Paraneoplastic neurologic syndromes: approaches to diagnosis and treatment

Interest of rare autoantibodies in autoimmune encephalitis and paraneoplastic neurological syndromes: the utility (or futility) of rare antibody discovery

PURPOSE OF REVIEW

The increasing recognition and diagnosis of autoimmune encephalitis (AE) and paraneoplastic neurological syndromes (PNS) is partly due to neural autoantibody testing and discovery. The past two decades witnessed an exponential growth in the number of identified neural antibodies. This review aims to summarize recent rare antibody discoveries in the context of central nervous system (CNS) autoimmunity and evaluate the ongoing debate about their utility.

RECENT FINDINGS

In the last 5 years alone 15 novel neural autoantibody specificities were identified. These include rare neural antibody biomarkers of autoimmune encephalitis, cerebellar ataxia or other movement disorders, including multifocal presentations.

SUMMARY

Although the clinical applications of these rare antibody discoveries may be limited by the low number of positive cases, they still provide important diagnostic, prognostic, and therapeutic insights.

Autoimmune limbic encephalitis presenting as relapsing psychosis

A 34-year-old woman with a history of relapsing psychosis presented with a 15-month history of impassivity and social withdrawal associated with cognitive impairment. The subsequent recurrence of psychomotor agitation, auditory hallucinations and delusional thinking resulted in an emergency admission under psychiatric services. Initial investigations, including MRI of the brain and cerebrospinal fluid studies were unremarkable and she was treated for a primary psychiatric disorder. The diagnosis of autoimmune limbic encephalitis was established after further investigations revealed the presence of antibodies to the NR1 subunit of the N-Methyl-d-aspartate receptor (NMDAR). Immunotherapy resulted in rapid resolution of psychosis and marked improvement in cognitive and social function. This case underlines the importance of considering anti-NMDAR encephalitis within the differential diagnosis of psychosis associated with cognitive impairment even in those with an apparent previous psychiatric history and response to antipsychotics.

Neurologic emergencies in patients who have cancer: diagnosis and management

The nervous system can be significantly affected by cancer. Neurologic symptoms are present in 30% to 50% of oncologic patients presenting to the emergency department or in neurologic consultation at teaching hospitals. Evaluation and treatment require collaborative effort between specialties. The causes of neurologic emergencies in patients with cancer are mostly related to effects of cancer, toxicities of treatments, infections, and paraneoplastic syndromes. These complications cause significant morbidity and mortality and require prompt and accurate diagnostic and treatment measures. This article reviews the common neurologic emergencies affecting patients with cancer and discusses epidemiology, clinical presentation, diagnosis, and treatment modalities.

Paraneoplastic Necrotizing Myelopathy in a Patient With Newly Diagnosed Diffuse Large B Cell Lymphoma

Paraneoplastic neurological disorders are rare but particularly devastating forms of paraneoplastic syndromes, in part due to the fact that the entity is not usually considered as the initial differentials of a cancer patient presenting with neurological symptoms. We report a case of paraneoplastic necrotizing myelopathy associated with Diffuse Large B-cell Lymphoma in an elderly Chinese lady. After extensive investigations, the diagnosis was confirmed on spinal cord biopsy which showed extensive necrotic tissue and absence of tumour or vascular involvement.

Clinical applications of a peptide-based vaccine for glioblastoma

Glioblastoma multiforme is a malignant, relentless brain cancer with no known cure, and standard therapies leave significant room for the development of better, more effective treatments. Immunotherapy is a promising approach to the treatment of solid tumors that directs the patient's own immune system to destroy tumor cells. The most successful immunologically based cancer therapy to date involves the passive administration of monoclonal antibodies, but significant antitumor responses have also been generated with active vaccination strategies and cell-transfer therapies. This article summarizes the important components of the immune system, discusses the specific difficulty of immunologic privilege in the central nervous system, and reviews treatment approaches that are being attempted, with an emphasis on active immunotherapy using peptide vaccines.

