Paraneoplastic neuropathies

Paraneoplastic Demyelinating Inflammatory Neuropathy Revealing Metastatic Seminoma: A Case Report

Paraneoplastic neurological syndrome (PNS) is uncommon and not well known. PNS can reveal cancer, but its role in seminomas has not been described explicitly. We report the case of a 36-year-old man with unremarkable medical history and no comorbidities who was diagnosed with a retroperitoneal metastatic seminoma. The patient's general condition deteriorated, and he developed progressive neurological palsy without other clinical anomalies. Electromyography revealed demyelinating, non-lengthy neuropathy. Guillain-Barré syndrome was initially suspected. However, a positron emission tomography scan revealed a retroperitoneal mass, and blood markers revealed increased human chorionic gonadotropin. The patient was diagnosed with PNS, and a computed tomography-guided biopsy revealed a metastatic seminoma without a primary tumor. No circulating neural antibodies were detected. Human polyvalent immunoglobulin was simultaneously administered with chemotherapy. After three cycles of a cisplatin-etoposide-bleomycin, a complete biological and metabolic response rate was observed, and his neurological symptoms rapidly improved. Four years later, the patient responded completely, without any neurological complaints. Paraneoplastic demyelinating inflammatory neuropathy can lead to advanced seminoma diagnosis. Prompt management of seminomas with cisplatin-based regimens provides the best chance of cure for both advanced seminoma and paraneoplastic syndrome.

Guillain-Barré Syndrome-Like Polyneuropathy Associated with Immune Checkpoint Inhibitors: A Systematic Review of 33 Cases

Immune checkpoint inhibitors (ICIs) have been increasingly used in the treatment of various types of tumors with favorable results. But these treatments also led to a variety of immune-related adverse events (irAEs). Neurological irAEs such as Guillain-Barré Syndrome are rare and may have serious consequences once they occur. A systematic literature search was performed in PubMed and Embase for all case reports of GBS associated with ICIs published in English reporting on human beings from 1990 up to date. A total of 30 case reports (total patients = 33) were used for final analysis. The included cases were from 11 countries, covering 10 tumor types, with melanoma accounting for the largest number. The mean age was 62.2 ± 11.1 years old, and males were dominant (male: 26 and female: 7). The median time of initial symptoms was 8.2 weeks after the 1^st dose of ICIs. The most common manifestations of GBS associated with ICIs were weakness, hyporeflexia or areflexia, and paresthesia in order. The GBS subtypes suggested by electrophysiological results were acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and Miller Fisher syndrome (MFS). The protein level of CSF in patients with GBS related to ICIs was 180.68 ± 152.51 mg/dl. Immediate termination of ICIs followed by intravenous immunoglobulin was the preferred treatment option. 72.7% of patients recovered or had residual mild dysfunction after treatment. Elderly male patients with melanoma were most likely to develop ICI-related GBS. The specific neurological symptoms, CSF analysis, and electrophysiological examination were important means of diagnosis.

Autoimmune Neurogenic Dysphagia

Autoimmune neurogenic dysphagia refers to manifestation of dysphagia due to autoimmune diseases affecting muscle, neuromuscular junction, nerves, roots, brainstem, or cortex. Dysphagia is either part of the evolving clinical symptomatology of an underlying neurological autoimmunity or occurs as a sole manifestation, acutely or insidiously. This opinion article reviews the autoimmune neurological causes of dysphagia, highlights clinical clues and laboratory testing that facilitate early diagnosis, especially when dysphagia is the presenting symptom, and outlines the most effective immunotherapeutic approaches. Dysphagia is common in inflammatory myopathies, most prominently in inclusion body myositis, and is frequent in myasthenia gravis, occurring early in bulbar-onset disease or during the course of progressive, generalized disease. Acute-onset dysphagia is often seen in Guillain–Barre syndrome variants and slowly progressive dysphagia in paraneoplastic neuropathies highlighted by the presence of specific autoantibodies. The most common causes of CNS autoimmune dysphagia are demyelinating and inflammatory lesions in the brainstem, occurring in patients with multiple sclerosis and neuromyelitis optica spectrum disorders. Less common, but often overlooked, is dysphagia in stiff-person syndrome especially in conjunction with cerebellar ataxia and high anti-GAD autoantibodies, and in gastrointestinal dysmotility syndromes associated with autoantibodies against the ganglionic acetyl-choline receptor. In the setting of many neurological autoimmunities, acute-onset or progressive dysphagia is a potentially treatable condition, requiring increased awareness for prompt diagnosis and early immunotherapy initiation.

Antibodies against cell adhesion molecules and neural structures in paraneoplastic neuropathies

Objective

Paraneoplastic neurological syndromes (PNS) are rare neurological disorders in which ectopic expression of neural antigens by a tumor results in an autoimmune attack against the nervous system. Onconeural antibodies not only guide PNS diagnosis but may also help detecting underlying malignancies. Our project aims to uncover new potential antibodies in paraneoplastic neuropathies (PN).

