Limbic encephalitis – a review

Neurosyphilis presenting as limbic encephalitis

A man in his 50s presented with focal seizures and was found to have an inflammatory cerebrospinal fluid (CSF) with bilateral mesiotemporal lobe hyperintensity on magnetic resonance imaging (MRI) of the brain. Corticosteroid treatment was initiated for management of limbic encephalitis. Focal seizures, imaging abnormalities and inflammatory CSF persisted despite treatment and the patient was found to have neurosyphilis after developing neuropsychiatric symptoms. Syphilis is a sexually transmitted bacterial infection with multisystem involvement including neurological and psychiatric manifestations. Case reports have emerged of neurosyphilis presenting as limbic encephalitis with CSF pleocytosis and temporal lobe hyperintensity on MRI of the brain. Persistence of CSF or MRI abnormalities despite immunosuppressive therapy for limbic encephalitis should prompt investigation for alternate causes of chronic meningoencephalitis, which can occasionally include neurosyphilis.

Autoimmune Encephalitis-A Multifaceted Pathology

Autoimmune encephalitis is a complex and multifaceted pathology that involves immune-mediated inflammation of the brain. It is characterized by the body's immune system attacking the brain tissue, leading to a cascade of inflammatory processes. What makes autoimmune encephalitis vast is the wide range of causes, mechanisms, clinical presentations, and diagnostic challenges associated with the condition. The clinical presentations of autoimmune encephalitis are broad and can mimic other neurological disorders, making it a challenging differential diagnosis. This diverse clinical presentation can overlap with other conditions, making it crucial for healthcare professionals to maintain a high level of suspicion for autoimmune encephalitis when evaluating patients. The diagnostic challenges associated with autoimmune encephalitis further contribute to its vastness. Due to the variable nature of the condition, there is no definitive diagnostic test that can confirm autoimmune encephalitis in all cases. In this context, personalized patient management is crucial for achieving favorable outcomes. Each patient's treatment plan should be tailored to their specific clinical presentation, underlying cause, and immune response. Our objective is to raise awareness about the frequent yet underdiagnosed nature of autoimmune encephalitis by sharing five cases we encountered, along with a brief literature review.

Review and meta-analysis of neuropsychological findings in autoimmune limbic encephalitis with autoantibodies against LGI1, CASPR2, and GAD65 and their response to immunotherapy

OBJECTIVES

It is assumed that autoimmune limbic encephalitis (ALE) demonstrates distinct neuropsychological manifestations with differential responses to immunotherapy according to which associated autoantibody (AAB), if any, is identified. Towards investigating whether this is the case, this study aims to summarize respective findings from the primary literature on ALE with AABs binding to cell surface neural antigens and ALE with AABs against intracellular neural antigens.

METHODS

We chose ALE with AABs against leucine-rich, glioma inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) as the most frequent cell surface membrane antigens, and ALE with AABs to Embryonic Lethal, Abnormal Vision, Like 1 (ELAVL) proteins (anti-Hu) and glutamic acid decarboxylase 65 (GAD65) as the most frequent intracellular neural antigens. The PubMed and Scopus databases were searched on March 1st, 2021 for neuropsychological test and -screening data from patients with ALE of these AAB-types. Findings were reviewed according to AAB-type and immunotherapy status and are presented in a review section and are further statistically evaluated and presented in a meta-analysis section in this publication.

RESULTS

Of the 1304 initial hits, 32 studies on ALE with AABs against LGI1, CASPR2, and GAD65 reporting cognitive screening data could be included in a review. In ALE with AABs against LGI1, CASPR2 and GAD65, memory deficits are the most frequently reported deficits. However, deficits in attention and executive functions including working memory, fluency, and psychological function have also been reported. This review shows that ALE patients with AABs against both LGI1 and CASPR2 show higher percentages of neuropsychological deficits compared to ALE patients with AABs against GAD65 before and after initiation of immunotherapy. However, the methodologies used in these studies were heterogenous, and longitudinal studies were not comparable. Moreover, 21 studies including ALE patients with AABs against LGI1 and GAD65 were also suitable for meta-analysis. No suitable study on ALE with AABs against ELAVL proteins could be identified. Meta-Analyses could be executed for cognitive screening data and only partially, due to the small number of studies. However, in statistical analysis no consistent effect of AAB or immunotherapy on performance in cognitive screening tests could be found.

CONCLUSION

Currently, there is no definite evidence supporting the notion that different AAB-types of ALE exhibit distinct neuropsychological manifestations and respond differently to immunotherapy. Overall, we could not identify evidence for any effect of immunotherapy on cognition in ALE. More systematic, in-depth and longitudinal neuropsychological assessments of patients with different AAB-types of ALE are required in the future to investigate these aspects.

Neuropsychological and Structural Neuroimaging Outcomes in LGI1-Limbic Encephalitis: A Case Study

OBJECTIVE

Anti-leucine-rich glioma-inactivated 1 limbic encephalitis (LGI1-LE) is a rare autoimmune condition that affects the structural integrity and functioning of the brain's limbic system. Little is known about its impact on long-term neuropsychological functioning and the structural integrity of the medial temporal lobe. Here we examined the long-term neuropsychological and neuroanatomical outcomes of a 68-year-old male who acquired LGI1-LE.

METHODS

Our case patient underwent standardized neuropsychological testing at two time points. Volumetric analyses of T1-weighted images were undertaken at four separate time points and qualitatively compared with a group of age-matched healthy controls.

