Update on diagnosis, treatment, and prognosis in opsoclonus-myoclonus-ataxia syndrome

Autoimmune neurologic disorders in children

Autoimmune neurologic diseases are of major clinical importance in children. Antibody-mediated diseases of the central nervous system are now increasingly recognized in childhood, where the antibodies bind to cell surface epitopes on neuronal or glial proteins, and the patients demonstrate either focal or more generalized clinical signs depending on the extent of brain regions targeted by the antibodies. The antibodies are directed towards ion channels, receptors, and membrane proteins; and the diseases include limbic encephalitis and N-methyl-d-aspartate receptor-antibody encephalitis, among many others. Additionally there are conditions where the wider immune system is implicated. Neurologic features like seizures, movement disorders, autonomic dysfunction, and sleep disorders, with neuroimaging and electrophysiologic features, may indicate a specific antibody-mediated or immune disorder. Often, phenotypic overlap is observed between these conditions, and phenotypic variation seen in children with the same condition. Nevertheless, many patients benefit from immunotherapy with substantial improvement, although huge efforts are still required to optimize the outcome for many patients. In many patients no antibodies have yet been identified, even though they respond to immunotherapies. Here we describe the known antibodies and associated diseases, discuss conditions that are thought to be immune-mediated but have no known immunologic biomarker, and provide guidelines for the investigation and classification of these disorders.

A child with myoclonus-dystonia (DYT11) misdiagnosed as atypical opsoclonus myoclonus syndrome

INTRODUCTION

DYT11 is an autosomal dominant inherited movement disorder characterized by myoclonus and dystonia.

CLINICAL PRESENTATION

We present a case with atypical symptoms and with episodes of ataxia and myoclonus preceded by infections. Atypical presentation of opsoclonus myoclonus syndrome was suspected and treatment with bolus steroids and immunoglobulin were initiated with some response over 28 months. A re-evaluation gave suspicion of a dyskinetic disorder and whole exome-sequencing was performed but no causal variant was identified.

OUTCOME

A specific analysis of the SGCE gene was subsequently initiated, which revealed a pathogenic aberration confirming the diagnosis of DYT11.

CONCLUSION

A clinical DYT11 diagnosis can be difficult to establish in early childhood without a known family history.

A nationwide survey of opsoclonus-myoclonus syndrome in Japanese children

BACKGROUND

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disease characterized by opsoclonus, myoclonus, ataxia, and behavioral changes. The aim of our study was to investigate the epidemiological characteristics of OMS in Japan and to clarify the association between therapy and prognosis.

METHODS

We retrospectively collected the data from 626 Japanese medical institutions from 2005 to 2010, and analyzed the clinical features of pediatric patients with OMS based on the data.

RESULTS

In this survey, there were 23 patients (10 males and 13 females). The median ages at the disease onset and the time of study were 16.5 months (range: 11-152 months) and 54 months (range: 24-160 months), respectively. The principal symptoms were opsoclonus (23 patients, 100%), myoclonus (21 patients, 91.3%), and ataxia (23 patients, 100%). The related factors were neuroblastoma (10, 43.5%), infection (9, 39.1%), and immunization (2, 8.7%). The treatments for OMS were included intravenous immunoglobulin (17, 73.9%), methylprednisolone pulse (13, 56.5%), oral prednisolone (12 patients, 52.2%), and chemotherapy and/or operation for the underlying tumors (6, 26.1%), and rituximab (2, 8.7%). Complete remissions were obtained in 35.3%, 23.1%, 33.3%, 66.7%, and 100% of these treatments, respectively. At the latest follow-up period, 8 (34.8%) and 17 patients (73.9%) showed neurological sequelae of motor and intellectual functions, respectively. Patients whose treatment was started more than 30 weeks after the disease onset suffered from the severest neurological sequelae (OMS severity 4) more frequently than those less than 30 weeks (p=0.022).

