Factors underlying the development of chronic temporal lobe epilepsy in autoimmune encephalitis

Prognostic factors underlying the development of drug-resistant epilepsy in patients with autoimmune encephalitis: a retrospective cohort study

OBJECTIVE

The aim of our study was to analyze the characteristics of patients with autoimmune encephalitis (AE) to identify prognostic factors associated with the development of drug-resistant epilepsy (DRE).

METHODS

In this retrospective observational cohort study, we enrolled adult patients with AE between January 2016 and December 2022. The patients were categorized into two groups based on the presence or absence of DRE at the last follow-up. The predictors of the development of DRE were investigated using logistic regression analysis.

RESULTS

Among 121 AE patients, 75.2% (n = 91) experienced acute symptomatic seizures, and 29.8% (n = 36) developed DRE at the last follow-up. On multivariate regression analysis, the factors associated with DRE were antibody negativity (OR 3.628, 95% CI 1.092-12.050, p = 0.035), focal seizure (OR 6.431, 95% CI 1.838-22.508, p = 0.004), refractory status epilepticus (OR 8.802, 95% CI 2.445-31.689, p = 0.001), interictal epileptiform discharges on EEG (OR 6.773, 95% CI 2.206-20.790, p = 0.001), and T2/FLAIR hyperintensity in the limbic system (OR 3.286, 95% CI 1.060-10.183, p = 0.039).

CONCLUSIONS

In this study, the risk of developing DRE was mainly observed among AE patients who were negative for antibodies or had focal seizures, refractory status epilepticus, interictal epileptiform discharges on EEG, and T2/FLAIR hyperintensity in the limbic system.

Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults

Autoimmune encephalitis is increasingly recognized as a neurologic cause of acute mental status changes with similar prevalence to infectious encephalitis. Despite rising awareness, approaches to diagnosis remain inconsistent and evidence for optimal treatment is limited. The following Canadian guidelines represent a consensus and evidence (where available) based approach to both the diagnosis and treatment of adult patients with autoimmune encephalitis. The guidelines were developed using a modified RAND process and included input from specialists in autoimmune neurology, neuropsychiatry and infectious diseases. These guidelines are targeted at front line clinicians and were created to provide a pragmatic and practical approach to managing such patients in the acute setting.

What is autoimmune encephalitis-associated epilepsy? Proposal of a practical definition

Seizures resulting from cerebral autoimmunity are either acutely symptomatic in the context of autoimmune encephalitis (AIE) with neural surface antibodies, or they are indicative of an enduring predisposition to seizures, that is, epilepsy. Here, we propose a practical definition for autoimmune encephalitis-associated epilepsy (AEAE): Seizures associated with antibodies against glutamic acid decarboxylase, paraneoplastic syndromes, or Rasmussen encephalitis are classified as AEAE. AEAE secondary to AIE with antibodies against the N-methyl-D-aspartate receptor, leucine-rich glioma inactivated protein 1, contactin-associated protein-2, or γ-aminobutyric acid-B receptor can be diagnosed if the following criteria are met: seizures persist for at least 2 years after immunotherapy initiation; no signs of encephalitis on magnetic resonance imaging and no fluorodeoxyglucose positron emission tomography hypermetabolism; normal cerebrospinal fluid cell count; and a substantial decrease in antibody titers. This classification corresponds to different disease mechanisms. While AIE results from the pathogenic effects of neural antibodies, AEAE is probably the consequence of encephalitis-related tissue damage and thereby mainly structurally mediated. The distinction between AIE and AEAE also has practical consequences: In AIE, immunotherapy is usually highly beneficial, whereas anti-seizure medication has little effect. In AEAE, immunotherapy is less promising and the usual anti-seizure interventions are preferable. In addition, the diagnosis of AEAE has social consequences in terms of driving and professional limitations.

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

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

Seizure outcome-related factors in autoimmune encephalitis: A systematic review and meta-analysis

Background

Identifying the predictors for seizure outcome in autoimmune encephalitis (AE) and investigating how to prevent persistent seizures would have major clinical benefits effectively. Thus, we aimed to perform a systematic review and meta-analysis to examine seizure outcome-related factors in AE patients.

