anti-LGI1 Encephalitis Research Articles

Clinical characteristics and prognosis analysis of acute symptomatic seizures secondary to autoimmune encephalitis.

This study aimed to analyze the clinical characteristics and prognosis of patients with autoimmune encephalitis (PWAE) who experienced seizures during the acute phase. Clinical data were collected from 84 patients diagnosed with AE at the General Hospital of Ningxia Medical University between January 2015 and January 2023. Patients were divided into seizure and non-seizure groups. Clinical characteristics of both groups were compared, including differences between anti-NMDAR and anti-LGI1 encephalitis within the seizure group. Due to the limited sample size and to avoid overfitting, we focused on univariate logistic regression analysis to identify individual prognostic factors. A total of 84 patients were enrolled, with 76.19% (64/84) in the seizure group and 23.81% (20/84) in the non-seizure group. The seizure group had a longer hospital stay (p = 0.013), higher rates of impaired consciousness (p = 0.001), and more frequent intensive care unit (ICU) admission (p = 0.011). They also had higher peripheral blood neutrophil-to-lymphocyte ratio (NLR), leukocyte count, and uric acid levels (p = 0.038, p = 0.006, p = 0.020), and were more likely to show slow-wave rhythms on electroencephalography (EEG) (p = 0.031). At 2-year follow-up, there was no significant difference in prognosis between the seizure and non-seizure groups (p = 0.653), with 35.94% (23/64) of the seizure group having a poor prognosis. Status epilepticus (SE), complications, endotracheal intubation, mRS score at discharge, APE2, and RITE2 scores increased the risk of poor prognosis (OR > 1), while intensive care and albumin reduced the risk (OR < 1). Seizures are common in the early stages of AE, with faciobrachial dystonic seizures (FBDS) characteristic of anti-LGI1 encephalitis and SE and super-refractory status epilepticus (Sup-RSE) frequently observed in anti-NMDAR encephalitis. Seizure semiology across AE subtypes lacks specificity, and no symptoms clearly distinguish immune-mediated from non-immune causes. While seizures are linked to AE severity, particularly in anti-NMDAR encephalitis, they do not appear to impact overall prognosis. SE, complications, endotracheal intubation, modified Rankin Scale (mRS) score at discharge, Antibody-Prevalence in Epilepsy and Encephalopathy (APE2) score, Response to Immunotherapy in Epilepsy and Encephalopathy (RITE2) score, intensive care, and albumin were identified as significant prognostic factors.

Clinical Features and Electroencephalogram Analysis ofBrain Network Functional Connectivityin Anti-Leucine-RichGlioma-Inactivated1Antibody Encephalitis.

To summarize the clinical manifestations, laboratory findings, and magnetic resonance imaging (MRI) characteristics of anti-leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis (anti-LGI1 antibody encephalitis) and explore the electroencephalogram (EEG) features. We retrospectively analyzed the medical history of 16 patients diagnosed with anti-LGI1 antibody encephalitis at the First Hospital of Hebei Medical University from 2021 to 2023. EEGs of patients with anti-LGI1 antibody encephalitis and healthy individuals were analyzed. Based on Video-EEG signal analysis of EEG δ, θ, α, β frequency bands, weighted phase lag index values were calculated to form brain network matrices, studying differences in coherence between brain regions of patients with anti-LGI1 antibody encephalitis and healthy individuals. Patients with anti-LGI1 antibody encephalitis often presented with subacute onset seizures and cognitive decline. Routine test of cerebrospinal fluid was mostly normal. Serum testing revealed hyponatremia in 62.50% of patients, along with positive serum antinuclear antibodies, decreased vitamin B12, and abnormal cytokines such as interleukin-6. Head MRI revealed abnormal lesions related to the disease in seven cases (43.75%), mainly located in the unilateral or bilateral frontal and temporal lobes of the hippocampus. The EEG mainly showed generalized and focal slow waves, sometimes with focal discharges. Brain network functional connectivity analysis found a significant weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands. Intravenous pulse corticosteroids and intravenous immunoglobulin are first-line immunotherapies for anti-LGI1 antibody-related encephalitis. The disease recovery and cognitive decline improved in most patients. Anti-LGI1 antibody encephalitis is characterized by seizures and cognitive dysfunction. Serum may show abnormalities in immune indicators such as cytokines. Head MRI mainly reveals abnormal signals in the frontal-temporal lobes and the hippocampus. EEG brain network connectivity analysis reveals characteristic weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands.

