Limbic encephalitis associated with anti-GAD antibody and common variable immune deficiency

MRI findings in autoimmune encephalitis

Autoimmune encephalitis encompasses a spectrum of conditions characterized by distinct clinical features and magnetic resonance imaging (MRI) findings. Here, we review the literature on acute MRI changes in the most common autoimmune encephalitis variants. In N-methyl-D-aspartate (NMDA) receptor encephalitis, most patients have a normal MRI in the acute stage. When lesions are present in the acute stage, they are typically subtle and non-specific white matter lesions that do not correspond with the clinical syndrome. In some NMDA receptor encephalitis cases, these T2-hyperintense lesions may be indicative of an NMDA receptor encephalitis overlap syndrome with simultaneous co-existence of multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Encephalitis with leucine-rich glioma-inactivated 1 (LGI1)-, contactin-associated protein-like 2 (CASPR2)- or glutamic acid decarboxylase (GAD)- antibodies typically presents as limbic encephalitis (LE) with unilateral or bilateral T2/fluid attenuated inversion recovery (FLAIR) hyperintensities in the medial temporal lobe that can progress to hippocampal atrophy. Gamma aminobutyric acid-B (GABA-B) receptor encephalitis also often shows such medial temporal hyperintensities but may additionally involve cerebellar lesions and atrophy. Gamma aminobutyric acid-A (GABA-A) receptor encephalitis features multifocal, confluent lesions in cortical and subcortical areas, sometimes leading to generalized atrophy. MRI is unremarkable in most patients with immunoglobulin-like cell adhesion molecule 5 (IgLON5)-disease, while individual case reports identified T2/FLAIR hyperintense lesions, diffusion restriction and atrophy in the brainstem, hippocampus and cerebellum. These findings highlight the need for MRI studies in patients with suspected autoimmune encephalitis to capture disease-specific changes and to exclude alternative diagnoses. Ideally, MRI investigations should be performed using dedicated autoimmune encephalitis imaging protocols. Longitudinal MRI studies play an important role to evaluate potential relapses and to manage long-term complications. Advanced MRI techniques and current research into imaging biomarkers will help to enhance the diagnostic accuracy of MRI investigations and individual patient outcome prediction. This will eventually enable better treatment decisions with improved clinical outcomes.

Comparison of B Cell Variable Region Gene Segment Characteristics in Neuro-autoantibodies

Autoimmune pediatric neurologic diseases have variable phenotypes and presentations, making diagnosis challenging. The pathologic mechanisms are also distinct, including cell-mediated and Ab-mediated autoimmunity, paraneoplastic syndromes, and postinfectious processes. In recent years a number of studies have described the characteristics of the autoantibodies involved in a number of these diseases. Some of the described Abs use a restricted set of variable gene segments. We sought to compare the Ab characteristics of autoantibodies related to some of the more common disorders to discover whether specific Ab signatures are universally associated with neuroautoimmune diseases. We initially performed a literature review to summarize the Ab characteristics of autoantibodies related to some of the more common disorders, including N-methyl-d-aspartate receptor (NMDAR) and leucine-rich, glioma-inactivated 1 (LGI-1). Next, we performed data analysis from selected studies that sequenced Ig genes to further characterize NMDAR and LGI-1 autoantibodies including CDR3 length distribution, variable gene sequence usage, and isotype use. We found that CDR3 length of NMDAR autoantibodies was normally distributed whereas the CDR3 length distribution of LGI-1 autoantibodies was skewed, suggesting that there is no global structural restriction on types of autoantibodies that can cause encephalitis. We also found that IgG1-IgG3 were the main NMDAR autoantibody isotypes detected, while IgG4 was the major isotype used in autoantibodies from LGI-1 encephalitis. These findings are useful for our understanding of autoimmune encephalitis and will help facilitate better diagnosis and treatment of these conditions in the future.

Successfully treated anti-GAD limbic encephalitis in a 15-year-old diabetic boy with intravenous immunoglobulin: case report

Introduction and importance

Limbic encephalitides (LE) have symptoms and signs of new-onset seizures accompanied by cognitive impairment and signal changes in the MRI of the limbic system in the brain. Numerous antibodies against the neurons and synapses have been detected so far. Of those, antiglutamic acid decarboxylase antibody (Anti-GAD Ab) impairs the gamma amino butyric acid, one of the primary mediators that naturally prevents abnormal neuronal activity causing seizure.

Case presentation

The authors have reported a case of anti-GAD Ab LE in a diabetic male adolescent who responded dramatically to intravenous immunoglobulin and reviewed all similar pediatric cases for 15 years now.

Clinical discussion

The symptoms in children suffering from anti-GAD LE in three categories, systemic, psychiatric, and neurological, are heterogeneous. The most common manifestations were seizures followed by altered mental status and behavioral changes, respectively. The two main clinical scenarios described in GAD65-mediated autoimmune epilepsy are (1) an acute/subacute onset of seizures alone or seizures (including new-onset refractory status epilepticus, NORSE) accompanied by some degrees of cognitive and psychiatric manifestations, including amnesia and mesiotemporal inflammatory involvement consistent with LE and (2) epilepsy without clinical or MRI evidence of active central nervous system inflammation.

Conclusion

Although rare, the neurologist should consider the potential role of anti-GAD ab-associated encephalitis in the presence of diabetes mellitus.

A case report of anti-GAD65 antibody-positive autoimmune encephalitis in children associated with autoimmune polyendocrine syndrome type-II and literature review

Background

Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for the synthesis of gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Antibodies against glutamic acid decarboxylase (GAD) are associated with various neurologic conditions described in patients, including stiff person syndrome, cerebellar ataxia, refractory epilepsy, and limbic and extra limbic encephalitis. While there are few case reports and research on anti-GAD65 antibody-associated encephalitis in adults, such cases are extremely rare in pediatric cases.

Methods

For the first time, we report a case of anti-GAD65-positive autoimmune encephalitis associated with autoimmune polyendocrine syndrome (APS) type II. We reviewed previously published pediatric cases of anti-GAD65 autoimmune encephalitis to discuss their clinical features, laboratory tests, imaging findings, EEG patterns, and prognosis.

