Opsoclonus-myoclonus and anti-Hu positive limbic encephalitis in a patient with neuroblastoma

Anti-Hu antibody associated paraneoplastic neurological syndrome in a child with ganglioneuroblastoma: A rare case report and literature review

RATIONALE

Paraneoplastic neurological syndrome with anti-Hu antibody (Hu-PNS) is a neurological disorder that occur in patients with malignancy. The syndrome has a wide range of presentations and can present before diagnosis of primary malignancy. Familiarity with these paraneoplastic neurological syndromes can help early recognition and take appropriate regimens.

PATIENTS CONCERNS

Diagnosis and treatment of Hu-PNS.

DIAGNOSES

This is retrospective study that analyzed the clinical data of this case. Through retrospective analysis and targeted antibody screening, serum anti-Hu antibody was detected. Subsequent spinal imaging revealed a mass in the paraspinal region, which was confirmed as ganglioneuroblastoma by pathologic examination.

INTERVENTIONS

The child was treated with a course of intravenous immunoglobulin and radical surgical operation without chemotherapy.

OUTCOMES

The neurological symptoms were gradually improved and no signs indicate disease progression or tumor recurrence.

LESSONS

Hu-PNS has rarely been reported in children with ganglioneuroblastomas. They can mimic non-neoplastic processes, making detection and diagnosis difficult. Serum and/or cerebrospinal fluid onconeural antibody can strongly indicate occult cancers. Early detection of paraneoplastic neurological syndromes can help take appropriate regimens and improve prognosis.

Early and Aggressive Treatment May Modify Anti-Hu Associated Encephalitis Prognosis

Anti-Hu encephalitis is a paraneoplastic syndrome in adults. In children, rare cases of anti-Hu encephalitis were reported mostly without underlying tumors and clinical outcome are usually severe. Here, we describe a 4-year-old girl who developed cerebellar syndrome with abnormal behavior. The brain magnetic resonance imaging showed several T2/fluid-attenuated inversion recovery bilateral brain lesions and autoimmune assessment showed positive anti-Hu antibodies. Computed tomography scan revealed ganglioneuroblastoma which was surgically removed 3 months after onset. Aggressive immunotherapy including dexamethasone, rituximab, and intravenous immunoglobulins were used and a marked neurological improvement soon after 9 months of onset was observed with the child being able to go back to school. The short delay between diagnosis and start of aggressive immunotherapy demonstrate the paramount importance of early diagnosis and early specific therapy after onset of symptoms.

Neuroblastoma Among Omani Children: Clinical characteristics and survival outcome from a dedicated centre

Objectives

A limited number of publications from the Middle East have focused on neuroblastoma, a common childhood malignancy. This study describes the clinical characteristics and survival outcome of Omani children with neuroblastoma treated at the National Oncology Centre, Oman, between 2010 and 2017.

Methods

From January 2010 to December 2017, data on Omani children aged less than 13 years with neuroblastoma were retrospectively collected. Survival data were statistically correlated with known prognostic factors, including age, stage of disease, MYCN profile and presence of metastasis.

Results

A total of 56 Omani children were included. in this study. The male to female ratio was 1:1. The mean age at presentation was one year and 10 months. The two most common presenting complaints were body masses (48.2%) and constitutional symptoms (33.9%). Approximately, 54.5% were high risk, 35.7% were intermediate risk and 9.8% were low risk. High-risk neuroblastoma was mainly found in children older than one year (76.6%), with low risk mainly observed in children less than one year of age (80%). The overall survival of all groups combined was 74% (P <0.05); the event-free survival (EFS) was 67% (P <0.05). The overall survival rates over five years for the high-risk, intermediate-risk and low risk groups were 60%, 88% and 100%, respectively, and the EFS was 51%, 79% and 100%, respectively.

Conclusion

Omani children with neuroblastoma mainly presented with masses or constitutional symptoms and had an advanced disease at presentation which was associated with inferior survival. The survival outcomes were reasonably similar to published international data.

