N-type calcium channel antibody-mediated autoimmune encephalitis: An unlikely cause of a common presentation

Autoimmune encephalitis: Early and late findings on serial MR imaging and correlation to treatment timepoints

Introduction

MRI is negative in a large percentage of autoimmune encephalitis cases or lacks findings specific to an antibody. Even rarer is literature correlating the evolution of imaging findings with treatment timepoints. We aim to characterize imaging findings in autoimmune encephalitis at presentation and on follow up correlated with treatment timepoints for this rare disease.

Methods

A full-text radiological information system search was performed for "autoimmune encephalitis" between January 2012 and June 2022. Patients with laboratory-identified autoantibodies were included. MRI findings were assessed in correlation to treatment timepoints by two readers in consensus. For statistical analysis, cell-surface vs intracellular antibody groups were assessed for the presence of early limbic, early extralimbic, late limbic, and late extralimbic findings using the χ2 test.

Results

Thirty-seven patients (female n = 18, median age 58.8 years; range 25.7 to 82.7 years) with 15 different autoantibodies were included in the study. Twenty-three (62%) patients were MRI-negative at time of presentation; 5 of these developed MRI findings on short-term follow up. Of the 19 patients with early MRI findings, 9 (47%) demonstrated improvement upon treatment initiation (7/9 cell-surface group). There was a significant difference (p = 0.046) between the MRI spectrum of cell-surface vs intracellular antibody syndromes as cell-surface antibody syndromes demonstrated more early classic findings of limbic encephalitis and intracellular antibody syndromes demonstrated more late extralimbic abnormalities.

Conclusion

MRI can be used to help narrow the differential diagnosis in autoimmune encephalitis and can be used as a monitoring tool for certain subtypes of this rare disease.

Language impairments in people with autoimmune neurological diseases: A scoping review

INTRODUCTION

Autoimmune neurological diseases (ANDs) are a specific type of autoimmune disease that affect cells within the central and peripheral nervous system. ANDs trigger various physical/neuropsychiatric symptoms. However, language impairments in people with ANDs are not well characterized. Here we aimed to determine the kinds of language impairment that most commonly emerge in 10 ANDs, the characteristics of the patients (demographic, neurological damage), and the assessment methods used.

METHODS

We followed the PRISMA Extension for Scoping Reviews (PRISMA-ScR). PubMed and Google Scholar were searched. We used a list of search terms containing 10 types of ANDs (e.g., multiple sclerosis, acute disseminated encephalomyelitis) in combination with the terms aphasia, dysphasia, fluency, language, listening, morphology, phonology, pragmatics, reading, semantics, speaking, syntax, writing. The reference lists and citations of the relevant papers were also investigated. The type of AND, patient characteristics, neurological damage and examination technique, language tests administered, and main findings were noted for each study meeting the inclusion criteria.

RESULTS

We found 171 studies meeting our inclusion criteria. These comprised group studies and case studies. Language impairments differed largely among types of ANDs. Neurological findings were mentioned in most of the papers, but specific language tests were rarely used.

CONCLUSIONS

Language symptoms in people with ANDs are commonly reported. These are often not full descriptions or only focus on specific time points in the course of the disease. Future research needs to assess specific language functions in people with ANDs and relate their language impairments to brain damage at different stages of disease evolution.

Autoimmune-mediated encephalitis and mimics: A neuroimaging review

Autoimmune encephalitis is a category of autoantibody-mediated neurological disorders that often presents a diagnostic challenge due to its variable clinical and imaging findings. The purpose of this image-based review is to provide an overview of the major subtypes of autoimmune encephalitis and their associated autoantibodies, discuss their characteristic clinical and imaging features, and highlight several disease processes that may mimic imaging findings of autoimmune encephalitis. A literature search on autoimmune encephalitis was performed and publications from neuroradiology, neurology, and nuclear medicine literature were included. Cases from our institutional database that best exemplify major imaging features were presented.

Use of anti-seizure medications in different types of autoimmune encephalitis: A narrative review

Seizures are the main manifestation of the acute phase of autoimmune encephalitis (AE). Anti-seizure medications (ASMs) play an important role in controlling seizures in AE patients, but there is currently a lack of consensus regarding the selection, application, and discontinuation of ASMs. This narrative review focuses on the use of ASMs in patients with AE driven by different antibodies. The PubMed, Embase, and MEDLINE databases were searched up until 30 October 2022 using prespecified search terms. We identified 2,580 studies; 23 retrospective studies, 2 prospective studies and 9 case reports were evaluated based on our inclusion criteria. Anti-N-methyl-D-aspartic-acid-receptor (anti-NMDAR) encephalitis is the type of AE that responds best to ASMs, and long-term or combined use of ASMs may be not required in most patients with seizures; these results apply to both adults and children. Sodium channel blockers may be the best option for seizures in anti-leucine-rich-glioma-inactivated-1 (anti-LGI1) encephalitis, but patients with anti-LGI1 encephalitis are prone to side effects when using ASMs. Cell surface antibody-mediated AE patients are more likely to use ASMs for a long period than patients with intracellular antibody-mediated AE. Clinicians can score AE patients' clinical characteristics on a scale to identify those who may require long-or short-term use of ASMs in the early stage. This review provides some recommendations for the rational use of ASMs in encephalitis mediated by different antibodies with the aim of controlling seizures and avoiding overtreatment.

