Functional connectivity in cortical networks is thought to be important for consciousness and can be disrupted during the anesthetized state. Recent work in adults has revealed dynamic connectivity patterns during stable general anesthesia, but whether similar connectivity state transitions occur in the developing brain remains undetermined. The hypothesis was that anesthetic-induced unconsciousness is associated with disruption of functional connectivity in the developing brain and that, as in adults, there are dynamic shifts in connectivity patterns during the stable maintenance phase of general anesthesia.
This was a preplanned analysis of a previously reported single-center, prospective, cross-sectional study of healthy (American Society of Anesthesiologists status I or II) children aged 8 to 16 yr undergoing surgery with general anesthesia (n = 50) at Michigan Medicine. Whole-scalp (16-channel), wireless electroencephalographic data were collected from the preoperative period through the recovery of consciousness. Functional connectivity was measured using a weighted phase lag index, and discrete connectivity states were classified using cluster analysis.
Changes in functional connectivity were associated with anesthetic state transitions across multiple regions and frequency bands. An increase in prefrontal–frontal alpha (median [25th, 75th]; baseline, 0.070 [0.049, 0.101] vs. maintenance 0.474 [0.286, 0.606]; P < 0.001) and theta connectivity (0.038 [0.029, 0.048] vs. 0.399 [0.254, 0.488]; P < 0.001), and decrease in parietal–occipital alpha connectivity (0.171 [0.145, 0.243] vs. 0.089 [0.055, 0.132]; P < 0.001) were among those with the greatest effect size. Contrary to the hypothesis, connectivity patterns during the maintenance phase of general anesthesia were dominated by stable theta and alpha prefrontal–frontal and alpha frontal–parietal connectivity and exhibited high between-cluster similarity (r = 0.75 to 0.87).
Changes in functional connectivity are associated with anesthetic state transitions but, unlike in adults, connectivity patterns are constrained during general anesthesia in late childhood and early adolescence.
- Patterns of connectivity between different brain regions (functional connectivity) undergo structured shifts during stable general anesthesia
- However, in the developing brain, the presence of these connectivity patterns and how they may change across time have not been investigated
- During the stable maintenance phase of general anesthesia, functional connectivity patterns in the developing brain are relatively static, in contrast to the dynamic structured transitions previously shown in adults
- Using conventional methods to measure functional connectivity, the developing brain demonstrated a hyperconnected frontal cortex during the loss of consciousness, maintenance, and emergence periods
- This was most marked for frequencies less than 14 Hz and between the prefrontal and frontal regions