Clinical characteristics and outcomes of patients with antibody-related autoimmune encephalitis presenting with disorders of consciousness: A prospective cohort study.

To explore the clinical characteristics, short- and long-term functional outcomes, and risk factors for antibody-related autoimmune encephalitis (AE) in patients with disorders of consciousness (DoC). Clinical data were collected from AE patients admitted to Xuanwu Hospital of Capital Medical University from January 2012 to December 2021, and patients were followed up for up to 24 months after immunotherapy. A total of 312 patients with AE were included: 197 (63.1%) with anti-NMDAR encephalitis, 71 (22.8%) with anti-LGI1 encephalitis, 20 (6.4%) with anti-GABAbR encephalitis, 10 (3.2%) with anti-CASPR2 encephalitis, 10 (3.2%) with anti-GAD65 encephalitis, and 4 (1.3%) with anti-AMPAR2 encephalitis. Among these patients, 32.4% (101/312) presented with DoC, and the median (interquartile range, IQR) time to DoC was 16 (7.5, 32) days. DoC patients had higher rates of various clinical features of AE (p < .05). DoC was associated with elevated lumbar puncture cerebrospinal fluid (CSF) pressure, CSF leukocyte count, and specific antibody titer (p < .05). A high percentage of patients in the DoC group had a poor prognosis at discharge and at 6 months after immunotherapy (p < .001), but no significant difference in prognosis was noted between the DoC group and the non-DoC group at 12 and 24 months after immunotherapy. Dyskinesia (OR = 3.266, 95% CI: 1.550-6.925, p = .002), autonomic dysfunction (OR = 5.871, 95% CI: 2.574-14.096, and p < .001), increased CSF pressure (OR = 1.007, 95% CI: 1.001-1.014, p = .046), and modified Rankin scale (mRS) score ≥3 at the initiation of immunotherapy (OR = 7.457, 95% CI: 3.225-18.839, p < .001) were independent risk factors for DoC in AE patients. DoC is a relatively common clinical symptom in patients with AE, especially critically ill patients. Despite requiring longer hospitalization, DoC mostly improves with treatment of the primary disease and has a good long-term prognosis after aggressive life support and combination immunotherapy.

Anti-LGI1 Antibody-Associated Encephalitis Misdiagnosed as Schizophrenia: A Case Report.

Anti-leucine-rich glioma-inactivated 1 (LGI1) antibody-associated encephalitis is a rare but clinically significant form of autoimmune encephalitis, predominantly affecting middle-aged men. Its heterogeneous clinical presentation often leads to misdiagnosis, commonly as other neurological or psychiatric disorders. This report details the case of a 46-year-old male who initially presented with depressive symptoms, personality changes, and visual hallucinations. Over time, his condition progressed to include memory impairment, disorganized behavior, and seizures. Initially misdiagnosed with schizophrenia, the correct diagnosis of LGI1 antibody-associated encephalitis was eventually established through positive serum and cerebrospinal fluid (CSF) tests for LGI1 antibodies. Neuroimaging findings revealed characteristic bilateral temporal lobe lesions. The patient demonstrated marked improvement following treatment with methylprednisolone and intravenous immunoglobulin, ultimately achieving significant recovery. This case highlights the critical importance of comprehensive antibody testing and neuroimaging in patients presenting with nonspecific psychiatric and neurological symptoms to prevent misdiagnosis and delays in appropriate treatment. The article also reviews the pathogenesis, clinical manifestations, diagnostic approaches, and therapeutic strategies for LGI1 antibody-associated encephalitis, aiming to enhance clinical awareness and optimize patient outcomes.