RESULTS

At the time of initial assessment, our case study exhibited focal impairments in verbal and visual episodic memory and these impairments continued to persist after undergoing a course of immunotherapy. Furthermore, in reference to an age-matched healthy control group, over the course of 11 months, volumetric brain imaging analyses revealed that areas of the medial temporal lobe including specific hippocampal subfields (e.g., CA1 and dentate gyrus) underwent a subacute period of volumetric enlargement followed by a chronic period of volumetric reduction in the same regions.

CONCLUSIONS

In patients with persisting neurocognitive deficits, LGI1-LE may produce chronic volume loss in specific areas of the medial temporal lobe; however, this appears to follow a subacute period of volume enlargement possibly driven by neuro-inflammatory processes.

Autoimmune Encephalitis: A Physician’s Guide to the Clinical Spectrum Diagnosis and Management

The rapidly expanding spectrum of autoimmune encephalitis in the last fifteen years is largely due to ongoing discovery of many neuronal autoantibodies. The diagnosis of autoimmune encephalitis can be challenging due to the wide spectrum of clinical presentations, prevalence of psychiatric features that mimic primary psychiatric illnesses, frequent absence of diagnostic abnormalities on conventional brain MR-imaging, non-specific findings on EEG testing, and the lack of identified IgG class neuronal autoantibodies in blood or CSF in a subgroup of patients. Early recognition and treatment are paramount to improve outcomes and achieve complete recovery from these debilitating, occasionally life threatening, disorders. This review is aimed to provide primary care physicians and hospitalists who, together with neurologist and psychiatrists, are often the first port of call for individuals presenting with new-onset neuropsychiatric symptoms, with up-to-date data and evidence-based approach to the diagnosis and management of individuals with neuropsychiatric disorders of suspected autoimmune origin.

18F-FDG-PET Imaging Patterns in Autoimmune Encephalitis: Impact of Image Analysis on the Results

Brain positron emission tomography imaging with 18Fluorine-fluorodeoxyglucose (FDG-PET) has demonstrated utility in suspected autoimmune encephalitis. Visual and/or assisted image reading is not well established to evaluate hypometabolism/hypermetabolism. We retrospectively evaluated patients with autoimmune encephalitis between 2003 and 2018. Patients underwent EEG, brain magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) sampling and autoantibodies testing. Individual FDG-PET images were evaluated by standard visual reading and assisted by voxel-based analyses, compared to a normal database. For the latter, three different methods were performed: two based on statistical surface projections (Siemens syngo.via Database Comparison, and 3D-SSP Neurostat) and one based on statistical parametric mapping (SPM12). Hypometabolic and hypermetabolic findings were grouped to identify specific patterns. We found six cases with definite diagnosis of autoimmune encephalitis. Two cases had anti-LGI1, one had anti-NMDA-R and two anti-CASPR2 antibodies, and one was seronegative. ¹⁸F-FDG-PET metabolic abnormalities were present in all cases, regardless of the method of analysis. Medial–temporal and extra-limbic hypermetabolism were more clearly depicted by voxel-based analyses. We found autoantibody-specific patterns in line with the literature. Statistical surface projection (SSP) methods (Neurostat and syngo.via Database Comparison) were more sensitive and localized larger hypermetabolic areas. As it may lead to comparable and accurate results, visual analysis of FDG-PET studies for the diagnosis of autoimmune encephalitis benefits from voxel-based analysis, beyond the approach based on MRI, CSF sample and EEG.

Emergency Department Evaluation of the Adult Psychiatric Patient

Many patients with acute behavioral or mental health emergencies use the emergency department for their care. Psychiatric patients have a higher incidence of chronic medical conditions and are at greater risk for injury than the general population. Patients with acute behavioral emergencies may stress already overcrowded emergency departments. This article addresses high-risk areas of the treatment and management of emergency department patients presenting with behavioral emergencies. This article identifies methods successful in determining whether the patient's behavioral emergency is the result of an organic disease process, as well as recognizing other potential acute medical emergencies in this high-risk population.

Limbic encephalitis associated with tuberculous mediastinal lymphadenitis

Introduction

Limbic encephalitis represents an autoimmune disorder that is commonly associated with malignancies. It is also seen in association with infectious or systemic autoimmune diseases. The literature reports two case reports of limbic encephalitis associated with tuberculosis.

Case Report

We report the case of a 42 year-old male referred to our clinic for a non-resolving pneumonia. He was found to have a limbic encephalitis associated with mediastinal tuberculous lymphadenitis. The diagnosis was made on a needle aspirate from a mediastinal lymph node obtained through endobronchial ultrasound. A paradoxical radiological progression was noted during therapy. He was successfully treated by anti-tuberculous drugs with clinical and radiological improvement.

Conclusion

Limbic encephalitis is associated with tuberculosis and should be included as part of the central nervous system involvement with tuberculosis. Endobronchial ultrasound has been shown to be useful in the diagnosis of mediastinal tuberculous lymphadenitis.

