spinal generators can determine the first-line treatment. Cortical myoclonus can be treated with levetiracetam, valproic acid, and clonazepam as first-line agents. Phenytoin and carbamazepine may paradoxically worsen myoclonus. Subcortical and brainstem myoclonus can be treated with clonazepam as a first-line agent, but levetiracetam and valproic acid can be tried as well. L-5-Hydroxytryptophan and sodium oxybate are agents used for refractory cases. Spinal myoclonus does not respond to anti-epileptic drugs, and clonazepam is a first-line agent. Botulinum toxin treatment can be useful for focal cases of spinal myoclonus. The etiology of propriospinal myoclonus is controversial, and a functional etiology is suspected in most cases. Treatment can include clonazepam, levetiracetam, baclofen, valproate, carbamazepine, and zonisamide. Functional myoclonus requires multimodal and multidisciplinary treatment that may include psychotropic drugs and physical and occupational therapy. Close collaboration between neurologists and psychiatrists is required for effective treatment. Finally, deep brain stimulation targeting the globus pallidus pars-interna bilaterally has been used in myoclonus-dystonia when pharmacological treatments have been exhausted.

Paraneoplastic immune-mediated neurological effects of systemic cancers

Cancer patients may develop paraneoplastic neurological conditions associated with autoantibodies directed against neural or neuromuscular tissues. These syndromes are frequently manifested in advance of the cancer presentation by several months or years necessitating a detailed and expensive investigation to search for the presence of a malignancy. In such cases additional assistance may be obtained by the early employment of whole body 18F flurodeoxyglucose positron emission tomography as a cancer screening imaging procedure for early cancer diagnosis and potential therapy. Effective therapy of the primary cancer consists the best current therapy for a given paraneoplastic syndrome. However, other forms of immune modulation, such as plasma exchange, intravenous gamma globulin, other immune therapies and symptomatic treatment for certain PNS may have additional benefit.