LGI1 encephalitis: potentially complement-activating anti-LGI1-IgG subclasses 1/2/3 are associated with the development of hippocampal sclerosis

Two-thirds of published patients with anti-leucine rich, glioma inactivated 1 (LGI1) encephalitis develop hippocampal sclerosis (HS). It is likely that this contributes to residual cognitive long-term deficits and the risk of epilepsy. Almost all patients harbor anti-LGI1-immunoglobulin G-(IgG-) subclass 4, which is considered a “benign”, non-destructive subclass. In contrast, neuropathological case studies have suggested that the classical complement cascade may contribute to mediotemporal cell death in patients with LGI1 antibodies. IgG subclasses 1, 2, or 3 are required to initiate this cascade. We hypothesized that patients with these anti-LGI1-IgG1/2/3 in addition to IgG4 have a higher risk of developing HS than patients with anti-LGI1-IgG4 alone. We retrospectively assessed all anti-LGI1 encephalitis patients from this center with anti-LGI1-IgG-subclass information and follow-up MRI available. Nine out of 20 patients had developed HS (45%). Volumetric FreeSurfer analysis confirmed the visual HS diagnoses. HS and a lower hippocampal volume were associated with anti-LGI1-IgG1/2/3. All six patients with this IgG subclass status developed HS. There was no association with older or younger age at onset, female sex, longer latency from disease onset to start of immunotherapy, less intense immunotherapy, higher serum titers of LGI1 antibodies, LGI1 antibodies in CSF or higher LGI1-specific antibody indices. There was no association between anti-LGI1-IgG1/2/3 status and neuropsychological performance, epilepsy, or general neurological performance. This confirms our hypothesis that anti-LGI1-IgG1/2/3 in serum puts patients at risk of developing HS. If these findings can be confirmed and clinically corroborated, patients with anti-LGI1-IgG1/2/3 might become candidates for anti-complement-directed immunological treatments.

MR Imaging Findings in Anti-Leucine-Rich Glioma Inactivated Protein 1 Encephalitis: A Systematic Review and Meta-analysis.

Antibodies against leucine-rich glioma inactivated protein 1 (LGI1) constitute a common form of autoimmune encephalitis. On MR imaging, it may show T2 FLAIR hyperintensities of the medial temporal lobe (T2 FLAIR-MTL), involve the basal ganglia, or be unremarkable. We performed a systematic review and meta-analysis to obtain prevalence estimates of abnormal findings on MR imaging in anti-LGI1 encephalitis. A human brain map of the LGI1 microarray gene expression was derived from the Allen Human Brain Atlas. PubMed and Web of Science were searched with the terms "LGI1" and "encephalitis" from inception to April 7, 2022. Thirty-one research publications, encompassing case series and retrospective cohort and case-control studies, with >10 patients with anti-LGI1 encephalitis and MR imaging data were included. Pooled prevalence estimates were calculated using Freeman-Tukey double-arcsine transformation. Meta-analysis used DerSimonian and Laird random effects models. Of 1318 patients in 30 studies, T2 FLAIR-MTL hyperintensities were present in 54% (95% CI, 0.48-0.60; I2 = 76%). Of 394 patients in 13 studies, 27% showed bilateral (95% CI, 0.19-0.36; I2 = 71%) and 24% unilateral T2 FLAIR-MTL abnormalities (95% CI, 0.17-0.32; I2 = 61%). Of 612 patients in 15 studies, basal ganglia abnormalities were present in 10% (95% CI, 0.06-0.15; I2 = 67%). LGI1 expression was highest in the amygdala, hippocampus, and caudate nucleus. Only part of the spectrum of MR imaging abnormalities in anti-LGI1 encephalitis could be included in a meta-analysis. MR imaging findings were not the main outcomes in most studies, limiting available information. I2 values ranged from 62% to 76%, representing moderate-to-large heterogeneity. T2 FLAIR-MTL hyperintensities were present in around one-half of patients with anti-LGI1. The prevalence of unilateral and bilateral presentations was similar, suggesting unilaterality should raise the suspicion of this disease in the appropriate clinical context. Around 10% of patients showed basal ganglia abnormalities, indicating that special attention should be given to this region. LGI1 regional expression coincided with the most frequently reported abnormal findings on MR imaging. Regional specificity might be partially determined by expression levels of the target protein.

Clinical features, cerebrospinal fluid changes, and prognosis in Chinese patients with autoimmune encephalitis.

