ObjectiveTo compare and analyze the electroencephalographic (EEG) characteristics of infants with infantile epileptic spasms syndrome (IESS) and healthy infants during sleep using power spectral density (PSD) analysis. MethodsInfants aged 5 to 9 months with IESS were included, along with an equal number of age-matched healthy controls. EEG signals during sleep were recorded using the Nihon Kohden EEG-1200C system. The energy distribution in the theta (θ), alpha (α), sigma (σ), and beta (β) frequency bands, as well as the morphology and values of PSD within the 4 ~ 30 Hz range, were analyzed. Additionally, spectral entropy (SpEn) was calculated to evaluate signal complexity. Results A total of 10 IESS patients and 10 healthy infants were included. There were no significant differences in gender or age between the two groups (P=0.64, P=0.88). In both groups, PSD values showed a linear decreasing trend with increasing frequency. However, the IESS group showed notable differences in PSD morphology, amplitude, and energy distribution compared to controls. These included the absence of a σ-band peak, greater PSD dispersion across electrodes, significant alterations in energy distribution across θ, α, σ, and β bands, and significantly higher PSD values in the 4 ~ 30 Hz range (P<0.000 1). SpEn analysis revealed significantly elevated spectral entropy across the sigma band in the IESS group, indicating a lack of dominant frequencies, increased complexity, reduced rhythmicity, and enhanced disorder. In contrast, healthy controls exhibited elevated SpEn in the alpha band, reflecting the physiological reduction or disappearance of dominant alpha rhythms during sleep. Conclusion Infants with IESS demonstrate distinct EEG characteristics in both PSD and SpEn analyses compared to healthy infants. These quantitative spectral features reflect the underlying abnormalities of EEG in IESS and provide objective insights that complement conventional visual assessment, offering a novel perspective for early diagnosis and therapeutic monitoring.
