Leucine-rich Glioma-inactivated 1 Antibody Research Articles

Predictors and Clinical Characteristics of Relapses in LGI1-Antibody Encephalitis.

Relapses occur in 15%-25% of patients with leucine-rich glioma-inactivated 1 antibody (LGI1-Ab) autoimmune encephalitis and may cause additional disability. In this study, we clinically characterized the relapses and identified factors predicting their occurrence. This is a retrospective chart review of patients with LGI1-Ab encephalitis diagnosed at our center between 2005 and 2022. Relapse was defined as worsening of previous or appearance of new symptoms after at least 3 months of clinical stabilization. Among 210 patients, 30 (14%) experienced a total of 33 relapses. The median time to first relapse was 23.9 months (range: 4.9-110.1, interquartile range [IQR]: 17.8). The CSF was inflammatory in 11/25 (44%) relapses, while LGI1-Abs were found in the serum in 16/24 (67%) and in the CSF in 12/26 (46%); brain MRI was abnormal in 16/26 (62%) relapses. Compared with the initial episode, relapses manifested less frequently with 3 or more symptoms (4/30 patients, 13% vs 28/30, 93%; p < 0.001) and had lower maximal modified Rankin scale (mRS) score (median 3, range: 2-5, IQR: 1 vs 3, range: 2-5, IQR: 0; p = 0.001). The median mRS at last follow-up after relapse (2, range: 0-4, IQR: 2) was significantly higher than after the initial episode (1, range: 0-4, IQR: 1; p = 0.005). Relapsing patients did not differ in their initial clinical and diagnostic features from 85 patients without relapse. Nevertheless, residual cognitive dysfunction after the initial episode (hazard ratio:13.8, 95% confidence interval [1.5; 129.5]; p = 0.022) and no administration of corticosteroids at the initial episode (hazard ratio: 4.8, 95% confidence interval [1.1; 21.1]; p = 0.036) were significantly associated with an increased risk of relapse. Relapses may occur years after the initial encephalitis episode and are usually milder but cause additional disability. Corticosteroid treatment reduces the risk of future relapses, while patients with residual cognitive dysfunction after the initial episode have an increased relapse risk.

Ultrahigh frequencies of peripherally matured LGI1- and CASPR2-reactive B cells characterize the cerebrospinal fluid in autoimmune encephalitis

Intrathecal synthesis of central nervous system (CNS)-reactive autoantibodies is observed across patients with autoimmune encephalitis (AE), who show multiple residual neurobehavioral deficits and relapses despite immunotherapies. We leveraged two common forms of AE, mediated by leucine-rich glioma inactivated-1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies, as human models to comprehensively reconstruct and profile cerebrospinal fluid (CSF) B cell receptor (BCR) characteristics. We hypothesized that the resultant observations would both inform the observed therapeutic gap and determine the contribution of intrathecal maturation to pathogenic B cell lineages. From the CSF of three patients, 381 cognate-paired IgG BCRs were isolated by cell sorting and scRNA-seq, and 166 expressed as monoclonal antibodies (mAbs). Sixty-two percent of mAbs from singleton BCRs reacted with either LGI1 or CASPR2 and, strikingly, this rose to 100% of cells in clonal groups with ≥4 members. These autoantigen-reactivities were more concentrated within antibody-secreting cells (ASCs) versus B cells (P < 0.0001), and both these cell types were more differentiated than LGI1- and CASPR2-unreactive counterparts. Despite greater differentiation, autoantigen-reactive cells had acquired few mutations intrathecally and showed minimal variation in autoantigen affinities within clonal expansions. Also, limited CSF T cell receptor clonality was observed. In contrast, a comparison of germline-encoded BCRs versus the founder intrathecal clone revealed marked gains in both affinity and mutational distances (P = 0.004 and P < 0.0001, respectively). Taken together, in patients with LGI1 and CASPR2 antibody encephalitis, our results identify CSF as a compartment with a remarkably high frequency of clonally expanded autoantigen-reactive ASCs whose BCR maturity appears dominantly acquired outside the CNS.

Discrimination between leucine-rich glioma-inactivated 1 antibody encephalitis and gamma-aminobutyric acid B receptor antibody encephalitis based on ResNet18.