Autoimmune encephalitis (AE) is a rare, treatable disease of the central nervous system (CNS) caused by an antibody-related immune response. This study is to investigate the correlation of clinical features, cerebrospinal fluid (CSF) characteristics, and prognosis in patients with AE. A total of 71 patients diagnosed with antibody-positive AE were retrospectively analyzed. The patients were divided into three groups: anti-NMDAR group, anti-LGI1 group, and other types. Clinical data were collected to analyze clinical features and CSF results, and prognosis was determined by modified Rankin Scale (mRS). There was statistical difference in the incidences of decreased consciousness level (P < 0.001), memory loss (P = 0.017), speech disorders (P = 0.035), and dyskinesia (P = 0.001) in different antibodies groups. Younger age (P = 0.018), elevated CSF chloride content (P = 0.006), and white blood cells > 50/mm3 (P = 0.026) were highly correlated with ICU admission. Anti-LGI1 encephalitis had a relatively small risk for ICU admission (P = 0.034), and a lower risk of poor functional recovery (P = 0.048) and recurrence (P = 0.041). Patients with first-line treatment failure (P = 0.021) had an increased risk of poor functional recovery. Delayed treatment (P = 0.011) would increase the risk of recurrence. There are differences in age, gender, clinical characteristics, and CSF results in different subtypes of AE. First-line therapy failure would have poor functional recovery, and delayed therapy would increase the risk of relapse. Chloride ion content and white blood cell count in cerebrospinal fluid are positively correlated with the patient's exacerbation and admission to ICU. These indicators have certain clinical value for the prognosis of AE patients.

Origin and significance of leucine-rich glioma-inactivated 1 antibodies in cerebrospinal fluid.

Whether antibodies against leucine-rich glioma-inactivated 1 (LGI1-Abs) in cerebrospinal fluid (CSF) are partially transferred from serum and the impact of CSF-LGI1-Ab positivity on clinical features and prognosis are unclear. Therefore, we aim to investigate the differences in serum titers, clinical features, and outcomes between LGI1-Ab CSF-positive and LGI1-Ab CSF-negative patients. Retrospective analysis of serum titers and clinical features according to CSF LGI1-Ab status. In addition, univariate and multivariate logistic regression were performed to identify predictors of worse outcomes. A total of 60 patients with anti-LGI1 encephalitis and positive serum LGI1-Abs were identified, of whom 8 (13.3%) patients were excluded due to the absence of CSF LGI1-Ab testing. Among the remaining 52 patients, 33 (63.5%) were positive for LGI1-Abs in CSF. CSF-positive patients were more likely to have high serum titers (≥ 1:100) than CSF-negative patients (p = 0.003), and Spearman's correlation analysis showed a positive correlation between CSF and serum titers in CSF-positive patients (r2 = 0.405, p = 0.019). Psychiatric symptoms and hyponatremia were more frequent in CSF-positive patients (p < 0.05). Both univariate and multivariate logistic regression analyses showed that CSF LGI1-Ab positivity and delayed immunotherapy are independent risk factors for incomplete recovery (modified Rankin Scale (mRS) > 0 at last follow-up). LGI1-Ab CSF-positive patients have higher serum titers, and their CSF titers are positively correlated with serum titers, indicating a possible peripheral origin of CSF LGI1-Abs. CSF-positive patients more often present with psychiatric symptoms, hyponatremia, and worse outcomes, suggesting more severe neuronal damage.

Acetazolamide as an effective treatment for pilomotor seizures in autoimmune encephalitis.

Pilomotor seizures are strongly associated with autoimmune encephalitis (AE), particularly anti-LGI1 encephalitis. The carbonic anhydrase inhibitor acetazolamide may have special efficacy for treating AE-associated pilomotor seizures. Six patients with AE (five anti-LGI1, one seronegative) and temporal lobe pilomotor seizures (five with seizures inducible by hyperventilation) were treated with acetazolamide, administered in a cycling (2-days-ON, 4-days-OFF) regimen to offset tolerance. Seizures were assessed during epilepsy monitoring unit (EMU) recordings in four inpatients (one of whom also maintained an outpatient seizure diary chronicling 1203 seizures over 1079 days); two outpatients self-reported seizure frequencies. The extended diary revealed an inverse correlation between acetazolamide and proportion of seizures/day: 6%, 2% (days 1, 2 ON); 3%, 13%, 31%, 45% (days 1, 2, 3, 4 OFF). This patient later developed focal status epilepticus upon wean of antiseizure medications during a seropositive AE relapse that was remarkably aborted with acetazolamide monotherapy. The other three EMU patients averaged .56 seizures/day ON, and 3.81 seizures/day OFF (p = .004). The two outpatients reported seizure reductions from 3-5/day to 2/week, and 15-20/day to none, respectively, after initiation of cycling acetazolamide. Likely related to cerebral CO2/pH sensitivity, acetazolamide can be unusually effective in controlling pilomotor seizures in AE, chronically or in acute settings.

