Extracellular markers of impending malignant brain edema in large hemispheric stroke
Background: The development of malignant brain edema is a life-threatening complication of large hemispheric stroke. Hemicraniectomy and hypothermia are two invasive therapeutic options aiming to reduce mortality and to improve outcome in space-occupying MCA-infarction. The earlier such interventions are initiated the better is the chance of favourable outcome. However, therapeutic decision making is quite arbitrary as clinical observation, imaging or ICP measurement do not yield reliable prognostic criteria. Objective: To assess potential predictors of evolution of malignant brain edema in large MCA-infarction by microdialysis. Subjects and Methods: Following an ongoing prospective clinical trial invasive monitoring was performed in eight patients with large MCA-infarction. 18–36 hours after stroke onset a microdialysis probe was inserted in the parenchyma of the ipsilateral frontal lobe together with an ICP measuring device. Extracellular concentrations of glutamate, lactate, pyruvate, glycerol and various aminoacids were measured continuously for five days. CCT scans were performed on admission, after 6–12 h and at day 5. Scans were scrutinized for presence of mass-effect and size of infarction. Neurological deficit was assessed using the National Institutes of Health Stroke Scale (NIHSS). Results: Median NIHSS at baseline was 18 pts. (range 15–29 pts.). All patients suffered from a large stroke covering more than two thirds of the MCA-territory. In 4/8 patients an infarction of the entire territory of the MCA developed, in 3 of them with fatal space-occupying brain edema. The dynamics of the different substances varied in accordance with the clinical course, size of infarction and local brain edema: in patients with a massive edema in CCT an increase in glutamate concentrations and lactate/pyruvate-ratio was found, whereas patients without mass-effect demonstrated generally low and stable concentrations of these substances. Conclusion: In patients with large hemispheric infarction, bedside monitoring with microdialysis is feasible and may be valuable to predict impending malignant brain edema.