A 9-year neuropsychological report of a patient with LGI1-associated limbic encephalitis

Introduction: Anti-leucine-rich glioma-inactivated 1 limbic encephalitis (LGI1-LE) is an autoimmune disorder associated with antibodies to voltage-gated potassium channels (VGKC). It is a non-paraneoplastic and partially reversible encephalitis that can be diagnosed via serological testing. Untreated LGI1-LE can be associated with neurocognitive as well as neuropsychiatric sequelae. Here we report the neuropsychological and clinical profile of a patient with LGI1-LE following three different treatment approaches: plasmapheresis (PA), intravenous immunoglobulin (IVIG), and corticosteroids (CO). Method: We investigated our patient with 10 neuropsychological evaluations obtained over a 9-year follow-up period. Multiple MRI scans, EEG recordings, neurological examinations, and serum tests were also obtained. Results: The neurocognitive profile of our patient was characterized by long-term memory impairment (verbal and visual-spatial), and deficits in aspects of executive functioning and language. Neuropsychiatric symptoms of depression and anxiety were noted intermittently. Conclusions: Non-specific treatment prior to diagnosis had marginal effects on neurocognitive profile, neuropsychiatric symptoms, or control of epileptic seizure. In contrast, specific treatments for LGI1-LE following diagnosis resulted in neurocognitive improvement and epileptic control. Among the three treatments, IVIG and CO had the most beneficial impact on neurocognitive status, likely due to the continuity of administration.

Limbic encephalitis: Experience of a moroccan center

OBJECTIVES

Histologically defined as an inflammation-degeneration of limbic structures, limbic encephalitis (LE) is a rare disease and often difficult to diagnose particularly in institutions with limited access to laboratory tests such as antineuronal antibodies or HSV-PCR, and functional imaging. We aimed to describe the demographic, clinical, paraclinical, and etiological features of LE, as well as its medium-term prognosis in Moroccan patients.

MATERIALS AND METHODS

We collected retrospectively all patients diagnosed with LE in the Department of Neurology of the University Hospital Hassan II of Fez (Morocco) between September 2008 and December 2016. We analyzed their demographic features, clinical manifestations, magnetic resonance imaging and laboratory findings, etiologies, and medium-term prognoses.

RESULTS

We included 22 men and 9 women aged 14-76 years (mean age: 45.8 years). In 64.5% of cases, the onset of symptoms was acute. The clinical manifestations included generalized status epilepticus (16.1%), confusional syndrome (29%), epileptic seizures (38.7%), psychiatric disorders (48.4%), and memory disorders (45.2%). The nonlimbic symptoms were nuchal stiffness (22.6%), headaches (9.7%), fever (61.3%), vesicular rash (3.2%), and language disorders (6.5%). The different etiologies found were herpes simplex virus (6.5%), syphilis (16.1%), tuberculosis (3.2%), varicella (3.2%), paraneoplastic autoimmune LE (22.6%), anti-NMDA-R LE (6.5%), and sarcoidosis (3.2%). We found 12 cases (38.7%) of LE without definite etiology and with an incomplete diagnostic workup. The medium-term clinical course includes a complete remission in 45.2% of cases and partial remission in 45.1% of cases. The different sequelae were temporal lobe epilepsy (9.7%), anterograde amnesia (16.1%), and severe cognitive impairment (19.4%). The mortality rate was 9.7% (3 patients).

CONCLUSION

Our study shows a wide diversity of etiologies of LE in Morocco with essentially an acute mode of onset of symptoms.

The role of cognitive rehabilitation in limbic encephalitis: A case report

RATIONALE

Limbic encephalitis is a parenchymal inflammation caused by viral, bacterial, or other microbial and postinfectious agents, which is usually expressed by multifocal neurological signs and cognitive impairment.

PATIENT CONCERNS

A 50-year-old female was admitted in postacute phase, at our rehabilitative Center, to undertake neuro-motor treatment for a period of 4 months.

DIAGNOSES

The patient was affected by limbic encephalitis. Clinical presentation revealed attention, memory and executive dysfunctions, as well as behavioral changes, emotional dysregulation and reduction of self-awareness.

INTERVENTIONS

The patients received an intensive cognitive and motor rehabilitation training.

OUTCOMES

Neuropsychological assessment and magnetic resonance imaging were performed before and after rehabilitative training to evaluate the cognitive and cerebral changes induced by treatment. The patient showed an improvement in cognitive performances and behavioral aspects.

LESSONS

The reducing cognitive deficits, especially memory deficits, could improve quality of life by using available cognitive resources.

A Simplified Approach to Encephalitis and Its Mimics: Key Clinical Decision Points in the Setting of Specific Imaging Abnormalities

RATIONALE AND OBJECTIVES

Infectious encephalitis is a relatively common cause of morbidity and mortality. Treatment of infectious encephalitis with antiviral medication can be highly effective when administered promptly. Clinical mimics of encephalitis arise from a broad range of pathologic processes, including toxic, metabolic, neoplastic, autoimmune, and cardiovascular etiologies. These mimics need to be rapidly differentiated from infectious encephalitis to appropriately manage the correct etiology; however, the many overlapping signs of these various entities present a challenge to accurate diagnosis. A systematic approach that considers both the clinical manifestations and the imaging findings of infectious encephalitis and its mimics can contribute to more accurate and timely diagnosis.

MATERIALS AND METHODS

Following an institutional review board approval, a health insurance portability and accountability act (HIPAA)-compliant search of our institutional imaging database (teaching files) was conducted to generate a list of adult and pediatric patients who presented between January 1, 1995 and October 10, 2013 for imaging to evaluate possible cases of encephalitis. Pertinent medical records, including clinical notes as well as surgical and pathology reports, were reviewed and correlated with imaging findings. Clinical and imaging findings were combined to generate useful flowcharts designed to assist in distinguishing infectious encephalitis from its mimics. Key imaging features were reviewed and were placed in the context of the provided flowcharts.