Neurological complications of pediatric cancer

Both the onset of various malignancies as well as the treatment of cancer can lead to neurologic symptoms which can be difficult to diagnose. In this review, we highlight the varied ways in which neurologic sequelae of cancer and its treatment manifest in children. Initial neurologic presentation may be secondary to mass effect or to immune-mediated paraneoplastic syndromes. Treatment effects on the nervous system may arise from surgery, chemotherapy, radiation, or bone marrow transplantation. In addition, the rapidly expanding field of immunotherapies for cancer has generated numerous new approaches to eradicating cancer including monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor T cells (CAR-T cells), which have neurologic side effects mediated by immune responses that are also being recognized. Here we review common consult questions to the neurologist and our general approach to these scenarios including altered mental status, headaches, seizures, and sensorimotor complaints, considering the multifactorial nature of each.

Autoimmune encephalitis in children and adolescents

Background

Autoimmune encephalitides with neural and glial antibodies have become an attractive field in neurology because the antibodies are syndrome-specific, explain the pathogenesis, indicate the likelihood of an underlying tumor, and often predict a good response to immunotherapy. The relevance and the management of antibody-associated encephalitides in the pediatric age group are to be discussed.

Main body

Subacutely evolving, complex neuropsychiatric conditions that are otherwise unexplained should raise the suspicion of autoimmune encephalitis. Determination of autoantibodies is the key diagnostic step. It is recommended to study cerebrospinal fluid and serum in parallel to yield highest diagnostic sensitivity and specificity. The most frequently found antibodies are those against the N-methyl-D-asparate receptor, an antigen on the neural cell surface. The second most frequent antibody is directed against glutamic acid decarboxylase 65 kDa, an intracellular protein, often found in chronic conditions with questionable inflammatory activity. Immunotherapy is the mainstay of treatment in autoimmune encephalitides. Steroids, apheresis and intravenous immunoglobulin are first-line interventions. Rituximab or cyclophosphamide are given as second-line treatments. Patients with surface antibodies usually respond well to immunotherapy whereas cases with antibodies against intracellular antigens most often do not.

Conclusion

With few exceptions, the experience in adult patients with autoimmune encephalitides can be applied to patients in the pediatric age range.

Movement disorders associated with neuronal antibodies

Movement disorders are one of the common clinical features of neurological disease associated with neuronal antibodies which is a group of potentially reversible disorder. They can present with hypokinetic or hyperkinetic types of involuntary movements and may have other associated neurological symptoms. The spectrum of abnormal movements associated with neuronal antibodies is widening. Some specific phenomenology of movement disorders are likely to give clue about the type of antibody, for instance, presence of paroxysmal dystonia (facio-brachial dystonic seizures) are a pointer toward presence of LGI-1 antibodies, and orofacial lingual dyskinesia is associated with NMDAR associated encephalitis. The presence of specific type of movement disorder allows high suspicion of testing of certain specific type of antibodies. In this review, we have discussed the various antibodies and the spectrum of movement disorder associated with them, highlighting if any distinct movement disorder allows the clinician to suspect type of antibody in a certain clinical context. We have also reviewed the treatment of the movement disorder associated with the neuronal antibodies. Physicians should have high index of suspicion of these disorders, as early institution of treatment options can lead to better outcome.

