Recognizing autoimmune encephalitis as a cause of seizures: Treating cause and not effect

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.

Brazilian consensus recommendations on the diagnosis and treatment of autoimmune encephalitis in the adult and pediatric populations

BACKGROUND

 Autoimmune encephalitis (AIE) is a group of inflammatory diseases characterized by the presence of antibodies against neuronal and glial antigens, leading to subacute psychiatric symptoms, memory complaints, and movement disorders. The patients are predominantly young, and delays in treatment are associated with worse prognosis.

OBJECTIVE

 With the support of the Brazilian Academy of Neurology (Academia Brasileira de Neurologia, ABN) and the Brazilian Society of Child Neurology (Sociedade Brasileira de Neurologia Infantil, SBNI), a consensus on the diagnosis and treatment of AIE in Brazil was developed using the Delphi method.

METHODS

 A total of 25 panelists, including adult and child neurologists, participated in the study.

RESULTS

 The panelists agreed that patients fulfilling criteria for possible AIE should be screened for antineuronal antibodies in the serum and cerebrospinal fluid (CSF) using the tissue-based assay (TBA) and cell-based assay (CBA) techniques. Children should also be screened for anti-myelin oligodendrocyte glucoprotein antibodies (anti-MOG). Treatment should be started within the first 4 weeks of symptoms. The first-line option is methylprednisolone plus intravenous immunoglobulin (IVIG) or plasmapheresis, the second-line includes rituximab and/or cyclophosphamide, while third-line treatment options are bortezomib and tocilizumab. Most seizures in AIE are symptomatic, and antiseizure medications may be weaned after the acute stage. In anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, the panelists have agreed that oral immunosuppressant agents should not be used. Patients should be evaluated at the acute and postacute stages using functional and cognitive scales, such as the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Modified Rankin Scale (mRS), and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE).

CONCLUSION

 The present study provides tangible evidence for the effective management of AIE patients within the Brazilian healthcare system.

Utilization of APE2 and RITE2 scores in autoimmune encephalitis patients with seizures

PURPOSE

Immune-mediated seizures are rare but are increasingly recognized as an etiology of seizures resistant to anti-seizure medications (ASMs). Antibody Prevalence in Epilepsy 2 (APE2) and Response to Immunotherapy in Epilepsy 2 (RITE2) scores were developed recently to identify patients who may be seropositive for serum central nervous system (CNS) specific antibodies (Ab) and may benefit from immunotherapy (Dubey et al. 2018). The goal of this study was to apply APE2 and RITE2 scores to an independent cohort of patients with seizures secondary to autoimmune encephalitis (AE) and to further verify the sensitivity and specificity of the scores.

PRINCIPAL RESULTS

We conducted a retrospective study at Stanford University Hospital between 2008 and 2021 and included patients who had acute seizures and AE using diagnostic criteria from Graus (n = 34 definite AE, 10 probable AE, and 12 possible AE) (Graus et al. 2016). Patients were excluded if they did not have a serum Ab panel investigated or had alternate diagnoses (n = 55). APE2 and RITE2 scores were calculated based on clinical and diagnostic data (n = 56). Serum Ab were positive in 73 % of patients, in which 63 % cases carried CNS specific Ab. An APE2 score ≥ 4 had a sensitivity of 97 % and specificity of 14 % to predict a positive serum CNS specific Ab. A RITE2 score ≥ 7 had a sensitivity of 93 % and specificity of 60 % to predict seizure responsiveness to immunotherapy.

CONCLUSION

APE2 and RITE2 scores had high sensitivities but low specificities to predict seropositivity and seizure responsiveness to immunotherapy in patients with autoimmune encephalitis with seizures.

Epileptic phenotypes in autoimmune encephalitis: from acute symptomatic seizures to autoimmune-associated epilepsy

OBJECTIVE

To describe the clinical and paraclinical findings, treatment options and long-term outcomes in autoimmune encephalitis (AE), with a close look to epilepsy.

METHODS

In this retrospective observational cohort study, we enrolled patients with new-onset seizures in the context of AE. We compared clinical and paraclinical findings in patients with and without evidence of antibodies.

RESULTS

Overall, 263 patients (138 females; median age 55 years, range 4-86) were followed up for a median time of 30 months (range 12-120). Antineuronal antibodies were detected in 63.50%.Antibody-positive patients had multiple seizure types (p=0.01) and prevalent involvement of temporal regions (p=0.02). A higher prevalence of episodes of SE was found in the antibody-negative group (p<0.001).Immunotherapy was prescribed in 88.60%, and effective in 61.80%. Independent predictors of favourable outcome of the AE were early immunotherapy (p<0.001) and the detection of antineuronal surface antibodies (p=0.01).Autoimmune-associated epilepsy was the long-term sequela in 43.73%, associated with cognitive and psychiatric disturbances in 81.73%. Independent predictors of developing epilepsy were difficult to treat seizures at onset (p=0.04), a high number of antiseizure medications (p<0.001), persisting interictal epileptiform discharges at follow-up (p<0.001) and poor response to immunotherapy during the acute phase (p<0.001).

CONCLUSIONS

The recognition of seizures secondary to AE represents a rare chance for aetiology-driven seizures management. Early recognition and treatment at the pathogenic level may reduce the risk of long-term irreversible sequelae. However, the severity of seizures at onset is the major risk factor for the development of chronic epilepsy.This study provides class IV evidence for management recommendations.

When should we test patients with epilepsy for autoimmune antibodies? Results from a French retrospective single center study

BACKGROUND AND PURPOSE

Seizures represent a core symptom of autoimmune encephalitides with specific therapeutic issues. To date, patients with new-onset seizures or established epilepsy are not systematically tested for autoimmune antibodies. We aimed to identify clinical and paraclinical criterion that could help to select patients requiring additional autoimmune antibodies serum and cerebrospinal fluid (CSF) detection.