Anti-LGI1 autoimmune encephalitis: insights from three cases with serial PET imaging

BackgroundAutoimmune encephalitis (AE) can be a disabling condition, but it is manageable when identified in its early phases. Multiple diagnostic modalities can aid the diagnosis and delineation of areas of involvement in the brain, which is essential in correlating the symptoms to their pathology.Case presentationThis case series focuses on three cases of anti-LGI1 encephalitis in their 3rd and 5th decades, each displaying facio-brachial dystonic seizures (FBDS) and varying symptoms, such as behavioural changes and hyperhidrosis. Their MRI brains were not conclusive, but when the patients underwent a PET scan, all three of them showed involvement of the Basal Ganglia, which reversed along with clinical improvement after standard treatment for AE.ConclusionsAE can be a morbid condition for a long time, but some factors that might predispose to better patient outcomes might be early diagnosis and treatment. A PET scan is a modality that might help pick up functional changes before structural changes set in, and so should be considered in the diagnostic workup. Patterns of involvement of brain areas in Anti LGI1 AE need delineation, and basal ganglia seems to be a consistent region of involvement.

Neurological, psychiatric, and sleep investigations after treatment of anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis in Spain: a prospective cohort study

Anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis is an autoimmune disorder that can be treated with immunotherapy, but the symptoms that remain after treatment have not been well described. We aimed to characterise the clinical features of patients with anti-LGI1 encephalitis for 1 year starting within the first year after initial immunotherapy. For this prospective cohort study, we recruited patients with anti-LGI1 encephalitis as soon as possible after they had received conventional immunotherapy for initial symptoms; patients were recruited from 21 hospitals in Spain. Patients were excluded if they had an interval of more than 1 year since initial immunotherapy, had pre-existing neurodegenerative or psychiatric disorders, or were unable to travel to Hospital Clínic de Barcelona (Barcelona, Spain). Patients visited Hospital Clínic de Barcelona on three occasions-the first at study entry (visit 1), the second 6 months later (visit 2), and the third 12 months after the initial visit (visit 3). They underwent neuropsychiatric and videopolysomnography assessments at each visit. Healthy participants who were matched for age and sex and recruited from Hospital Clínic de Barcelona underwent the same investigations at study entry and at 12 months. Cross-sectional comparisons of clinical features between groups were done with conditional logistic regression, and binary logistic regression was used to assess associations between cognitive outcomes at 12 months and clinical features before initial immunotherapy and at study entry. Between May 1, 2019, and Sept 30, 2022, 42 participants agreed to be included in this study. 24 (57%) participants had anti-LGI1 encephalitis (mean age 63 years [SD 12]; 13 [54%] were female and 11 [46%] were male) and 18 (43%) were healthy individuals (mean age 62 years [10]; 11 [61%] were female and seven [39%] were male). At visit 1 (median 88 days [IQR 67-155] from initiation of immunotherapy), all 24 patients had one or more symptoms; 20 (83%) patients had cognitive deficits, 20 (83%) had psychiatric symptoms, 14 (58%) had insomnia, 12 (50%) had rapid eye movement (REM)-sleep behaviour disorder, nine (38%) had faciobrachial dystonic seizures, and seven (29%) had focal onset seizures. Faciobrachial dystonic seizures were unnoticed in four (17%) of 24 patients and focal onset seizures were unnoticed in five (21%) patients. At visit 1, videopolysomnography showed that 19 (79%) patients, but no healthy participants, had disrupted sleep structure (p=0·013); 15 (63%) patients and four (22%) healthy participants had excessive fragmentary myoclonus (p=0·039), and nine (38%) patients, but no healthy participants, had myokymic discharges (p=0·0051). These clinical and videopolysomnographic features led to additional immunotherapy in 15 (63%) of 24 patients, which resulted in improvement of these features in all 15 individuals. However, at visit 3, 13 (65%) of 20 patients continued to have cognitive deficits. Persistent cognitive deficits at visit 3 were associated with no use of rituximab before visit 1 (odds ratio [OR] 4·0, 95% CI 1·5-10·7; p=0·0015), REM sleep without atonia at visit 1 (2·2, 1·2-4·2; p=0·043), and presence of LGI1 antibodies in serum at visit 1 (11·0, 1·1-106·4; p=0·038). Unsuspected but ongoing clinical and videopolysomnography alterations are common in patients with anti-LGI1 encephalitis during the first year or more after initial immunotherapy. Recognising these alterations is important as they are treatable, can be used as outcome measures in clinical trials, and might influence cognitive outcome. Fundació La Caixa.