Paraneoplastic movement disorders

Paraneoplastic movement disorders are rare, autoimmune-mediated, nonmetastatic complications of malignant neoplasms. Common paraneoplastic movement disorders include paraneoplastic chorea, dystonia, cerebellar degeneration, different types of encephalitis, opsoclonus-myoclonus syndrome, stiff person syndrome, and neuromyotonia. Syndromes usually develop before tumor diagnosis, have subacute onset, and are associated with serum or cerebrospinal fluid antibodies. Two types of antibodies can be distinguished: antibodies against nuclear and cytoplasmic neuronal antigens (anti-Hu, anti-Ri, anti-Yo, anti-Ma, anti-CV2/CRMP5, anti-Gephrin, and anti-GABATRAP) and antibodies recently identified against cell surface and synaptic proteins (anti-NMDAR, anti-LGI1, and anti-Caspr2). These two types differ from each other in a few important aspects. Antibodies against cell surface and synaptic protein disrupt cell-surface antigens. Clinical symptoms are related to the disruption of antigens and potentially can be reversed by immunotherapy. The association between these antibodies and malignancy is much less consistent. On the other hand, antibodies against nuclear and cytoplasmic neuronal antigens seem to be not pathogenic; however, they most likely indicate a T-cell-mediated immune response against neurons. Due to T-cell-mediated neuronal loss, response to immunotherapy is generally disappointing. Early recognition of all these diseases is crucial because it may lead to the disclosure of occult cancer. This review is focused on paraneoplastic movement disorders with emphasis on clinical presentations, investigational findings, and therapeutic results.

Cancer and Autoimmunity: Paraneoplastic Neurological Disorders Associated With Neuroblastic Tumors

Cancer and autoimmunity come together in paraneoplastic syndromes (PNS), which reflect the remote, not direct, effects of cancer. In the pediatric population, a variety of PNS have been described, but the most common of these rare disorders are instigated by neuroblastic tumors, such as neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. The main pediatric-onset neurological PNS are ROHHAD syndrome, anti-ANNA1 (anti-Hu), and opsoclonus-myoclonus syndrome. They manifest distinctive neurological features, which aid the diagnosis, though under-recognition still poses serious challenges and risks. In each clinical syndrome, a large subgroup of patients had no demonstrated tumor. Most neurological PNS are immunologically mediated, and CSF neuroimmunological studies show common elements of immune involvement in PNS as well as important differences. Future immunotherapy strategies may be able to take advantage of these abnormalities.

Myoclonus in the critically ill: Diagnosis, management, and clinical impact

Myoclonus is the second most common involuntary non-epileptic movement in intensive care units following tremor-like gestures. Although there are several types of myoclonus, they remain underappreciated, and their diagnostic and prognostic associations are largely ignored. This review discusses clinical, electrophysiological, neuroanatomical, and neuroimaging characteristics of different types of myoclonus in critically ill adults along with their prognostic impact and treatment options. Myoclonus is characterized by a sudden, brief, and sometimes repetitive muscle contraction of body parts, or a brief and sudden cessation of tonic muscle innervation followed by a rapid recovery of tonus. Myoclonus can resemble physiologic and other pathologic involuntary movements. Neurologic injuries, anesthetics, and muscle relaxants interfere with the typical appearance of myoclonus. Identifying "real myoclonus" and determining the neuroanatomical origin are important, as treatment responses depend on the involved neuroanatomical structures. The identification of the type of myoclonus, the involved neuroanatomical structures, and the associated illnesses is essential to direct treatment. In conclusion, the combined clinical, electrophysiological, and neuroradiological examination reliably uncovers the neuroanatomical sources and the pathophysiology of myoclonus. Recognizing cortical myoclonus is critical, as it is treatable and may progress to generalized convulsive seizures or status epilepticus.

Different Kinds of Paraneoplastic Syndromes in Childhood Neuroblastoma

BACKGROUND

Clinical presentations of paraneoplastic syndromes in neuroblastoma may multiply. Review of the clinical data and the literature on this syndrome may help in the diagnosis of neuroblastoma.

OBJECTIVES

In order to make more accurate diagnosis, we reviewed the clinical data and the literature on this syndrome.

PATIENTS AND METHODS

Between April 2007 and April 2012, 68 children were diagnosed with neuroblastoma or ganglioneuroblastoma in our institution, 9 of which presented exclusively with paraneoplastic syndromes and were not treated with chemotherapy prior to diagnosis. After the diagnosis, all patients received chemotherapy and operation on NB97 protocol.

