Neuronal Networks during Burst Suppression as Revealed by Source Analysis.
BACKGROUND
Burst-suppression (BS) is an electroencephalography (EEG) pattern consisting of alternant periods of slow waves of high amplitude (burst) and periods of so called flat EEG (suppression). It is generally associated with coma of various etiologies (hypoxia, drug-related intoxication, hypothermia, and childhood encephalopathies, but also anesthesia). Animal studies suggest that both the cortex and the thalamus are involved in the generation of BS. However, very little is known about mechanisms of BS in humans. The aim of this study was to identify the neuronal network underlying both burst and suppression phases using source reconstruction and analysis of functional and effective connectivity in EEG.


METHODS
Dynamic imaging of coherent sources (DICS) was applied to EEG segments of 13 neonates and infants with burst and suppression EEG pattern. The brain area with the strongest power in the analyzed frequency (1-4 Hz) range was defined as the reference region. DICS was used to compute the coherence between this reference region and the entire brain. The renormalized partial directed coherence (RPDC) was used to describe the informational flow between the identified sources.


CONCLUSIONS
Delta activity during the burst phases was associated with coherent sources in the thalamus and brainstem as well as bilateral sources in cortical regions mainly frontal and parietal, whereas suppression phases were associated with coherent sources only in cortical regions. Results of the RPDC analyses showed an upwards informational flow from the brainstem towards the thalamus and from the thalamus to cortical regions, which was absent during the suppression phases. These findings may support the theory that a "cortical deafferentiation" between the cortex and sub-cortical structures exists especially in suppression phases compared to burst phases in burst suppression EEGs. Such a deafferentiation may play a role in the poor neurological outcome of children with these encephalopathies.
Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany.
Natia
N
Japaridze
Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
Muthuraman
M
Muthuraman
Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany.
Christine
C
Reinicke
Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom.
Friederike
F
Moeller
Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
Abdul Rauf
AR
Anwar
Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
Kidist Gebremariam
KG
Mideksa
Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom.
Ronit
R
Pressler
Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom.
Günther
G
Deuschl
Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany.
Ulrich
U
Stephani
Institute of Medical Psychology and Medical Sociology, Christian-Albrechts-University of Kiel, Kiel, Germany.
Michael
M
Siniatchkin
D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D063132:Connectome; D003700:Delta Rhythm; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology*