EEG in autoimmune encephalitis

The electroencephalogram (EEG) is an important paraclinical, noninvasive, reproducible investigation method for the diagnostic clarification of autoimmune encephalitis. It is also used for treatment monitoring in the event of epileptic seizures or status epilepticus. In the latter case, the continuous EEG recording is important. The EEG changes are mainly found over the temporal and frontal brain regions; they are mostly nonspecific and can also be observed in many other brain disorders. Only the so-called extreme delta brush indicates an anti-N-methyl-D-aspartate (NMDA) receptor-associated autoimmune encephalitis; its absence does not in any way mean the exclusion of such a disease. Faciobrachial dystonic seizures lasting only 1-2s appear in the context of autoimmune encephalitis due to anti-leucin-rich glioma-induced protein-1 (LGI-1) antibodies. They are almost pathognomonic and usually have no EEG correlate. In autoimmune encephalitis, the EEG seems to have a certain predictive power with respect to the course and prognosis.