Seizures in autoimmune encephalitis: Findings from an EEG pooled analysis

Area of Science:

• Neurology
• Immunology
• Epileptology

Background:

• Seizures are a common manifestation of autoimmune encephalitis (AE), necessitating thorough investigation to rule out other causes.
• Identifying specific clinical and electroencephalographic (EEG) features can aid in diagnosing AE-related seizures, especially in late-onset cases.

Purpose of the Study:

• To identify clinical and EEG peculiarities suggestive of autoimmune encephalitis (AE) in patients with late-onset seizures.
• To improve the diagnostic accuracy for AE as a cause of new-onset seizures in adults.

Main Methods:

• Retrospective review of video-electroencephalographic (EEG) and ambulatory EEG (AEEG) recordings from 30 patients diagnosed with AE (median age 68 years).
• Analysis of posterior dominant rhythm, interictal epileptiform discharges (IEDs), clinical seizures (CSs), and subclinical seizures (SCSs).

Main Results:

• High-frequency focal seizures with prominent autonomic and emotional features were observed in a subset of AE patients.
• Subclinical seizures (SCSs) were more frequently detected via AEEG than clinical seizures (CSs).
• Multiple ictal EEG patterns were associated with widespread neuronal excitability in AE.

Conclusions:

• Adult-onset seizures, particularly focal ones with autonomic and emotional manifestations, warrant investigation for AE.
• Multiple ictal EEG patterns serve as a potential indicator of AE, suggesting underlying immune-mediated neuronal hyperexcitability.
• Prolonged EEG monitoring is vital for detecting subclinical and recurrent seizures in AE.