RESULTS

Four flowcharts were presented based on the primary anatomic site of imaging abnormality: group 1: temporal lobe; group 2: cerebral cortex; group 3: deep gray matter; and group 4: white matter. An approach that combines features on clinical presentation was then detailed. Imaging examples were used to demonstrate similarities and key differences.

CONCLUSIONS

Early recognition of infectious encephalitis is critical, but can be quite complex due to diverse pathologies and overlapping features. Synthesis of both the clinical and imaging features of infectious encephalitis and its mimics is critical to a timely and accurate diagnosis. The use of the flowcharts presented in this article can further enable both clinicians and radiologists to more confidently differentiate encephalitis from its mimics and improve patient care.

Limbic encephalitis associated with anti-NH2-terminal of α-enolase antibodies: A clinical subtype of Hashimoto encephalopathy

Several types of autoantibodies have been reported in autoimmune limbic encephalitis (LE), such as antibodies against the voltage-gated potassium channel (VGKC) complex including leucine-rich glioma inactivated 1 (LGI1). We recently reported a patient with autoimmune LE and serum anti-NH2-terminal of α-enolase (NAE) antibodies, a specific diagnostic marker for Hashimoto encephalopathy (HE), who was diagnosed with HE based on the presence of antithyroid antibodies and responsiveness to immunotherapy. This case suggests that LE patients with antibodies to both the thyroid and NAE could be diagnosed with HE and respond to immunotherapy. The aim of this study was to clarify the clinicoimmunological features and efficacy of immunotherapy in LE associated with anti-NAE antibodies to determine whether the LE is a clinical subtype of HE.We examined serum anti-NAE antibodies in 78 LE patients with limbic abnormality on magnetic resonance imaging and suspected HE based on positivity for antithyroid antibodies. Nineteen of the 78 patients had anti-NAE antibodies; however, 5 were excluded because they were double positive for antibodies to the VGKC complex including LGI1. No antibodies against the N-methyl-D-aspartate receptor (NMDAR), contactin-associated protein 2 (Caspr2), γ-aminobutyric acid-B receptor (GABABR), or α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) were detected in the 19 patients. Among the remaining 14 who were positive only for anti-NAE antibodies, the median age was 62.5 (20-83) years, 9 (64%) were women, and 8 (57%) showed acute onset, with less than 2 weeks between onset and admission. Consciousness disturbance (71%) and memory disturbance (64%) were frequently observed, followed by psychiatric symptoms (50%) and seizures (43%). The frequency of these symptoms significantly differed between the acute- and subacute-onset groups. Abnormalities in cerebrospinal fluid and electroencephalogram were commonly observed (92% for both). Tumors were not identified in any cases. All patients responded to immunotherapy or spontaneously remitted, thereby fulfilling the criteria of HE.This study demonstrated that LE associated with anti-NAE antibodies is a nonparaneoplastic LE and various limbic symptoms that depend on the onset type. Favorable therapeutic efficacy suggests that this LE can be considered a clinical subtype of HE and that anti-NAE antibodies may be a promising indicator of the need for immunotherapy.

Autoimmune paraneoplastic syndromes associated to lung cancer: A systematic review of the literature: Part 3: Neurological paraneoplastic syndromes, involving the central nervous system

The development of new immune treatment in oncology and particularly for lung cancer may induce new complications, particularly activation or reactivation of auto-immune diseases. In this context, a systematic review on the auto-immune paraneoplastic syndromes that can complicate lung cancer appears useful. This article is the third of a series of five and deals mainly with neurological paraneoplastic syndromes involving the central nervous system.

Autoimmune neurological syndromes associated limbic encephalitis and paraneoplastic cerebellar degeneration

INTRODUCTION

Autoimmune neurological syndrome is a group of disorders caused by cancer affecting nervous system by different immunological mechanisms. In this study, we aim to study the clinical symptoms, cerebrospinal fluid (CSF) findings, autoantibody tests, computed tomography (CT), magnetic resonance imaging (MRI) signs and treatment outcome of patients with autoimmune syndromes.

METHODS

In this study, 7 patients (4 male, 3 female) diagnosed with autoimmune neurological syndrome were retrospectively examined.

RESULTS

Five of patients were diagnosed with limbic encephalitis, two of them were paraneoplastic cerebellar degeneration. Confusion and seizure were the most seen symptoms. Two patients had psychiatric disturbances (28,5%) followed by seizure. Headache was seen in 2 patients (% 28,5), disartria in 1 patient (% 14,2), and gait disorder in 2 patients (28,5%). The duration of symptoms was 46 (3-150) days on average. CSF abnormalities were detected in 2 patients. CT and MRI of the brain was available in all patients. Five patients had involvement of mesiotemporal region, two patients had diffuse cerebellar atrophy. One of patients had anti-GABAR B1 positivity. Tumors were detected in 2 patients while investigation for paraneoplasia screening.

CONCLUSION

Remission is only possible with the detection and treatment of the malignancy. Early diagnosis and treatment are of paramount importance.

