Dynamic Phase Amplitude Coupling Between ICP and EEG in Traumatic Brain Injured Patients

Mahsa Malekmohammadi1, Shadnaz Asgari, PhD1, Paul Vespa, MD1, Xiao Hu, PhD1

1Los Angeles, CA United States

Keywords: traumatic brain injury, electroencephalography, intracranial pressure, outcome, neurophysiological monitoring

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     Control of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) are cornerstones of management of traumatic brain injured (TBI) patients. B-waves in ICP have been attributed to periodic changes in cerebral blood volume (CBV) due to vasomotor instability when CPP is at the lower limit of pressure autoregulation. Fluctuations in neuronal electrophysiological activity are also known to induce CBV changes. However, the relationship between neuronal activity and ICP in head injured patients has not been characterized.
     We investigate dynamic coupling between EEG and ICP during B-waves to see whether coupling characteristics change relative to baseline conditions.
     We used Phase Amplitude Coupling (PAC) to quantify non-linear relationship between the phase of very slow periodic changes in ICP (0.02-0.4Hz) and the power in discrete frequency bands of EEG (0.5-30 Hz), as measured using depth electrodes. We used data from 5 subjects with TBI, including 10 minutes data segments containing baseline ICP and others containing B waves.
     In segments with B-waves, we report phase-amplitude coupling such that low-frequency ICP fluctuations are coupled to the amplitude of delta band EEG activity (1-4 Hz). This coupling is absent during baseline ICP episodes.
     This is a retrospective study.
     This is the first report of a dynamic relationship between electrophysiological activity and ICP in brain-injured patients during B-waves, a relationship which is absent during baseline conditions.
     This novel metric may have significant prognostic, management, and physiologic implications.


Project Roles:

M. Malekmohammadi (), S. Asgari (), P. Vespa (), X. Hu ()