Methods

PubMed and EMBASE were systematically searched from inception to 10 June 2022 for studies investigating seizure outcome-related factors in AE. The pooled effect estimates, including standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs), were calculated to estimate the effect of each included factor on the seizure outcome.

Results

A total of 10 studies were included in the meta-analysis. Our pooled results of this meta-analysis showed that five factors were found to increase the risk of persistent seizures in AE patients, including onset with seizures (OR = 2.106, 95% CI = 1.262–3.514, p = 0.004), status epilepticus (OR = 3.017, 95% CI = 1.995–4.563, p < 0.001), EEG abnormalities (OR = 1.581, 95% CI = 1.016–2.46, p = 0.042), MRI abnormalities (OR = 1.554, 95% CI = 1.044–2.283, p = 0.03), and longer time from clinical onset to immunotherapy (SMD = 1.887, 95% CI = 0.598–3.156, p = 0.004).

Conclusion

Our meta-analysis indicated that onset with seizures, status epilepticus, EEG abnormalities, MRI abnormalities, and longer time from clinical onset to immunotherapy were risk factors for persistent seizures in AE patients.

Prevalence, risk factors, and prognosis of drug-resistant epilepsy in autoimmune encephalitis

OBJECTIVE

To evaluate the prevalence and biomarkers of drug-resistant epilepsy (DRE) in patients with autoimmune encephalitis (AIE).

METHODS

Sixty-nine patients with AIE were recruited retrospectively and electroencephalographies (EEGs) were reviewed using a standard reporting proforma. Associations between EEG biomarkers and DRE development at 12 months were examined using logistic regression modeling and were utilized to create a DRE risk score.

RESULTS

Sixteen percent of patients with AIE developed DRE at 12-month follow-up. The presence of status epilepticus (SE) (OR 11.50, 95% CI [2.81, 51.86], p-value <0.001), temporal lobe focality (OR 9.90, 95% CI [2.60, 50.71], p-value 0.001) and periodic discharges (OR 19.12, 95% CI [3.79, 191.10], p-value 0.001) on the admission EEG were associated with the development of DRE at 12 months. These variables were utilized to create a clinically applicable risk score for the prediction of DRE development.

CONCLUSIONS

Drug-resistant epilepsy is an infrequent complication of AIE. Electroencephalography changes during the acute illness can predict the risk of DRE at 12 months post-acute AIE.

SIGNIFICANCE

The identified EEG biomarkers provide the basis to generate a clinically applicable prediction tool which could be used to inform treatment, prognosis, and select patients for acute treatment trials.

Acute Symptomatic Seizures and Risk of Epilepsy in Autoimmune Encephalitis: A Retrospective Cohort Study

Purpose

To investigate the clinical characteristics of acute symptomatic seizures and the predictors of the development of epilepsy in patients with anti-NMDAR, anti-LGI1, and anti-GABABR encephalitis.

Methods

We retrospectively screened the medical records of 86 hospitalized patients with confirmed autoimmune encephalitis (AE). The clinical characteristics of acute symptomatic seizures were analyzed. The predictors of the development of epilepsy were investigated using logistic regression analysis.

Results

A total of 86 patients with AE were finally included. Eighty-six percent of patients (n = 74) experienced acute symptomatic seizures, and 28.4% of patients developed epilepsy during follow-up. Abnormal EEG findings were more frequent in AE patients with acute symptomatic seizures. A greater number of anti-seizure medications (ASMs), abnormal EEG findings, and delayed immunotherapy were found to be independently associated with the development of epilepsy.

Conclusion

Acute symptomatic seizures are a common manifestation in AE patients. During follow-up, 28.4% of AE patients developed epilepsy. The independent factors that predicted the development of epilepsy after the acute phase included a larger number of ASMs, EEG abnormalities, and delayed immunotherapy. In clinical practice, we should prioritize immunotherapy to control acute seizures as soon as possible. For AE patients with an increased risk of developing epilepsy, early withdrawal of ASM is not recommended.

Long-term seizure outcomes in patients with autoimmune encephalitis: A prospective observational registry study update

OBJECTIVE

To update and evaluate long-term seizure outcomes in patients with autoimmune encephalitis (AE) based on a large cohort study with long follow-up.

