Concurrent monitoring of cerebral electrophysiology and metabolism after traumatic brain injury: An experimental and clinical study

Oscar L. Alves, Ross Bullock, Tobias Clausen, Michael Reinert, Thomas M. Reeves

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Multiparameter cerebral monitoring has been widely applied in traumatic brain injury to study posttraumatic pathophysiology and to manage head-injured patients (e.g., combining O2 and pH sensors with cerebral microdialysis). Because a comprehensive approach towards understanding injury processes will also require functional measures, we have added electrophysiology to these monitoring modalities by attaching a recording electrode to the microdialysis probe. These dual-function (microdialysis/electrophysiology) probes were placed in rats following experimental fluid percussion brain injuries, and in a series of severely head-injured human patients. Electrical activity (cell firing, EEG) was monitored concurrently with microdialysis sampling of extracellular glutamate, glucose and lactate. Electrophysiological parameters (firing rate, serial correlation, field potential occurrences) were analyzed offline and compared to dialysate concentrations. In rats, these probes demonstrated an injury-induced suppression of neuronal firing (from a control level of 2.87 to 0.41 spikes/sec postinjury), which was associated with increases in extracellular glutamate and lactate, and decreases in glucose levels. When placed in human patients, the probes detected sparse and slowly firing cells (mean = 0.21 spike/sec), with most units (70%) exhibiting a lack of serial correlation in the spike train. In some patients, spontaneous field potentials were observed, suggesting synchronously firing neuronal populations. In both the experimental and clinical application, the addition of the recording electrode did not appreciably affect the performance of the microdialysis probe. The results suggest that this technique provides a functional monitoring capability which cannot be obtained when electrophysiology is measured with surface or epidural EEG alone.

Original languageEnglish (US)
Pages (from-to)733-749
Number of pages17
JournalJournal of neurotrauma
Issue number7
StatePublished - Jul 2005


  • Cerebral monitoring
  • Electrophysiology
  • Extracellular glutamate
  • Metabolic dysfunction
  • Microdialysis
  • Traumatic brain injury

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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