This study aims to discriminate between leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis and gamma-aminobutyric acid B (GABAB) receptor antibody encephalitis using a convolutional neural network (CNN) model. A total of 81 patients were recruited for this study. ResNet18, VGG16, and ResNet50 were trained and tested separately using 3828 positron emission tomography image slices that contained the medial temporal lobe (MTL) or basal ganglia (BG). Leave-one-out cross-validation at the patient level was used to evaluate the CNN models. The receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) were generated to evaluate the CNN models. Based on the prediction results at slice level, a decision strategy was employed to evaluate the CNN models' performance at patient level. The ResNet18 model achieved the best performance at the slice (AUC = 0.86, accuracy = 80.28%) and patient levels (AUC = 0.98, accuracy = 96.30%). Specifically, at the slice level, 73.28% (1445/1972) of image slices with GABAB receptor antibody encephalitis and 87.72% (1628/1856) of image slices with LGI1 antibody encephalitis were accurately detected. At the patient level, 94.12% (16/17) of patients with GABAB receptor antibody encephalitis and 96.88% (62/64) of patients with LGI1 antibody encephalitis were accurately detected. Heatmaps of the image slices extracted using gradient-weighted class activation mapping indicated that the model focused on the MTL and BG for classification. In general, the ResNet18 model is a potential approach for discriminating between LGI1 and GABAB receptor antibody encephalitis. Metabolism in the MTL and BG is important for discriminating between these two encephalitis subtypes.

A Pediatric Case of LGI1 Autoimmune Encephalitis Presenting with Faciobrachial Dystonic Seizures (P5-5.014)

<h3>Objective:</h3> NA <h3>Background:</h3> 15-year-old male presented with acute behavioral changes (agitation, confusion, declining grades), frequent falls, and abnormal movements involving the right corner of the mouth, cheek, arm and hand. His lower face appeared to be pulling to the right with concomitant flexion of the ipsilateral elbow and wrist in a motion that brought his hand close to his face <h3>Design/Methods:</h3> NA <h3>Results:</h3> Continuous EEG demonstrated approximately 70 seizures with either right or left rhythmic delta activity and superimposed spikes with associated twitching or dystonia in the contralateral arm or hand. MRI imaging showed T2 hyperintensity of the left hippocampus and amygdala. His seizures were controlled after loading 3 ASM’s (lacosamide, levetiracetam, valproate) followed by IVIG and methyl prednisolone administration. The diagnosis was confirmed by Mayo autoimmune encephalitis panel that was positive in the CSF and serum for LGI1 (leucine-rich glioma-inactivated 1) antibody. <h3>Conclusions:</h3> LGI1 autoimmune encephalitis is the second most common autoimmune encephalitis after NMDA(N-Methyl-D-aspartate). It is most commonly seen in middle aged men and estimated to occur in 0.83 per million. LGI1 autoimmune encephalitis is associated with multiple seizure types including focal seizures and tonic clonic seizures. The most distinctive feature of LGI1 autoimmune encephalitis is faciobrachial dystonic seizures that have been reported extensively in adult patients. LGI1 autoimmune encephalitis with seizures is exceedingly rare in the pediatric population. We found only 6 reported cases. Our case is the first reported faciobrachial dystonic seizures at presentation in a pediatric patient. <b>Disclosure:</b> Dr. Fields has nothing to disclose. Dr. Dalvi has nothing to disclose. Dr. Duberstein Coad has nothing to disclose. Dr. Eizadkhah has nothing to disclose. Dr. Moshe has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier/Neurobiology Of Disease. Dr. Moshe has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for MedLink. Dr. Moshe has received publishing royalties from a publication relating to health care. Dr. Moshe has received personal compensation in the range of $500-$4,999 for serving as a Reviewer of study sections with NINDS.

Autoimmune parkinsonism with faciobrachiocrural dystonic seizures: a new phenotype of leucine-rich glioma-inactivated 1 (LGI1) autoimmunity.

