ABSTRACT
<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>