Value of Hu antibody determinations in the follow-up of paraneoplastic neurologic syndromes

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.

Opsoclonus-myoclonus syndrome associated with neuroblastoma: Insights into antitumor immunity

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder. Half of these cases occur in children with neuroblastoma. Neuroblastoma patients with OMS usually have better oncological outcomes than those without OMS even after stratification by tumor stage and age, indicating that factors mediating OMS may also inhibit tumor cell proliferation. Although the mechanisms underlying OMS remain undefined, the cytokines and lymphocytes alterations in the cerebrospinal fluid support the concept that it is a pattern of neuroinflammation due to an autoimmune effect. The presence of lymphoid follicles consisting of follicular dendritic cells, CD20⁺ B lymphocytes, CD3⁺ T lymphocytes, and CD68⁺ macrophages in the tumor microenvironment in OMS-associated neuroblastoma support the autoimmune nature of this disorder. This review focuses on the clinical and genetic features of OMS-associated neuroblastoma, and we update readers on immune features of neuroblastoma with or without OMS to gain insights into antitumor immunity as it relates to tumor biology and prognosis.

Validation of Predictive Models for Autoimmune Encephalitis-Related Antibodies to Cell-Surface Proteins Expressed in Neurons: A Retrospective Study Based in a Hospital

Objective: Autoimmune encephalitis (AE) is a severe but treatable autoimmune disorder that is diagnosed by antibody (Ab) testing. However, it is unrealistic to obtain an early diagnosis in some areas since the Ab status cannot be immediately determined due to time and technology restrictions. In our study, we aimed to validate the Antibody Prevalence in Epilepsy and Encephalopathy (APE²) score among patients diagnosed with possible AE as a predictive model to screen AE patients with antibodies to cell-surface proteins expressed in neurons.

Methods: A total of 180 inpatients were recruited, and antibodies were detected through serological and/or cerebrospinal fluid (CSF) evaluations. The APE² score was used to validate the predictive models of AE with autoantibodies.

Results: The mean APE² score in the Ab-positive cases was 7.25, whereas the mean APE² score in the Ab-negative cases was 3.18 (P < 0.001). The APE² score had a receiver operating characteristic (ROC) area under the curve of 0.924 [P < 0.0001, 95% confidence interval (CI) = 0.875–0.973]. With a cutoff score of 5, the APE² score had the best psychometric properties, with a sensitivity of 0.875 and a specificity of 0.791.

Conclusion: The APE² score is a predictive model for AE with autoantibodies to cell-surface proteins expressed in neurons and was validated and shown to have high sensitivity and specificity in our study. We suggest that such a model should be used in patients with a suspected diagnosis of AE, which could increase the detection rate of Abs, reduce testing costs, and help patients to benefit from treatment quickly.

An evolving redefinition of autoimmune encephalitis

Autoimmune encephalitis encompasses a wide variety of protean pathologic processes associated with the presence of antibodies against neuronal intracellular proteins, synaptic receptors, ion channels and/or neuronal surface proteins. This type of encephalitis can also involve children with complex patterns of seizures and unexpected behavioural changes, which jeopardize their prompt recognition and treatment. Many epidemiological studies have shown that numerous immune-based forms of encephalitis can be encountered, almost surpassing the rate of postinfectious encephalitides. However, the overall exact prevalence of autoimmune encephalopathies remains underestimated, and the definition of diagnostic algorithms results muddled. The spectrum of neuropsychiatric manifestations in the pediatric population with autoimmune encephalitis is less clear than in adults, but the integration of clinical, immunological, electrophysiological and neuroradiological data is essential for a general approach to patients. In this review we report the most relevant data about both immunologic and clinical characteristics of the main autoimmune encephalitides recognized so far, with the aim of assisting clinicians in the differential diagnosis and favouring an early effective treatment. Correlations between phenotype and autoantibodies involved in the neurological damage of autoimmune encephalitis are largely unknown in the first years of life, because of the relatively small number of pediatric patients adequately studied. Future multicenter collaborative studies are needed to improve the diagnostic approach and tailor personalized therapies in the long-term.

