A Special Electroencephalography Pattern Might Help in the Diagnosis of Antibody-positive Encephalitis

Patterns observed with electroencephalography (EEG) for patients who have encephalitis are usually known as generalized nonspecific cerebral abnormalities. The aim of this study was to investigate the presence of a special EEG pattern for patients with encephalitis and to explore features related to this special and uncommon pattern.

EEG monitoring was performed for every patient aged >15 years with encephalitis who was hospitalized between December 2011 and March 2014. Clinical characteristics and EEG recordings were collected and evaluated.

Fifty-two patients with encephalitis were enrolled in our study with a 2-h median EEG recording time, and extreme beta brushes (EBBs) occurred in 17 patients (32.7%). Its presence was not significant regarding gender, age, psychiatric medication use, EEG rhythmic disorganization (P > 0.05). Nevertheless, among the patients with EBBs, nine patients (52.9%) had epileptic seizures that had a significant detection rate (P < 0.05); moreover, the cerebrospinal fluid (CSF) or serum of 15 patients (88.2%) with EBBs was positive for antibodies (P < 0.05). Four patients (23.5%) who had EBB had corresponding regional distributions on neuroimaging scans. The EBBs completely correlated with the regional distributions of spike discharges for four patients.

EBB is a special EEG pattern for patients with encephalitis, especially those with epileptic seizures or who have antibody-positive CSF/serum, and should be considered in clinical practice.