Incident anti-LGI1 autoimmune encephalitis during dementia with Lewy bodies: When Occam razor is a double-edged sword

In Dementia with Lewy bodies (DLB), rapid cognitive decline and seizures seldom complicate the typical clinical course. Nevertheless, concurrent, treatable conditions may be responsible. We report a case of DLB with superimposed anti-LGI1 encephalitis, emphasizing the importance of thorough diagnostic reasoning beyond the simplest explanation amid distinct clinical cues.

Anti-leucine-rich Glioma-inactivated 1 Encephalitis Manifesting as Frequent Ictal Pouting and Subtle Memory Disturbance.

Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is a treatable form of limbic encephalitis, marked by frequent focal seizures and cognitive decline (particularly memory disturbance); however, it can be difficult to diagnose in patients with subtle cognitive decline. Ictal pouting, a rare seizure feature, has not yet been reported in anti-LGI1 encephalitis. A 73-year-old man with anti-LGI1 encephalitis presented with subacute onset of frequent ictal pouting without apparent cognitive decline. Steroid treatment alone resolved seizures and improved subtle visual memory. Middle-aged and older patients experiencing subacute-onset frequent focal seizures should be thoroughly evaluated for memory disturbances to determine the need for anti-LGI1 antibody measurement.

Basal ganglia hemorrhage associated with anti-LGI1 encephalitis with faciobrachial dystonic seizures (FBDS) a case report

Basal ganglia hemorrhage associated with anti-LGI1 encephalitis with faciobrachial dystonic seizures (FBDS) a case report

Acute Symptomatic Seizures and Risk of Seizure Recurrence in Patients with Anti-NMDAR, Anti-LGI1, and Anti-GABABR Encephalitis.

To analyze the clinical characteristics of acute symptomatic seizures and predict the risk factors for seizure recurrence in patients with anti-N-methyl-D-aspartate receptor (NMDAR), anti-leucine-rich glioma-inactivated 1 (LGI1), and anti-gamma-aminobutyric acid B receptor (GABABR) encephalitis. In this retrospective study, we included hospitalized patients who had been diagnosed with anti-NMDAR, anti-LGI1, and anti-GABABR encephalitis between November 2014 and April 2021. Binary logistic regression analysis was performed to identify the potential risk factors for seizure recurrence. In total, 262 patients with anti-NMDAR, anti-LGI1, and anti-GABABR encephalitis were included, 197 (75.2%) of whom presented with acute symptomatic seizures. During follow-up, 42 patients exhibited seizure recurrence. In anti-NMDAR encephalitis, frontal lobe abnormality on brain magnetic resonance imaging, delayed immunotherapy, early seizures, and focal motor onset were associated with seizure recurrence. Acute symptomatic seizure is a common clinical feature observed in patients with anti-NMDAR, anti-LGI1, and anti-GABABR encephalitis, with 50% of patients presenting with seizures as an initial symptom. The prognosis of patients with acute symptomatic seizures can be improved after receiving immunotherapy. Nevertheless, a minority of patients will experience seizure recurrence; therefore, restarting immunotherapy is recommended.

Mimics of Autoimmune Encephalitis: Validation of the 2016 Clinical Autoimmune Encephalitis Criteria.

