Clinical Presentation, Seizure Characteristics and Treatment Outcome in Seronegative Autoimmune Encephalitis – a Single Center Retrospective Cohort Study
Abstract number :
1.207
Submission category :
4. Clinical Epilepsy / 4B. Clinical Diagnosis
Year :
2023
Submission ID :
273
Source :
www.aesnet.org
Presentation date :
12/2/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Yixuan Huang, BA – University of California, Berkeley
Mark Waheed, D.O. – Neurology – Kaiser Permanente Sacramento Medical Center; Ning Zhong, M.D., Ph.D. – Neurology – Kaiser Permanente Sacramento Medical Center
Rationale: Seizures/epilepsy are often the prominent clinical feature in autoimmune encephalitis (AE). AE is mediated by the autoimmune system generating a series of autoantibodies to target the antigens of the central nervous system. The rapid and ongoing expansion of this field has been driven by the identification of more and more pathogenic autoantibodies. However, the diagnosis remains challenging and relies on the recognition of certain clinical manifestations, biomarkers identification, and therapy response. Seizures/epilepsy of autoimmune etiology can be further categorized into subcategories 1) autoimmune-associated epilepsy (AAE) and 2) acute symptomatic seizures in autoimmune encephalitis (ASSAE). Seronegative autoimmune encephalitis (SNAE) refers to the subcategory AE when clinical and imaging features suspicious for AE, but without any identifiable pathogenic autoantibody. SNAE remains less well characterized, possibly in part to because of its heterogeneous, and lack of established diagnostic criteria. Seizures in SNAE have received less research attention compared to other forms of AE due to the complexity in diagnosing.
Methods: We conducted a retrospective study that examined SNAE patients between 2015 and 2023. We analyzed the clinical characteristics, diagnostic workup (including laboratory tests, EEG, and neuroimaging), and treatment outcomes. To gain further insights, we compared the findings of SNAE patients with those of antibody positive autoimmune encephalitis (Ab-AE).
Results: The diagnosis of SNAE was carefully reviewed and validated by both epileptologists and neuroimmunologists, following the recommended criteria set forth by the AE alliance and the Antibody Prevalence in Epilepsy and Encephalopathy (APE2) Score (with a score greater than 6 indicating validation). Our analysis included 22 patients with SNAE and 25 patients with Ab-AE. The summarized findings, presented in the table, revealed that patients with SNAE exhibited fewer cognitive symptoms at clinical onset compared to those with Ab-AE. A lower proportion of patients in the SNAE group presented with pleocytosis in the CSF. However, there was a significant delay in the diagnosis of SNAE compared to Ab-AE. Notably, the SNAE group had a higher incidence of drug-resistant epilepsy (DRE) and refractory neuropsychiatric symptoms, which can be attributed to the fact that approximately 55% of these patients did not receive immunotherapy. Several distinct features were observed in patients with DRE, including a poor response to immunotherapy or the lack of its administration, persistent abnormal T2/FLAIR signals on brain MRI, and the presence of sustained focal epileptiform features and frequent ictal patterns on EEGs.
Conclusions: Based on our cohort, we found that making a timely diagnosis of autoimmune encephalitis (AE) remains a significant challenge. However, it is crucial to recognize the characteristic clinical presentation suggestive of AE, even in the absence of detectable autoantibodies, in order to initiate immunotherapy promptly. Early recognition and timely intervention are vital to prevent long-term neurological complications and sequelae.
Funding: No
Clinical Epilepsy