Paraneoplastic neurologic syndromes: approaches to diagnosis and treatment

There is increasing evidence that many paraneoplastic neurologic syndromes are immune-mediated. Because symptoms usually have an acute onset and precede the tumor diagnosis, the recognition of a neurologic disorder as a paraneoplastic syndrome is challenging. The poor response to treatment of many paraneoplastic neurologic syndromes has been attributed to the early, irreversible pathological changes involving the nervous system. This may account for the more frequent responses to therapy of some paraneoplastic neurologic syndromes affecting the peripheral nerves and neuromuscular junction compared with those that produce neuronal degeneration. This review focuses on the current therapeutic approaches to immune-mediated paraneoplastic neurologic syndromes, including prompt recognition of the disorder, detection and treatment of the associated tumor, and, in some disorders, immunosuppressive therapy.     

Paraneoplastic Neurologic Disorders in Children

Paraneoplastic neurologic syndromes are rare disorders that have potentially devastating effects on the developing brain. Recently, there has been increased interest in possible immunotherapy for these disorders. Recognition of paraneoplastic syndromes in children may lead to early detection and treatment of the pediatric cancer and may diminish the neurologic damage that is the major source of morbidity in children with successfully treated tumors. This article reviews the presenting symptoms, immunology, long-term sequelae, and management options for paraneoplastic neurologic syndromes, focusing on those most commonly reported in children: opsoclonus-myoclonus ataxia, limbic encephalitis, and anti-NMDAR encephalitis. The child neurologist plays an important role in recognizing these disorders, initiating a tumor search, and directing ongoing treatment and management of neurologic symptoms after oncologic treatment is complete. Given the rarity of these conditions, multisite collaborative efforts are needed to develop standardized approaches to characterization and treatment.     

Paraneoplastic sensory neuronopathy and spontaneous regression of small cell lung cancer

BACKGROUND: Spontaneous tumour regression in small cell lung cancer has previously been suggested in patients with paraneoplastic neurologic syndromes. Rare documentation of this event has occurred in the literature. CASE REPORT: The authors report a patient with anti-Hu associated paraneoplastic sensory neuronopathy who had a spontaneous regression of her small cell lung cancer. CONCLUSIONS: This case supports the hypothesis that anti-Hu neurologic syndromes are the consequence of a misdirected immune response to small cell tumours.     

Nervous system dysfunction in children with paraneoplastic syndromes.

Paraneoplastic syndromes are complexes of symptoms and signs that occur in association with cancer and that are unexplained by the known anatomic and physiologic characteristics of the tumor. Many of these syndromes are neurologic in nature or have consequences for the central or peripheral nervous system. These syndromes have been well characterized in adults. With the exception of opsoclonus-myoclonus, little has been written about the occurrence of such syndromes in children. This review looks at published reports of paraneoplastic syndromes in children and concludes that paraneoplastic syndromes in childhood differ from those seen in adulthood because of differences in both the host and the kinds of neoplasms most prevalent in each age group. Paraneoplastic syndromes may be underreported in childhood because of the difficulty in eliciting specific neurologic complaints from children and because a thorough neurologic examination is often not undertaken as a matter of routine.     

Paraneoplastic syndromes of the spinal cord, nerve, and muscle

Cancer can affect the peripheral nervous system by non-metastatic, sometimes immune-mediated mechanisms. Recognition of these paraneoplastic syndromes is important because it can lead to the detection of the tumor, and also helps to avoid unnecessary studies to determine the cause of the neurologic symptoms in patients with cancer. Many paraneoplastic syndromes of the peripheral nervous system are not associated with serum antibodies that serve as markers of paraneoplasia. For this group of disorders the diagnosis depends on the clinician's index of suspicion and conventional electrophysiologic and laboratory tests. Treatment of the tumor, immunotherapy, or both may improve some of these syndromes. This review focuses on paraneoplastic syndromes of the spinal cord, peripheral nerve, and muscle.     

Paraneoplastic syndromes of the CNS

Major advances in the management of paraneoplastic neurologic disorders (PND) include the detection of new antineuronal antibodies, the improved characterisation of known syndromes, the discovery of new syndromes, and the use of CT and PET to reveal the associated tumours at an early stage. In addition, the definition of useful clinical criteria has facilitated the early recognition and treatment of these disorders. In this article, we review some classic concepts about PND and recent clinical and immunological developments, focusing on paraneoplastic cerebellar degeneration, opsoclonus-myoclonus, and encephalitides affecting the limbic system.     

