Continuous monitoring of cerebral metabolism in traumatic brain injury: a focus on cerebral microdialysis

Purpose of review This review highlights recent advances in cerebral microdialysis as a tool for neurochemical monitoring of patients with traumatic brain injury. Recent findings Progress in microdialysis research has come from validation studies of microdialysis biomarkers and clinical outcome in large cohorts of traumatic brain injury, patients and by combining microdialysis with other methods, such as positron emission tomography, magnetic resonance spectroscopy, brain tissue oximetry and electrophysiology. The combination of rapid-sampling microdialysis and electrocorticography has revealed complex, transient fluctuations of microdialysis glucose and lactate and depolarization-like events that may affect the secondary injury process. The,use of microdialysis to monitor global cerebral metabolic events (related to intracranial hypertension, or reduced cerebral perfusion pressure for, example) as opposed to focal events in peri-lesional brain tissue need to be clearly distinguished and the microdialysis catheter location verified by neuroimaging to ensure proper data interpretation. Differences in microdialysis biomarker levels between grey and white matter following traumatic brain injury need clarification. Summary Microdialysis is established as a neurochemical research tool in neurointensive care, particularly in combination with other monitoring methods, and contributes to a growing knowledge of secondary injury, mechanisms in traumatic brain injury. The value of microdialysis as a tool in routine neurointensive care decision-making remains unclear.