Case presentation

An 8-year-old, male child presented to the outpatient department after experiencing generalized convulsions for twenty days. The child was admitted for epilepsy and had received oral sodium valproate (500 mg/day) in another center, where investigations such as USG abdomen and MRI brain revealed no abnormalities, however, had abnormal EEG with diffuse mixed activity in the left anterior middle prefrontal temporal region. On the follow-up day, a repeat blood test showed a very low serum drug concentration of sodium valproate hence the dose was increased to 750 mg/day. Then, the child experienced adverse effects including increased sleep, thirst, and poor appetite, prompting the parents to discontinue the medication. A repeat MRI showed increased signals on FLAIR sequences in the right hippocampus hence admitted for further management. The child's past history included a diagnosis of hypothyroidism at the age of 4, and receiving levothyroxine 75 mcg once daily. His parents are healthy with no history of any similar neurological, autoimmune, or genetic diseases, but his uncle had a history of epilepsy. At presentation, he had uncontrolled blood glucose levels with elevated HbA1c levels. Additionally, the serum and CSF autoantibodies were positive against the anti-GAD65 antibody with the titer of 1:100 and 1:32 respectively. The patient was managed with a mixed type of insulin regimen and received first-line immunotherapy (intravenous immunoglobulin, IVIG) for five consecutive days, followed by oral prednisone and sodium valproate as an antiepileptic drug. Upon achieving a favorable clinical outcome, the patient was discharged with oral medications.

Results

Among the 15 pediatric patients reported in this literature, nine presented with limbic encephalitis (LE), three with extralimbic encephalitis (ELE), and three with a combination of limbic and extralimbic encephalitis. Most of these cases exhibited T2-W FLAIR hyperintensities primarily localized to the temporal lobes in the early phase, progressing to hippocampal sclerosis/atrophy in the later phase on MRI. EEG commonly showed slow or spike waves on frontotemporal lobes with epileptic discharges. Prognostic factors varied among patients, with some experiencing persistent refractory seizures, type-1 diabetes mellitus (T1DM), persistent memory impairment, persistent disability requiring full assistance, and, in severe cases, death.

Conclusion

Our findings suggest that anti-GAD65 antibody-positive autoimmune encephalitis patients may concurrently present with other APS. Our unique case presented with multiple endocrine syndromes and represents the first reported occurrence in children. Early diagnosis and timely initiation of immunotherapy are crucial for improving clinical symptoms and reducing the likelihood of relapses or permanent disabilities. Therefore, emphasis should be placed on prompt diagnosis and appropriate treatment implementation to achieve better patient outcomes.

Anti-Glutamic Acid Decarboxylase (GAD) 65 Encephalitis Mistaken for Herpes Encephalitis and Hashimoto’s Encephalitis (HE): A Case Report

Autoimmune encephalitis is increasingly recognized in clinical practice. We are presenting a 72-year-old female patient who initially presented with a new onset seizure with temporal lobe abnormality on imaging. This was initially attributed to herpes encephalitis although herpes polymerase chain reaction (PCR) was negative. The patient was treated with acyclovir and antiepileptic medication (AEM) with some clinical improvement. She presented again with refractory seizure evolving to status epilepticus. Escalation of AEMs was pursued and positive anti-thyroid peroxidase (TPO) antibody prompted consideration of Hashimoto's encephalitis (HE) and treatment with high-dose corticosteroids and intravenous immunoglobulin (IVIG). However, poor response to steroid argued against HE, and extended autoimmune encephalitis panel revealed positive anti-glutamic acid decarboxylase (GAD) antibody. This case raises the clinical pearl that anti-thyroid antibodies, e.g anti-TPO antibody, can be seen in those with autoimmune encephalopathies other than HE and HE remains a diagnosis of exclusion. It also helps to remind clinicians that a new onset refractory seizure even with temporal lobe changes is not pathognomonic for herpes encephalitis, and although negative serology does not rule out the diagnosis, it is recommended to rule out autoimmune encephalitis as it shares similar clinical and radiological picture.

Autoimmune Encephalitis in Children

Autoimmune encephalitis is a group of central nervous system (CNS) inflammatory disorders that most commonly affect young adults and children. These disorders are closely associated with antibodies against neuronal cell-surface proteins, receptors, and ion channels; however, some forms of the disorder have no known antibody at this time. In children, neurological manifestations such as seizure, movement disorders, and focal neurological deficits are more prominent at initial presentation than psychiatric or behavioral symptoms. When psychiatric symptoms do occur, they often manifest as temper tantrums, aggression, agitation, and rarely psychosis. Prompt diagnosis and early treatment can lead to improved outcomes and decreased relapses. First-line therapies include intravenous steroids, intravenous immunoglobulin, and plasmapheresis, whereas rituximab and cyclophosphamide are utilized for refractory or relapsing disease. This review highlights the different forms of this disorder, discusses approach to diagnosis and treatment, and reviews the outcome and prognosis of children diagnosed with different forms of autoimmune encephalitis.

Stiff Person Syndrome and Encephalitis with GAD Antibodies with Severe Anterograde Amnesia in an Adolescent: A Case Study and Literature Review

Antiglutamic acid decarboxylase (GAD65) encephalitis is rare and few pediatric cases have been reported, with variable clinical presentations. A 14-year-old female adolescent was managed in our department. She had been treated for several months for drug-resistant temporal lobe epilepsy and gradually presented major anterograde amnesia with confusion. Upon her arrival at the University Hospital Centre, she showed a classical form of stiff person syndrome. The brain magnetic resonance imaging showed bitemporal hyperintensities and hypertrophy of the amygdala. The blood and cerebrospinal fluid were positive for GAD65 antibodies. At 2 years of immunosuppressive treatment and rehabilitation, the course showed partial improvement of the memory and neuropsychiatric impairment, and epilepsy that continued to be active. GAD65 antibodies are associated with various neurological syndromes, and this presentation combining limbic encephalitis and stiff person syndrome is the first pediatric form published to date; there are also few cases described in adults.

Autoantibodies in neurological disease

The realization that autoantibodies can contribute to dysfunction of the brain has brought about a paradigm shift in neurological diseases over the past decade, offering up important novel diagnostic and therapeutic opportunities. Detection of specific autoantibodies to neuronal or glial targets has resulted in a better understanding of central nervous system autoimmunity and in the reclassification of some diseases previously thought to result from infectious, 'idiopathic' or psychogenic causes. The most prominent examples, such as aquaporin 4 autoantibodies in neuromyelitis optica or NMDAR autoantibodies in encephalitis, have stimulated an entire field of clinical and experimental studies on disease mechanisms and immunological abnormalities. Also, these findings inspired the search for additional autoantibodies, which has been very successful to date and has not yet reached its peak. This Review summarizes this rapid development at a point in time where preclinical studies have started delivering fundamental new data for mechanistic understanding, where new technologies are being introduced into this field, and - most importantly - where the first specifically tailored immunotherapeutic approaches are emerging.