CONCLUSION

The annual incidence of OMS was estimated to be 0.27-0.40 cases per million in Japanese children. More than 70% of OMS patients had neurological sequelae, especially intellectual function. Early effective treatments within 30 weeks after the onset may be required to prevent the serious neurological outcome.

Opsoclonus-myoclonus syndrome associated with a nasopharyngeal tumor in an adult: a case report

Introduction

Opsoclonus-myoclonus syndrome is a rare autoimmune syndrome usually seen in children and very rarely in adults. It typically presents with a triad of opsoclonus, myoclonus and ataxia, and is most often associated with a tumor or after an infection or vaccination. Around half of all adult cases are paraneoplastic in origin, and isolated case reports include associations with lung, breast and ovarian cancers. To the best of our knowledge, this is the first-ever reported case of paraneoplastic opsoclonus-myoclonus syndrome occurring in association with a nasopharyngeal carcinoma.

Case presentation

A 50-year-old British Caucasian woman presented with left-sided otalgia and subjective hearing loss. Over the coming weeks she developed subacute confusion and dizziness, leading to recurrent falls. Her clinical examination revealed opsoclonus, myoclonus and signs of cerebellar dysfunction. Subsequent magnetic resonance imaging revealed a left-sided nasopharyngeal carcinoma, which was confirmed on biopsy. A tapering dose of steroids and a five-day course of intravenous immunoglobulins, followed by a combination of chemo-radiotherapy for the nasopharyngeal carcinoma, led to a significant clinical improvement. At six months follow-up she had no signs of focal neurological deficit, apart from the inability to tandem walk. We believe that the typical clinical features, presence of a tumor and response to treatment support a paraneoplastic aetiology.

Conclusions

We show that a nasopharyngeal carcinoma can be associated with adult onset opsoclonus-myoclonus syndrome. Both neurologists and otorhinolaryngologists must be aware of such a presentation. Prognosis of the syndrome depends on early and adequate management of the tumor, therefore prompt identification of the syndrome and the underlying tumor is essential.

Pediatric movement disorders

On the basis of some research evidence and consensus, identification of acute opsoclonus, ataxia, or myoclonus should prompt consideration of an underlying neuroblastoma. On the basis of some research evidence and consensus, surgical treatment options should be considered for children with dystonia, including secondary dystonias, such as those related to cerebral palsy, and include intrathecal baclofen pumps and deep brain stimulation. On the basis of some research evidence and clinical experience, tetrabenazine may be effective in treating chorea. On the basis of strong research evidence, although seldom inherently dangerous, tics may be uncomfortable for affected children and interfere with academic achievement and social development. On the basis of some research evidence and clinical experience, topiramate may be an effective treatment for tic disorders.

Neuroblastoma: paradigm for precision medicine

Neuroblastoma (NB) is the third most common pediatric cancer. Although NB accounts for 7% of pediatric malignancies, it is responsible for more than 10% of childhood cancer-related mortality. Prognosis and treatment are determined by clinical and biological risk factors. Estimated 5-year survival rates for patients with non-high-risk and high-risk NB are more than 90% and less than 50%, respectively. Recent clinical trials have continued to reduce therapy for patients with non-high-risk NB, including the most favorable subsets who are often followed with observation approaches. In contrast, high-risk patients are treated aggressively with chemotherapy, radiation, surgery, and myeloablative and immunotherapies.

Paraneoplasia, cancer development and immunity: what are the connections?

Paraneoplasia literally means conditions adjacent to, or associated with, abnormal cancerous tissue growth. In this Comment article, I discuss what the immune-mediated paraneoplasias teach us about the immune response and cancer development.

Opsoclonus-myoclonus syndrome attributable to West Nile encephalitis: a case report

Introduction

Opsoclonus-myoclonus syndrome is a very rare neurological disorder associated with some viral infections and exceptionally with the West Nile virus.