The clinical criteria for autoimmune encephalitis (AE) were proposed by Graus et al. in 2016. In this study, the AE criteria were validated in the real world, and common AE mimics were described. In addition, criteria for probable anti-LGI1 encephalitis were proposed and validated. In this retrospective cohort study, patients referred to our national referral center with suspicion of AE and specific neuroinflammatory disorders with similar clinical presentations were included from July 2016 to December 2019. Exclusion criteria were pure cerebellar or peripheral nerve system disorders. All patients were evaluated according to the AE criteria. In total, 239 patients were included (56% female; median age 42 years, range 1-85). AE was diagnosed in 104 patients (44%) and AE mimics in 109 patients (46%). The most common AE mimics and misdiagnoses were neuroinflammatory CNS disorders (26%), psychiatric disorders (19%), epilepsy with a noninflammatory cause (13%), CNS infections (7%), neurodegenerative diseases (7%), and CNS neoplasms (6%). Common confounding factors were mesiotemporal lesions on brain MRI (17%) and false-positive antibodies in serum (12%). Additional mesiotemporal features (involvement extralimbic structures, enhancement, diffusion restriction) were observed more frequently in AE mimics compared with AE (61% vs 24%; p = 0.005). AE criteria showed the following sensitivity and specificity: possible AE, 83% (95% CI 74-89) and 27% (95% CI 20-36); definite autoimmune limbic encephalitis (LE), 10% (95% CI 5-17) and 98% (95% CI 94-100); and probable anti-NMDAR encephalitis, 50% (95% CI 26-74) and 96% (95% CI 92-98), respectively. Specificity of the criteria for probable seronegative AE was 99% (95% CI 96-100). The newly proposed criteria for probable anti-LGI1 encephalitis showed a sensitivity of 66% (95% CI 47-81) and specificity of 96% (95% CI 93-98). AE mimics occur frequently. Common pitfalls in AE misdiagnosis are mesiotemporal lesions (predominantly with atypical features) and false-positive serum antibodies. As expected, the specificity of the criteria for possible AE is low because these criteria represent the minimal requirements for entry in the diagnostic algorithm for AE. Criteria for probable AE (-LGI1, -NMDAR, seronegative) and definite autoimmune LE are applicable for decisions on immunotherapy in early disease stage, as specificity is high.

Clinical study of autonomic dysfunction in patients with autoimmune encephalitis

BackgroundAutoimmune encephalitis (AE) is a collective name, covering an emerging spectrum of autoimmune-mediated neurological diseases related to antibodies and synaptic or intracellular proteins. Anti-NMDAR, anti-LGI1, and anti-GABABR are three types of neuronal cell surface antibodies. Autonomic dysfunction represents a frequently occurring clinical manifestation. This observational study purposes to investigate comparisons between two groups with or without autonomic dysfunction and detect the autonomic dysfunction and other indexes in anti-NMDAR, anti-LGI1, and anti-GABABR cohorts. MethodsPatients with anti-NMDAR, anti-LGI1 and anti-GABABR encephalitis were recruited from the May 2017 to the April 2022. The following information was recorded: age, age at onset, tumor presence, gender, prodromal symptoms, clinical manifestations, cranial magnetic resonance imaging, cerebrospinal fluid and blood examinations, and immunotherapy. ResultsThere were totally 161 patients enrolled in this study. Among these participants, 104 individuals (64.6%) presented autonomic dysfunction and the remaining 57 (35.4%) were free of autonomic dysfunction. Sinus tachycardia was the most common autonomic dysfunction, followed by pollakiuria/uroclepsia, feverscence, central hypoventilation, sinus bradycardia, constipation, uroschesis, hyperhidrosis, hypersalivation, hypotension, and early satiety/emesis. Compared to patients without autonomic dysfunction, those with autonomic dysfunction had a higher incidence of central hypoventilation and ICU admissions. Meanwhile, in both groups with or without autonomic dysfunction, meatal behavior disorder, cognitive impairment, and epileptic seizure were three most common clinical manifestations. There were no significant differences in cranial magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) examination, antibody titers and number of immunotherapy types. Further analysis of AE mediated by distinct neuronal surface antibodies demonstrated that there were 85 anti-NMDAR, 56 anti-LGI1, and 20 anti-GABABR encephalitis patients. The significant differences between these three cohorts appeared in age, tumor presence, fervescence presence and antibody titers. ConclusionThis study demonstrated the comparisons between autonomic dysfunction group and autonomic dysfunction-free group and provided insights into better diagnosis and treatment.

Efficacy of immunotherapy and prognosis in anti-LGI1 encephalitis patients: A meta-analysis.