RESULTS

Among 68 pediatric patients with neuroblastoma or ganglioneuroblastoma, 4 (5.9%) patients suffered from neurological complications at diagnosis, 2 (2.9%) patients had digestive tract disorders, 2 (2.9%) patients had immune diseases, and 1 (1.5%) suffered from hematological disorder (without bone marrow involvement). All paraneoplastic syndrome patients achieved complete remission on paraneoplastic syndrome before completion of chemotherapy.

CONCLUSIONS

Neuroblastoma may present with a range of non-specific neurologic symptoms in addition to the well-known opsoclonus-myoclonus syndrome and cerebellar ataxia. In any case, the presence of unexplained neurologic manifestations and other common clinical presentations such as rash, constipation, diarrhea, and especially immune disorders in an otherwise healthy child had raised the possibility of paraneoplastic syndrome due to the presence of an undiagnosed 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.

Paraneoplastic neurological syndromes: general treatment overview

OPINION STATEMENT

Major recent discoveries have bringing out a revised definition of paraneoplastic neurological syndromes (PNS), bringing out the concept of antibody-mediated neurological disorders, triggered or not by cancer. Classification of these diseases is not based anymore on the clinical pattern or an underlying tumor, but on the location of the targeted antigens. Indeed, evolution, response to treatment, and pathophysiology are radically different according to the associated antibodies. In some patients with newly described antibodies targeting cell-surface antigens, humoral immunity seems to play a direct role and a dramatic improvement is observed with immunomodulator treatments. In these patients, an associated tumor is less frequent. Conversely, patients with antibodies directed against intracellular targets are, in most cases, characterized by a high degree of irreversible neuronal death mediated by cytotoxic T-cells and do not improve after immunomodulator treatments. In these patients, an associated tumor is highly frequent and must be cured as soon as possible. A third group of patients can be identified with anti-GAD65 and anti-Amphiphysin antibodies. In patients with these antibodies, the efficiency of immunomodulator treatments is less clear as well as the type of immune response that could be a mix between humoral and cellular. In this last group, the antigen is intracellular, but patients may improve with immunomodulator treatments and associated tumors are rare. Thus, identification of associated antibodies should be prompt and the treatment guided according the identified antibody. Mainstream of treatment include the quest of a tumor and its cure. Immunotherapy must be promptly initiated, targeting humoral, or cellular immune response, or both, according to the associated antibodies. Furthermore, in some situations such as Lambert-Eaton Myasthenic Syndromes and Stiff-Person Syndromes, symptomatic drugs can be useful to control the symptoms.

Two patients with an anti-N-methyl-D-aspartate receptor antibody syndrome-like presentation and negative results of testing for autoantibodies

We describe two boys whose distinct and remarkable clinical pictures suggested the possibility of anti-N-methyl-d-aspartate receptor antibody encephalitis. Both patients responded to immunotherapy, but neither manifested that antibody. Patient 1 exhibited florid encephalopathy with psychotic manifestations including inappropriate affect, intermittent delirium, visual hallucinations, severe anorexia, agitation, paranoid ideation, and abnormal electroencephalogram results. He responded to intravenous immunoglobulin, with steady improvement over 3 months to almost complete remission for 1 year, followed by a relapse that again responded, more quickly, to intravenous immunoglobulin. A second relapse occurred 1 month later, and again responded to intravenous immunoglobulin. Patient 2 exhibited progressive, severely debilitating limb dystonia that worsened over 1.5 years, with milder psychiatric symptoms including mood instability, aggressiveness, impulsivity, and depression. When he developed thymic hyperplasia 1.5 years into his illness, he underwent a thymectomy, and improved significantly on a regimen of plasmapheresis and intravenous immunoglobulin. Patients presenting with symptoms suggestive of autoimmune encephalitis, but without antibodies, may still respond to immunotherapy.