Abstract
Background/Aims: Near-infrared spectroscopy (NIRS) is used to study the hemodynamic response to visual stimulation in slee** neonates. The specific aims of this study were to determine whether a response in the visual cortex can be detected in term neonates during the first days of life and, if so, to determine the direction and magnitude of changes in deoxyhemoglobin (HHb) during stimulation.
Methods: Ten healthy, term neonates, aged 2 to 14 d, were subjected to binocular visual stimulation using red lights, flashing at a frequency of 0.5 or 1 Hz. Lights were directed towards each eye at a distance of approximately 5 cm. Stimulation periods of 20 s were alternated with rest periods of approximately 20 s. An in-house developed NIRS imaging instrument, the MCP-II, measured localized changes in concentrations of oxyhemoglobin (O2Hb) and HHb. The NIRS sensor contains 4 light sources and 4 photodetectors covering an area of 2.5 by 3.75 cm with 10 different light paths at 100 Hz. The centre of the sensor was positioned 1 cm above the inion.
Results: The concentrations of O2Hb and HHb during the last 10 s of the stimulation period were compared to the concentrations during the 10 s preceding stimulation. In 6 out of 10 subjects, a significant (p< 0.01) increase in O2Hb and/or a significant decrease in HHb was observed in one or more locations. During stimulation, O2Hb increased by a mean of 1.3 micromol/l, HHb decreased by a mean 0.5 micromol/l, and total Hb increased by a mean of 0.9 micromol/l.
Conclusions: Our results show that a hemodynamic response to visual stimulation, similar to that observed in adults, can be measured in slee** neonates. The increase in O2Hb and simultaneous decrease in HHb during stimulation suggest an increase in cerebral blood flow that overcompensates for the increased oxygen consumption in the activated cortical area.
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Morren, G., Karen, T., Haensse, D. et al. 258 Investigation of the Hemodynamic Response to Flash Visual Stimulation in Neonates Using Near Infrared Spectroscopy. Pediatr Res 58, 398 (2005). https://doi.org/10.1203/00006450-200508000-00287
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DOI: https://doi.org/10.1203/00006450-200508000-00287
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