Modulation of EEG spectral edge frequency during patterned pneumatic oral stimulation in preterm infants

Abstract

Background: Stimulation of the nervous system plays a central role in brain development and neurodevelopmental outcomes. Thalamocortical and corticocortical development is diminished in premature infants and correlated to electroencephalography (EEG) progression. The purpose of this study was to determine the effects of orocutaneous stimulation on the modulation of spectral edge frequency fc = 90% (SEF-90), which is derived from EEG recordings in preterm infants.

Methods: A total of 22 preterm infants were randomized to experimental and control conditions. Pulsed orocutaneous stimulation was presented during gavage feedings begun at ~32 wk postmenstrual age. The SEF-90 was derived from two-channel EEG recordings.

Results: Compared with the control condition, the pulsed orocutaneous stimulation produced a significant reorganization of SEF-90 in the left (P = 0.005) and right (P < 0.0001) hemispheres. Notably, the left and right hemispheres showed a reversal in the polarity of frequency shift, demonstrating hemispheric asymmetry in the frequency domain. Pulsed orocutaneous stimulation also produced a significant pattern of short-term cortical adaptation and a long-term neural adaptation manifested as a 0.5 Hz elevation in SEF-90 after repeated stimulation sessions.

Conclusion: This is the first study to demonstrate the modulating effects of a servo-controlled oral somatosensory input on the spectral features of EEG activity in preterm infants.

Figure 1

Examples of EEG/aEEG using the C3-P3 and C4-P4 electrode montage on two preterm infants recorded at 32 weeks PMA. 3-minute orocutaneous stimulation epochs are indexed by vertical cursors in the aEEG record (upper panel:13,15 and 17; lower panel:7, 8 and 9). Note the presence of aEEG modulation during pulsed orocutaneous stimulation. Wake-sleep cycles preceding orocutaneous stimulation periods are present.

Figure 2

Interval plot of SEF-90 for cross-head (C3-P3 and C4-P4) montage for blind ‘sham’ pacifier (circle symbols) versus the ‘pulsed’ pacifier (triangle symbols). Data are included from all stimulation sessions of all infants. Filled symbols represent stimulation conditions. Open symbols indicate periods when neither sham nor pulsed pacifier was in the baby's mouth. Contiguous EEG periods (data blocks) labeled 1 through 9 (periods). All periods are 3 minutes except for periods 4 and 6 which are 5.5 minutes in duration.

Figure 3

Plot of the SEF-90 for cross-head (C3-P3 and C4-P4) montage for blind ‘sham’ pacifier (circle symbols) versus the ‘pulsed’ pacifier (triangle symbols) for the first stimulation session only. Filled symbols represent stimulation conditions. Open symbols indicate periods when neither sham nor pulsed pacifier was in the baby's mouth. Contiguous EEG periods (data blocks) labeled 1 through 9 (periods). All periods are 3 minutes except for periods 4 and 6 which are 5.5 minutes in duration.

Figure 4

Frequency-modulated orocutaneous stimulus burst pattern consisting of 6 pulses followed by a 2-second pause period. A servo-controlled microprocessor generates the signal gating function (a) to dynamically ‘charge’ the intraluminal pressure of the silicone pacifier (b) resulting in rapid changes in pacifier geometry (c).

Figure 5

Preterm infant with aEEG and pneumatically pulsed stimulation through a silicone pacifier coupled to the handpiece of the Ntrainer System (Innara Health, Inc., Shawnee, KS).