Treatment of Anti-GAD65 Autoimmune Encephalitis With Methylprednisolone

Background: Anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody encephalitis is a rare form of autoimmune encephalitis that can lead to severe neurologic impairment, coma, and death. Case Report: We present the case of a 54-year-old male with severely altered mental status and profound neurologic impairment who rapidly progressed to a comatose state. Because of the patient's rapidly deteriorating status, lack of yield with diagnostic testing, and lack of clinical improvement with broad empiric treatments, the clinical decision was made to treat the patient with high-dose methylprednisolone, and the treatment returned the patient to his baseline mental status. After the patient's discharge, the autoimmune encephalitis panel returned positive for anti-GAD65 antibodies. Conclusion: This case illustrates the importance of considering a diagnosis of autoimmune encephalitis for patients with rapidly deteriorating mental status. Unless contraindicated, treatment with high-dose glucocorticoids can be successful for these patients. This case also shows a potential association between hypothyroidism and anti-GAD65 antibodies.

Thalamic Lesions in a Toddler with Glutamic Acid Decarboxylase Autoimmune Encephalitis

We present a child with glutamic acid decarboxylase (GAD) autoimmune encephalitis (AE) with bilateral thalamic lesions on magnetic resonance imaging (MRI) of the brain. A healthy 21-month-old girl, after superrefractory status epilepticus (SE) and fever developed dyskinesia and ataxia, which we subsequently diagnosed as GAD AE. She showed remarkable response to treatment with methylprednisolone and intravenous immunoglobulin (IVIg). Following an initial normal MRI of her brain, a further brain imaging showed bilateral thalamic lesions. This is an unusual finding since brain imaging abnormalities, when found in GAD AE, mostly involve the mesial temporal lobe structures. Thalamic lesions in GAD AE have not been reported previously.

Case Report: Autoimmune Encephalitis Associated With Anti-glutamic Acid Decarboxylase Antibodies: A Pediatric Case Series

Background: Antibodies against glutamic acid decarboxylase (GAD) are associated with various neurologic conditions described in patients, including stiff person syndrome, cerebellar ataxia, refractory epilepsy, and limbic and extralimbic encephalitis. There have been some case reports and investigations regarding anti-GAD65 antibody-associated encephalitis in adult populations, but pediatric cases are rare. We retrospectively analyzed the clinical data of three anti-GAD65 antibody-positive patients to explore the diversity and clinical features of anti-GAD65 antibody-associated pediatric autoimmune encephalitis.

Methods: The clinical data of a series of three patients positive for anti-GAD65 antibody were retrospectively analyzed. GAD65 antibodies were determined in serum and CSF using a cell-based assay.

Results: All three patients were female, and the onset ages were 4 years and 9 months, 6 years, and 16 years old. Their clinical phenotypes included autoimmune limbic encephalitis, extralimbic encephalitis, and encephalitis combining limbic and extralimbic encephalitis. The clinical symptoms included seizures, memory deficits, drowsiness, dysautonomia, and headache. All patients had abnormal carinal MRI and EEG. All patients received immunotherapy and had transiently good responsiveness, but one patient then experienced relapse. In follow-up, one patient with extralimbic encephalitis recovered completely, while two patients with limbic involvement had poor outcomes with refractory focal epilepsy.

Conclusion: In addition to limbic encephalitis, extralimbic encephalitis is also an important phenotype in patients who are positive for anti-GAD65 antibodies. Early diagnosis and immunotherapy can improve the symptoms. However, patients with limbic encephalitis often have refractory epilepsy in the chronic phase and have a poor long-term outcome.

Rare presentation of anti-GAD-65 antibody-positive autoimmune encephalitis and simultaneous onset of type 1 diabetes mellitus in a paediatric patient

A 16-year-old female patient presented with subacute onset of headaches, changes in acute mental status, expressive aphasia and auditory hallucinations. New oedema and enhancement of the temporal lobe were seen on brain MRI, with correlating subclinical seizures seen on electroencephalogram. Simultaneously, our patient was diagnosed with new-onset type 1 diabetes mellitus, with positive anti-glutamic acid decarboxylase (anti-GAD-65) antibodies in the serum. Cerebrospinal fluid studies remained negative, including anti-GAD-65 antibodies. Clinical remission was achieved with corticosteroids and intravenous immunoglobulins.

Psychiatric symptoms in anti glutamic acid decarboxylase associated limbic encephalitis in adults: a systematic review

Autoimmune Limbic Encephalitis (LE) is a relatively new category of immune-mediated diseases with a wide range of neuropsychiatric symptoms. LE associated with Glutamic Acid Decarboxylase (GAD) antibodies is difficult to diagnose due to its possible atypical presentation with neuropsychiatric and behavioral features. We performed a systematic review of literature and retrieved 21 cases of anti GAD-associated LE with neuropsychiatric signs. Median age at onset was 27 years with a female predominance (81.0 %) and median diagnostic delay of 6 months. Clinical presentation included typical LE symptoms such as anterograde amnesia (95.2 %) and temporal lobe or tonico-clonic seizures (95.2 %). Psychiatric symptoms were described in 61.9 % of patients, presenting as anxiety, depressive symptoms, apathy and behavioral changes. Extra-limbic symptoms were present in 14.3 % of patients. No neoplasia associated was found. Some patients had poor epileptic, cognitive and psychiatric outcomes requiring prolonged immunosuppressive treatment. The description of the neuropsychiatric spectrum of anti-GAD LE and its specificities aims to improve our understanding of this entity, and may lead to earlier diagnosis as well as better outcome.

Intravenous methylprednisolone or immunoglobulin for anti-glutamic acid decarboxylase 65 antibody autoimmune encephalitis: which is better?

BACKGROUND

Patients positive for anti-glutamic acid decarboxylase 65 (GAD65) antibodies have attracted increasing attention. Their clinical manifestations are highly heterogeneous and can be comorbid with tumors. Currently, there is no consensus on the therapeutic regimen for anti-GAD65-associated neurological diseases due to the clinical complexity, rarity and sporadic distribution. We reported six anti-GAD65 autoimmune encephalitis (AE) patients who received intravenous methylprednisolone (IVMP) or immunoglobulin (IVIG) or both. Then, we evaluated the therapeutic effect of both by summarizing results in previous anti-GAD65 AE patients from 70 published references.