The great masquerader of malignancy: chronic intestinal pseudo-obstruction

Paraneoplastic syndromes can precede the initial manifestation and diagnosis of cancer. Paraneoplastic syndromes are a heterogeneous group of disorders caused by mechanisms other than the local presence of tumor cells. These phenomena are mediated by humoral factors secreted by tumor cells or by tumor mediated immune responses. Among paraneoplastic syndromes, chronic intestinal pseudo-obstruction (CIPO) is rare and represents a particularly difficult clinical challenge. Paraneoplastic CIPO is a highly morbid syndrome characterized by impaired gastrointestinal propulsion with symptoms and signs of mechanical bowel obstruction. Clinical outcomes of paraneoplastic CIPO are often deleterious. The current standard of care for the management of CIPO includes supportive treatment with promotility and anti-secretory agents. However, the majority of patients with CIPO eventually require the resection of the non-functioning gut segment. Here, we present a 62-year-old patient with anti-Hu antibody associated paraneoplastic CIPO and underlying small cell lung cancer who underwent treatment with cisplatin and etoposide. Herein, we discuss diagnosis, prognosis, proposed mechanisms, treatment options, and future potential therapeutic strategies of paraneoplastic CIPO.

Autoimmune epilepsies

In patients with immune-associated disorders of the gray central nervous system matter (including recurrent seizures), antibodies against intracellular antigens have been discovered since the 1980s/1990s. In recent years, new antibodies against surface antigens have also been discovered. In two respects, these antibodies are even more interesting than the ones to intracellular antigens as, first, they promise a better response to immunotherapy; and, second, these antibodies contribute greatly to the understanding of the disease mechanisms. Whereas in encephalitides with antibodies against intracellular antigens, a cytotoxic T-cell-mediated response seems to be responsible for neuronal cell loss, in encephalitides with autoantibodies against surface antigens these antibodies are probably the relevant pathogenic agents in the associated disease conditions. On the one hand, antibodies to the NR1 subunit of N-methyl-D-aspartate receptors have been suggested to cause internalization and loss of these receptors without any cell destruction. This mechanism can explain the reversible functional effects caused by these antibodies. On the other hand, antibody- and complement-mediated destructive, and the irreversible effects of antibodies against the voltage-gated potassium channel antigens have been noted. These emerging findings make it plausible that immunological therapies, preferably early after characterization of the antibodies, offer opportunities to restore the health of affected patients.

Ofatumumab for refractory opsoclonus-myoclonus syndrome following treatment of neuroblastoma

Opsoclonus-myoclonus syndrome (OMS) may be associated with ANNA-1 (anti-Hu) autoantibodies. The standard treatment with IVIG, steroids, and anti-CD20 monoclonal antibody may fail, and optimal therapy is unknown. A patient developed OMS with high-titer ANNA-1 following recovery from neuroblastoma. She failed standard therapy and had only transient response to rituximab. Treatment with the humanized anti-CD20 monoclonal antibody ofatumumab combined with methotrexate resulted in transient neurologic improvement and decrease of ANNA-1. This suggests that ofatumumab combined with methotrexate should further be considered OMS patients, particularly in refractory disease.

[Pathophysiology of antibody-associated diseases of the central nervous system]

Antibodies against intracellular antigens have been known since the 1980s and 1990s but in recent years antibodies against surface antigens have also been discovered. These are "more interesting" than those to intracellular targets in two respects: they result in a better response to immunotherapy and are probably directly pathogenic, which helps to understand the disease mechanisms. There are the destructive and irreversible effects of the antibodies to antigens that are complexed with voltage-gated potassium channels (VGKC complex antibodies), especially antibodies to leucine-rich glioma inactivated 1 (LGI1) on the one hand. On the other hand, antibodies may have reversible functional effects, such as antibodies against the N-methyl-D-aspartate receptor, which cause an internalization of these receptors but do not lead to cell destruction: LGI1 antibodies also seem to have functional, in this case epileptogenic effects. These emerging findings make plausible why antibody-reducing therapies provide opportunities for the restoration of health in affected patients.