Neuroimmunogastroenterology: At the Interface of Neuroimmunology and Gastroenterology

The central nervous system (CNS) is an important regulator of the gastrointestinal tract, and CNS dysfunction can result in significant and disabling gastrointestinal symptom manifestation. For patients with neuroimmunologic and neuroinflammatory conditions, the recognition of gastrointestinal symptoms is under-appreciated, yet the gastrointestinal manifestations have a dramatic impact on quality of life. The current treatment strategies, often employed independently by the neurologist and gastroenterologist, raise the question of whether such patients are being treated optimally when siloed in one specialty. Neuroimmunogastroenterology lies at the borderlands of medical specialties, and there are few resources to guide neurologists in this area. Here, we provide an overview highlighting the potential mechanisms of crosstalk between immune-mediated neurological disorders and gastrointestinal dysfunction.

Rituximab for Autoimmune Encephalitis with Epilepsy

Intractable epilepsy remains a significant medical challenge, resulting in recurrent and prolonged intensive care unit (ICU) admissions. Autoimmune encephalitis is emerging as a treatable cause of intractable epilepsy. It is characterized by antibodies against cerebral antigens, such as potassium channels such as leucine-rich, glioma inactivated 1 (LGI1) and contactin-associated protein 2 (CASPR2), calcium channels such as the voltage-gated calcium channel (VGCC), or neurotransmitter receptors such as the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), gamma aminobutyric acid receptor (GABAR), and N-methyl-D-aspartate receptor (NMDAR). Diagnosis requires a syndrome consistent with an antibody identified in serum or cerebrospinal fluid (CSF) using methods that minimize risk of false-positives. Although there is no officially approved therapy for these disorders, typical approaches involve chronic high-dose steroids, intravenous immunoglobulin (IVIG), or plasma exchange. Rituximab is effective for antibody-associated disorders such as lupus, myasthenia gravis, and neuromyelitis optica. Here, we present three patients who were admitted with recalcitrant status epilepticus and demonstrated serum antibodies against NMDAR, LGI1, or VGCC using a cell-based assay. All patients demonstrated complete, long-term epilepsy control and improvement in symptoms with rituximab.

Clinical Presentation and Outcome in Autoimmune Encephalitis Associated With N-Type Voltage-Gated Calcium Channels in Children

OBJECTIVE

We present the diagnostic and clinical course of the first multicenter case series of pediatric patients with autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies.

METHODS

Data from 2 university hospitals were retrospectively reviewed and records of 3 patients with autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies were evaluated.

RESULTS

The 3 pediatric patients (all female) had symptoms that spanned the clinical spectrum. All 3, however, had regression of expressive language and agitation. Neuroimaging in all 3 patients was normal; electroencephalographic (EEG) findings varied among the 3 patients. Positive titers against the N-type voltage-gated calcium channel antibody were found in their cerebrospinal fluid. Following administration of intravenous immunoglobulin, all 3 had improvement in their core presenting symptoms.

CONCLUSION

Autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies in the pediatric population presents with a wide clinical spectrum, although expressive language delay and agitation seem to be common symptoms. Treatment with intravenous immunoglobulin improves core symptoms.

Non paraneoplastic immune-mediated calcium channel chorea

Antibodies to the N-type voltage-gated calcium channel have rarely been reported in association with chorea. Prior reported cases have been either paraneoplastic in nature or presented in the setting of other concurrent antibody elevations. Moreover, the identified studies showed only mild elevation of calcium channel antibodies. We present a case of chorea in association with an isolated serum elevation in N-type calcium channel antibodies and clinical improvement with intravenous immunoglobulin.

The role of the laboratory in the expanding field of neuroimmunology: Autoantibodies to neural targets

Accelerated identification of autoantibodies associated with previously idiopathic neurological disease has provided insights into disease mechanisms, enhanced understanding of neurological function, and opportunities for improved therapeutic interventions. The role of the laboratory in the expanding field of neuroimmunology is critical as specific autoantibody identification provides guidance to clinicians in diagnosis, prognosis, tumor search strategies, and therapeutic interventions. The number of specific autoantibodies identified continues to increase and newer testing strategies increase efficiencies in the laboratory and availability to clinicians. The need for broadly targeted efficient testing is underscored by the variability in clinical presentation and tumor associations attributable to a specific autoantibody, and conversely the various autoantibody specificities that can be the cause of a given clinical presentation. While many of the antineural antibodies were first recognized in the setting of neoplastic disease, idiopathic autoimmune neurological disease in the absence of underlying tumor is increasingly recognized. Appropriation of therapeutic modalities used to treat autoimmune disease to treat these autoantibody mediated neurological diseases has improved patient outcomes. Interaction between clinicians and laboratorians is critical to our understanding of these diseases and optimization of the clinical benefits of our increasing knowledge in neuroimmunology.

