Neurochemical Monitoring of Therapeutic Effects in Large Human MCA Infarction

Background and purpose Cerebral microdialysis is an invasive monitoring tool allowing analysis of various substances derived from the extracellular space in brain tissue such as glutamate, glycerol, lactate, and pyruvate. In order to assess the potential effects of hemicraniectomy, hypothermia and conservative therapy on these substances, we used neurochemical monitoring with microdialysis in large human stroke patients. Methods This is an open, prospective observational study in 24 patients with large MCA infarction undergoing either hypothermia (33C), hemicraniectomy, or maximum conservative therapy. Microdialysis probe placement was aimed at the peri-infarct tissue within 24 h after stroke onset. Glutamate, glycerol, pyruvate, and lactate were analyzed every 60 min. Measurements of two consecutive days were pooled for statistical analysis. Results Average glutamate concentrations in patients treated with hemicraniectomy (5.3 +/- 0.5 mu mol/l, P < 0.0001; n = 6) and hypothermia (14.5 +/- 3.6 mu mol/l, P < 0.0001; n = 14) were significantly lower than in conservatively treated patients (68.3 +/- 5.2 mu mol/l; n = 4). Glycerol concentration was significantly lower in patients treated by hypothermia (111 +/- 17 mu mol/l; P < 0.0001) and hemicraniectomy (138 +/- 8 mu mol/l; P < 0.0001) as compared to conservatively treated patients with 612 +/- 27 mu mol/l. The lactate-pyruvate ratio was significantly lower both in the hypothermia (16.2 +/- 3.3) and hemicraniectomy groups (31.3 +/- 1.5) than in the conservative treatment group (56 +/- 2.9). Conclusion Microdialysis allows bed-side monitoring of neuroprotective effects of stroke rescue therapies such as hypothermia and hemicraniectomy. Rescue of peri-infarct tissue and/or prevention of secondary ischemic injury could be associated with a lower mortality in invasively treated patients.