Onconeural antibodies in patients with neurological symptoms: detection and clinical significance

BACKGROUND

Onconeural antibodies are strongly associated with cancer and paraneoplastic neurological syndromes (PNS). Most of these antibodies are well-characterized (antibodies against Hu, Yo, Ri, CRMP5, amphiphysin, Ma2 and Tr) and are in common use for the diagnosis of definite PNS.

MATERIALS AND METHODS

Literature on detection and clinical significance of onconeural antibodies were identified by using relevant search terms in PubMed and reviewed.

CONCLUSIONS

The onconeural antibodies are directed against intracellular antigens and their pathogenic role is still largely unknown. They are highly specific markers of paraneoplastic aetiology in patients with neurological symptoms. Detection of an onconeural antibody in a patient with neurological symptoms should lead to prompt investigation for cancer. However, absence of detectable onconeural antibodies does not exclude the PNS diagnosis. In particular, failure to detect antibodies in patients without classical PNS symptoms may result in less vigorous cancer screening and diagnostic delay. Neuronal antibodies that are directed to synaptic proteins or proteins of the cell membrane are also associated with neurological symptoms, and probably have pathogenic effects. The association between these antibodies and cancer is less robust, and they are usually not included among the onconeural antibodies.

Demyelinating neuropathy with anti-CRMP5 antibodies predating diagnosis of breast carcinoma: favorable outcome after cancer therapy

INTRODUCTION

Breast cancer is exceptionally associated with anti-collapsin response mediator protein 5 (anti-CRMP5) antibody or demyelinating neuropathy. This paraneoplastic antibody is itself not associated with demyelinating neuropathy.

METHODS

Herein we describe a patient with a predominantly sensory ataxic demyelinating neuropathy associated with an IgG-kappa monoclonal gammopathy of uncertain significance (MGUS). Further investigations led to identification of anti-CRMP5 antibodies. An initial search for a malignancy proved negative. No immunomodulatory therapy was administered.

RESULTS

The patient developed breast carcinoma 2 years after the initial neurological symptoms, which was effectively treated by surgery, chemotherapy, hormone therapy, and radiotherapy. At neurological follow-up, 16 months after cancer treatment, she remained in remission and had made substantial neurological recovery. Electrophysiology showed significant amelioration, and serum anti-CRMP5 antibodies were undetectable. MGUS paraprotein level was unchanged.

CONCLUSION

This case widens the range of paraneoplastic manifestations of breast carcinoma to include anti-CRMP5 antibody-positive sensory ataxic demyelinating neuropathy, which, in this patient, improved after cancer treatment.

Paraneoplastic antibody during follow-up of a patient with anti-Ri-associated paraneoplastic neurological syndrome

BACKGROUND

The role of classical antineuronal antibody determinations to confirm the paraneoplastic aetiology of a neurological syndrome is well established. However, the value of antineuronal antibody estimation during follow-up of paraneoplastic neurological syndromes (PNS) is not known.

AIMS OF THE STUDY

Prospective analysis of antibody concentrations in follow-up serum samples from a patient with anti-Ri-associated PNS.

METHODS

Semiquantitative estimation of antibody concentrations with an ELISA using recombinant Ri antigen.

RESULTS

Semiquantitative estimation of circulating anti-Ri antibodies demonstrated a renewed increase in antibody levels preceding relapse of the cancer, as confirmed using F-fluorodeoxyglucose positron emission tomography (FDG-PET).

CONCLUSIONS

This is the first prospective report on serial anti-Ri antibody determinations. As a large increase in antineuronal antibody concentrations in follow-up serum samples preceded relapse of the cancer, paraneoplastic antineuronal antibodies may represent a marker for tumour activity in this case. These results warrant further multicentre studies to investigate the ability of serial quantification of classical antineuronal antibodies in monitoring PNS and in predicting relapse of cancers.