Methods

Thirty‐four patients fulfilling diagnostic criteria of possible (n = 9; 26.5%) and definite (n = 25; 73.5%) PN without onconeural antibodies and 28 healthy controls were included in our study. Sera were tested for known antibodies against neural cell adhesion molecules and screened for novel IgG and IgM reactivities against nerve components: dorsal root ganglia (DRG) neurons, motor neurons, and Schwann cells. Patients showing autoantibodies against any of these cell types were used for immunoprecipitation (IP) studies.

Results

Overall, 9 (26.5%) patients showed significant reactivity against DRG neurons, motor neurons, or Schwann cells, whereas 5 (17.9%) healthy controls only showed moderate reactivity. Compared with control sera, serum samples from patients with paraneoplastic sensory‐motor neuropathies had a higher frequency of IgM antibodies against Schwann cells (0% vs. 40%; P = 0.0028). No novel antigens were identified from our IP experiments. Antibodies against the neural adhesion molecules CNTN1, NF155, NF140, NF186, NCAM1, L1CAM, and the CNTN1/CASPR1 complex were not detected in patients with PN. One (2.9%) patient with CIDP and thymoma had CASPR2 antibodies.

Interpretation

Almost 30% of patients with PN harbor antibodies targeting neural structures, suggesting that novel neoplasm‐associated antigens remain to be discovered.

Autoimmune Movement Disorders: a Clinical and Laboratory Approach

Autoimmune movement disorders are caused by an aberrant immune response to neural self-antigens. These disorders may be paraneoplastic, parainfectious, or (most commonly) idiopathic. The neurological presentations are diverse, and sometimes multifocal. Movement disorders can occur as part of the spectrum with phenotypes including chorea, myoclonus, ataxia, CNS hyperexcitability (including stiff-person syndrome), dystonia, and parkinsonism. Symptoms are subacute in onset and may have a fluctuating course. The best characterized disorders are unified by neural autoantibodies identified in serum or cerebrospinal fluid. The antibody specificity may predict the association with cancer and the response to immunotherapy. In this article, we review autoimmune-mediated movement disorders, associated cancers, diagnosis, and treatment.

Paraneoplastic Peripheral Nervous System Manifestations of Renal Cell Carcinoma: A Case Report and Review of the Literature

Neurologic symptoms secondary to a paraneoplastic syndrome may be the presenting manifestation of a previously undiagnosed cancer, and alertness to these syndromes may provide an opportunity for early detection and treatment of a cancer. Paraneoplastic weakness is a rare manifestation of renal cell carcinoma and may present with variable electrophysiological features. We present a case of a patient with progressive weakness, sensory changes, and urinary retention, with electrophysiological features suggestive of a complex peripheral nervous system syndrome. Ultimately, a renal cell mass was detected and resected, resulting in significant clinical improvement. We review the literature, cataloging the known neurologic syndromes and antibodies associated with renal cell carcinoma. This case highlights that paraneoplastic neurological disorders associated with RCC can take on many features and provides a resource to practitioners for early detection of a neurologic paraneoplastic syndrome arising from renal cell carcinoma.

Double trouble: para-neoplastic anti-PCA-2 and CRMP-5-mediated small fibre neuropathy followed by chorea associated with small cell lung cancer and evolving radiological features

Patients with Purkinje cell cytoplasmic autoantibody type 2 (PCA-2) and collapsin response-mediator protein-5 (CRMP-5) autoantibody can present with multifocal elements of encephalomyeloneuropathy. Except for an anecdotal report, case descriptions of paraneoplastic small fibre neuropathy are lacking. We report paraneoplastic small fibre neuropathy followed by chorea associated with small cell lung cancer. A man aged 57 years with a 35 pack-year smoking history presented with painless subacute paresthesia and weight fluctuation. A non-length-dependent small fibre neuropathy was confirmed by skin biopsy. Further testing revealed positive serum PCA-2 and CRMP-5 autoantibodies, which after positron emission tomography-CT led to histological confirmation of a small cell lung cancer. Initially, abnormal MRI and cerebrospinal fluid studies suggested central nervous system (CNS) involvement which was subclinical; however, 6 months later during antitumour therapy, the patient became symptomatic with choreoathetosis. After combined chemoradiation as well as immunosuppressive and symptomatic therapies, the clinical course stabilised, although residual neurological deficits remained at follow-up a year later. Coexistent PCA-2 and CRMP-5 autoantibodies may occur in the setting of small fibre peripheral neuropathy and choreoathetosis and predict cancer type. Two paraneoplastic syndromes can present successively over months; subclinical CNS involvement with evolving basal ganglia abnormalities can be a paraneoplastic manifestation. In the appropriate clinical setting, paraneoplastic testing should be considered in patients presenting with small fibre neuropathy.

Immune-Mediated Neurological Disorders

Autoimmune disorders are increasingly recognized causes of several neurological disorders leading to significant clinical disability. This article reviews recent developments in our understanding on the pathophysiology, clinical presentations, and diagnoses of selected immune-mediated neurological disorders. It also provides a brief summary of current theories on autoimmunity and the role that certain environmental factors play in the development of immune-mediated neurological disorders. Recently recognized biomarkers might play a pathogenetic role or simply serve as a diagnostic tool.