RESULTS

Our six patients all achieved clinical improvements in the short term. Unfortunately, there was no significant difference between IVMP and IVIG in terms of therapeutic response according to the previous references, and the effectiveness of IVMP and IVIG was 45.56% and 36.71%, respectively. We further divided the patients into different subgroups according to their prominent clinical manifestations. The response rates of IVMP and IVIG were 42.65% and 32.69%, respectively, in epilepsy patients; 60.00% and 77.78%, respectively, in patients with stiff-person syndrome; and 28.57% and 55.56%, respectively, in cerebellar ataxia patients. Among 29 anti-GAD65 AE patients with tumors, the response rates of IVMP and IVIG were 29.41% and 42.11%, respectively. There was no significant difference in effectiveness between the two regimens among the different subgroups.

CONCLUSION

Except for stiff-person syndrome, we found that this kind of AE generally has a poor response to IVMP or IVIG. Larger prospective studies enrolling large numbers of patients are required to identify the optimal therapeutic strategy in the future.

Structural Noninfectious Manifestations of the Central Nervous System in Common Variable Immunodeficiency Disorders

BACKGROUND

Central nervous system (CNS) disease in adult common variable immunodeficiency (CVID) is rare, and therefore diagnostic and therapeutic protocols are lacking.

OBJECTIVE

To provide clinical information aiming to establish awareness and first experience-based recommendations.

METHODS

We reviewed clinical manifestations, genetic and immunological characteristics, diagnostic evaluation, and treatment of patients with CVID with abnormal magnetic resonance imaging (MRI) of the CNS disease in our cohort.

RESULTS

Seventeen patients with CNS manifestation and a previous diagnosis of CVID were identified. Presenting symptoms of the CNS disease included loss of sensory or motoric function, headache, or epilepsy. Contrast-enhancing lesions of the brain or solely the spinal cord were the most common findings on MRI. The prevalence of splenomegaly, lymphadenopathy, interstitial lung disease, and autoimmune cytopenia was significantly increased compared with control CVID patients. In 8 patients, a molecular defect was identified, including mutations in CTLA4, NFKB1, and CECR1. Patients with CVID with CNS involvement generally displayed lymphopenia, skewed CD4⁺ T-cell subsets, and increased proportions of CD21^low B cells in the peripheral blood. CNS involvement usually responded well to high-dose steroids, but regularly required maintenance therapy to prevent relapse.

CONCLUSION

CNS disease is a severe but rare complication in CVID disorders, particularly affecting patients with other noninfectious disease symptoms. Diagnostic evaluation needs to rule out infectious causes by all means; a genetic evaluation is recommended given the high probability of an underlying monogenic disorder. Possible treatment consists of steroids with yet to be determined optimal maintenance therapy in case of relapse.

Investigation of neuronal auto-antibodies in children diagnosed with epileptic encephalopathy of unknown cause

AIM

Cryptogenic forms of epileptic encephalopathies (EE) with their well-known features of drug-resistance, mental deterioration and partial response to immunotherapies are ideal candidates for screening for neuronal autoantibodies (NAA).

METHOD

Fifty consecutive pediatric patients with a diagnosis of EE of unknown cause were included. Nine NAAs were tested by ELISA, RIA or cell-based assays. Clinical features of seronegative and seropositive patients were compared.

RESULTS

NAAs were found in 7/50 (14%) patients. They were N-methyl-d-aspartate receptor in two (4%), glycine receptor in two (4%), contactin-associated protein-like 2 in one (2%), glutamic acid decarboxylase in one (2%) and type A gamma aminobutyric acid receptor in one patient (2%). Furthermore, serum IgGs of two patients negative for well-characterized NAAs, showed strong reactivity with the uncharacterized membrane antigens of live hippocampal neurons. There were no significant differences between seropositive and seronegative patients by means of epilepsy duration, anti-epileptic drug resistance, EE type, types of seizures, seizure frequencies, EEG features or coexisting autoimmune diseases. Some seropositive patients gave good-moderate response to immunotherapy.

DISCUSSION

Potential clues for the possible role of autoimmunity in seropositive patients with EE were atypical prognosis of the classical EE type, atypical progression and unusual neurological findings like dyskinesia.

Intravenous immunoglobulin for the treatment of autoimmune encephalopathy in children with autism

The identification of brain-targeted autoantibodies in children with autism spectrum disorder (ASD) raises the possibility of autoimmune encephalopathy (AIE). Intravenous immunoglobulin (IVIG) is effective for AIE and for some children with ASD. Here, we present the largest case series of children with ASD treated with IVIG. Through an ASD clinic, we screened 82 children for AIE, 80 of them with ASD. IVIG was recommended for 49 (60%) with 31 (38%) receiving the treatment under our care team. The majority of parents (90%) reported some improvement with 71% reporting improvements in two or more symptoms. In a subset of patients, Aberrant Behavior Checklist (ABC) and/or Social Responsiveness Scale (SRS) were completed before and during IVIG treatment. Statistically significant improvement occurred in the SRS and ABC. The antidopamine D2L receptor antibody, the anti-tubulin antibody and the ratio of the antidopamine D2L to D1 receptor antibodies were related to changes in the ABC. The Cunningham Panel predicted SRS, ABC, parent-based treatment responses with good accuracy. Adverse effects were common (62%) but mostly limited to the infusion period. Only two (6%) patients discontinued IVIG because of adverse effects. Overall, our open-label case series provides support for the possibility that some children with ASD may benefit from IVIG. Given that adverse effects are not uncommon, IVIG treatment needs to be considered cautiously. We identified immune biomarkers in select IVIG responders but larger cohorts are needed to study immune biomarkers in more detail. Our small open-label exploratory trial provides evidence supporting a neuroimmune subgroup in patients with ASD.

Severe dysautonomia as a main feature of anti-GAD encephalitis: Report of a paediatric case and literature review

INTRODUCTION

Anti-glutamic acid decarboxylase (anti-GAD65) antibodies are a rare cause of autoimmune encephalitis. This entity is mainly recognized in adults and very few cases were reported in children. We report on a paediatric case of anti-GAD encephalitis with severe presentation and uncontrollable dysautonomia.

CASE STUDY

A 9-year-old girl was referred to our department for refractory seizures and behavioral disturbances. Brain magnetic resonance imaging (MRI) was normal. Repeat screening for antineuronal antibodies showed negative results for anti-NMDA receptor antibodies but positive results for anti-GAD65 with a low positivity of anti-Ma2 antibodies. Although a transient improvement was noticed after immunomodulatory treatment, the patient developed severe intractable autonomic imbalance including dysrythmia, alternating bradycardia/tachycardia, hypotension/hypertension, hypothermia/hyperthermia and hyperhidrosis. She deceased six months after onset.