Current therapies for neuromuscular manifestations of paraneoplastic syndromes

The neuromuscular manifestations of paraneoplastic disorders result in diverse syndromes that may also occur in patients without cancer. In general, treatment of these disorders is the same whether or not there is an underlying malignancy. However, when the disorder is believed to be paraneoplastic, the main concern should be prompt detection and treatment of the tumor, as this has been shown to offer the best chance for neurologic stabilization or improvement. The paraneoplastic neuromuscular disorders can be divided into two main categories: those that are directly mediated by antibodies and those that are believed to result from other immune-mediated mechanisms, including cytotoxic T-cell responses with or without association with specific antibodies. For disorders in which the antibodies are pathogenic, therapy is aimed at removing the antibodies. For the other disorders, adjuvant therapies are for the most part empiric and include a variety of immunosuppressant and immunomodulatory agents.     

Current therapies for neuromuscular manifestations of paraneoplastic syndromes

The neuromuscular manifestations of paraneoplastic disorders result in diverse syndromes that may also occur in patients without cancer. In general, treatment of these disorders is the same whether or not there is an underlying malignancy. However, when the disorder is believed to be paraneoplastic, the main concern should be prompt detection and treatment of the tumor, as this has been shown to offer the best chance for neurologic stabilization or improvement. The paraneoplastic neuromuscular disorders can be divided into two main categories: those that are directly mediated by antibodies and those that are believed to result from other immune-mediated mechanisms, including cytotoxic T-cell responses with or without association with specific antibodies. For disorders in which the antibodies are pathogenic, therapy is aimed at removing the antibodies. For the other disorders, adjuvant therapies are for the most part empiric and include a variety of immunosuppressant and immunomodulatory agents.     

Autoantibodies in paraneoplastic syndromes associated with small-cell lung cancer

An antineuronal autoantibody has been identified in serum from 14 patients, 8 women and 6 men, with small-cell lung carcinoma (SCLC) and a neurologic disorder. Neurologic symptoms began prior to diagnosis of the SCLC in 12 patients. The dominant neurologic disorder was a subacute sensory neuronopathy (SSN) in eight patients, SSN plus lower motor neuron weakness (2 patients), SSN plus autonomic neuropathy (1 patient), cerebellar ataxia (1 patient), myelopathy (1 patient), and multifocal nervous system disease (encephalomyelitis) in one patient. The presence of the same autoantibody in patients with SSN, encephalomyelitis, and autonomic neuropathy suggests that these diseases are different manifestations of the same nosologic process. With one exception, treatment of the tumor, immunosuppressive drugs, and plasmapheresis did not influence the course of the neurologic illness. The autoantibody was not identified in sera from more than 400 controls subjects, including patients with SSN associated with other tumors, SSN without malignancy, other paraneoplastic syndromes, and SCLC without neurologic symptoms. The autoantibody is a highly specific marker of the paraneoplastic syndromes associated with SCLC and its detection in a patient not known to have cancer should prompt a careful search for SCLC.     

Update on paraneoplastic syndromes

PURPOSE OF REVIEW: This review discusses the varied clinical spectrum of neurologic paraneoplastic disorders, describes recent advances in our understanding of autoimmunity in these disorders, and outlines a practical clinical approach to patient management. RECENT FINDINGS: Paraneoplastic disorders may affect any part of the central or peripheral nervous system. Although relatively uncommon, these disorders are a significant cause of severe and permanent neurologic disability. Syndromes such as limbic encephalitis or opsoclonus-myoclonus should always raise suspicion of a paraneoplastic condition, but any paraneoplastic syndrome can also occur in patients without a neoplasm. Most neurologic paraneoplastic disorders are thought to be caused by an autoimmune reaction directed against 'onconeural' antigens expressed by neurons and tumor cells. Some syndromes such as Lambert-Eaton myasthenic syndrome and neuromyotonia are clearly mediated by autoantibodies. Much less is known about the immunopathogenesis of syndromes that affect the central nervous system, although a growing body of evidence implicates cellular immune effectors in causing neuronal injury. Many patients have circulating antineuronal antibodies, which can be useful in identifying a neurologic disorder as paraneoplastic and in finding the associated neoplasm. Early diagnosis of the neurologic disorder and prompt initiation of tumor treatment probably increase the likelihood of neurologic improvement. SUMMARY: Neurologists must be able to recognize the clinical manifestations of neurologic paraneoplastic disorders, and to distinguish them from other causes of neurologic dysfunction in cancer patients. Early diagnosis of paraneoplastic syndromes maximizes the likelihood of a favorable oncologic and neurologic outcome.     