Extrapyramidal symptoms are seen in patients with leucine-rich glioma-inactivated 1 (LGI1) antibody-positive patients infrequently and this can be successfully treated with immunotherapy. This is a retrospective hospital-based study from 2013 to 2021 at a tertiary care referral hospital in South India. LGI1 antibody-positive cases with Faciobrachio-crural dystonic seizures [FBCDS] were identified by reviewing electronic medical records and Neuroimmunology laboratory register. Clinical and laboratory details and treatment outcomes were analysed. There was a total of 23 patients who were positive for LGI1 antibody. Of these, three cases had FBCDS (2 males, age range 30-76years). Upon reviewing the records they had additional asymmetric parkinsonian features. All had similar presentations with progressive slowness of activities and gait and later went on to have paroxysmal events of sudden falls with vocalization. Prolonged VEEG monitoring captured the habitual event, which were confirmed to be FBCDS. MRI did not show significant structural abnormalities, CSF showed elevated proteins and normal cell in two and lymphocytic pleocytosis in one, PET scans ruled out malignancy. Of the three patients, two were completely relieved of FBCDS with immunosuppression and there was complete resolution of extrapyramidal features in all. Thus, the patients in our series of FBCDS showed additional features of parkinsonism which responded well to immunotherapy. Involvement of basal ganglia can explain all the manifestations of this phenotype. This series reveals a unique phenotype of the LGI1 antibody.

Isaacs\u2019 syndrome as the initial presentation of malignant thymoma and associated with double-positive voltage-gated potassium channel complex antibodies, a case report

BackgroundIsaacs’ syndrome is a peripheral nerve hyperexcitability (PNH) syndrome due to peripheral motor nerve instability. Acquired Isaacs’ syndrome is recognized as a paraneoplastic autoimmune disease with possible pathogenic voltage-gated potassium channel (VGKC) complex antibodies. However, the longitudinal correlation between clinical symptoms, VGKC antibodies level, and drug response is still unclear.Case presentationA 45-year-old man had progressive four limbs soreness, muscle twitching, cramps, and pain 4 months before admission. Electromyography (EMG) studies showed myokymic discharges, neuromyotonia, and an incremental response in the high-rate (50 Hz) repetitive nerve stimulation (RNS) test. Isaacs’ syndrome was diagnosed based on clinical presentations and EMG reports. Serum studies showed positive VGKC complex antibodies, including leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies. The acetylcholine receptor antibody was negative. Whole-body computed tomography (CT) and positron emission tomography revealed a mediastinal tumor with the great vessels encasement, right pleura, and diaphragm seeding. Biopsy confirmed a World Health Organization type B2 thymoma, with Masaoka stage IVa. His symptoms gradually improved and both LGI1 and CASPR2 antibodies titer became undetectable after concurrent chemoradiotherapy (CCRT) and high dose steroid treatment. However, his Isaacs’ syndrome recurred after the steroid was reduced 5 months later. Follow-up chest CT showed probable thymoma progression. LGI1 antibody turned positive again while CASPR2 antibody remained undetectable.ConclusionsOur patient demonstrates that Isaacs’ syndrome could be the initial and only neuromuscular manifestation of malignant thymoma. His Isaacs’ syndrome is correlated well with the LGI1 antibody level. With an unresectable thymoma, long-term immunosuppressant therapy may be necessary for the management of Isaacs’ syndrome in addition to CCRT for thymoma.

LGI1 antibody encephalitis: acute treatment comparisons and outcome

ObjectiveTo compare acute treatment responses and long-term outcome in leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis.MethodsRetrospective case series of 118 patients with LGI1 antibody encephalitis evaluated at Mayo Clinic across all...

Neuromuscular junction disorders beyond myasthenia gravis.

To give an overview of the recent data on three autoimmune neuromuscular junction disorders with the recent Food Drug Administration (FDA) approval of amifampridine [3,4-Diaminopyridine (3,4-DAP) and 3,4-diaminopyridine phosphate (3,4-DAPP) for the treatment of Lambert-Eaton myasthenic syndrome (LEMS). In LEMS, the most important recent development is the introduction of FDA approved amifampridine for the symptomatic treatment. Randomized controlled studies showed an extremely effective improvement with amifampridine with daily dose of ≤ 80 mg with minimal side reactions. The next important development is in the electrodiagnostic criteria. Now 10 s exercise and an incremental response ≥ 60% either after 10 s exercise or at the high-rate stimulation in the repetitive nerve stimulation test are recommended as the standard tests.In 2016, myasthenia-gravis Lambert-Eaton overlap syndrome (MLOS) was coined as new syndrome for patients with myasthenia gravis and LEMS combined symptoms in same patients.In Isaacs syndrome, voltage gated calcium channel antibody order is no longer recommended because of low specificity for immunotherapy responsive disorders. Instead, ' leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated like-2 (CASPR2) autoantibody tests' are recommended. In LEMS, amifampridine (3,4 DAP and 3,4-DAPP) is approved by the FDA as an effective symptomatic treatment. MLOS is coined as new syndrome recently. In Isaacs syndrome, LGI1 and CASPR2 antibody tests are recommended.