CONCLUSION

Our report intends to raise awareness of autoimmune encephalitis with anti-GAD65 antibodies which may involve extralimbic brain regions and manifest with fatal dysautonomia. We highlight the need for prompt diagnosis and aggressive management for this underdiagnosed entity in children.

Autoimmune Epilepsies

Autoimmune epilepsies describe clinical syndromes wherein the immune system is suspected to be involved in the pathogenesis of seizures or as a mechanism for neuronal injury following seizures. These diseases typically affect otherwise healthy children and are characterized by explosive onset of focal seizures, encephalopathy, cognitive deterioration, or other focal neurological deficits, or all of these. Traditional neurological diagnostics lack sensitivity and specificity in the diagnosis of autoimmune epilepsies, and results must be considered in the clinical context. Consideration of an autoimmune etiology early in the clinical course is important to ensure timely initiation of immunotherapy, as appropriate, as conventional antiepileptic drugs alone are typically unable to control seizures and other neurological symptoms. This article discusses the autoimmune epilepsies of autoimmune encephalitis (including anti-N-methyl-D-aspartate receptor encephalitis), Rasmussen's encephalitis, and febrile infection-related epilepsy syndrome. Further research is needed to better understand pathogenic mechanisms, optimal immunotherapy, and the effect of treatment on prognosis.

Neurologic Complications of Common Variable Immunodeficiency

Common variable immunodeficiency is a rare disorder of immunity associated with a myriad of clinical manifestations including recurrent infections, autoimmunity, and malignancy. Though rare, neurologic complications have been described in a small number of case reports and case series of CVID patients. In this article, we present a patient with CVID who suffered significant neurologic morbidity and categorize the reported range of neurologic complications associated with CVID. Our case highlights the complex nature of neurologic manifestations in CVID patients, and our review of the current database suggests that infection and inflammatory neurologic disorders are the cause of most neurologic presentations.

Type 1 diabetes and GAD65 limbic encephalitis: a case report of a 10-year-old girl

Limbic encephalitis is a rare neurological disorder that may be difficult to recognize. Clinical features include memory impairment, temporal lobe seizures and affective disturbance. We report the case of a 10-year-old girl with type 1 diabetes mellitus that presented with seizures, depressed mood and memory changes. The diagnosis of glutamic acid decarboxylase 65 (GAD65) mediated limbic encephalitis relied on cerebral magnetic resonance imaging lesions and high serological and cerebrospinal fluid GAD65-antibodies titers. High-dose steroidal therapy was started with clinical improvement. Relapse led to a second high-dose steroid treatment followed by rituximab with remission. A correlation between serum GAD65-antibodies levels and symptoms was found, demonstrating GAD65-antibodies titers may be useful for clinical follow-up and immunotherapy guidance. This report raises awareness of this serious neurological condition that may be associated with type 1 diabetes, underlining the importance of an early diagnosis and prompt treatment for a better prognosis.

Antibody-Mediated Autoimmune Encephalitis in Childhood

BACKGROUND

The differential diagnosis of encephalitis in childhood is vast, and evaluation for an etiology is often unrevealing. Encephalitis by way of autoimmunity has long been suspected, as in cases of acute disseminated encephalomyelitis; however, researchers have only recently reported evidence of antibody-mediated immune dysregulation resulting in clinical encephalitis.

MAIN FINDINGS

These pathologic autoantibodies, aimed at specific neuronal targets, can result in a broad spectrum of symptoms including psychosis, catatonia, behavioral changes, memory loss, autonomic dysregulation, seizures, and abnormal movements. Autoimmune encephalitis in childhood is often quite different from adult-onset autoimmune encephalitis in clinical presentation, frequency of tumor association, and ultimate prognosis. As many of the autoimmune encephalitides are sensitive to immunotherapy, prompt diagnosis and initiation of appropriate treatment are paramount.

CONCLUSIONS

Here we review the currently recognized antibody-mediated encephalitides of childhood and will provide a framework for diagnosis and treatment considerations.

Limbic Encephalitis Associated With GAD65 Antibodies: Brief Review of the Relevant literature

Recently, many cases of autoimmune limbic encephalitis with positive GAD65 (glutamic acid decarboxylase) antibodies have been described in the scientific literature. However, it remains an understudied topic of great relevance to practicing neurologists. Thus, we report here a review of published cases, in English, of autoimmune limbic encephalitis with this type of antibodies, focusing on presenting symptoms and signs, associated conditions, and findings upon investigation. We also report treatment responses. We aim to offer a better description of the clinical spectrum of autoimmune limbic encephalitis associated with GAD65 antibodies as well as to expose its paraclinical features and outcome.

Differences in epileptic symptoms depending on the type of autoimmune-mediated limbic encephalitis

Limbic encephalitis (LE) is an inflammatory disease of the central nervous system that is characterized by the selective involvement of limbic structures. The clinical manifestations of LE include the acute or sub-acute onset of recent memory disorders, mental disorders and seizures. Autoimmune-mediated LE is a major type of non-infectious LE; seizure is a hallmark of this type of LE. The treatment of epilepsy, which is a key factor that affects the prognosis of LE patients, warrants special attention. Understanding the characteristics of epilepsy caused by autoimmune-mediated LE and providing the appropriate treatment will help to improve patients' outcomes. In this article, we extensively review the literature related to autoimmune-mediated LE epidemiology, mechanisms, characteristics and seizure frequency and onset, and we discuss the possible diagnosis and treatment of this disease.

A spectrum of inflammation and demyelination in acute disseminated encephalomyelitis (ADEM) of children

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the central nervous system that involves multifocal areas of the white matter, rarely the gray matter and spinal cord, mainly affecting children and mostly occurring 1-2weeks after infections or more rarely after vaccinations. Though a specific etiologic agent is not constantly identified, to evaluate carefully patient's clinical history and obtain adequate samples for the search of a potential ADEM causal agent is crucial. In the case of a prompt diagnosis and adequate treatment, most children with ADEM have a favorable outcome with full recovery, but in the case of diagnostic delays or inappropriate treatment some patients might display neurological sequelae and persistent deficits or even show an evolution to multiple sclerosis. The suspicion of ADEM rises on a clinical basis and derives from systemic and neurologic signs combined with magnetic resonance imaging of the central nervous system. Other advanced imaging techniques may help an appropriate differential diagnosis and definition of exact disease extension. Although there is no standardized protocol or management for ADEM, corticosteroids, intravenous immunoglobulin, and plasmapheresis have been successfully used. There is no marker that permits to identify the subset of children with worse prognosis and future studies should try to detect any biological clue for prevision of neurologic damage as well as should optimize treatment strategies using an approach based on the effective risk of negative evolution.