Uncommon epiloptogenic lesions affecting the temporal lobe

There are several processes implicated as uncommon causes of temporal lobe epilepsy. Trauma is the leading cause of epilepsy in young adults, intracerebral blood collection being the most consistent risk factor of seizures, especially subdural hematomas and brain contusions. Infarction is the entity most commonly related to epilepsy in the elderly population. Seizures usually present as complex seizures with high recurrence between 6 months and 2 years after stroke. There are some radiological characteristics of the affectation associated with high risk of early and late seizures. Noninfectious limbic encephalitis is a syndrome characterized by seizures, memory loss, and confusion. It includes paraneoplasic and non-paraneoplasic limbic encephalitis, both presenting as hyperintense lesion affecting temporobasal regions more evident with fluid-attenuated inversion recovery sequences. Paraneoplasic limbic encephalitis is associated with several types of tumor-induced autoimmunity against the nervous system. The tumors most frequently implicated are the lungs, testis, and breast, including Hodgkin's lymphoma, teratoma, and thymoma in young patients. Once a tumor is excluded, non-paraneoplasic limbic encephalitis has to be considered by investigating the presence of antibodies against voltage-gated potassium channels. It is associated with hyponatremia and responds to regimens of steroids, plasma exchange, and intravenous immunoglobulins. Finally, herpetic limbic encephalitis is also associated with seizures, accompanied by fever and neurologic symptoms. It presents characteristic findings and distribution on magnetic resonance imaging, which shows abnormalities in more than 90% of patients with proven Herpes simplex virus type 1.

Neurological course of long-term surviving patients with SCLC and anti-Hu syndrome

Patients with small-cell lung cancer (SCLC) have a poor prognosis with a three year survival rate of 4%. Our report concerns three patients with histologically proven SCLC and anti-Hu associated paraneoplastic neurological syndrome who have survived for 11 in two cases and 16 years respectively. The patients showed progressive deterioration which was only partly beneficially modulated by steroid therapy or tumor treatment, even in the cases with complete tumor remission.

Limbic encephalitis: a cause of temporal lobe epilepsy with onset in adult life

Limbic encephalitis (LE) was described in the 1960s as a clinical-pathological syndrome in adults. Initially, the paraneoplastic form was the center of interest. An increasing number of diagnostically valuable autoantibodies in patients' sera (and cerebrospinal fluid) have been identified. Lately, the impact of non-paraneoplastic LE cases has been acknowledged. In the serum of some of these patients, antibodies against voltage-dependent potassium channels (VGKC antibodies) have been detected. The characteristic MRI course of LE patients has recently been described in detail: hippocampal swelling and T2/FLAIR signal increase are early findings. After a few months, the swelling regresses, followed by hippocampal atrophy with continuous signal increase. A general consensus on formal diagnostic criteria for all LE subsyndromes has not yet been reached. This article proposes such diagnostic criteria and formulates suggestions for treatment.

Clinical and immunological diversity of limbic encephalitis: a model for paraneoplastic neurologic disorders

The most important contribution to the understanding and management of paraneoplastic neurologic disorders (PND) is the discovery that many of these diseases are immune mediated. It is believed that cytotoxic T-cell responses and antibodies that target neuronal proteins usually expressed by the underlying tumor cause the neurologic symptoms. The detection of these antibodies has provided diagnostic tests that allow recognition of the disorder as paraneoplastic and direct the search of the tumor to selected organs. This article summarizes the authors' findings of limbic encephalitis and postulates that a similar approach can be used for syndromes involving other areas of the nervous system.

