Recurrent seizures of autoimmune origin: emerging phenotypes

Area of Science:

• Neurology
• Immunology
• Epileptology

Background:

• Recurrent seizures of autoimmune origin (AEp) are a significant cause of epilepsy, often presenting with unknown etiology.
• Identifying specific phenotypes of AEp is crucial for accurate diagnosis and management.

Purpose of the Study:

• To identify specific phenotypes corresponding to autoimmune epilepsy (AEp).
• To assess the prevalence and characteristics of AEp in patients with recurrent seizures of unknown cause.

Main Methods:

• Retrospective review of patients with recurrent seizures of unknown cause investigated for AEp (January 2015-May 2018).
• Classification into AEp with positive autoantibodies (AEpAb+), suspected AEp without autoantibodies (AEpAb-), and non-autoimmune epilepsy (NAEp).
• Analysis of clinical features, cerebrospinal fluid (CSF) antibody detection, and associated conditions.

Main Results:

• 61.4% of eligible epileptic patients were diagnosed with AEp (21% AEpAb+, 40.4% AEpAb-).
• AEp was associated with higher antibody prevalence in epilepsy (APE) scores, encephalitic phase, psychiatric involvement, cognitive impairment, and status epilepticus.
• Over one-third of chronic epilepsy patients (NEP) without an encephalitic phase were diagnosed with AEp (AEpAb+ and AEpAb-), linked to non-cerebral autoimmune disorders and cognitive impairment.

Conclusions:

• Autoimmune causes should be evaluated in patients with recurrent seizures of unknown origin.
• Acute encephalitis is a primary AEp phenotype, but AEp is also present in over a third of chronic epilepsy cases.
• AEp can be associated with other autoimmune comorbidities, shorter seizure duration, and cognitive deficits.