Association With Autoimmune Diseases Differs Between Epilepsy Types

Researchers of a new study have characterized 2 distinct patterns of epilepsy syndromes and their association with autoimmune diseases, publishing their findings in Epileptic Disorders.

Collecting data from patients with idiopathic generalized epilepsies (IGEs) and mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), the researchers of the single-center study found that the relationships between epilepsy and autoimmune diseases may be a result of the different etiopathogenetic mechanisms that underly seizure development in each syndrome.

“This study represents an initial step toward better understanding of the different associations among these comorbid conditions,” commented the researchers. “By identifying shared mechanisms underlying development of these conditions, potential mediators and biomarkers may be discovered to predict the occurrence of epilepsy and autoimmune diseases.”

Between 2016 and 2020, over 600 patients—422 with IGEs and 242 with MTLE-HS—were consecutively enrolled in the study. Across the groups, the prevalence of autoimmune diseases was comparable at approximately 5%. Patients with IGEs were, on average, 15 years younger than those with MTLE-HS and were an average of 16 years younger at the age of autoimmune disease onset (20 vs 36.7 years).

Approximately 1 in 3 patients with an IGE had an autoimmune disease diagnosis that preceded their epilepsy, while all but 1 patient with MTLE-HS received their epilepsy diagnosis before their autoimmune disease diagnosis. This finding, explained the researchers, highlights the different patterns of association that the 2 epilepsy syndromes have with autoimmune diseases, with IGEs having a bidirectional relationship and MTLE-HS having a unidirectional relationship.

“The inflammatory mechanisms observed in MTLE-HS, such as the overproduction of proinflammatory cytokines and other inflammatory mediators, may activate an autoimmune response and lead to the development of autoimmune diseases in susceptible patients,” wrote the group. “In MTLE-HS, a better understanding of this unidirectional relationship may lead to the development of therapeutic approaches that target tissue-specific inflammatory processes, thereby preventing ongoing inflammation and avoid exacerbating inflammation that triggers autoimmune mechanisms leading to autoimmune diseases.”

Three patients with IGE had polyautoimmunity diagnosed: one patient with type 1 diabetes and psoriasis, one with Hashimoto’s thyroiditis and psoriasis, and one with alopecia areata and antiphospholipid syndrome. Among patients with MTLE-HS, 2 had polyautoimmunity: for immune thrombocytopenic purpura and antiphospholipid syndrome and for Hashimoto’s thyroiditis and Sjӧgren syndrome.

Among both groups of patients, skin manifestation was the most common manifestation, occurring in 56.5% of patients with IGEs and 63.6% of patients with MTLE-HS. Connective tissue disorders were more common among patients with MTLE-HS than among patients with IGEs (45.4% vs 8.7%). Multiple sclerosis was only observed in patients with IGEs, occurring in 17.4% of these patients.

Reference

Chaves J, Leal B, Sardoeira A, et al. Different relationships between epilepsy syndromes and autoimmune diseases. Epileptic Disord. Published online March 31, 2023. doi:10.1002/epd2.20048