METHODS

In this retrospective single center study from the French Salpêtrière Hospital, data from 286 adult patients with epilepsy who received an autoantibody assay for the first time were analyzed. All patients were evaluated at our institution between January 2007 and December 2018 for assessment of new-onset epilepsy (n = 90) or established epilepsy (n = 196). We only analyzed patients that were screened for autoimmune antibodies. Demographic, clinical and neuroimaging measures were compared between patients with and without autoimmune encephalitis using Fisher's exact test for categorical variables and Welch's t test for continuous variables. Our primary goal was to identify significant factors that differentiated patients with and without autoimmune encephalitis.

RESULTS

We identified 27 patients with autoimmune epilepsy (9.4% of the patients who had been tested for autoantibodies). The significant factors differentiating patients with and without autoimmune encephalitis were: (i) the existence of a new-onset focal epilepsy + (e.g., newly diagnosed epilepsy < 6 months associated with additional symptoms, mainly cognitive or psychiatric symptoms), (ii) the presence of faciobrachial dystonic seizures very suggestive of anti- Leucine-rich glioma inactivated 1 (LGI1) encephalitis, and (iii) the presence of magnetic resonance imaging (MRI) abnormalities suggestive of encephalitis.

CONCLUSION

New-onset focal seizures combined with cognitive or psychiatric symptoms support the test for autoimmune antibodies. Further clinical already known red flags for an autoimmune origin are the presence of faciobrachial dystonic seizures and MRI signal changes consistent with encephalitis. On the other hand, isolated new-onset seizures and chronic epilepsy, even with associated symptoms, seem rarely linked to autoimmune encephalitis and should not lead to systematic testing.

Specific B- and T-cell populations are associated with cognition in patients with epilepsy and antibody positive and negative suspected limbic encephalitis

OBJECTIVE

Neuropsychological impairments are major symptoms of autoimmune limbic encephalitis (LE) epilepsy patients. In LE epilepsy patients with an autoimmune response against intracellular antigens as well as in antibody-negative patients, the antibody findings and magnetic resonance imaging pathology correspond poorly to the clinical features. Here, we evaluated whether T- and B-cells are linked to cognitive impairment in these groups.

METHODS

In this cross-sectional, observational, case-controlled study, we evaluated 106 patients with adult-onset epilepsies with a suspected autoimmune etiology. We assessed verbal and visual memory, executive function, and mood in relation to the presence or absence of known auto-antibodies, and regarding T- and B-cell activity as indicated by flow cytometry (fluorescence-activated cell sorting = FACS, peripheral blood = PB and cerebrospinal fluid = CSF).

RESULTS

56% of the patients were antibody-negative. In the other patients, auto-antibodies were directed against intracellular antigens (GAD65, paraneoplastic: 38%), or cellular surface antigens (LGI1/CASPR2/NMDA-R: 6%). Excluding LGI1/CASPR2/NMDA-R, the groups with and without antibodies did not differ in disease features, cognition, or mood. CD4+ T-cells and CD8+ T-cells in blood and CD4+ T-cells in CSF were prominent in the auto-antibody positive group. Regression analyses indicated the role education, drug load, amygdala and/or hippocampal pathology, and CD4+ T-cells play in verbal memory and executive function. Depressed mood revealed no relation to flow cytometry results.

CONCLUSION

Our results indicate a link between T- and B-cell activity and cognition in epilepsy patients with suspected limbic encephalitis, thus suggesting that flow cytometry results can provide an understanding of cognitive impairment in LE patients with autoantibodies against intracellular antigens.

Antibody Prevalence in Epilepsy before Surgery (APES) in drug-resistant focal epilepsy

OBJECTIVE

There is a growing recognition of immune-mediated causes in patients with focal drug-resistant epilepsy (DRE); however, they are not systematically assessed in the pre-surgical diagnostic workup. Early diagnosis and initiation of immunotherapy is associated with a favorable outcome in immune-mediated seizures. Patients with refractory focal epilepsy with neuronal antibodies (Abs) tend to have a worse surgical prognosis when compared to other etiologies.

METHODS

We studied the prevalence of serum Abs in patients ≥18 years of age with DRE of unknown cause before surgery. We proposed and calculated a clinical APES (Antibody Prevalence in Epilepsy before Surgery) score for each subject, which was modified based on Dubey's previously published APE² score. RESULTS`: A total of 335 patients were screened and 86 subjects were included in final analysis. The mean age at the time of recruitment was 44.84 ± 14.86 years, with age at seizure onset 30.89 ± 19.88 years. There were no significant differences among baseline clinical features between retrospective and prospective sub-cohorts. The prevalence of at least one positive Ab was 33.72%, and central nervous system (CNS)-specific Abs was 8.14%. APES score ≥4 showed slightly better overall prediction (area under the curve [AUC]: 0.84 vs 0.74) and higher sensitivity (100% vs 71.4%), with slightly lower but similar specificity (44.3% vs 49.4%), when compared to APE² score ≥4. For subjects who had available positron emission tomography (PET) results and all components of APES score (n = 60), the sensitivity of APES score ≥4 yielded a similar prediction potential with an AUC of 0.80.

SIGNIFICANCE

Our findings provide persuasive evidence that a subset of patients with focal DRE have potentially immune-mediated causes. We propose an APES score to help identify patients who may benefit from a workup for immune etiologies during the pre-surgical evaluation for focal refractory epilepsy with unknown cause.