Pseudo-sawtooth pattern on amplitude-integrated electroencephalography in neonatal hypoxic–ischemic encephalopathy

The objective of this study was to describe a novel amplitude-integrated electroencephalography (aEEG) pattern in infants with hypoxic–ischemic encephalopathy (HIE) and to assess the clinical significance. The aEEG traces of infants with HIE who were treated with therapeutic hypothermia (TH) from 2012 to 2017 were analyzed. A pseudo-sawtooth (PST) pattern was defined as a periodic increase of the upper and/or lower margin of the trace on aEEG without showing seizure activities on conventional EEG (CEEG). Of the 46 infants, 6 (13%) had the PST pattern. The PST pattern appeared following a flat trace or a continuous low-voltage pattern and was followed by a burst-suppression pattern. On CEEG, the PST pattern consists of alternating cycles of low-voltage irregular activities and almost flat tracing. The PST pattern was associated with neuroimaging abnormalities and with various degrees of neurodevelopmental outcomes. Positive predictive values of the PST or worse pattern for adverse outcomes were high at 12 h after birth. A novel aEEG background pattern in infants with HIE was reported. The PST pattern likely indicates a suppressed background pattern and may be linked to unfavorable outcomes. Further multicenter validation study is needed to clarify its clinical significance.