METHODS

In this prospective observational registry study, we analyzed data from patients with AE mediated by common types of neuronal surface antibodies (anti-NMDAR, anti-LGI1/Caspr2, anti-GABA_B R). All patients were recruited from the Department of Neurology at the West China Hospital between October 2011 and June 2019, and data were collected prospectively on their demographic and clinical characteristics, treatment strategy, and seizure outcomes with a median follow-up of 42 months (range 6-93 months). Potential risk factors associated with seizure recurrence were also assessed.

RESULTS

Of 320 AE patients, 75.9% had acute seizures, among whom more than 90% of patients had their last seizure within 12 months of disease onset. During our follow-up, 21 (9.3%) patients experienced seizure recurrence. Patients with anti-GABA_B R encephalitis had a higher cumulative incidence of seizure recurrence than those with anti-NMDAR (log-rank P = 0.03) or anti-LGI1/Caspr2 encephalitis (log-rank P = 0.04). Among patients with anti-NMDAR encephalitis, women had a significantly higher cumulative incidence of seizure recurrence than men (log-rank P = 0.01). Interictal epileptiform discharges (IEDs) or seizures captured on continuous EEG in the acute phase were identified as potential risk factors for seizure recurrence (P=0.04; P=0.007). Among 163 patients with ≥ 24 months of follow-up, five (3.1%) showed persistent seizures and required ongoing anti-seizure medications (ASMs) despite aggressive immunotherapy.

SIGNIFICANCE

Seizure recurrence occurred in a small number of patients and chronic epilepsy occurred in 3.1% of patients during prolonged follow-up. Across all types of AE, risk factors for seizure recurrence were IEDs or seizures captured on EEG in the acute phase; for anti-NMDAR encephalitis, female sex was also a risk factor.

Role of responsive neurostimulation and immunotherapy in refractory epilepsy due to autoimmune encephalitis: A case report

Autoimmune encephalitis (AE) frequently presents with seizures in the acute setting. Seizures are often refractory to anti-seizure medications (ASM) but have been shown to be responsive to immunomodulatory therapies. A subset of patients with AE continues to have refractory epilepsy, recently named "autoimmune-associated epilepsy (AAE)," for years after the acute AE presentation. Optimal treatment for AAE has not been determined. Furthermore, the efficacy of neuromodulation and immunotherapy has not been well established in AAE. Here, we report a patient with probable autoantibody negative AE who initially presented with new onset refractory status epilepticus (NORSE). After his acute presentation, he continued to have frequent seizures that were refractory to four ASMs at therapeutic doses. A responsive neurostimulation (RNS^®, NeuroPace) system was implanted for diagnostic and therapeutic purposes, with minimal change in seizure frequency. Due to continued frequent seizures despite ASMs and neurostimulation, he underwent a trial of immunotherapy consisting of high-dose intravenous (IV) corticosteroids and intravenous immunoglobulin (IVIG). Despite the addition of immunotherapy to his treatment regimen, the patient experienced no significant clinical or electrographic change in seizure frequency. This case does not support the use of immunotherapy for treatment of AAE and illustrates the need for consensus guidelines in the management of patients with AAE. Further, the use of electrocorticography (ECoG) data provided an objective surrogate measure of seizure frequency; this may support the role for early neuromodulation in the management of AAE.

Limbic encephalitis

Limbic encephalitis (LE) is a clinical syndrome defined by subacutely evolving limbic signs and symptoms with structural and functional evidence of mediotemporal damage in the absence of a better explanation than an autoimmune (or paraneoplastic) cause. There are features common to all forms of LE. In recent years, antibody(ab)-defined subtypes have been established. They are distinct regarding underlying pathophysiologic processes, clinical and magnetic resonance imaging courses, cerebrospinal fluid signatures, treatment responsivity, and likelihood of a chronic course. With immunotherapy, LE with abs against surface antigens has a better outcome than LE with abs to intracellular antigens. Diagnostic and treatment challenges are, on the one hand, to avoid overlooking and undertreatment and, on the other hand, to avoid overdiagnoses and overtreatment. LE can be conceptualized as a model disease for the consequences of new onset mediotemporal damage by different mechanisms in adult life. It may be studied as an example of mediotemporal epileptogenesis.