Autoimmune encephalitis with elevated N-type calcium channel antibodies as a multiple sclerosis mimic

BACKGROUND

Voltage gated calcium channels (VGCC) are well-known targets for antibody-associated disease. Of the 5 VGCC subtypes, the most well-known is the P/Q subtype associated with Lambert-Eaton Myasthenic Syndrome (LEMS). However, this case focuses on the much less understood N-type calcium channel antibody. The objective of this case is to review the literature regarding the clinical significance of the N-type calcium channel antibody and its relationship to MS.

METHODS

A 37-year old male presented with vertigo, paranoia, and tremor and had MRI changes suggestive of demyelinating disease. Evaluation revealed positive N-type calcium channel antibodies. Steroids dramatically improved symptoms and normalized antibodies. Years later recurrent symptoms were again associated with elevated antibodies.

RESULTS AND CONCLUSION

This patient likely has autoimmune encephalitis associated with elevated N-type calcium channel antibodies. This case highlights the clinical significance of N-type calcium channel antibodies and the importance of correctly diagnosing patients with antibody mediated disease that may very well mimic more common neurologic diseases such as multiple sclerosis (MS).

Auto-antibodies against P/Q- and N-type voltage-dependent calcium channels mimicking frontotemporal dementia

The behavioral variant of frontotemporal dementia is usually a sporadic and progressive neurodegenerative disorder. Here, we report the subacute onset of a frontotemporal dementia phenotype with a treatable etiology. The patient has a history of rheumatoid arthritis, episcleritis, and thyroid eye disease on immunosuppressive therapy. He experienced a rapid personality change, including inappropriate behavior, which suggested frontotemporal dementia. Results of imaging and neuropsychological testing also suggested frontotemporal dementia. Because of his autoimmune diseases and unusually short onset of symptoms, serum paraneoplastic panel and cerebrospinal fluid were analyzed and revealed elevated P/Q- and N-type calcium channel antibodies. Treatment with therapeutic plasma exchange resulted in a rapid improvement of his behavior and cognition. This case suggests that there may be some treatable causes of frontotemporal dementia symptomatology, that is, paraneoplastic antibodies. In the context of atypical features of frontotemporal dementia, practitioners should maintain a high index of suspicion.

Autoimmune Encephalitis: Pathophysiology and Imaging Review of an Overlooked Diagnosis

Autoimmune encephalitis is a relatively new category of immune-mediated disease involving the central nervous system that demonstrates a widely variable spectrum of clinical presentations, ranging from the relatively mild or insidious onset of cognitive impairment to more complex forms of encephalopathy with refractory seizure. Due to its diverse clinical features, which can mimic a variety of other pathologic processes, autoimmune encephalitis presents a diagnostic challenge to clinicians. Imaging findings in patients with these disorders can also be quite variable, but recognizing characteristic findings within limbic structures suggestive of autoimmune encephalitis can be a key step in alerting clinicians to the potential diagnosis and ensuring a prompt and appropriate clinical work-up. In this article, we review antibody-mediated encephalitis and its various subtypes with a specific emphasis on the role of neuroimaging in the diagnostic work-up.

N-type calcium channel antibody-mediated paraneoplastic limbic encephalitis: a diagnostic challenge

BACKGROUND

The etiology of encephalitis presents a diagnostic challenge and often remains a mystery. However, current technological advances using antibodies can enable a definitive diagnosis in cases that would previously have been suspected to be idiopathic or viral encephalitis. Our objective is to show that tonsil neuroendocrine carcinoma can present initially as limbic encephalitis mediated by N-type calcium channel antibodies and to highlight the diagnostic confusion before cancer detection.

METHODS

We report a rare case of neuroendocrine cancer presenting as limbic encephalopathy, Lambert-Eaton myasthenic syndrome and neuropathy. The patient was diagnosed and treated at The University of Texas MD Anderson Cancer Center in November 2011.

RESULTS

Paraneoplastic limbic encephalitis was diagnosed based on clinical presentation of seizures, short-term memory loss, retrograde amnesia, disorientation, distractibility, and abulia; on the exclusion of brain metastases, CNS infection, stroke, metabolic or nutritional deficits, or medication-related events; and on CSF results with inflammatory findings and an abnormal electroencephalography study that showed seizure activity in the left temporal lobe. Serum paraneoplastic panel was positive for P/Q-type calcium channel antibody and N-type calcium channel antibody. Magnetic resonance imaging of brain was unremarkable.

CONCLUSION

This case highlights limbic encephalitis as an atypical presentation of neuroendocrine cancer. It also illustrates how treatment of the underlying cancer can reverse limbic encephalitis and Lambert-Eaton myasthenic syndrome in a neuroendocrine carcinoma patient even before the paraneoplastic panel becomes negative.