Treatment of immune-mediated temporal lobe epilepsy with GAD antibodies

PURPOSE

Temporal lobe epilepsy with antibodies (abs) against the glutamic acid decarboxylase 65 isoform (GAD-TLE) is known as an immune-mediated neurological syndrome. Here we evaluate the therapy response to various immunotherapies and epilepsy surgery in this syndrome.

METHOD

All patients with GAD-TLE and follow-up data and stored serum and CSF samples, identified and treated at the Bonn centre from 2002 to 2010, were studied retrospectively. Seizure freedom for ≥1 year and reduction of ≥50%, i.e. therapy response, were assessed. GAD-ab titres and neuropsychological performances were documented prior and after individual interventions.

RESULTS

Thirteen patients with GAD-TLE were identified with the following seizure responses: corticosteroids (5 responders out of 11 treated patients); i.v. immunoglobulins (1/5), apheresis therapy (1/8); and natalizumab (1/1), selective amygdala-hippocampectomy (2/3). None of the patients achieved sustained seizure freedom apart from one patient. This patient was on antiepileptic drug treatment after discontinuation of immunotherapy.

CONCLUSION

The seizure response to immunotherapies in patients with GAD-TLE was poor. Corticosteroids were the most effective regarding seizure response. Especially the poor effects of apheresis therapies support the idea that GAD-abs are not directly pathogenic. None of three patients was seizure-free after temporal lobe surgery suggesting that GAD-TLE patients respond worse than others to this type of intervention. Our results reflect the chronic course of the disease with low likelihood for patients with GAD-TLE to attain long-term seizure freedom.

Limbic encephalitis with antibodies to glutamic acid decarboxylase presenting with brainstem symptoms

Limbic encephalitis (LE) is a neurological syndrome that may present in association with cancer, infection, or as an isolate clinical condition often accompanying autoimmune disorders. LE associated with glutamic acid decarboxylase antibodies (anti-GAD) is rare in children. Here, we characterized the clinical and laboratory features of a patient presenting with brainstem involvement with non-paraneoplastic LE associated with anti-GAD antibodies. In our patient, after plasma exchange, we determined a dramatic improvement of the neurological deficits.

The recognition and treatment of autoimmune epilepsy in children

There is emerging interest in autoimmune epilepsy, which represents a small but potentially treatable form of epilepsy. Most insights into autoimmune epilepsy derive from the recent descriptions of autoimmune encephalitis that takes two general forms: a focal encephalitis (such as limbic) or a diffuse encephalitis (such as anti-N-methyl-D-aspartate receptor [NMDAR] encephalitis). The features of autoimmune epilepsy include acute or subacute onset of seizures, usually in the context of encephalopathy, and inflammation of the central nervous system on testing cerebrospinal fluid or magnetic resonance imaging. Neuronal antibodies associated with autoimmune encephalitis and seizures in children include NMDAR, voltage-gated potassium channel complex, glycine receptor, γ-Aminobutyric acid type A receptor (GABA(A)R), γ-Aminobutyric acid type B receptor (GABA(B)R), and glutamic acid decarboxylase antibodies. These antibodies support the diagnosis of autoimmune epilepsy, but are not essential for diagnosis. When autoimmune epilepsy is suspected, first-line immune therapy with corticosteroids in addition to intravenous immunoglobulin or plasma exchange should be considered. Second-line therapy with rituximab or cyclophosphamide can be considered if the syndrome is severe. A response to immune therapy supports the diagnosis of autoimmune epilepsy. Neuronal antibodies are increasingly found in patients with focal epilepsy of unknown cause who do not have 'encephalitis'. Recent epidemiological studies support the link between epilepsy and autoimmune diseases. Future studies need to define the spectrum of autoimmune epilepsy and focus on early identification and treatment.

The Peptide Network between Tetanus Toxin and Human Proteins Associated with Epilepsy

Sequence matching analyses show that Clostridium tetani neurotoxin shares numerous pentapeptides (68, including multiple occurrences) with 42 human proteins that, when altered, have been associated with epilepsy. Such a peptide sharing is higher than expected, nonstochastic, and involves tetanus toxin-derived epitopes that have been validated as immunopositive in the human host. Of note, an unexpected high level of peptide matching is found in mitogen-activated protein kinase 10 (MK10), a protein selectively expressed in hippocampal areas. On the whole, the data indicate a potential for cross-reactivity between the neurotoxin and specific epilepsy-associated proteins and may help evaluate the potential risk for epilepsy following immune responses induced by tetanus infection. Moreover, this study may contribute to clarifying the etiopathogenesis of the different types of epilepsy.

Atypical neurologic presentations of new onset type 1 diabetes mellitus in pediatric age group: a report of five unusual cases and review of the literature

Type 1 diabetes mellitus (T1DM) is one of the most common chronic diseases in childhood and is caused by insulin deficiency resulting from the autoimmune destruction of insulin producing beta cells of the pancreas. Most children in the US with new onset T1DM present with the classic signs and symptoms of hyperglycemia and 30% with diabetic ketoacidosis (DKA). Neurologic manifestations are relatively rare and mostly include lethargy, decreased level of consciousness, and coma as a result of DKA. In this article, five cases of new onset T1DM with exceedingly rare or unreported neurologic manifestations in the pediatric age group are presented, along with a review of the literature.

Anti-glutamic Acid decarboxylase antibody associated limbic encephalitis in a child: expanding the spectrum of pediatric inflammatory brain diseases

Anti-glutamic acid decarboxylase directed antibodies are a rare cause of autoimmune limbic encephalitis that is relatively resistant to immunotherapy. Here we report a 15-year-old boy with nonparaneoplastic, anti-glutamic acid decarboxylase limbic encephalitis presenting with subacute headache, memory disturbance, psychiatric symptoms, and seizures. At onset, his memory disturbance manifested as transient global amnesia-like episodes. Clinical remission was achieved with rituximab, intravenous immunoglobulin, and corticosteroids.