[(18)F]-Fluoro-Deoxy-Glucose Positron Emission Tomography Scan Should Be Obtained Early in Cases of Autoimmune Encephalitis

Introduction. Autoimmune encephalitis (AE) is a clinically challenging diagnosis with nonspecific neurological symptoms. Prompt diagnosis is important and often relies on neuroimaging. We present a case series of AE highlighting the importance of an early [¹⁸F]-fluoro-deoxy-glucose positron emission tomography (FDG-PET) scan. Methods. Retrospective review of seven consecutive cases of autoimmune encephalitis. Results. All patients had both magnetic resonance imaging (MRI) and FDG-PET scans. Initial clinical presentations included altered mental status and/or new onset seizures. Six cases had serum voltage-gated potassium channel (VGKC) antibody and one had serum N-methyl-D-aspartate (NMDA) antibody. MRI of brain showed mesial temporal lobe hyperintensity in five cases of VGKC. The other two patients with VGKC or NMDA AE had restiform body hyperintensity on MRI brain or a normal MRI, respectively. Mesial temporal lobe hypermetabolism was noted in three cases on FDG-PET, despite initial unremarkable MRI. Malignancy workup was negative in all patients. Conclusion. A high index of suspicion for AE should be maintained in patients presenting with cognitive symptoms, seizures, and limbic changes on neuroimaging. In cases with normal initial brain MRI, FDG-PET can be positive. Additionally, extralimbic hyperintensity on MRI may also be observed.

Electroencephalographic Evaluation for Early Diagnosis of Limbic Encephalitis

Limbic encephalitis (LE) is an inflammation of structures of limbic system. It may be an autoimmune disease or secondary to a neoplasia. Onset is subacute within a few weeks and clinical presentation is characterized by behavioral changes, psychiatric symptoms, short-term memory loss, and epileptic seizures. Diagnosis is typically set after a magnetic resonance imaging (MRI) scan, revealing hyperintensity in limbic structures on T2, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) sequences or detection of antineuronal antibodies; EEG aspecific alterations on temporal areas usually match with MRI and laboratory findings. Specific diagnostic criteria are still under debate. We describe a case presenting with EEG alterations before MRI ones.A 36-year-old woman came to our attention for a first generalized tonic-clonic seizure, several episodes of likely epigastric auras and memory loss. Her clinical history was unremarkable. Neurological examination and brain MRI with gadolinium were normal. Electroencephalographic (EEG) recordings showed theta activity and sharp elements in frontotemporal regions. Therapy with levetiracetam 1000 mg/day was started, but she had another generalized seizure and episodes of epigastric auras increased to 10 per day. After 2 months, another cerebral MRI revealed areas of swelling and signal alteration in deep left temporal areas, especially in hippocampal and parahippocampal gyrus. A spectroscopic evaluation revealed decreased N-acetyl aspartate peak and increased choline and myo-inositol peaks in left frontotemporal areas. These findings were consistent with LE. Cerebrospinal fluid (CSF) analysis was normal; viral serology and onconeuronal antibodies on CSF and blood were negative. Patient was treated with high-dosage steroids, with improvement in memory, epileptic seizures and auras. A third MRI revealed no signal alterations.In conclusion, the clinical picture initially did not meet accepted diagnostic criteria for LE. Effective steroid therapy was consequently delayed. With this case report we would emphasize diagnostic relevance of EEG alterations early in suspected LE in order to start immunosuppressive therapy as soon as possible.

Clinical analysis of leucine-rich glioma inactivated-1 protein antibody associated with limbic encephalitis onset with seizures

We summarized the clinical characteristics of patients presenting with seizures and limbic encephalitis (LE) associated with leucine-rich glioma inactivated-1 protein antibody (LGI1) in order help recognize and treat this condition at its onset.We analyzed clinical, video electroencephalogram (VEEG), magnetic resonance imaging (MRI), and laboratory data of 10 patients who presented with LGI1-LE and followed up their outcomes from 2 to 16 (9.4 ± 4.2) months.All patients presented with seizures onset, including faciobrachial dystonic seizure (FBDS), partial seizure (PS), and generalized tonic-clonic seizure (GTCS). Four patients (Cases 3, 5, 7, and 8) had mild cognitive deficits. Interictal VEEG showed normal patterns, focal slowing, or sharp waves in the temporal or frontotemporal lobes. Ictal VEEG of Cases 4, 5, and 7 showed diffuse voltage depression preceding FBDS, a left frontal/temporal origin, and a bilateral temporal origin, respectively. Ictal foci could not be localized in other cases. MRI scan revealed T2/fluid-attenuated inversion recovery (FLAIR) hyperintensity and evidence of edema in the right medial temporal lobe in Case 3, left hippocampal atrophy in Case 5, hyperintensities in the bilateral medial temporal lobes in Case 7, and hyperintensities in the basal ganglia and frontal cortex in Case 10. All 10 serum samples were positive for LGI1 antibody, but it was only detected in the cerebrospinal fluid (CSF) of 7 patients. Five patients (Cases 2, 4, 6, 7, and 8) presented with hyponatremia. One patient (Case 2) was diagnosed with small cell lung cancer. While responses to antiepileptic drugs (AEDs) were poor, most patients (except Case 2) responded favorably to immunotherapy.LGI1-LE may initially manifest with various types of seizures, particularly FBDS and complex partial seizures (CPS) of mesial temporal origin, and slowly progressive cognitive involvement. Clinical follow-up, VEEG monitoring, and MRI scan are helpful in early diagnosis. Immunotherapy is effective for the treatment of both seizure and LE associated with LGI1 antibody. Although mostly nonparaneoplastic, tumor screening is recommended in some cases.