Intrathecal B-cell activation in LGI1 antibody encephalitis.

ObjectiveTo study intrathecal B-cell activity in leucine-rich, glioma-inactivated 1 (LGI1) antibody encephalitis. In patients with LGI1 antibodies, the lack of CSF lymphocytosis or oligoclonal bands and serum-predominant LGI1 antibodies suggests a peripherally initiated immune response. However, it is unknown whether B cells within the CNS contribute to the ongoing pathogenesis of LGI1 antibody encephalitis.MethodsPaired CSF and peripheral blood (PB) mononuclear cells were collected from 6 patients with LGI1 antibody encephalitis and 2 patients with other neurologic diseases. Deep B-cell immune repertoire sequencing was performed on immunoglobulin heavy chain transcripts from CSF B cells and sorted PB B-cell subsets. In addition, LGI1 antibody levels were determined in CSF and PB.ResultsSerum LGI1 antibody titers were on average 127-fold higher than CSF LGI1 antibody titers. Yet, deep B-cell repertoire analysis demonstrated a restricted CSF repertoire with frequent extensive clusters of clonally related B cells connected to mature PB B cells. These clusters showed intensive mutational activity of CSF B cells, providing strong evidence for an independent CNS-based antigen-driven response in patients with LGI1 antibody encephalitis but not in controls.ConclusionsOur results demonstrate that intrathecal immunoglobulin repertoire expansion is a feature of LGI1 antibody encephalitis and suggests a need for CNS-penetrant therapies.

Clinical characteristics and short-term prognosis of LGI1 antibody encephalitis: a retrospective case study

BackgroundRecently, most reports of Leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis are from Europe and the US, while the short term outcome and clinical characteristics of Chinese patients are rarely reported,we study the clinical manifestations, laboratory results and brain magnetic resonance images (MRI) of eight patients who were recently diagnosed with LGI1 antibody encephalitis in our hospital to improve the awareness and knowledge of this disease.MethodsEight patients (five males and three females; mean age, 63.4) with LGI1 antibody encephalitis who were diagnosed and treated in the Department of Neurology of Shengjing Hospital of China Medical University from September 2016 to June 2017 were recruited for the current study. Their general information, clinical manifestations, treatment regimens, and short-term prognoses were retrospectively analyzed, as were the results from MRI and laboratory findings.ResultsOverall, patient symptoms included cognitive impairment, which manifested primarily as memory deficits (8/8), seizures (including faciobrachial dystonic seizure, (FBDS)) (8/8), psychiatric and behavioral disorders (7/8), sleep disorders (4/8), and autonomic abnormalities (3/8). Five patients also had abnormal findings on brain MRI, mainly involving the hippocampus, basal ganglia and insula. Hyponatremia occurred in six cases. All patients tested positive for LGI1 antibodies in their serum/cerebrospinal fluid (CSF)and patients were negative for tumors. Symptoms rapidly improved after treatment with immunoglobulin and/or steroid therapy. The patients were followed up for 4–13 months after discharge, and two patients relapsed.ConclusionPrimary symptoms of LGI1 antibody encephalitis include memory impairments, seizures, FBDS, and mental and behavioral abnormalities. Increased titers of LGI1 antibodies are also present in the serum/CSF of patients. Patients often have hyponatremia, and MRIs show abnormalities in various brain regions. Finally, immunotherapy shows good efficacy and positive benefits, although patients may relapse in the short-term.

