Benign Neonatal Sleep Myoclonus Evokes Somatosensory Responses.

PURPOSE: Benign neonatal sleep myoclonus is a common nonepileptic condition occurring in neurologically normal full-term newborns. During jerks, EEG has always been described as normal. The aim of this study was to describe EEG changes associated with the myoclonic jerks. METHODS: Polygraphic video-EEG recordings of four full-term neonates presenting benign neonatal sleep myoclonus were studied. Myoclonic jerks were analyzed regarding their topography, frequency, propagation pattern, and reflex component. EEG averaging time-locked to myoclonic jerks and to somatosensory stimuli (realized by tapping on palms and feet) was performed to study eventual EEG correlates of myoclonus and to asses somatosensory evoked responses-for the latter, two control newborns were added. RESULTS: Visual analysis of the EEG disclosed theta band slow waves on central and vertex electrodes concomitant to myoclonic jerks and jerk-locked back-averaging disclosed a sequence of deflections, not preceding, but following the myoclonus. This response predominated on the vertex electrode (CZ) and consisted of five components (N1, P1, N2, P2, and N3), with only the three later components being constantly present (at 110, 200, and 350-500 ms, respectively). Back-averaging locked to the tactile stimuli in four subjects and two control newborns showed similar components and were comparable to those described in the literature as late somatosensory evoked responses in full-term newborns. CONCLUSIONS: Myoclonic jerks in benign neonatal sleep myoclonus can evoke visually identifiable EEG potentials on vertex electrodes corresponding to somatosensory responses. This EEG aspect may be misleading and could give rise to an anti-seizure treatment that mostly worsens the condition.

Positive slow waves in the EEG of premature infants between 24 and 36 weeks of conceptional age.

OBJECTIVE: The aim of this prospective and longitudinal study was to characterize EEG patterns during the first weeks of life in extremely premature infants. METHODS: Twenty-five extremely premature infants were included and weekly EEG recordings were obtained between 24 and 36 weeks of conceptional age (CA). RESULTS: Central (rolandic) positive slow waves (CPSW) were found to be the most reliable and characteristic pattern. CPSWs were frequent at 24 weeks CA and progressively diminished and disappeared around 34 weeks CA. CPSWs appeared isolated or in sequences, they occurred during periods of continuous or discontinuous EEG activity, during bursts or during intervals of discontinuous activity, and unilaterally or bilaterally. Temporal positive slow waves and theta rhythms occurred less often and did not decrease as a function of CA. In addition, the amount of discontinuity progressively decreased until 36 weeks CA. The duration of bursts stayed constant, while inter-burst intervals decreased as a function of CA. CONCLUSIONS: Central positive slow waves are characteristic features of the EEG in the extremely premature infant. SIGNIFICANCE: The presence of CPSWs and their progressive disappearance until 34 weeks CA may represent a maturational marker in the EEG.