Continuous EEG Findings in Autoimmune Encephalitis

Area of Science:

• Neurology
• Neurophysiology
• Immunology

Background:

• Autoimmune encephalitis (AE) is a significant cause of new-onset seizures and new-onset refractory status epilepticus.
• Limited research exists on the specific electroencephalogram (EEG) patterns associated with AE.
• Understanding AE's EEG signature is crucial for diagnosis and prognosis.

Purpose of the Study:

• To investigate the characteristic EEG patterns in patients diagnosed with autoimmune encephalitis.
• To identify potential EEG signatures specific to different subtypes of AE.
• To determine the prognostic value of EEG findings in AE, including seizures and status epilepticus.

Main Methods:

• A multicenter retrospective review was conducted on patients diagnosed with AE.
• Continuous EEG monitoring data from these patients were analyzed.
• Patients were categorized based on antibody status and AE subtype.

Main Results:

• Electrographic seizures were present in 53% of patients, and new-onset refractory status epilepticus occurred in 19%.
• Periodic or rhythmic EEG patterns were observed in 63% of patients, with 38% showing plus modifiers.
• Generalized rhythmic delta activity plus fast activity, termed extreme delta brush, was significantly associated with anti-N-methyl-D-aspartate receptor AE and predicted poor outcomes, as did seizures and new-onset refractory status epilepticus.

Conclusions:

• A specific EEG pattern, generalized rhythmic delta activity plus fast activity (extreme delta brush), is confirmed as a signature for anti-N-methyl-D-aspartate receptor AE.
• No other specific EEG patterns were associated with different AE subtypes.
• The presence of periodic/rhythmic patterns, seizures, and new-onset refractory status epilepticus independently increased the risk of poor outcomes in AE patients.