Case presentation

A 57-year-old Caucasian woman presented with fever, dizziness, balance difficulties, vomiting, dancing eye, altered speech, tremor, generalized myoclonus and failure to rise or stand. Our objective is to describe a patient with West Nile infection, which was identified both in her serum and cerebrospinal fluid and was associated with encephalitis and opsoclonus-myoclonus-ataxia syndrome.

Conclusions

Opsoclonus-myoclonus-ataxia syndrome continued for 4 weeks after onset, when she died. There was no evidence for any other etiology responsible for her opsoclonus-myoclonus syndrome. Her opsoclonus-myoclonus syndrome appeared associated with West Nile encephalitis and had an unfavorable evolution despite treatment.

Kinsbourne syndrome: case report

BACKGROUND AND OBJECTIVES

Kinsbourne syndrome is a rare neurological disorder that primarily affects children previously healthy and aged between 6 and 36 months. It is characterized by opsoclonus (rapid, irregular, horizontal and vertical eye movements) and myoclonus that may affect trunk, limbs or face, and cerebellar ataxia. It may be considered a paraneoplastic syndrome by association with neuroblastomas, hepatoblastomas and, rarely, ganglioneuromas. The aim of this paper was to present the most relevant aspects of Kinsbourne syndrome, as well as the technique used for resection of mediastinal tumor in a child with this syndrome.

CASE REPORT

Child, 1 year and 5 months, with a diagnosis of posterior mediastinal tumor and Kinsbourne syndrome. Premedicated with oral midazolam. Anesthesia induced with sevoflurane, nitrous oxide, fentanyl, and rocuronium. Maintenance of anesthesia with sevoflurane, nitrous oxide, fentanyl, and rocuronium. Neuromuscular block reversal with neostigmine combined with atropine. Postoperative analgesia with the use of dipyrone, morphine, and ketoprofen. Taken to the intensive care unit extubated, with stable hemodynamic and respiratory parameters. ICU discharge four days after surgery and hospital discharged on the seventh postoperative day without complications. Anatomopathological examination revealed ganglioneuroblastoma.

CONCLUSIONS

Kinsbourne syndrome is a rare neurological disorder. The drugs used in our patient proved safe and allowed an uneventful anesthesia. Drugs that trigger or aggravate opsoclonus and myoclonus, such as ketamine and etomidate, should be avoided in these patients.

Approach to acute ataxia in childhood: diagnosis and evaluation

Ataxia refers to motor incoordination that is usually most prominent during movement or when a child is attempting to maintain a sitting posture. The first part of the review focuses on the anatomic localization of ataxia--both within the nervous system and without--using a combination of historical features and physical findings. The remainder of the review discusses etiological considerations that vary depending on the age group under consideration. In infancy, certain specific diseases, such as opsoclonus myoclonus ataxia syndrome, must receive special mention because the underlying disease process may be amenable to surgical intervention. In the toddler- and school-age groups, certain conditions (such as stroke and acute cerebellitis) require immediate recognition and imaging, whereas others (such as post-infectious ataxia and concussion) require close follow-up. Finally, mention must be made of diseases outside of the central nervous system that can present with ataxia, such as Guillain-Barré syndrome.

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.

Anti-N-methyl-D-aspartate receptor-mediated encephalitis in infants and toddlers: case report and review of the literature

BACKGROUND

Anti-N-methyl-D-aspartate receptor encephalitis is an increasingly well-recognized inflammatory encephalitis in children and adults.

PATIENT

We report a previously healthy 21-month-old girl who presented with behavioral change, self-mutilatory behavior, and echolalia. Over the ensuing weeks, symptoms progressed to include unilateral upper extremity dystonia, gait impairment, dysphagia, and mutism. Magnetic resonance imaging of the brain showed a tiny area of signal abnormality in the subcortical white matter, but was otherwise normal. Continuous video electroencephalography showed slowing of the background rhythm, but was without epileptiform discharges. Lumbar puncture showed a mild pleocytosis of mixed cellularity; bacterial culture and testing for various viral encephalitides were negative. Serum and cerebrospinal fluid was positive for autoantibodies directed against the N-methyl-D-aspartate receptor, and she was diagnosed with anti-N-methyl-D-aspartate receptor encephalitis. The patient was successfully treated with a regimen of immunotherapy that included dexamethasone, intravenous immunoglobulin, and rituximab. One year after initial presentation, the patient remained symptom-free. We further review the clinical characteristics, results of diagnostic studies, treatment, and outcome of infants and toddlers diagnosed with anti-N-methyl-D-aspartate receptor encephalitis that have been previously reported in the literature.