Antithyroid Antibodies Are Implicated in Epileptogenesis of Adult Patients With Epilepsy

Antithyroid antibodies (Abs) are associated with epilepsy in steroid-responsive encephalopathy, but have been rarely studied in unselected epilepsy patients. This study aimed to characterize the prevalence and associated factors of antithyroid Abs and other auto-Abs in adult patients with epilepsy.Epilepsy patients without autoimmune disorders were surveyed for antinuclear antibody (ANA), anti-β2 glycoprotein 1 antibody (aβ2GP1), anticardiolipin IgG Ab, antimicrosomal antibody (AMA), antithyroglobulin antibody (ATA), and thyroid function test.Of 319 patients, 75 (23.5%) were positive for at least 1 Ab. The most common Ab was anticardiolipin antibody (aCL) (30/319, 9.4%), followed by AMA (24/319, 7.5%), ANA (18/319, 5.6%), aβ2GP1 (18/319, 6.5%), and ATA (6/319, 3.25%). Antimicrosomal Abs were significantly more frequent in patients who were female, older at disease onset, older at the time of study, and had unknown seizure etiology. The presence of aCL was significantly associated with more frequent seizures. Most patients with antithyroid Ab were female and had focal seizures with unknown etiology.The association of different auto-Abs with different factors suggests that they may have different roles in adult patients with epilepsy. Recurrent seizures and certain antiepileptic medications may cause the production of aCL. The role of antithyroid Abs in adult focal epilepsy with unknown cause, especially in females, warrants further evaluation because of the potential implications on treatment.

Autoimmune limbic encephalitis: A manifestation of systemic lupus erythematosus in the central nervous system

Autoimmune limbic encephalitis (ALE) associated with systemic lupus erythematosus (SLE) is a rare entity with few reports in the literature to date. In general, ALE associated with SLE has a satisfactory response to immunosuppressive treatment (RIT), but the pathogenesis of this association is poorly understood and may include an autoimmunity component. We report a case study describing the diagnosis and management of limbic encephalitis in a patient with active Systemic Lupus Erythematosus disease (SLE) and past medical history of cancer (endometrial adenocarcinoma in 2004 and papillary urothelial carcinoma in 2011 with curative treatment), followed over a one-year period. We discuss the possible association between limbic encephalitis and all past neoplastic and immune-mediated conditions of this patient. In this particularly case, autoimmunity was the most relevant factor associated with limbic encephalitis given negative neoplastic screening. Moreover, a good response was observed to immunotherapy, not seen with paraneoplastic limbic encephalitis, which is associated with poor response. In this case, the association of ALE with SLE is possible, since laboratory testing disclosed lupic activity and the patient had involvement of other systems (such as hematologic) during the period. However, the presence of other surface membrane antibodies are possible in the search for alternative etiologies.

Memory, scene construction, and the human hippocampus

We evaluated two different perspectives about the function of the human hippocampus--one that emphasizes the importance of memory and another that emphasizes the importance of spatial processing and scene construction. We gave tests of boundary extension, scene construction, and memory to patients with lesions limited to the hippocampus or large lesions of the medial temporal lobe. The patients were intact on all of the spatial tasks and impaired on all of the memory tasks. We discuss earlier studies that associated performance on these spatial tasks to hippocampal function. Our results demonstrate the importance of medial temporal lobe structures for memory and raise doubts about the idea that these structures have a prominent role in spatial cognition.

Identification of a common epitope between enterovirus 71 and human MED25 proteins which may explain virus-associated neurological disease

Enterovirus 71 (EV71) is a major causative pathogen of hand, foot and mouth disease with especially severe neurologic complications, which mainly account for fatalities from this disease. To date, the pathogenesis of EV71 in the central neurons system has remained unclear. Cytokine-mediated immunopathogenesis and nervous tissue damage by virus proliferation are two widely speculated causes of the neurological disease. To further study the pathogenesis, we identified a common epitope (co-epitope) between EV71 VP1 and human mediator complex subunit 25 (MED25) highly expressed in brain stem. A monoclonal antibody (2H2) against the co-epitope was prepared, and its interaction with MED25 was examined by ELISA, immunofluorescence assay and Western blot in vitro and by live small animal imaging in vivo. Additionally, 2H2 could bind to both VP1 and MED25 with the affinity constant (Kd) of 10⁻⁷ M as determined by the ForteBio Octet System. Intravenously injected 2H2 was distributed in brain stem of mice after seven days of EV71 infection. Interestingly, 2H2-like antibodies were detected in the serum of EV71-infected patients. These findings suggest that EV71 infection induces the production of antibodies that can bind to autoantigens expressed in nervous tissue and maybe further trigger autoimmune reactions resulting in neurological disease.

Uncommon 18F-FDG-PET/CT findings in patients affected by limbic encephalitis: hyper-hypometabolic pattern with double antibody positivity and migrating foci of hypermetabolism

Autoimmune limbic encephalitis (LE) is a rare disorder; its diagnosis can be challenging. We report two uncommon cases of LE evaluated by brain 2-deoxy-2-[18F]fluoro-d-glucose ((18)F-FDG) positron emission tomography/computed tomography describing the metabolic imaging patterns, which were different from those observed in previous studies: the first one presented an unprecedented (18)F-FDG brain mixed pattern, involving also the midbrain, despite negative magnetic resonance imaging exams; the second one showed migrating foci of hypermetabolism, one of which turned into hypometabolism at a later examination.

