The EEG Features of Four Cases of Subacute Sclerosing Panencephalitis in North China: SSPE EEG Features.

Objective. To analyze the EEG features of four subacute sclerosing panencephalitis cases in North China. Methods. We retrospectively analyzed the EEG features in four patients with subacute sclerosing panencephalitis and 12 patients in control group from North China. Results. The periodic long-interval diffuse discharges were found in all of the four cases with subacute sclerosing panencephalitis. The morphology and component of periodic complexes were varied in different patients and different wakefulness states. Some EEG parameter settings help to identify periodic long-interval diffuse discharges including the slowed sweep speed, decreased sensitivity and reduced number of montages. In each patient with subacute sclerosing panencephalitis, the periodic long-interval diffuse discharges associated with two types of brief episodes (1:1) during awake period were found and none of the patients in the control group had this EEG pattern. The score system based on the periodic discharges and brief episodes also shows that all the patients with SSPE reached score 5 while none of the patients in the control group has a score greater than 3, which suggests that this EEG pattern may have diagnostic value. Conclusions. In subacute sclerosing panencephalitis, the morphology and component of periodic long-interval diffuse discharges were varied in different patients and different wakefulness states. Specific EEG parameter settings help to identify periodic long-interval diffuse discharges. Periodic long-interval diffuse discharges associated with two types of brief episodes (1:1) during awake period may strongly suggest the diagnosis of subacute sclerosing panencephalitis.