Hemodynamic response to burst-suppressed and discontinuous electroencephalography activity in infants with hypoxic ischemic encephalopathy

Abstract

Abstract. Burst suppression (BS) is an electroencephalographic state associated with a profound inactivation of the brain. BS and pathological discontinuous electroencephalography (EEG) are often observed in term-age infants with neurological injury and can be indicative of a poor outcome and lifelong disability. Little is known about the neurophysiological mechanisms of BS or how the condition relates to the functional state of the neonatal brain. We used simultaneous EEG and diffuse optical tomography (DOT) to investigate whether bursts of EEG activity in infants with hypoxic ischemic encephalopathy are associated with an observable cerebral hemodynamic response. We were able to identify significant changes in concentration of both oxy and deoxyhemoglobin that are temporally correlated with EEG bursts and present a relatively consistent morphology across six infants. Furthermore, DOT reveals patient-specific spatial distributions of this hemodynamic response that may be indicative of a complex pattern of cortical activation underlying discontinuous EEG activity that is not readily apparent in scalp EEG.

Long-term continuous monitoring of the preterm brain with diffuse optical tomography and electroencephalography: a technical note on cap manufacturing

“…6,13,[25][26][27][28][29][30][31] Prior studies in this field have raised the issue related to the cap tolerance by the neonates as a possible factor limiting the duration of DOT data acquisition. Singh et al 6 and Chalia et al 13 adopted a soft and flexible cap (EasyCap, Germany, i.e., our outer layer), with a whole-head coverage for a multimodal DOT-EEG acquisition. Ferradal and colleagues 14 employed a custom-made optode holder, composed of five triangular patches joined together with a neoprene headband, fixed to the head via Velcro straps.…”

“…Austin et al 32 employed a custom-made helmet with whole-head coverage, made of an outer shell of thermoplastic and an inner part of NIR-absorbing foam. Crucially, in all these DOT studies, the length of registration did not exceeded 2 h, with a minimal length of 60 min 6,14 up to a maximum of 115 min 13 and the gestational age ranged from 34 weeks gestation 13 to term. Here, we showed that the adoption of our hand-made cap (NeoCAP) enabled a safe continuous DOT monitoring for a 7-day period in a very preterm infant.…”

“…[5][6][7][8][9][10][11][12] For instance, it can be employed in multimodal acquisitions with electroencephalography (EEG), which is used for seizure detection in clinical practice. So far, DOT studies in neonates have monitored hemodynamic changes in the whole brain up to a maximum of 2 h. 6,[13][14][15] Prolonging this "monitoring window" would, however, increase the chance to document important intracranial events in the neonatal population, such as seizures or intracranial hemorrhages. 16 The reasons that could explain the limited monitoring time lie primarily in (1) the discomfort of the optode holder for the baby and the skin damage that it can possibly produce and (2) a possible interference of the cap with clinical procedures and nursing.…”

Diffuse optical tomography to investigate the newborn brain

“…However, accurate DOT image reconstruction requires high-quality structural models of the subject's head to act as a prior for image reconstruction. Significant efforts have therefore been made to optimize an age-matched fourdimensional neonatal head model (74) using MRI head atlases as an alternative to subject-specific data (36,49,55). An advantage of using a standard atlas is that it facilitates group comparisons across subjects, as it defines a common coordinate space (75), although this reduces the spatial specificity of the DOT images (76).…”

Neurovascular coupling in the developing neonatal brain at rest

“…On the other hand, the CBF index was higher during wakefulness compared to quiet sleep in preterm infants (Greisen et al, ). A significant hemodynamic response to burst EEG activity (increase in HbO and variable changes in HbR) has been identified in term‐age infants with neurological injury (Chalia et al, ).…”