LGI1 antibody encephalopathy overlapping with sporadic Creutzfeldt-Jakob disease

Objective:To report a rare case of leucine-rich, glioma inactivated 1 (LGI1) antibody–mediated autoimmune encephalopathy clinically overlapping with pathologically confirmed sporadic Creutzfeldt-Jakob disease (CJD).Methods:The patient was investigated with repeated brain MRI, EEG, CSF examination, whole-body fluorodeoxy-glucose positron emission tomography, genetic analysis of the prion protein gene (PRNP), and extensive serologic screening for paraneoplastic and autoimmune encephalopathy markers. Written informed consent was obtained from the patient's next of kin for access to clinical files for research purposes and for publication.Results:The patient was a 77-year-old man who presented with faciobrachial dystonic seizures (FBDS) secondary to LGI1 antibody–mediated autoimmune encephalopathy, with suggestive MRI findings and a complete response to treatment with combinatorial immunosuppression. Stereotactic biopsy of a nonenhancing T1 hyperintense basal ganglia lesion during the initial FBDS phase, albeit following immunosuppression, did not disclose evidence of lymphocytic inflammation. Following full remission of the FBDS, the patient manifested a rapidly progressive dementia associated with gross motor decline confirmed to be CJD at autopsy (molecular subtype VV3), with no evidence of a pathogenic PRNP mutation.Conclusions:Our patient highlights that these rare diseases are not invariably mutually exclusive and underscores the benefits of comprehensive neuropathologic examination of the brain to achieve an accurate diagnosis, especially in complex cases when the clinical trajectory dramatically deviates and a concomitant disease may need to be conscientiously considered to best explain the new clinical course.

Clinical characterization of autoimmune LGI1 antibody limbic encephalitis.

Autoimmune encephalitis associated with antibodies to leucine-rich glioma inactivated 1 (LGI1) has recently been identified and is characterized by an acute to subacute onset of cognitive impairment and convulsion, faciobrachial dystonic seizures (FBDSs), and psychiatric disturbances. This study analyzed the clinical characteristics and outcomes of 10 patients with LGI1 antibody encephalitis in order to further understand this disease and to improve its therapeutic strategies. Between January 2013 and March 2015, we identified 10 patients with LGI1 antibody encephalitis. We retrospectively analyzed the clinical details, laboratory results, electrophysiological and imaging findings, and the treatment outcomes. All patients tested had LGI1 antibodies. Immunotherapy was effective in all patients. Seizures in patients with FBDS showed a poor response to antiepileptic drugs. Two patients examined by magnetoencephalogram (MEG) during the acute disease phase showed a small quantity of spike-wave dipoles in the temporal lobe close to the lateral fissure and insular lobe. Patients with LGI1 antibody encephalitis responded well to immunotherapy. We speculate that FBDS is likely a form of insular epilepsy.

Treating seizures and preventing amnesia in LGI1-antibody encephalitis: A new MRI signature?

Leucine-rich glioma-inactivated 1 (LGI1)-antibody encephalitis is a treatable disease within the ever-expanding group of autoimmune encephalitides. The illness is typically characterized by the subacute onset of amnesia, confusion, and seizures in middle age, with approximately 60% of patients showing medial temporal lobe T2 hyperintensities.1,2,e1,e2 The most characteristic seizure syndrome associated with the LGI1 antibody is the recently termed entity of faciobrachial dystonic seizures (FBDS).3–5 FBDS consist of brief, frequent dystonic movements that most commonly affect the arm and ipsilateral hemiface. They occur an average of 50 times per day and can affect the leg and trunk. The leg involvement appears to be a hitherto overlooked cause of falls.e3 Of importance, FBDS appear to respond preferentially to immunotherapies over antiepileptic drugs. J.A.V. is supported by the Association of British Neurologists and the Oxford BRC, NIHR. S.R.I. is supported by the Wellcome Trust, British Medical Association Research grant—Vera Down grant and Epilepsy Research UK.

P91. Faciobrachio-crural dystonic seizures in early LGI1 antibody limbic encephalitis – A rare differential diagnosis of falls