Dixièmes Journées des Maladies du Système Nerveux Périphérique

Sensory ganglionopathies have a frequent association with neoplastic disorders (paraneoplastic subacute sensory neuronopathy, or SSN) or dysimmune disorders, with drugs, such as cisplatin or pyridoxine, and with inherited disorders with degeneration of dorsal root ganglion cells. Unsteady gait and pseudoathetoid movements of the hand are the distinctive signs encountered in these disorders. The chronic disorders are characterized by non-length-dependent abnormalities of sensory nerve action potentials (SNAPs) and differ from other sensory neuropathies in showing a global, rather than distal, decrease in SNAP amplitudes. This review focuses on recent advances in defining the mechanisms involved in sensory ganglionopathies, and describes the differential diagnosis including the rarely encountered hereditary neuronopathies and the infectious causes.

Sensory neuron diseases

Sensory neuron diseases (SND) are a distinct subgroup of peripheral-nervous-system diseases, first acknowledged in 1948. Acquired SND have a subacute or chronic course and are associated with systemic immune-mediated diseases, vitamin intoxication or deficiency, neurotoxic drugs, and life-threatening diseases such as cancer. SND are commonly idiopathic but can be genetic diseases; the latter tend to involve subtypes of sensory neurons and are associated with certain clinical pictures. The loss of sensory neurons in dorsal root ganglia causes the degeneration of short and long peripheral axons and central sensory projections in the posterior columns. This pathological process leads to a pattern of sensory nerve degeneration that is not length dependent and explains distinct clinical and neurophysiological abnormalities. Here we propose a comprehensive approach to the diagnosis of acquired and hereditary SND and discuss clinical, genetic, neurophysiological, neuroradiological, and neuropathological assessments.

Treatment-responsive limbic encephalitis identified by neuropil antibodies: MRI and PET correlates

We report seven patients, six from a single institution, who developed subacute limbic encephalitis initially considered of uncertain aetiology. Four patients presented with symptoms of hippocampal dysfunction (i.e. severe short-term memory loss) and three with extensive limbic dysfunction (i.e. confusion, seizures and suspected psychosis). Brain MRI and [(18)F]fluorodeoxyglucose (FDG)-PET complemented each other but did not overlap in 50% of the patients. Combining both tests, all patients had temporal lobe abnormalities, five with additional areas involved. In one patient, FDG hyperactivity in the brainstem that was normal on MRI correlated with central hypoventilation; in another case, hyperactivity in the cerebellum anticipated ataxia. All patients had abnormal CSF: six pleocytosis, six had increased protein concentration, and three of five examined had oligoclonal bands. A tumour was identified and removed in four patients (mediastinal teratoma, thymoma, thymic carcinoma and thyroid cancer) and not treated in one (ovarian teratoma). An immunohistochemical technique that facilitates the detection of antibodies to cell surface or synaptic proteins demonstrated that six patients had antibodies to the neuropil of hippocampus or cerebellum, and one to intraneuronal antigens. Only one of the neuropil antibodies corresponded to voltage-gated potassium channel (VGKC) antibodies; the other five (two with identical specificity) reacted with antigens concentrated in areas of high dendritic density or synaptic-enriched regions of the hippocampus or cerebellum. Preliminary characterization of these antigens indicates that they are diverse and expressed on the neuronal cell membrane and dendrites; they do not co-localize with VGKCs, but partially co-localize with spinophilin. A target autoantigen in one of the patients co-localizes with a cell surface protein involved in hippocampal dendritic development. All patients except the one with antibodies to intracellular antigens had dramatic clinical and neuroimaging responses to immunotherapy or tumour resection; two patients had neurological relapse and improved with immunotherapy. Overall, the phenotype associated with the novel neuropil antibodies includes dominant behavioural and psychiatric symptoms and seizures that often interfere with the evaluation of cognition and memory, and brain MRI or FDG-PET abnormalities less frequently restricted to the medial temporal lobes than in patients with classical paraneoplastic or VGKC antibodies. When compared with patients with VGKC antibodies, patients with these novel antibodies are more likely to have CSF inflammatory abnormalities and systemic tumours (teratoma and thymoma), and they do not develop SIADH-like hyponatraemia. Although most autoantigens await characterization, all share intense expression by the neuropil of hippocampus, with patterns of immunolabelling characteristic enough to suggest the diagnosis of these disorders and predict response to treatment.