CONCLUSION

Anti-N-methyl-D-aspartate receptor encephalitis is relatively common among infants and toddlers and often presents with a pattern of defining characteristics in this age group, particularly the absence of associated tumor.

Narcolepsy with cataplexy as presenting symptom of occult neuroblastoma

Neuroblastoma associated with the paraneoplastic syndrome of opsoclonus-myoclonus is well-described. However, presentation with narcolepsy-cataplexy is not well-documented in the literature. Narcolepsy with cataplexy is also rare in children younger than 5 years of age. Here we describe three patients, each presenting in early childhood with complex neurological symptoms including narcolepsy with cataplexy that were subsequently found to have paraspinal neuroblastoma. In two of the cases, neurological symptoms resolved with treatment of the tumor and/or immunosuppression, but in one case, the child persistently had a devastating course despite complete resection of the tumor and aggressive immunosuppression.

Pediatric scorpion envenomation in the United States: morbidity, mortality, and therapeutic innovations

In the Southwestern United States, the venom of the scorpion Centruroides sculpturatus (common name bark scorpion) can cause serious and potentially fatal neurotoxicity, with young children most vulnerable to its effects. Historically, advances in the quality of supportive care have made significant improvements in morbidity and mortality. In recent years, the development of effective antivenom therapies has changed the landscape of caring for these patients. This article reviews the background, pathophysiology, diagnosis, and treatment options for C. sculpturatus envenomation. Recent advances in immunotherapy and subsequent implications for pediatric emergency care providers are discussed.

Clinical responses to rituximab in a case of neuroblastoma with refractory opsoclonus myoclonus ataxia syndrome

Opsoclonus myoclonus ataxia syndrome (OMS) is a rare neurologic syndrome. In a high proportion of children, it is associated with neuroblastoma. The etiology of this condition is thought to be immune mediated. In children, immunotherapy with conventional treatments such as corticosteroids, intravenous immunoglobulin, adrenocorticotropic hormone, and even antiepileptic drugs has been tried. Recently rituximab has been used safely for refractory OMS in children with neuroblastoma. Our patient was a 3.5-year-old girl referred for ataxia and dancing eye movements starting since 1.5 years ago. She was diagnosed with neuroblastoma on imaging studies on admission. The OMS was refractory to surgical resection, chemotherapy, corticosteroids, and intravenous immunoglobulin. Patient received rituximab simultaneously with chemotherapy. The total severity score decreased by 61.1% after rituximab. Patient's ataxia markedly improved that she was able to walk independently after 6 months. Our case confirmed the clinical efficacy and safety of rituximab in a refractory case of OMS.

Childhood cerebellar ataxia

Childhood presentations of ataxia, an impairment of balance and coordination caused by damage to or dysfunction of the cerebellum, can often be challenging to diagnose. Presentations tend to be clinically heterogeneous, but key considerations may vary based on the child's age at onset, the course of illness, and subtle differences in phenotype. Systematic investigation is recommended for efficient diagnosis. In this review, we outline common etiologies and describe a comprehensive approach to the evaluation of both acquired and genetic cerebellar ataxia in children.

