Faculty Bibliography

OBJECTIVE:Autoimmune encephalitis can be followed by treatment-resistant epilepsy. Understanding its predictors and mechanisms are crucial to future studies to improve autoimmune encephalitis outcomes. Our objective was to determine the clinical and imaging predictors of postencephalitic treatment-resistant epilepsy. METHODS:We performed a retrospective cohort study (2012-2017) of adults with autoimmune encephalitis, both antibody positive and seronegative but clinically definite or probable. We examined clinical and imaging (as defined by morphometric analysis) predictors of seizure freedom at long term follow-up. RESULTS:Of 37 subjects with adequate follow-up data (mean 4.3 yrs, SD 2.5), 21 (57 %) achieved seizure freedom after a mean time of 1 year (SD 2.3), and one third (13/37, 35 %) discontinued ASMs. Presence of mesial temporal hyperintensities on the initial MRI was the only independent predictor of ongoing seizures at last follow-up (OR 27.3, 95 %CI 2.48-299.5). Morphometric analysis of follow-up MRI scans (n = 20) did not reveal any statistically significant differences in hippocampal, opercular, and total brain volumes between patients with postencephalitic treatment-resistant epilepsy and those without. SIGNIFICANCE/CONCLUSIONS:Postencephalitic treatment-resistant epilepsy is a common complication of autoimmune encephalitis and is more likely to occur in those with mesial temporal hyperintensities on acute MRI. Volume loss in the hippocampal, opercular, and overall brain on follow-up MRI does not predict postencephalitic treatment-resistant epilepsy, so additional factors beyond structural changes may account for its development.

Fulminant IIH in pregnancy requires multidisciplinary collaboration and immediate CSF diversion.

The International League Against Epilepsy (ILAE) seizure classification scheme has been periodically updated to improve its reliability and applicability to clinicians and researchers alike. Here, members of the Epilepsy Study Consortium propose a pragmatic seizure classification, based on the ILAE scheme, designed for use in clinical trials with a focus on outcome measures that have high reliability, broad interpretability across stakeholders, and clinical relevance in the context of the development of novel antiseizure medications. Controversies around the current ILAE classification scheme are discussed in the context of clinical trials, and pragmatic simplifications to the existing scheme are proposed, for intended use by investigators, industry sponsors, and regulatory agencies.

Importance/UNASSIGNED:The literature on neural autoantibody positivity in epilepsy has expanded over the last decade, with an increased interest among clinicians in identifying potentially treatable causes of otherwise refractory seizures. Observations/UNASSIGNED:Prior studies have reported a wide range of neural autoantibody positivity rates among various epilepsy populations, with the highest frequency reported in individuals with focal epilepsy of unknown cause and new-onset seizures. The antibodies in some cases are of uncertain significance, and their presence can cause conundrums regarding therapy. Conclusions and Relevance/UNASSIGNED:There is likely some role for neural autoantibody assessment in patients with unexplained epilepsy who lack clear evidence of autoimmune encephalitis, but the clinical implications of such testing remain unclear owing to limitations in previous published studies. A framework for study design to bridge the current gaps in knowledge on autoimmune-associated epilepsy is proposed.

OBJECTIVES/OBJECTIVE:To determine whether neuronal and neuroaxonal injury, neuroinflammation and synaptic dysfunction associate with clinical course and outcomes in antibody-mediated encephalitis (AME), we measured biomarkers of these processes in CSF from patients presenting with AME and cognitively normal individuals. METHODS:Biomarkers of neuronal (total-tau, VILIP-1) and neuroaxonal damage (neurofilament light chain [NfL]), inflammation (YKL-40) and synaptic function (neurogranin, SNAP-25) were measured in CSF obtained from 45 patients at the time of diagnosis of NMDA receptor (n=34) or LGI1/CASPR-2 (n=11) AME, and 39 age- and sex-similar cognitively normal individuals. The association between biomarkers and modified Rankin Scores were evaluated in a subset (n=20) of longitudinally followed patients. RESULTS:(YKL-40/SNAP-25) [(ρ=0.48; p=0.04] associated with greater disease severity (higher modified Rankin Score) in prospectively followed patients. Higher YKL-40 (ρ=0.60; p=0.02) and neurogranin (ρ=0.55; p=0.03) at presentation were associated with higher modified Rankin Scores 12-months following hospital discharge. CONCLUSIONS:CSF biomarkers suggest that neuronal integrity is acutely maintained in AME patients, despite neuroaxonal compromise. Low-levels of biomarkers of synaptic function may reflect antibody-mediated internalization of cell-surface receptors, and may represent an acute correlate of antibody-mediated synaptic dysfunction, with the potential to inform disease severity and outcomes.

Systemic autoimmune disorders occur more frequently in patients with epilepsy than in the general population, suggesting shared disease mechanisms. The risk of epilepsy is elevated across the spectrum of systemic autoimmune disorders but is highest in systemic lupus erythematosus and type 1 diabetes mellitus. Vascular and metabolic factors are the most important mediators between systemic autoimmune disorders and epilepsy. Systemic immune dysfunction can also affect neuronal excitability, not only through innate immune activation and blood-brain barrier dysfunction in most epilepsies but also adaptive immunity in autoimmune encephalitis. The presence of systemic autoimmune disorders in subjects with acute seizures warrants evaluation for infectious, vascular, toxic and metabolic causes of acute symptomatic seizures, but clinical signs of autoimmune encephalitis should not be missed. Immunosuppressive medications may have antiseizure properties and trigger certain drug interactions with antiseizure treatments. A better understanding of mechanisms underlying the co-existence of epilepsy and systemic autoimmune disorders is needed to guide new antiseizure and anti-epileptogenic treatments. This review aims to summarize the epidemiological evidence for systemic autoimmune disorders as comorbidities of epilepsy, explore potential immune and non-immune mechanisms, and provide practical implications on diagnostic and therapeutic approach to epilepsy in those with comorbid systemic autoimmune disorders.

OBJECTIVE:To determine the prevalence of cerebrospinal fluid (CSF) markers associated with inflammation (i.e., elevated white blood cell count, protein concentration, and CSF-specific oligoclonal bands) in patients with early active autoimmune encephalitis (AE). METHODS:CSF characteristics, including WBC count, protein concentration, and oligoclonal banding, were analyzed in patients diagnosed with AE at two tertiary care centers. RESULTS:(range: 0-544) and the median CSF protein concentration was 0.42 g/L (range: 0.15-3.92). CONCLUSIONS:White blood cell counts and protein levels were within normal limits in the CSF of a substantial proportion of patients with early active AE. Inclusion of CSF oligoclonal banding identified a higher proportion of patients with an inflammatory CSF profile, especially when CSF was sampled early in the disease process.

Seizures are a well-recognized and often prominent manifestation of autoimmune encephalitic syndromes. Progress in detection of pathogenic neural autoantibodies has led to increased awareness of autoimmune causes of seizures. Clinical studies of patients with these autoantibodies have improved our understanding of the seizure characteristics, treatments, and seizure prognosis in these disorders. The International League Against Epilepsy (ILAE) Autoimmunity and Inflammation Taskforce proposes conceptual definitions for two main diagnostic entities: (a) acute symptomatic seizures secondary to autoimmune encephalitis, and (b) autoimmune-associated epilepsy, the latter of which suggests an enduring predisposition to seizures. Such a distinction is relevant when discussing the pathophysiology, treatment, prognosis, and social consequences of these disorders. We discuss the role of biomarkers in the application of these conceptual definitions and illustrate their use in patients cared for by members of the task force.