Hippocampal sclerosis in feline epilepsy

Hippocampal sclerosis (HS) refers to loss of hippocampal neurons and astrogliosis. In temporal lobe epilepsy (TLE), HS is a key factor for pharmacoresistance, even though the mechanisms are not quite understood. While experimental TLE models are available, there is lack of models reflecting the natural HS development. Among domestic animals, cats may present with TLE-like seizures in natural and experimental settings. With this study on the prevalence, segmental pattern and clinicopathological correlates of feline HS, we evaluated the translational value for human research. Evaluation schemes for human brains were applied to epileptic cats. The loss of neurons was morphometrically assessed and the degree of gliosis was recorded. Hippocampal changes resembling human HS were seen in about one third of epileptic cats. Most of these were associated with infiltrative diseases such as limbic encephalitis. Irrespective of the etiology and semiology of seizures, total hippocampal sclerosis was the most prevalent form seen in epileptic animals. Other HS types also occur at varying frequencies. Segmental differences to human HS can be explained by species-specific synaptic connectivities and a different spectrum of etiologies. All these variables require consideration when translating results from feline studies regarding seizure-associated changes of the temporal lobe and especially HS.

Limbic encephalitis: Clinical spectrum and long-term outcome from a developing country perspective

INTRODUCTION

Limbic encephalitis (LE) is characterized by rapidly progressive short-term memory loss, psychiatric symptoms and seizures. We describe the clinical spectrum, underlying etiology and long-term follow-up of patients with LE from India.

MATERIALS AND METHODS

This prospective study included patients during the period of January 2009 and December 2011 with the clinical features consistent with LE with one or more of the following: (1) Magnetic resonance imaging (MRI) evidence of temporal lobe involvement; (2) cerebrospinal fluid inflammatory abnormalities, or (3) detection of antineuronal antibodies. Patients with metastasis, infection, metabolic and nutritional deficits, stroke, were excluded.

RESULTS

There were 16 patients (9 females), mean age of presentation was 36.6 years (range 15-69 years). The mean duration of symptoms before presentation was 11 months (range 5 days-2 years). The most common symptom at presentation was short-term memory impairment in 7 patients followed by seizures in 5 and behavioral changes in three. Nine patients had seizures, 11 had change in behavior, language involvement in eight, cerebellar features in 3 and autonomic dysfunction in two. Four patients had associated malignancy, 3 of four presented with neurological symptoms and on investigations found to be have malignancy. Antineuronal antibody testing was done in 6 of 12 non paraneoplastic and two paraneoplastic patients, one positive for N-methyl-D-aspartate and one for anti-Hu antibody. MRI brain showed typical fluid attenuated inversion recovery or T2 bilateral temporal lobe hyperintensities in 50% of patients. At a mean follow-up of 21 months (3-36 months), 10 patients improved, 4 patients remained same and two patients expired.

CONCLUSION

Early recognition of LE is important based upon clinical, MRI data in the absence of antineuronal surface antibody screen in developing nations. Early institution of immunotherapy will help in improvement in outcome of these patients in long-term.

Voltage gated potassium channel antibodies positive autoimmune encephalopathy in a child: A case report and literature review of an under-recognized condition

Autoimmune limbic encephalitis (LE) associated with voltage gated potassium channel antibodies (VGKC-Abs) in children is more common than previously thought and is not always paraneoplastic. Non-neoplastic, autoimmune LE associated with VGKC-Abs has been described recently. However, only few case reports in children as the disease is predominantly described in the adult population. It is likely that this type of autoimmune encephalitis is currently under-diagnosed and hence, under-treated, especially in children. We present a 13-year-old previously fit and healthy African girl diagnosed with LE and we reviewed the literature for its current management.

Syphilitic limbic encephalitis revealed by status epilepticus

Limbic encephalitis (LE) is an inflammatory disorder of the limbic system; the clinical features are diverse, characterised by the development of neuropsychiatric symptoms, its aetiologies are various; syphilis is a rare entity. We report the case of a 50-year-old-man with syphilitic LE revealed by an inaugural status epilepticus. Diagnosis was made considering clinical, biological and radiological arguments. The patient received specific treatment for neurosyphilis. Evolution was marked by improved neuropsychological symptoms, the negativity of venereal disease research laboratory test in blood and cerebrospinal fluid and regression of the mesiotemporal signal abnormalities on MRI.

GAD65 Positive Autoimmune Limbic Encephalitis: A Case Report and Review of Literature

Limbic encephalitis is a rare disorder affecting the medial temporal lobe of the brain, sometimes also involving hippocampus atrophy. It was initially considered to be only of paraneoplastic origin but now auto-immune (non-paraneoplastic) cases have also been reported. Most common non paraneoplastic antibodies associated with limbic encephalitis are Voltage gated potassium channel antibodies, NMDA receptor antibodies and GAD receptor antibodies. We present a case of limbic encephalitis which presented with sudden onset seizures which was preceded by confusion, disorientation and other psychiatric symptoms for a period of 5 weeks. No tumor was found on imaging and the classic paraneoplastic panel was negative. CSF and serum examination showed high titers GAD65 antibody guiding towards a diagnosis of non paraneoplastic limbic encephalitis. Her symptoms and GAD 65 antibody titers showed significant improvement following immunomodulatory therapy. The case presented here is unique and scientifically relevant, as it intends to raise awareness of Auto-immune Limbic Encephalitis, a potentially reversible cause of a medical emergency.

