LGI1-antibody associated epilepsy successfully treated in the outpatient setting

Review and meta-analysis of neuropsychological findings in autoimmune limbic encephalitis with autoantibodies against LGI1, CASPR2, and GAD65 and their response to immunotherapy

OBJECTIVES

It is assumed that autoimmune limbic encephalitis (ALE) demonstrates distinct neuropsychological manifestations with differential responses to immunotherapy according to which associated autoantibody (AAB), if any, is identified. Towards investigating whether this is the case, this study aims to summarize respective findings from the primary literature on ALE with AABs binding to cell surface neural antigens and ALE with AABs against intracellular neural antigens.

METHODS

We chose ALE with AABs against leucine-rich, glioma inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) as the most frequent cell surface membrane antigens, and ALE with AABs to Embryonic Lethal, Abnormal Vision, Like 1 (ELAVL) proteins (anti-Hu) and glutamic acid decarboxylase 65 (GAD65) as the most frequent intracellular neural antigens. The PubMed and Scopus databases were searched on March 1st, 2021 for neuropsychological test and -screening data from patients with ALE of these AAB-types. Findings were reviewed according to AAB-type and immunotherapy status and are presented in a review section and are further statistically evaluated and presented in a meta-analysis section in this publication.

RESULTS

Of the 1304 initial hits, 32 studies on ALE with AABs against LGI1, CASPR2, and GAD65 reporting cognitive screening data could be included in a review. In ALE with AABs against LGI1, CASPR2 and GAD65, memory deficits are the most frequently reported deficits. However, deficits in attention and executive functions including working memory, fluency, and psychological function have also been reported. This review shows that ALE patients with AABs against both LGI1 and CASPR2 show higher percentages of neuropsychological deficits compared to ALE patients with AABs against GAD65 before and after initiation of immunotherapy. However, the methodologies used in these studies were heterogenous, and longitudinal studies were not comparable. Moreover, 21 studies including ALE patients with AABs against LGI1 and GAD65 were also suitable for meta-analysis. No suitable study on ALE with AABs against ELAVL proteins could be identified. Meta-Analyses could be executed for cognitive screening data and only partially, due to the small number of studies. However, in statistical analysis no consistent effect of AAB or immunotherapy on performance in cognitive screening tests could be found.

CONCLUSION

Currently, there is no definite evidence supporting the notion that different AAB-types of ALE exhibit distinct neuropsychological manifestations and respond differently to immunotherapy. Overall, we could not identify evidence for any effect of immunotherapy on cognition in ALE. More systematic, in-depth and longitudinal neuropsychological assessments of patients with different AAB-types of ALE are required in the future to investigate these aspects.

A case report of Morvan syndrome

Authors describe the case of a 22-year-old Caucasian male who presented acutely with psychomotor agitation, insomnia and muscle twitching with painful cramps. Autonomic symptoms were as well present, with profuse sweating, blood pressure fluctuations and tachycardia. He presented a miliary rash in his left forearm as well as in the neck. Electromyography documented myokymic movements bilaterally at both gastrocnemii and pretibial muscles. Brain imaging had no abnormalities, and anti-LGI1 and anti-CASPR2 resulted positive; this data together with electrophysiological findings suggested a Morvan syndrome. High-dose steroid therapy and plasma exchange improved substantially the clinical picture of the patient.

Clinical Course and Features of Seizures Associated With LGI1-Antibody Encephalitis

OBJECTIVE

To determine risk factors associated with clinical relapses and development of chronic epilepsy in patients with anti-leucine-rich glioma-inactivated 1 (LGI1) IgG encephalitis.

METHODS

Patients with seizures related to LGI1-antibody encephalitis with ≥ 24 months of follow-up from disease onset were identified in the Mayo Clinic electronic medical record and Neuroimmunology lab records. Charts were reviewed to determine clinical factors, seizure types, imaging, treatment, occurrence of relapse, and outcome. Binary logistic regression analysis was performed to identify predictors of the development of chronic epilepsy. Univariate Cox proportional hazards regression was used to examine the influence of baseline characteristics on relapse risk.

