Abstract
Objective: This study was conducted to elucidate prevalence, clinical features, outcomes, and best treatment in patients with late-onset seizures due to autoimmune encephalitis (AE).Methods: This is a single-institution prospective cohort study (2012–2019) conducted at the Epilepsy Center at the University of Greifswald, Germany. A total of 225 patients aged ≥50 years with epileptic seizures were enrolled and underwent an MRI/CT scan, profiling of neural antibodies (AB) in serum and cerebrospinal fluid (CSF), and neuropsychological testing. On the basis of their work-up, patients were categorized into the following three cohorts: definite, suspected, or no AE. Patients with definite and suspected AE were subsequently treated with immunosuppressive therapy (IT) and/or anti-seizure drug (ASD) therapy and were followed up (FU) regarding clinical and seizure outcome.Results: Of the 225 patients, 17 (8%) fulfilled the criteria for definite or suspected AE according to their AB profile and MRI results. Compared with patients with no evidence of AE, those with AE were younger (p = 0.028), had mesial temporal neuropsychological deficits (p = 0.001), frequently had an active or known malignancy (p = 0.006) and/or a pleocytosis (p = 0.0002), and/or had oligoclonal bands in CSF (p = 0.001). All patients with follow-up became seizure-free with at least one ASD. The Modified Rankin scale (mRS) at hospital admission was low for patients with AE (71% with mRS ≤2) and further decreased to 60% with mRS ≤2 at last FU.Significance: AE is an important etiology in late-onset seizures, and seizures may be the first symptom of AE. Outcome in non-paraneoplastic AE was favorable with ASD and IT. AB testing in CSF and sera, cerebral MRI, CSF analysis, and neuropsychological testing for mesial temporal deficits should be part of the diagnostic protocol for AE following late-onset seizures.
Highlights
Epilepsy and new onset seizures in elderly patients are an important health issue of the aging population [1, 2]
A total of nine patients (n = 9/225; 4%) met the criteria for definite autoimmune encephalitis (dAE): All patients presented with well-defined neural AB in cerebrospinal fluid (CSF) and serum [anti-GAD AB (n = 1), anti-LGI1 AB (n = 1), anti-CASPR2 AB (n = 3), anti-NMDAR AB (n = 1), antiAmphiphysin/neuropil AB (n = 1), anti-Hu/Sox/Zic/GABA B AB (n = 1), and anti-Hu/Zic-4 AB (n = 1)]
Two patients (n = 2/9) had neuropsychological deficits consistent with autoimmune encephalitis (AE) (Supplementary Table 1). Neither of these patients fulfilled the clinical diagnostic criteria for definite autoimmune limbic encephalitis defined by Graus et al [4], as they did not present with bilateral magnetic resonance imaging (MRI) brain abnormalities
Summary
Epilepsy and new onset seizures in elderly patients are an important health issue of the aging population [1, 2]. Autoimmune Encephalitis in Late-Onset Seizures encephalitis proposed by Graus et al [4] enable the diagnosis of AE even in the absence of neural antibodies and include neuropsychiatric symptoms of new-onset seizures, bilateral changes in magnetic resonance imaging (MRI), such as T2/fluidattenuated inversion recovery (FLAIR) hyperintense signal alterations prominently in the medial temporal lobes, and either cerebrospinal fluid (CSF) pleocytosis or EEG abnormalities [4]. Diagnostic criteria for possible AE include subacute neuropsychiatric deficits and either new focal CNS findings, seizures, CSF pleocytosis, or pathognomonic MRI features [4]. The diagnostic criteria for neural antibody (AB) negative but probable AE include the detection of oligoclonal bands (OCB) in CSF [4]. Small case series suggest using FDG-PET in cases of suspected AE and normal MRI, as FDG-PET has been reported to be more sensitive than MRI [7,8,9]
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