Geoepidemiology and autoimmune manifestations of lymphoproliferative disorders

The pathogenesis of lymphoproliferative disorders represents an underlying dysfunction in lymphocyte development and homeostasis. This typically manifests with the accumulation of lymphocytes in the bone marrow, peripheral blood or lymph nodes and spleen. It has been hypothesized that the mechanism for elimination of dysfunctional and autoreactive lymphocytes is defective and contributes to the pathogenesis of these disorders. Based on this hypothesis, it would not be surprising to find an increased incidence of autoimmune manifestations that are associated with these disorders. Autoimmune paraneoplastic syndromes (PNS) are often the result of a dysfunctional immune response, which is related to an underlying malignant process. While all the PNS that are associated with lymphoproliferative disorders do not have an autoimmune basis, many do. Here we review the literature of PNS associated with lymphoproliferative disorders. A concise overview of each syndrome is provided with a focus on clinical manifestations, diagnostics, pathophysiology, and treatment. While the treatment is typically directed at managing the underlying lymphoproliferative process, and can be assumed to be case throughout this review, there are exceptions that are described within the context of each disorder.

Cancer-Induced, Immune-Mediated Ocular Degenerations

The means whereby vision can be lost from a disease located distant from the eye include autoimmunity, with sensitization resulting from extraocular stimuli, a process illustrated here by the immunologic confusion caused by cancers. The uncontrolled proliferation of malignancies commonly involves the expression of components of the central nervous system, but a damaging loss of tolerance is rare. When autoimmunity does develop, organ-specific antigens are more often involved than the more generalized and widely disseminated common neuronal components. A focus upon a single antigen is typical of the immune-mediated paraneoplasia, a collection of syndromes identified by unusual antibody reactions. This review provides an outline of the immunologic trail that led to the recognition of autoimmunity in paraneoplastic ocular degenerations, how specific antibody reactions aid in diagnosis, and the possibility of including antibodies in modes for sight-saving intervention. 'Those who do not know history are destined to repeat it'.

Paraneoplastic neurological syndromes: a review

BACKGROUND

Paraneoplastic neurologic syndromes (PNS) constitute a rare group of disorders resulting from damage to the nervous system in the setting of cancer physically unrelated to the tumor site. PNS are believed to result from an autoimmune attack of normal neuronal tissue, spurred by similar neuronal antigens ectopically expressed by tumor cells.

REVIEW SUMMARY

The most common PNS are reviewed and also their association with specific onconeural antibodies, some directly pathogenic, others whose role in the disease process is less clear-cut. This diversity in pathogenesis is likely due to the relative role of humoral versus cellular immunity in PNS. Virtually any cancer may result in PNS but certain tumors, small cell lung cancer, gynecologic cancers (breast and ovarian), thymoma, and plasma cell tumors are more frequently encountered. In most instances, immunosuppressive therapy is unhelpful and outcome is poor.

CONCLUSIONS

PNS have diverse presentations, affecting both the central and peripheral nervous system and commonly, it is the PNS, not cancer that is the presenting symptom. Only subsequently, after onconeural antibodies are discovered or cancer is found, is PNS diagnosed. Neurologists should familiarize themselves with these rare syndromes and treatment principles, as rapid detection and treatment of the underlying tumor offer the best chance for recovery or prevention of further neurologic deterioration.

FDG-pet in paraneoplastic syndromes

Paraneoplastic syndromes are rare disorders, but recognition is important because clinical manifestations of paraneoplastic syndromes may precede those of the underlying malignancy by months or even years. As tumor therapy still is the mainstay of treatment for paraneoplastic syndromes, early diagnosis of the initial tumor or its recurrence is of utmost clinical importance. For finding the associated tumor, the combined use of FDG-PET and CT seems to have the highest sensitivity and may contribute to accurately distinguishing a true tumor or recurrence from benign lesions or physiologic or inflammatory uptake. Further, this approach helps localize the tumor for further management of the patient such as surgery or more invasive diagnostic procedures. Cerebral FDG-PET proved to confirm paraneoplastic encephalitis and may help monitor tumor therapy.