RESULTS

Forty-nine patients with LGI1-antibody encephalitis and acute symptomatic seizures were identified. Almost all patients (n=48, 98%) were treated with immunotherapy. Eight had definite, and two had possible chronic epilepsy at last follow-up (10/49, 20.4%). Female sex (P=0.048) and younger age at disease onset (P=0.02) were associated with development of chronic epilepsy. Relapses occurred in 20 (40.8%), with a median time to first relapse of 7.5 months (range 3-94 months). Initial treatment with chronic steroid sparing immunotherapy was associated with reduced risk of relapse (hazards ratio=0.28, 95% CI 0.11-0.73, P=0.009).

CONCLUSIONS

Chronic epilepsy occurred in 20.4% of our patients with LGI1-antibody encephalitis despite aggressive immunotherapy. Risk factors for chronic epilepsy were female sex and earlier age of onset. Relapses occurred in 40.8% of patients with prolonged follow-up, and chronic steroid sparing immunotherapy was associated with a lower relapse rate.

Autoimmune Encephalitis in Latin America: A Critical Review

Autoimmune encephalitis is an increasingly recognized cause of encephalitis. The majority of case series report patients residing in developed countries in the northern hemisphere. The epidemiologic features of autoimmune encephalitis in Latin America are still unclear. The aim of the study was to perform a review of the clinical presentation of autoimmune encephalitis in Latin America and compare to world literature. References were identified by an in-depth literature search and selected on the basis of relevance to the topic and authors' judgment. We selected clinical studies and case reports published from 2007 to July, 2020 including patients from Latin American countries. Of the 379 patients included, the majority were cases of anti-NMDA receptor encephalitis (93.14%), followed by anti-VGKC-complex encephalitis (N = 17; 4.48%), anti-GAD encephalitis (N = 9; 2.37%), anti-AMPA receptor encephalitis (N = 1; 0.26%), anti-GABA receptor encephalitis (N = 1; 0. 26%), anti-mGluR5 encephalitis (N = 1; 0. 26%), and anti-mGluR1 encephalitis (N = 1; 0. 26%). Reported cases of Anti-NMDA encephalitis in Latin-America had a very slight female predominance, lower prevalence of associated tumors and a lower incidence of extreme delta brush on electroencephalogram. Autoimmune encephalitis is possibly underdiagnosed in underdeveloped countries. Its outcome after treatment, however, appears to be similarly favorable in Latin American patients as has been reported in developed countries based on available case reports and case series. Regional specificities in the manifestation of autoimmune encephalitis could be related to epidemiologic factors, such as the presence of different triggers and different genetic and immunologic background, that need to be studied by future research.

Seizures in steroid-responsive encephalopathy

Steroid-responsive encephalopathy is a general term for diseases that are characterized by diffuse brain injury and respond well to corticosteroids or immunosuppressive agents, including Hashimoto's encephalopathy (HE), limbic encephalitis (LE), systemic lupus erythematosus encephalopathy (SLEE), antineutrophil cytoplasmic antibodies (ANCA)-associated systemic vasculitis encephalopathy (AASV), viral encephalitis (VE), and primary central nervous system lymphoma (PCNSL). Epilepsy and status epilepticus are the main manifestations of steroid-responsive encephalopathy. The spectrum of "autoimmune epilepsy" diseases, which has been approved by the epilepsy diagnostic recommendations of the International Antiepileptic League, is characterized by a high prevalence of epilepsy in central nervous system (CNS) autoimmune diseases and a variety of neuron-specific autoantibodies. Steroid-responsive encephalopathy with different causes may have different pathogeneses and has been suggested to be associated with some internal commonality producing seizure as the main symptom. Determining the regularity of seizures caused by steroid-responsive encephalopathy and implementing appropriate measures will help us improve the prognosis of patients. This paper summarizes the epidemiology, seizure onset, seizure type, and other characteristics of seizures in steroid-responsive encephalopathy (including HE, LE, SLEE, ANCA-associated systemic vasculitis encephalopathy, VE, and PCNSL) and then discusses the use of antiepileptic drugs to treat steroid-responsive encephalopathy.