Prevalence of Neural Autoantibodies in Paired Serum and Cerebrospinal Fluid in Adult Patients with Drug-Resistant Temporal Lobe Epilepsy of Unknown Etiology

In order to determine the prevalence of neural autoantibodies in adult patients with drug-resistant temporal lobe epilepsy (DRTLE) of unknown etiology, we compared the characteristics of patients with and without autoantibodies and applied antibody predictive scores to the patients. Patients aged ≥18 years with DRTLE of unknown etiology and ≥12 months of evolution were prospectively recruited. Neural autoantibodies in serum and CSF were systematically determined in all patients. We created the ARTE (antibody in drug-resistant temporal lobe epilepsy) score based on the variables associated with the presence of neural autoantibodies. Twenty-seven patients were included. The mean (SD) age in years at the index date was 52 (±14.2) and at epilepsy onset was 32 (±17.1). The mean epilepsy duration was 19 (±12.5) years. Neural autoantibodies were detected in 51.85% (14/27) of patients. The presence of bitemporal, independent, interictal epileptiform discharges (BIIED) had a higher frequency in patients with neural autoantibodies (57.1% vs. 15.4%; p = 0.025) as well as those patients with a previous history of status epilepticus (49.2% vs. 0.0%; p = 0.007). The ARTE score showed an area under the curve (AUC) of 0.854. Using a cut-off point of ≥1, the sensitivity was 100% and the specificity was 46.1%, whereas when using a cut-off point of ≥3, the results were 35.7% and 100%, respectively. We found a high prevalence of neural autoantibodies in patients with DRTLE of unknown etiology, indicating an autoimmune mechanism. The presence of BIIED and a history of SE in DRTLE of unknown etiology are possible markers for autoimmune-associated epilepsy. The proposed ARTE score requires future validation in larger independent cohorts.

Predictors and prognoses of epilepsy after anti-neuronal antibody-positive autoimmune encephalitis

PURPOSE

This study aimed to investigate the incidence and predictors of epilepsy after anti-neuronal antibody-positive autoimmune encephalitis (AIE). The clinical outcomes of patients with epilepsy after AIE were also explored.

METHODS

A total of 111 AIE patients were retrospectively evaluated. Post-AIE epilepsy (PAEE) was defined as at least one unprovoked seizure occurring six or more months after discharge from hospital.

RESULTS

The incidence of acute symptomatic seizures was 80.2% (89/111) in our AIE patients. Furthermore, of the 89 AIE patients with seizures, 29 (32.6%) presented with seizures as the initial symptom. Overall, 44 out of 111 AIE patients (39.6%) had unprovoked seizures after six months, meeting our definition of PAEE. The independent risk factors for PAEE incidence included an initial presentation with new-onset refractory status epilepticus (NORSE), delayed immunotherapy treatment, the complication of a lung infection during admission, the requirement for mechanical ventilation during hospitalization, parietal lesions observed in magnetic resonance imaging (MRI), and focal slow waves on electroencephalographic (EEG) monitoring.

CONCLUSIONS

Early initiation of immunotherapy and lung infection treatment may reduce the risk of conversion of symptomatic seizures to chronic epilepsy in the acute phase of AIE. In general, PAEE patients could have a good prognosis if treated properly and in a timely fashion.

Risk of Developing Epilepsy after Autoimmune Encephalitis

BACKGROUND

Acute symptomatic seizures (ASS) are a common manifestation of autoimmune encephalitis (AE), but the risk of developing epilepsy as a sequela of AE remains unknown, and factors predisposing the development of epilepsy have not been fully identified.

OBJECTIVE

To assess the risk of developing epilepsy in AE and study related risk factors.

MATERIALS AND METHODS

This was a retrospective single centre study including patients diagnosed with AE according to criteria described by Graus et al., with a minimum follow-up of 12 months after AE resolution. The sample was divided according to whether patients developed epilepsy or not.

RESULTS

A total of 19 patients were included; 3 (15.8%) had AE with intracellular antibodies, 9 (47.4%) with extracellular antibodies, and 7 (36.8%) were seronegative. During follow-up, 3 patients (15.8%) died, 4 (21.1%) presented relapses of AE, and 11 (57.89%) developed epilepsy. There was a significant association between the development of epilepsy and the presence of hippocampal atrophy in control brain magnetic resonance imaging (MRI) (p = 0.037), interictal epileptiform discharges (IED) on control electroencephalogram (EEG) (p = 0.045), and immunotherapy delay (p = 0.016).