Introduction Faciobrachial dystonic seizures (FBDS) are described to be closely associated with LGI1 (leucine-rich, glioma inactivated 1 protein) antibodies and precede a limbic encephalitis ( Irani et al., 2011 ). Studies demonstrated very brief and very frequent dystonic seizure semiology that always affected the arm and commonly also the ipsilateral face ( Irani et al., 2011 ). Little has been reported on the leg involvement, termed faciobrachio-crural dystonic seizures (FBCDS) ( Irani et al., 2011 , Maramattom et al., 2013 ). Case report We present an 83-year-old woman whose main symptoms were sudden falls without loss of consciousness. The falls first appeared two weeks prior to admission to our ward. While standing or walking, the right leg was frequently involved causing buckling at the knee and falls to her right side. She sustained several hematomas on the right arm and knee. Previous medical history included arterial hypertension and type 2 diabetes mellitus. Hence, she was first admitted to cardiology where a cardiac cause could be excluded. Following that she was admitted to our ward for long-term video-EEG (electroencephalography) monitoring. Frequent unilateral but side-alternating (right more than left), very brief dystonic seizures up to five times an hour involving the face, arm, trunk and leg were recorded. They occurred during the day as well as at night during sleep and led to arousal. Ictal electrographic abnormalities were not observed. Interictal EEG showed focal slowing right (fronto-) temporal with periodical enclosed 1–1, 5/s sharp- and sharp-slow-waves for max. 20 s. The patient was tested for antibodies to LGI1 component of the VGKC (voltage-gated potassium channel) complex. Anti-LGI1 antibodies were identified in serum and cerebrospinal fluid (CSF). The routine CSF examination (cell counts, glucose and protein) was unremarkable. Further investigations demonstrated moderate hyponatremia (127 mmol/l in serum). Brain MRI showed unilateral temporomesial T2 signal intensity on the right side. Cognitive impairments were not detected. FBCDS frequency was significantly reduced after immunotherapy with corticosteroids. In contrast, antiepileptic treatment with levetiracetam as first-line therapy was ineffective. Conclusion Based on our case report and other case studies ( Maramattom et al., 2013 ), FBCDS can be a rare differential diagnosis of falls without loss of awareness. The leg ictal dystonia is not to be confused with drop attacks with backward falls ( Irani et al., 2011 ). The timely immunotherapy with corticosteroids can lead to freedom from seizures( Irani et al., 2013 ).

Isolated Chorea Associated with LGI1 Antibody.

BackgroundLeucine-rich glioma inactivated 1 (LGI1) antibody produces a syndrome of limbic encephalitis, hyponatremia, and facio-brachial dystonic seizures that is non-paraneoplastic and responsive to corticosteroids. Parkinsonism, tremor, and generalized chorea are rare manifestations of LGI1, but, when present, commonly accompany other signs of limbic encephalitis.Case ReportWe present a case of LGI1-related isolated chorea in a 53-year-old Japanese male. His chorea responded to high-dose steroids, suggesting a potential role for this synaptic antibody in triggering chorea.DiscussionThis case highlights a new treatable etiology of chorea.

Isolated Chorea Associated with LGI1 Antibody

<strong>Background:</strong> Leucine-rich glioma inactivated 1 (LGI1) antibody produces a syndrome of limbic encephalitis, hyponatremia, and facio-brachial dystonic seizures that is non-paraneoplastic and responsive to corticosteroids. Parkinsonism, tremor, and generalized chorea are rare manifestations of LGI1, but, when present, commonly accompany other signs of limbic encephalitis. <strong>Case Report:</strong> We present a case of LGI1-related isolated chorea in a 53-year-old Japanese male. His chorea responded to high-dose steroids, suggesting a potential role for this synaptic antibody in triggering chorea. <strong>Discussion:</strong> This case highlights a new treatable etiology of chorea.

Faciobrachial dystonic seizureで初発したくすぶり型の抗leucine-rich glioma-inactivated 1（LGI1）抗体陽性辺縁系脳炎の1例

We report a 59-year-old right-handed woman with smoldering leucine-rich glioma-inactivated 1 (LGI1) antibody-associated limbic encephalitis (LE) following faciobrachial dystonic seizures. During 8 months before her admission, she developed partial seizures manifesting very brief and very frequent dystonia in her right hand sometimes with oral automatism and loss of awareness. In addition, she showed psychiatric disturbances such as emotionally labile condition and personality changes. On admission, neuropsychological examination revealed short-term memory impairment. During electroencephalography (EEG) monitoring, ictal EEG showed rhythmic delta waves and interictal EEG showed intermittent irregular slow waves at the bilateral frontotemporal area. Brain MRI demonstrated high T2/FLAIR signal changes in the left amygdala expanding into the left hippocampus. FDG-PET showed hypermetabolism in the left amygdala, hippocampus and the bilateral basal ganglia. Cerebrospinal fluid analysis was unremarkable. There were no signs of malignant tumor detected on systemic examination. LGI1 antibody was positive in the serum and the cerebrospinal fluid and the clinical diagnosis of LGI1 antibody-associated LE was confirmed. Her symptoms and the abnormalities in the brain MRI/FDG-PET showed immediate improvement after anti-epileptic and steroid therapy.