Cerebral microdialysis – mechanism of action and application in clinical practice

Cerebral microdialysis enables bedside assessment of the concentration of selected metabolites in the patient’s brain. The modern microdialysis device consists of a double-lumen probe. Its interior is made of an impermeable material, while the outer layer is a semipermeable membrane through which the tested microdialysate penetrates from the brain. At the end of the probe, there is an opening connecting the outer lumen with the inner lumen, used to deliver the so-called perfusate − a solution isotonic with the brain’s extracellular fluid. Chemical compounds diffuse through the semipermeable membrane of the outer probe according to the concentration gradient, reaching the collection chamber. Therefore, the microdialysis probe placed in the brain parenchyma can be compared to an artificial capillary vessel, where substances are exchanged based on the concentration gradient. The microdialysate reflects the biochemical state of the area in which the probe is placed. There are reports on the benefits of cerebral microdialysis in patients after subarachnoid haemorrhage, traumatic brain injury, and cerebrovascular accidents. Further studies suggest the potential for its use in epilepsy, bacterial meningitis, and in the assessment of drug distribution and pharmacokinetics in the brain. Advances in temporal and spatial resolution create opportunities for the increasingly widespread use of microdialysis in both research and clinical practice. The aim of this study is to describe the principles of microdialysis, discuss examples of its application in clinical practice, and outline the limitations and indications for implanting an intracerebral microdialysis probe.