CONCLUSIONS

Hippocampal atrophy in neuroimaging, IED on EEG during follow-up, and immunotherapy delay could be predictors of the development of epilepsy in patients with AE.

Case Report/Case Series: Rare case of anti-LGI1 limbic encephalitis with rapidly progressive dementia, psychiatric symptoms, and frequently seizures: A case report

RATIONALE

Anti leucine-rich glioma inactivated 1 (LGI1) limbic encephalitis (LE) is rare autoimmune encephalitis, characterized by acute or subacute cognitive impairment, faciobrachial dystonic seizures, mental disorders, and refractory hyponatremia. As a type of treatable rapidly progressive dementia with a good prognosis, early, and accurate diagnosis is essential. We present a case of anti-LGI1 LE who was initially misdiagnosed with Alzheimer disease because his clinical manifestations were similar to Alzheimer disease.

PATIENT CONCERNS

A male patient presenting with rapidly progressive dementia, faciobrachial dystonic seizures, psychiatric disturbance, and refractory hyponatremia was admitted. The scores of Mini-Mental State Examination, Montreal Cognitive Assessment, and Neuropsychiatric Inventory were 19/30, 16/30, and 91/144, respectively. Brain magnetic resonance images indicated moderate atrophy of the hippocampus and abnormally hyperintensities in the left medial temporal and hippocampus.

DIAGNOSIS

The patient was diagnosed with anti-LGI1 LE based on the presence of LGI-1 antibodies in the cerebrospinal fluid and serum and clinical manifestations.

INTERVENTIONS

Patient was treated with glucocorticoid against LGI1, antiepileptic drug, cholinesterase inhibitors, and other adjuvant therapy.

OUTCOMES

The patient showed marked improvement on immunotherapy. Clinical symptoms were disappeared and the LGI-1 antibodies in cerebrospinal fluid and serum were both negative at the time of discharge.

CONCLUSIONS

Recognition of the specific symptoms and LGI-1 antibody test will be helpful for the early diagnosis, prompt immunotherapy, and good prognosis. This case raises the awareness that rapidly progressive dementia with frequent seizures could be caused by immunoreactions.

Characteristics and outcome-related factors of seizure at the first onset of autoimmune encephalitis: A retrospective study

Aims

Seizure outcome of autoimmune encephalitis (AE) varies from seizure‐free to refractory epilepsy, and the associated factors remain unclear. We aimed to describe seizure characteristics, identify seizure outcome‐related factors, and discuss the medication strategy of antiepileptic drugs (AEDs) at the first onset of AE.

Methods

We retrospectively studied the data of 86 patients with clinically diagnosed AE. The clinical characteristics were described using a chi‐square test. Seizure outcome‐related factors were assessed using multivariable logistic regression analysis.

Results

56 patients were finally enrolled, with antibodies to N‐methyl‐D‐aspartate receptor found in 29, to γ‐aminobutyric acid receptor B found in 13, and to leucine‐rich glioma‐inactivated protein 1 found in 14. Status epilepticus occurrence and onset with seizure lead to a poor seizure outcome, while administration of human gamma globulin and a low antibody titer contributed to a good seizure outcome.

Conclusions

In the acute phase, seizure characteristics may be considered in the utilization of AEDs. For patients with seizure‐free status in the acute phase, clinical manifestation (onset with seizure or not, whether status epilepticus occurs or not), therapy regimen (human gamma globulin administered or not), and antibody titer may be considered when formulating the strategy for withdrawal of AEDs post‐acute phase.

Continuous Visual Focal Status Epilepticus as the Primary Presentation of NMDA-R and GAD65-R Autoimmune Epilepsy

Epilepsia partialis continua (EPC) has changed in its clinical and pathophysiological definition throughout time. Several etiologies have been described in addition to classic causes of EPC. The following case depicts a young woman who had a peculiar onset of epilepsy with a continuous visual aura becoming a form of chronic recurrent and non-progressive EPC. The patient was initially misdiagnosed as a non-neurological entity (assumed psychiatric in origin), but finally, an immune-mediated epilepsy was diagnosed, and EEG showed focal status epilepticus during evolution. Once the diagnosis was achieved and immune treatment was established, the patient is seizure free. Early identification of an immune basis in patients with epilepsy is important because immunotherapy can reverse the epileptogenic process and reduce the risk of chronic epilepsy. To date, this is the only case reported with EPC manifesting as a continuous visual aura associated with antiglutamic acid decarboxylase 65 (anti-GAD65) and anti-N-methyl-d-aspartate (anti-NMDA) antibodies.