Immune-mediated encephalopathies with an emphasis on paraneoplastic encephalopathies

Recent identification of syndromes encompassing psychiatric symptoms, seizures, and movement disorders has led to effective treatments for several previously obscure conditions now known to be immune-mediated encephalopathies. In contrast to long-recognized paraneoplastic neurologic syndromes associated with antibodies to intracellular antigens, these more recently described disorders are not always paraneoplastic, are associated with cell surface antibodies, and may respond to immunosuppressive therapies. In this review, the author discusses clinical presentations, differential diagnosis, immunologic evaluation, and therapeutic options for both groups of disorders.     

Paraneoplastic neurological syndromes: from the diagnosis of exclusion to the use of immunological and molecular markers

For many years paraneoplastic neurological syndromes have been identified through the exclusion of other neurological complications in patients with cancer. The discovery that many paraneoplastic syndromes are associated with immunological reactions allows a specific and comprehensive definition of these disorders, which often can be promptly recognized by the serological detection of antineuronal antibodies. In a significant number of paraneoplastic syndromes the genes coding for the target onconeuronal antigens have been cloned and their functions are being elucidated. This study reviews the pathogenic mechanisms of paraneoplastic neurological syndromes and addresses the most frequently asked questions regarding their diagnosis and treatment.     

Neuro-ophthalmology and paraneoplastic syndromes

PURPOSE OF REVIEW: To describe the neuro-ophthalmological manifestations of paraneoplastic syndromes and their immunological associations. RECENT FINDINGS: Neuro-ophthalmological signs and symptoms are usually present in paraneoplastic syndromes of the central nervous system. Unlike opsoclonus, less characteristic eye movement abnormalities are difficult to recognize as presenting symptoms of paraneoplastic syndromes. In this setting, the detection of several antibodies, including anti-Hu, Yo, Ma2, Ri, Tr, CV2/CRMP5 or voltage-gated calcium channel antibodies may help to establish that the neuro-ophthalmological disorder is paraneoplastic. Among the recently characterized antibodies, those against the Ma proteins often associate with brainstem encephalitis and vertical gaze paralysis. A small subset of patients with opsoclonus and ataxia harbor anti-Ri antibodies. In other patients, there is preliminary evidence that the autoantigens of opsoclonus reside in the postsynaptic density, but no dominant antibody marker has been identified. Uveitis and optic neuritis are rare accompaniments of paraneoplastic encephalomyelitis; some of these patients harbor anti-CV2/CRMP5 in association with other antibodies. Studies on paraneoplastic retinopathy indicate that immunity to retinal proteins other than recoverin can result in a similar syndrome to that associated with recoverin antibodies, and that melanoma-associated retinopathy may associate with several retinal antibodies. SUMMARY: There is increasing recognition of an extensive variety of neuro-ophthalmological abnormalities as manifestations of paraneoplastic syndromes and of several antineuronal antibodies as clinical markers of these disorders. Basic immunological studies support the pathogenic role of some of these antibodies, and are elucidating the pathogenic mechanisms that underlie these and other antibody-associated paraneoplastic syndromes.     

Screening for autoantibodies in children with opsoclonus-myoclonus-ataxia

Various paraneoplastic autoantibodies have been linked to discrete neurologic syndromes and tumors in adults, but little is known about their incidence in children. We report a cross-sectional study of known paraneoplastic antibodies in 59 children with opsoclonus-myoclonus-ataxia, 86% of whom were moderately or severely symptomatic, and 68% of whom had relapsed at the time of testing. This total number of patients includes 18 children with low-stage neuroblastoma (tested after tumor resection), six of whom had never been treated with immunosuppressants. All were seronegative for anti-Hu, anti-Ri, and anti-Yo, the three paraneoplastic antibodies most associated with opsoclonus-myoclonus or ataxia in adults. These data contrast with reports of anti-Hu-positive sera in children with high-stage tumors and suggest that anti-Hu, anti-Ri, and anti-Yo do not explain relapses in pediatric opsoclonus-myoclonus-ataxia. They underscore the need to search for unique autoantibodies, as well as cellular mechanisms of pediatric paraneoplastic disease.     