Paraneoplastic neurological disorders in children with benign ovarian tumors

AIM

Paraneoplastic neurological diseases (PND) are rare, but potentially treatable disorders. Paraneoplastic encephalitis is rapidly emerging as an important but likely under-recognized condition in children. The aim of this study was to assess the prevalence and spectrum of PND in children with benign ovary tumor and the long-term outcome.

PATIENTS AND METHODS

We retrospectively reviewed the charts of all female patients below 18years of age diagnosed with a benign ovarian tumor proven by pathology between January 1993 and December 2010. All the clinical symptoms developed within 5years of tumor diagnosis and the related investigations were recorded.

RESULTS

There were total 133 children and adolescents with benign ovarian tumors, mostly mature teratoma. Six patients (4.5%) had neuropsychiatric manifestations and all but one were beyond age 10years. The most common neuropsychiatric presentations were depression or low mood (84%), headache (50%), mutism (50%), hypoventilation (50%), seizures (30%), hallucination (30%), vomiting and hypersalivation (30%). Three patients (2.2%) had serious PND including acute disseminated encephalomyelitis in 1 and anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in 2. Although all of three improved after tumor removal, one without immunotherapy had neurological sequelae and prolonged ICU stay.

CONCLUSION

The prevalence of PND in benign ovary tumor is not so uncommon in children. It is important to survey ovary tumors in female adolescents with subacute presentation of multiple-level involvement of neuraxis where no clear alternate diagnosis is possible. Treatment of serious PND associated with ovary tumors should include immunotherapy in addition to tumor removal.

Autoimmune Limbic Encephalitis With GAD Antibodies

The neurologic presentation of limbic encephalitis is variable and when it occurs due to a rare cause the diagnosis may be problematic. We present a case of autoimmune limbic encephalitis due to glutamic acid decarboxylase antibody and consider the magnetic resonance imaging and antineural antibody screening aspects in the diagnosis of this entity.

Immune-mediated pediatric epilepsies

Apart from Rasmussen encephalitis, other immune-mediated brain disorders have emerged that are frequently associated with recurrent epileptic seizures: (1) limbic encephalitis, (2) anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis, and (3) steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT, formerly called Hashimoto encephalopathy). Limbic encephalitis mainly affects the mediotemporal aspect of the cortex giving rise to temporal lobe seizures and memory and affective disturbances. It can occur as a paraneoplastic or, even more frequently, a nonparaneoplastic condition. Detection of specific autoantibodies may suggest underlying cancer (onconeural antibodies) and may give hints regarding the long-term prognosis. VGKC-complex or GAD antibodies have been identified in children. Anti-NMDAR encephalitis is a disorder mainly of female adolescents and young adults. Patients present with seizures in around one-third of cases, and 80% of patients develop recurrent, mainly extratemporal seizures at some stage of their disorder. The clinical course is that of a mostly monophasic, but sometimes multiphasic, severe cortico-subcortical encephalopathy. Ovarian teratomas underlie the disorder in 30-60% of adult cases but are rare in young children. Tumor removal and early intense immunotherapy are predictors for a favorable outcome. SREAT is not a disorder with definite pathogenesis but rather a "catch all" for encephalopathic immune-mediated brain diseases (often with seizures) which have in common thyroid antibodies and a good response to steroid therapy.

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.

Autoimmune encephalitis in children

The causes of encephalitis are numerous, and extensive investigations for infectious agents and other etiologies are often negative. The discovery that many of these encephalitis are immune mediated has changed the approach to the diagnosis and treatment of these disorders. Moreover, the broad spectrum of symptoms including, psychosis, catatonia, alterations of behavior and memory, seizures, abnormal movements, and autonomic dysregulation usually requires a multidisciplinary treatment approach. This review focuses in several forms of encephalitis that occur in children, and for which an autoimmune etiology has been demonstrated (eg, anti-N-methyl-d-aspartate receptor encephalitis) or is strongly suspected (eg, Rasmussen encephalitis, limbic encephalitis, opsoclonus-myoclonus). The authors also review several disorders that may be immune mediated, such as the rapid onset obesity with hypothalamic dysfunction, hypoventilation and autonomic dysregulation (ROHHAD) syndrome and some encephalopathies with fever and status epilepticus. Recognition of novel immune-mediated encephalitis is important because some of these disorders are highly responsive to immunotherapy.

The association of anti-glutamic acid decarboxylase antibodies with different neurological findings in childhood

Glutamic acid decarboxylase antibodies can rarely be associated with various neurological syndromes, which are usually present in adults. Here, we present 2 affected children. Our first patient had a diagnosis of epilepsy and presented with continuous involuntary movements and multifocal myoclonic seizures following an infection at the age of 9 months. Anti-glutamic acid decarboxylase antibodies were found in the serum and cerebrospinal fluid. A partial response was obtained from intravenous immunoglobulin, steroid, and plasmapheresis treatment. The other patient presented with a clinical picture of acute cerebellar ataxia and mutism at the age of 6 years and recovered fully following intravenous immunoglobulin treatment. Neurological findings due to anti-glutamic acid decarboxylase antibodies may be more common in children than previously thought, and achieving an early diagnosis can be important for prompt treatment.

An immunologic case study of acute encephalitis with refractory, repetitive partial seizures

Acute encephalitis with refractory, repetitive partial seizures (AERRPS) is a neurologic syndrome characterized by extraordinarily frequent and refractory partial seizures, which immediately evolve into refractory epilepsy. To elucidate the pathophysiology of AERRPS, we performed an immunologic study of an affected boy, revealing decreased natural killer (NK) cell activity in the peripheral blood mononuclear cells. IgG antibodies against the glutamate receptor (GluR)ε2, ζ1, and δ2 subunits were all positive in both the serum and cerebrospinal fluid (CSF). There were raised plasma concentrations of interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor-α, and interferon-γ as well as an extremely elevated CSF level of IL-6. These findings suggest that AERRPS is immune-mediated encephalitis, in which both autoimmunity and exaggerated cytokine production are involved. NK cell dysfunction may be the underlying abnormality in this AERRPS case, which might have contributed to the production of GluR autoantibodies.

An Emerging Problem in Clinical Practice: How to Approach Acute Psychosis

Limbic encephalitis (LE) is rare, presents with memory impairment, seizures and behavioral disorder. We present a 44-year-old female with an agitation-depressive disorder associated with delusions and hallucinations, admitted to our hospital with the diagnosis of psychosis. A computed tomography (CT) scan of the brain and lumbar puncture on admission were normal. Because of clinical deterioration and addition of seizures in the clinical picture, further workup with serum and repeat cerebrospinal fluid studies, magnetic resonance imaging (MRI), and electroencephalogram disclosed a lesion in the left medial temporal lobe consistent with LE. The patient was treated symptomatically with antidepressive, antipsychotic and anticonvulsant drugs. Aggressive diagnostic tests for the presence of an occult cancer were negative. An 8-year follow up has not revealed a tumor to support a paraneoplasmatic origin of LE. This case, initially diagnosed and treated as psychosis, is a case of non-paraneoplasmatic, non-infective LE, probably caused by an autoimmune mechanism.