Paraneoplastic vasculitis of central nervous system presenting as recurrent cryptogenic stroke

We report the case of paraneoplastic vasculitis of the central nervous system associated with breast cancer. A 54-year old woman had a complete workup because of recidive seizures. Magnetic resonance imaging (MRI) showed cerebral and medullary cryptogenic lesions, and a diagnosis of encephalomyelitis of unknown origin was made. She was treated with corticosteroids, but because of cognitive impairment and recurrence of epileptic seizures, she was finally transferred to our Neurology Department. The previous diagnosis was then changed, because a poorly differentiated invasive lobular breast cancer was discovered. Thoracic and abdominal computed tomography (CT) scans diagnosed pulmonary, pericardial, adrenal, and renal metastases. Because MRI findings did not fit with the diagnosis of brain metastases, a CT-guided cerebral biopsy was performed, and she was eventually diagnosed with paraneoplastic vasculitis of the central nervous system.

An update on the classification and treatment of vasculitic neuropathy

Vasculitic neuropathy usually presents with painful mononeuropathies or an asymmetric polyneuropathy of acute or subacute onset. The disorder should be classified as being systemic or non-systemic. Systemic vasculitis should be further classified into one of the primary and secondary forms. Although specific treatment regimens vary among neurologists, basic principles can be applied. Corticosteroids and cytotoxic drugs have been the mainstay of treatment for most forms of vasculitic neuropathy. Here we discuss dosing, potential side-effects, and management recommendations of conventional treatments. New treatments showing promise include intravenous immunoglobulin and biological agents and trials of the newest treatments are being reviewed. Future trials should compare commonly used treatment regimens and better establish the efficacy of newer, potentially safer, treatments.

Paraneoplastic recurrent multifocal encephalitis presenting with epilepsia partialis continua

We report a 46-year-old female patient in whom epilepsia partialis continua was the initial presentation of small cell lung cancer. Magnetic resonance imaging revealed multiple, bilateral cortical lesions, which were originally misinterpreted and treated as brain metastases. Intracranial lesions and neurological symptoms remitted after corticosteroids, chemotherapy, and radiotherapy. After an asymptomatic interval of 18 months, neurological symptoms recurred with more extensive involvement of completely different parts of the central nervous system (limbic, brainstem and cerebellar structures) without any evidence of tumor recurrence. Both episodes showed a distinctive response to immunosuppressive therapy. The diagnostic challenges of the highly variable clinical presentations and therapeutic approaches to paraneoplastic multifocal encephalitis are discussed with relevant literature review.

Immunological features of neurological paraneoplastic syndromes

Neurological paraneoplastic syndromes are a rare group of disorders that occur in 1-2% of people with malignancy. They are usually caused by an immune response, triggered by and directed against a tumour, that cross-reacts with protein expressed by the peripheral or central nervous system. Any part of the nervous system can be affected and patients often develop severe and permanent disability. Diagnosis can be difficult as in two-thirds of patients the neurological problems appear up to 5 years before the tumour manifests. However, certain of these syndromes are often associated with specific serum autoantibodies that can be useful both in diagnosis of the neurological syndrome and in focusing the search for a particular tumour. Thus, these antibodies can allow earlier identification and treatment of cancer and, potentially, a reduction in morbidity and mortality. It was only in the 1980s that the first anti-neuronal autoantibodies were characterized and their associations with clinical syndromes and tumours defined. Further antibodies have been isolated over the past 20 years and novel pathogenic mechanisms for several syndromes have been recognized. For example, voltage-gate ion channels seem to be a common target for autoantibodies involved in peripheral nerve diseases such as the Lambert-Eaton myasthenic syndrome and neuromyotonia (Isaacs' syndrome). However, the place of most paraneoplastic antibodies in the pathogenesis of central syndromes is yet to be fully elucidated.