Neurologic complications of systemic cancer

Patients with cancer commonly suffer neurologic disabilities. These neurologic disorders can be either metastatic to the brain, spinal cord, leptomeninges, or peripheral nerves or nonmetastatic including infections, vascular problems, metabolic abnormalities, side effects of therapy, or paraneoplastic syndromes. Careful diagnostic evaluation of patients with cancer and neurologic symptoms often indicates effective therapy.     

Paraneoplastic neurological syndromes

PURPOSE OF REVIEW: This review discusses recent advances and current controversies in the aetiology, investigation and management of paraneoplastic neurological syndromes. RECENT FINDINGS: Antibody studies continue to define potential target autoantigens in paraneoplastic neurological syndromes and although pathogenic activity has been demonstrated for anti-glutamate receptor antibodies identified in a subset of patients with cerebellar ataxia, a role for paraneoplastic antibodies in the development of neuronal dysfunction has not been established in the majority of cases. As a result, attention has turned towards clarifying the role of adaptive cellular immunity in the pathogenesis of paraneoplastic neurological syndromes and several studies have defined expanded populations of cytotoxic T lymphocytes specific for epitopes derived from neuronal antigens in patients with paraneoplastic neurological syndromes. In vitro studies demonstrate the potential for antigen-specific cytotoxic T lymphocytes to restrict tumour growth and metastasis, but further investigation is needed to identify the mechanisms by which cytotoxic T lymphocytes could induce neuronal death. Clinical studies have demonstrated that effective tumour treatment can in some instances lead to improvement or stabilization of neurological symptoms. This is an encouraging observation since increased numbers of diagnostic paraneoplastic antibodies can now be reliably tested for and the use of [18F] fluoro-2-deoxyglucose positron emission tomography can facilitate earlier tumour diagnosis in patients presenting with paraneoplastic neurological syndromes. SUMMARY: Advances in the clinical management of patients with paraneoplastic neurological syndromes have occurred despite the fact that in most cases the immune effector mechanisms that lead to the development of neurological dysfunction remain to be characterized.     

Remote neurologic manifestations of cancer.

Paraneoplastic disorders may affect any part of the central or peripheral nervous systems. Although relatively uncommon, these disorders are a significant cause of neurologic morbidity for cancer patients. At least some paraneoplastic syndromes are believed to be caused by an autoimmune reaction against shared tumor-neural antigens. This article summarizes the clinical features of paraneoplastic disorders, the current evidence for autoimmunity, and guidelines for diagnosis and treatment.     

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

The long-term evolution of Hu antibody (Hu-Ab) titers in patients with paraneoplastic neurologic syndromes (PNSs) is not known. Described is the evolution of Hu-Ab titers in 35 patients with PNS with a median follow-up of 32 months (range 6 to 108 months). No correlation was observed between Hu-Ab titers and neurologic outcome, tumor evolution, or type of treatment. Serial Hu-Ab determinations are not useful for monitoring the clinical outcome of patients with PNS.     

Management of paraneoplastic neurological syndromes: report of an EFNS Task Force

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer on the nervous system. An overview of the management of classical PNS, i.e. paraneoplastic limbic encephalitis, subacute sensory neuronopathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert–Eaton myasthenic syndrome and paraneoplastic peripheral nerve hyperexcitability is given. Myasthenia gravis and paraproteinemic neuropathies are not included in this report. No evidence-based recommendations were possible, but good practice points were agreed by consensus. Urgent investigation is indicated, especially in central nervous system (CNS) syndromes, to allow tumour therapy to be started early and prevent progressive neuronal death and irreversible disability. Onconeural antibodies are of great importance in the investigation of PNS and can be used to focus tumour search. PDG-PET is useful if the initial radiological tumour screen is negative. Early detection and treatment of the tumour is the approach that seems to offer the greatest chance for PNS stabilization. Immune therapy usually has no or modest effect on the CNS syndromes, whereas such therapy is beneficial for PNS affecting the neuromuscular junction. Symptomatic therapy should be offered to all patients with PNS.