Neuroimaging and other investigations in patients presenting with headache

Headache is very common. In the United Kingdom, it accounts for 4.4% of primary care consultations, 30% of referrals to neurology services and 0.5-0.8% of alert patients presenting to emergency departments. Primary headache disorders account for the majority of patients and most patients do not require investigation. Warning features (red flags) in the history and on examination help target those who need investigation and what investigations are required. This article summarizes the typical presentations of the common secondary headaches and what neuroimaging and other investigations are appropriate for each headache type.

Neurological manifestation of colonic adenocarcinoma

Paraneoplastic neurologic disorders are extremely rare in cancer patients and are most commonly associated with certain tumors, such as ovarian cancer, small cell lung cancer, and breast cancer. We report here a paraneoplastic neurological syndrome in a 53-year-old man with colonic adenocarcinoma with a solitary liver metastasis. His paraneoplastic syndrome was successfully treated by methylprednisolone and primary oncologic therapies including neoadjuvant chemotherapy and definitive surgery. This is also the first documented case of simultaneous manifestation of a sensory neuropathy and limbic encephalitis with colon cancer.

Towards therapeutic applications of arthropod venom k(+)-channel blockers in CNS neurologic diseases involving memory acquisition and storage

Potassium channels are the most heterogeneous and widely distributed group of ion channels and play important functions in all cells, in both normal and pathological mechanisms, including learning and memory processes. Being fundamental for many diverse physiological processes, K⁺-channels are recognized as potential therapeutic targets in the treatment of several Central Nervous System (CNS) diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, schizophrenia, HIV-1-associated dementia, and epilepsy. Blockers of these channels are therefore potential candidates for the symptomatic treatment of these neuropathies, through their neurological effects. Venomous animals have evolved a wide set of toxins for prey capture and defense. These compounds, mainly peptides, act on various pharmacological targets, making them an innumerable source of ligands for answering experimental paradigms, as well as for therapeutic application. This paper provides an overview of CNS K⁺-channels involved in memory acquisition and storage and aims at evaluating the use of highly selective K⁺-channel blockers derived from arthropod venoms as potential therapeutic agents for CNS diseases involving learning and memory mechanisms.

Limbic encephalopathy and central vestibulopathy caused by mefloquine: a case report

Mefloquine is a 4-methanolquinoline anti-malarial that in recent years has fallen out of favor for use as chemoprophylaxis against infection with chloroquine-resistant Plasmodium falciparum malaria owing in part to growing concerns of side effects and potential neurotoxicity. Despite over 20 years of licensed use, the pathophysiological mechanisms underlying mefloquine's neuropsychiatric and physical side effects and the clinical significance of the drug's neurotoxicity have remained poorly understood. In this report, an adverse reaction to mefloquine chemoprophylaxis is described characterized by prodromal symptoms of anxiety with subsequent development of psychosis, short-term memory impairment, confusion and personality change accompanied by complaints of disequilibrium and vertigo, with objective findings of central vestibulopathy. It is posited that these effects represent an idiosyncratic neurotoxic syndrome of progressive limbic encephalopathy and multifocal brainstem injury caused by the drug. This case provides insights into the clinical significance of mefloquine neuronal gap junction blockade and neurotoxicity demonstrated in animal models, points to recommendations for the management of affected patients including diagnostic considerations and appropriate referrals, and highlights critical implications for the continued safe use of the medication.

An initial MRI picture of limbic encephalitis in subacute sclerosing panencephalitis

BACKGROUND

Subacute sclerosing panencephalitis (SSPE) is a rare and severe long-term complication of measles. Hallmarks of this entity include progressive cognitive decline, myoclonia, a generalized periodic pattern on EEG and deep white matter abnormalities on MRI. However, imaging can be normal in early stages.

AIM

We report herein the case of a previously healthy 13-years-old girl with an unusual radiological presentation.

RESULTS

She presented with unilateral myoclonia, cognitive decline with memory impairment and a first brain MRI with swelling of both hippocampi mimicking limbic encephalitis. Measles antibodies were positive in CSF and the EEG showed slow periodic complexes.

CONCLUSION

This unusual radiological presentation has never been described in SSPE. Relationship between virus and limbic system are discussed.

Autoimmune encephalitis: a case series and comprehensive review of the literature

Encephalitic syndromes are a common medical emergency. The importance of early diagnosis and appropriate treatment is paramount. If initial investigations for infectious agents prove negative, other diagnoses must be considered promptly. Autoimmune encephalitides are being increasingly recognized as important (and potentially reversible) non-infectious causes of an encephalitic syndrome. We describe four patients with autoimmune encephalitis--3 auto-antibody positive, 1 auto-antibody negative--treated during the last 18 months. A comprehensive review of the literature in this expanding area will be of interest to the infectious diseases, general medical and neurology community.

Autoimmune-mediated encephalitis

Autoimmune-mediated encephalitis may occur as a paraneoplastic or as a non-paraneoplastic condition. The role of neuroimaging in autoimmune-mediated encephalitis has changed in the last decade partly due to improvements in sequence optimisation and higher field strength and partly due to the discovery of an increasing number of antibodies to neuronal cell and cell membrane antigens. Imaging is important since it can support the clinical diagnosis particularly in the absence of antibodies. Structural imaging findings can be subtle and are usually best seen on FLAIR images. A progressive as well as a relapsing-remitting course can be observed. Autoimmune-mediated encephalitis is classically linked to involvement of the hippocampus and amygdala, but extensive changes in the temporal cortex, basal ganglia, hypothalamus, brain stem, frontal and parietal cortex are not unusual. This report is based on a review of the literature (except the literature in Japanese) and own findings in patients with autoimmune-mediated encephalitis.