To assess the efficacy and safety of immunotherapy for LGI1 antibody encephalitis, and consider the predictors of poor outcomes following immunotherapy. We searched PubMed and Embase for articles reporting the immunotherapy data of anti-LGI1 encephalitis patients. The proportions of patients with poor outcomes (modified Rankin Scale [mRS] score > 2) at 3 months, 12 months, and the last follow-up, as well as the odds ratio [OR] of predictors were pooled. The review included 162 articles with 1066 patients. The proportion of patients with poor functional outcomes was 21% at 3 months, 14% at 12 months, and 14% at the last follow-up after receiving immunotherapy. The proportion of patients with reported relapse was 16.6%. The mean duration from onset to the first relapse was 15.6 months. Predictors significantly associated with poor outcomes were age (increase of 1 year), the presence of cognitive impairment, and CSF LGI1 antibody positive. We did not find a statistically significant association between the worst mRS score in the acute phase, the presence of faciobrachial dystonic seizures (FBDS), days from symptom onset to immunotherapy, second-line treatment, maintenance immunotherapy, or follow-up time and outcomes. Although most patients respond to immunotherapy, a minority of patients still have poor outcomes. Advanced age, cognitive impairment, and CSF LGI1 antibody positive are associated with an increased risk of poor outcomes. However, due to the insufficiency of the data, these conclusions need to be interpreted with caution.

Clinical characteristics of Leucine-rich glioma-inactivated protein 1 antibody-mediated autoimmune encephalitis in a 6-year-old girl: case report and literature reviews

BackgroundAutoimmune encephalitis related to the leucine-rich glioma-inactivated protein 1(LGI1) antibody is the most prevalent in older adults, manifesting as seizures, faciobrachial dystonic seizures (FBDS), cognitive impairment, memory disturbance, hyponatremia and neuropsychiatric disorders. However the data pertaining to children affected by the disease is still limited.Case presentation and literature reviewsThis study presents a detailed report of a 6-year-old Chinese girl who experienced nose aches and faciobrachial dystonic seizures (FBDS). Electrolyte testing revealed that she had hyponatremia and brain MRI showed an abnormality in the left temporal pole. Additionally, anti-LGI1 antibodies were detected in both her serum (1:100) and CSF (1:30). The patient was treated with immunotherapy and symptom management, which proved effective. Furthermore, we provide a summary of 25 pediatric cases of anti-LGI1 encephalitis. Pediatric patients rarely exhibited FBDS and hyponatremia, and some cases presented with isolated syndromes. But the therapeutic outcomes of pediatric patients were generally good.ConclusionsIn this report, we describe a patient who developed a rare symptom of nose aches possibly as one of symptoms of anti-LGI1 encephalitis, which highlights the possibility of atypical symptoms in children that may be misdiagnosed. Reviewing the literature, the clinical features differed between pediatric and adult cases. Therefore, it is crucial to collect and analyze data from more cases to promote accurate diagnosis and timely treatment.

P.026 Frontal cognitive-behavioural deficits in patients with anti-leucine-rich glioma-inactivated protein 1 antibody encephalitis

Background: Cognitive impairment is a common manifestation of anti-LGI1 encephalitis and is typically defined as prominent memory deficits. We frequently encounter frontal cognitive-behavioural deficits when evaluating these patients, but this has yet to be well described in the literature. Methods: Patients with anti-LGI1 encephalitis were retrospectively identified from three tertiary centres in Toronto, Ontario between 2013 and 2022. Their medical records were evaluated and frontal features were categorized based on diagnostic criteria for behavioural variant frontotemporal dementia (bvFTD). Results: Nineteen patients were identified (median age 60 years [range 18–84]; 10 [52.6%] male). Eighteen (94.7%) had frontal cognitive-behavioural symptoms. Two developed these symptoms during treatment with steroids and were excluded from further analysis. The remaining 16 presented with behavioural disinhibition (n=13), apathy or inertia (n=6), perseverative, stereotyped or compulsive/ritualistic behaviours (n=6), hyperorality and dietary changes (n=4), a neuropsychological profile with predominant deficits in executive tasks (n=4), and loss of sympathy or empathy (n=4). Nine (47.3%) met diagnostic criteria for possible bvFTD. Anterograde memory impairment was common (n=14). Of the 16 patients with frontal features, 6 had faciobrachial dystonic seizures. Conclusions: Patients with anti-LGI1 encephalitis exhibit frontal cognitive-behavioural symptoms in addition to memory impairment. Clinicians should consider anti-LGI1 encephalitis in the differential diagnosis of bvFTD.