Neuroblastoma presenting with acute kidney injury, hyponatremic-hypertensive-like syndrome and nephrotic proteinuria in a 10-month-old child

Neuroblastoma is the most common extracranial solid tumor in childhood. Its presenting signs and symptoms may be highly variable, depending on the location of the primary tumor and its local or metastatic diffusion and, rarely, with paraneoplastic syndrome such as opsoclonus-myoclonus-ataxia syndrome and gastrointestinal disturbances, due to autoantibodies or to aberrant secretion of vasoactive intestinal peptide. Herein we describe a 10-month-old child with neuroblastoma presenting with a complex clinical picture characterized by acute kidney injury manifested by renal insufficiency and signs and symptoms of tubulointerstitial damage, with polyuria, polydipsia, glucosuria, aminoaciduria and hypochloremic metabolic alkalosis, and of glomerular damage with heavy proteinuria. Imaging study documented a suprarenal mass enveloping the aorta and its abdominal and renal ramifications and bilaterally renal veins. This clinical picture shows some analogies with the hyponatremic-hypertensive syndrome concerning the renovascular disease; however, in absence of systemic arterial hypertension, the heavy proteinuria and the polyuria could be explained by sectional increased intraglomerular pressure, due to local renal blood vessels constriction. Hypochloremic metabolic alkalosis probably developed because of local production of renin, responsible of renin-angiotensin-aldosterone system activation, but above all because of chloride loss through sweating. The long lasting dehydration, due to vomiting, sweating and polyuria, caused prolonged prerenal failure evolving in proximal tubular damage manifestations.

Pharmacologic management of high-risk neuroblastoma in children

Neuroblastoma is the most common extracranial solid tumor of childhood. It accounts for 15% of pediatric cancer deaths. Children with high-risk disease have a 3-year event-free survival rate of only 20%. Chemotherapy is the mainstay of treatment in children with advanced neuroblastoma. The aim of this article was to review and critically evaluate the pharmacotherapy of neuroblastoma, using peer reviewed and review literature from 2000-11. All peer reviewed, published human subject studies of therapy for neuroblastoma in children were included. Animal model and in vitro studies were included only if they added to the understanding of the mechanism of a proposed or existing human neuroblastoma therapy. Current therapeutic options for neuroblastoma involve insufficient differentiation of normal from neoplastic tissue. Critically needed new approaches will increasingly exploit targeting of therapy for unique characteristics of the neuroblastoma cell. Pharmacotherapy for neuroblastoma still suffers from an inadequate therapeutic window. Enhancement of toxicity for tumor and safety for normal tissues will entail innovation in targeting neuroblastoma cells and rescuing or protecting normal tissue elements.

Movement disorders in paraneoplastic and autoimmune disease

PURPOSE OF REVIEW

The most relevant advances in immune-mediated movement disorders are described, with emphasis on the clinical--immunological associations, novel antigens, and treatment.

RECENT FINDINGS

Many movement disorders previously considered idiopathic or degenerative are now recognized as immune-mediated. Some disorders are paraneoplastic, such as anti-CRMP5-associated chorea, anti-Ma2 hypokinesis and rigidity, anti-Yo cerebellar ataxia and tremor, and anti-Hu ataxia and pesudoathetosis. Other disorders such as Sydenham's chorea, or chorea related to systemic lupus erythematosus and antiphospholipid syndrome occur in association with multiple antibodies, are not paraneoplastic, and are triggered by molecular mimicry or unknown mechanisms. Recent studies have revealed a new category of disorders that can be paraneoplastic or not, and associate with antibodies against cell-surface or synaptic proteins. They include anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, which may cause dyskinesias, chorea, ballismus or dystonia (NMDAR antibodies), the spectrum of Stiff-person syndrome/muscle rigidity (glutamic acid decarboxylase, amphiphysin, GABA(A)-receptor-associated protein, or glycine receptor antibodies), neuromyotonia (Caspr2 antibodies), and opsoclonus--myoclonus--ataxia (unknown antigens).

SUMMARY

Neurologists should be aware that many movement disorders are immune-mediated. Recognition of these disorders is important because it may lead to the diagnosis of an occult cancer, and a substantial number of patients, mainly those with antibodies to cell-surface or synaptic proteins, respond to immunotherapy.