Seizures in autoimmune encephalitis: Findings from an EEG pooled analysis

PURPOSE

Seizures are common in autoimmune encephalitis (AE), and an extensive work-up is required to exclude alternative etiologies. The aim of our study was to identify possible clinical/EEG peculiarities suggesting the immune-mediated origin of late-onset seizures.

METHODS

Thirty patients diagnosed with AE (19 men, median age 68 years, 18 seronegative) were included. Overall 212 video-electroencephalographic (EEG) and 31 24-h ambulatory EEG (AEEG) recordings were retrospectively reviewed. Posterior dominant rhythm, interictal epileptiform discharges (IEDs), clinical (CSs) and subclinical seizures (SCSs) were analyzed.

RESULTS

Six-hundred-nineteen ictal events were recorded in 19/30 subjects, mostly (568/619) during AE acute stage. Among ten patients with CSs other than faciobrachial dystonic seizures, 7 showed prominent autonomic and emotional manifestations. SCSs were detected in 11 subjects, mainly via AEEG (260/287 SCSs vs 150/332 CSs, p < 0.001). Eight patients presented seizures during hyperventilation. IEDs, documented in 21 cases, were bilateral in 14 and focal temporal in 13. Multiple ictal EEG patterns were detected in 9/19 patients, 6 of whom had both CSs and SCSs, bilateral asynchronous seizures and ictal activities arising from temporal and extra-temporal regions. No correlation was found between the lateralization of MRI alterations and that of EEG findings.

CONCLUSION

Our study confirms that adult-onset, high frequency focal seizures with prominent autonomic and emotional manifestations should be investigated for AE. Multiple ictal EEG patterns could represent a 'red flag', reflecting a widespread neuronal excitability related to the underlying immune-mediated process. Finally, our work enhances the crucial role of long-lasting EEG monitoring in revealing subclinical and relapsing seizures.

Seizures and risk of epilepsy in anti-NMDAR, anti-LGI1, and anti-GABAB R encephalitis

Background

Accumulating data have suggested seizures occur frequently in patients with neuronal surface antibody‐mediated autoimmune encephalitis. We aimed to evaluate seizure outcomes and potential factors associated with the development of epilepsy in patients with anti‐N‐methyl‐D‐aspartate receptor (NMDAR), anti‐leucine‐rich glioma‐inactivated 1 (LGI1), and anti‐gamma‐aminobutyric‐acid B receptor (GABA_BR) encephalitis.

Methods

Patients with anti‐NMDAR, anti‐LGI1, and anti‐GABA_BR encephalitis were prospectively recruited from 2014 to June 2019, with a median follow‐up period of 30.5 months (range 8–67 months). Seizure outcomes were assessed and risk factors of epilepsy were analyzed.

Results

A total of 119 patients with anti‐NMDAR, anti‐LGI1, and anti‐GABA_BR encephalitis were included, and 83 (69.7%) of them developed new‐onset seizures. By the end of follow‐up, 17 (21.3%) of 80 patients had seizure relapses after intermittent seizure remission or exhibited uncontrolled seizure episodes, contributing to epilepsy. Immunotherapy delay and interictal epileptic discharges (IEDs) were identified to be associated with the development of epilepsy in patients with anti‐NMDAR, anti‐LGI1, and anti‐GABA_BR encephalitis, particularly anti‐NMDAR encephalitis. Furthermore, multivariate logistic regression analysis demonstrated that immunotherapy delay was an independent predictor for epilepsy.

Conclusion

Our study suggested that immunotherapy delay and IEDs were associated with the development of epilepsy in patients with anti‐NMDAR, anti‐LGI1, and anti‐GABA_BR encephalitis. Early diagnosis and treatment were required, and particular consideration should be given to patients with these risk factors.