Current approaches to the treatment of paraneoplastic encephalitis

Paraneoplastic neurological syndromes (PNSs) cover a wide range of diseases and involve both the central nervous system (CNS) and peripheral nervous system. Paraneoplastic encephalitis comprises several diseases such as paraneoplastic cerebellar degeneration (PCD), limbic encephalitis (LE), paraneoplastic encephalomyelitis (PEM), brainstem encephalitis, opsomyoclonus syndrome, in addition to other even less frequently occurring entities. LE was the first historically identified CNS PNS, and similarities between other temporal lobe diseases such as herpes encephalitis have been elucidated. In the past few decades several autoantibodies have been described in association with LE. These encompass the classical 'onconeuronal' antibodies (abs) such as Hu, Yo, Ri and others, and now additionally abs towards either ion channels or surface antigens. The clinical core findings in LE are various mental changes such as amnesia or confusion, often associated with seizures. Careful characterization of psychiatric manifestations and/or associated neurological signs can help to characterize the syndrome and type of ab. The treatment options in LE depend on the aetiology. In LE caused by onconeuronal abs, the treatment options are poor. In two types of abs associated with LE, abs against ion channels and surface antigens (e.g. NMDA), immunomodulatory treatments seem effective, making these types of LE treatable conditions. However, LE can also occur without being associated with cancer, in which case only immunomodulation is required. Despite effective treatments, some patients' residual deficits remain, and recurrences have also been described.

Biomarkers of inflammatory and auto-immune central nervous system disorders

PURPOSE OF REVIEW

Inflammatory and auto-immune disorders of the central nervous system are a heterogeneous group of disorders. Many of these disorders are potentially treatable with immune therapies that can reduce disability or prevent death. We review the clinical value of biomarkers which can aid in the diagnosis of paediatric inflammatory and auto-immune central nervous system (CNS) disorders.

RECENT FINDINGS

This review will first describe the clinical usefulness of nonspecific biomarkers of CNS inflammation such as cerebrospinal fluid neopterin and oligoclonal bands. Neopterin is produced by immune and neuronal cells after stimulation by interferon species and is increased in a broad range of inflammatory and auto-immune CNS disorders. Oligoclonal bands represent clonal production of immunoglobulin G in the CNS and are present in demyelinating, auto-immune, and infectious CNS disorders. In addition, we will review new advances in the immunogenetic investigation of familial auto-inflammatory disorders such as Aicardi-Goutières syndrome and Chronic Infantile Neurologic Cutaneous Articular syndrome. Finally, we will review the clinical utility of auto-antibodies in CNS disorders, with specific focus on auto-antibodies that bind to cell surface proteins such as N-methyl-D-asparate receptor, voltage-gated potassium channels, myelin oligodendrocyte glycoprotein, and aquaporin-4.

SUMMARY

These biomarkers are increasingly important in the recognition and treatment of inflammatory and auto-immune CNS disorders. Like many biomarkers in paediatric practice, it is essential to interpret the findings in the context of the patient history and examination.

Non-paraneoplastic limbic encephalitis characterized by mesio-temporal seizures and extratemporal lesions: a case report

Limbic encephalitis (LE) can be either paraneoplastic or a non-paraneoplastic autoimmune disorder. Magnetic resonance imaging (MRI) of the brain on T2-weighted fluid-attenuated inversion recovery (FLAIR) classically shows hyperintensities of the temporal structures, but multifocal involvement of extratemporal cortex has also been described in paraneoplastic LE. Here we describe a 27-year-old woman whose idiopathic autoimmune (glutamic acid decarboxylase-antibody positive) LE debuted with multiple daily mesio-temporal seizures, amnesia and multifocal extratemporal cortical MRI abnormalities. Mesio-temporal MRI signal increase was found after 20 days. This case report highlights that early diagnosis of non-paraneoplastic LE may be considered in patients with multiple daily mesio-temporal seizures and amnesia even in the absence of early typical MRI abnormalities.

[A case of immune-mediated encephalopathy showing refractory epilepsy and extensive brain MRI lesions associated with anti-glutamic acid decarboxylase antibody]

We reported a patient with immune-mediated encephalopathy showing refractory epilepsy and multiple brain lesions on MRI. The patient had high titers of anti-glutamic acid decarboxylase (GAD) antibody in sera and cerebrospinal fluid (CSF). A 36-year-old previously healthy woman was admitted to our hospital with onset of sudden generalized seizure that then persisted for one month. She had repeated epileptic attacks accompanied with loss of consciousness, and was refractory to valproic acid, zonisamide (200 mg/day) and phenobarbital (200 mg/day). Brain MRI showed multiple hyperintense lesions in predominantly bilateral frontal lobes, parietal lobes, occipital lobes and cingulate cortices. EEG showed epileptic activities (frequent sharp waves) in bilateral frontal regions. After admission, attacks disappeared through the administration of clonazepam (1.5 mg/day), though the patient remained slightly disoriented. As titers of anti-GAD antibody in sera and CSF were extremely high, we implemented plasma exchanges. After treatment, titers of anti-GAD antibody in sera and CSF decreased. The patient completely recovered to an alert state and the abnormal MRI lesions almost disappeared. Since GAD catalyzes production of gamma-aminobutyric acid (GABA), it is proposed that anti-GAD antibodies reduce synthesis of GABA or interferes with exocytosis of GABA in the nervous system. Anti-GAD antibodies are detected in some rare neurological disorders such as stiff-person syndrome. Recently, anti-GAD antibodies have been reported as implicated in cerebellar ataxia, palatal myoclonus, refractory epilepsy and limbic encephalitis. Epilepsy associated with the anti-GAD antibody is mostly pharmacoresistant temporal lobe epilepsy; with brain MRI showing no abnormality or only hippocampal sclerosis. It is very rare that brain MRI shows extensive abnormal lesions except in the hippocampus. This case suggests that anti-GAD antibodies could contribute to unexplained encephalopathy with extensive brain MRI lesions and drug-resistant symptomatic epilepsy.