Purpose
To analyse cases with suspected autoimmune-associated epilepsy (AAEp) and to compare them to patients with acute symptomatic seizures secondary to autoimmune encephalitis (ASS-AEn).
Methods
Single-centre retrospective analysis of patients with suspected AAEp seen in an outpatient epilepsy clinic between 2014 and 2021. Differences according to autoimmune testing results and their responsiveness to immunotherapy were assessed and compared with our cohort of patients with ASS-AEn.
Results
A total of 30 patients were included: 18 women (60%); mean age 28.2 years at seizure-onset. AAEp was diagnosed in 14 (46.6%), on the basis of antineuronal antibodies, CSF pleocytosis/OCB (oligoclonal bands), MRI with neuroinflammation, and/or PET hypermetabolism. Thirteen patients (43.3%) received immunotherapy, of whom 5 responded (38.4%). Delay between epilepsy-onset and autoimmune testing was longer in patients with negative autoimmune-testing and in non-responders. Viral prodrome (P < .035), associated neurological signs/symptoms and MRI showing neuroinflammation were more common in responders. ASS-AEn patients were older (P < .019), and more frequently presented coexisting neurological signs/symptoms (P < .0001), antineuronal cell-surface antibodies (P < .009), neuroinflammation on MRI, PET hypermetabolism (P < .01), CSF pleocytosis (P < .047), and higher APE (antibody prevalence in epilepsy)/RITE (response to immunotherapy in epilepsy)-scores (P < .022/P < .004). Drug-refractoriness (P < .033) was more common in AAEp. ASS-AEn received immunotherapy more frequently, with better outcomes. Diagnosis and treatment delay were longer in AAEp (P < .0001).
Conclusion
Isolated/chronic AAEp is a rare, drug-resistant epileptic-disorder. Early diagnosis is essential for immunotherapy. However, diagnostic and therapeutic delay is longer in AAEp than in ASS-AEn. This may indicate that currently there is less capacity to detect AAEp than ASS-AEn.