ABSTRACT
Multimodal cerebral monitoring was utilized to examine the relationship between pathological changes in microdialysis parameters and the occurrence of spreading depolarizations (SD) in brain-injured patients. SD are a relatively newly discovered phenomenon in man found to be linked to secondary insults and infarct growth and they can be detected via electrocorticography (ECoG). A total of 24 brain-injured patients (mean age: 52±11 years) requiring craniotomy took part in this prospective observational study. Each patient was monitored with a linear strip electrode for ECoG data and a cerebral microdialysis probe. SD were detected in 13 of the 24 patients. Pathological concentrations of glucose and lactate in brain parenchyma were significantly correlated with various time points prior to and/or immediately following the SD. Severe systemic hyperglycemia and systemic hypoglycemia were also found to be correlated with the occurrence of SD. The present study shows a clear relationship between SD and pathological changes in cerebral metabolism; further studies are needed to elucidate these complex interactions with the ultimate goal of developing therapeutic strategies for improving outcome in brain-injured patients.
Subject(s)
Brain Injuries/pathology , Cerebral Cortex/metabolism , Cerebral Cortex/physiopathology , Cortical Spreading Depression/physiology , Glucose/metabolism , Lactic Acid/metabolism , Adult , Electroencephalography/methods , Female , Humans , Male , Microdialysis/methods , Middle Aged , Prospective Studies , Severity of Illness Index , Statistics as Topic , Time FactorsABSTRACT
We evaluated the effect of intracranial hypertension on cerebral metabolism in patients with high grade aneurysmal subarachnoid hemorrhage (SAH) using bedside cerebral microdialysis (MD). Thirty-six patients with SAH were studied and classified into two groups (intracranial pressure, ICP > 20 mmHg, n = 25) and (ICP < 20 mmHg, n = 11). ICP was monitored hourly using an intraventricular drainage (n = 36). The MD catheter was placed after aneurysm clipping into the vascular territory of interest and was perfused with Ringer's solution (0.3 microl/min). The MD samples were collected hourly for measurements of glucose, lactate, and glutamate (CMA 600, Sweden). Lactate/pyruvate ratio was also calculated. To calculate group specific differences, the 24 hours median values of the first 7 days after SAH were compared. Differences were considered statistically significant at P < 0.05. Patient groups were comparable for age, severity of SAH, Fisher's grade and duration of MD sampling. In patients with ICP > 20 mmHg from day 1 to 7 after SAH, extracellular concentrations of glucose were significantly lower, while the lactate/ pyruvate ratio was higher compared to SAH patients with normal ICP values. The differences between groups in glutamate levels was only significant on day 1 after SAH due to high inter-individual differences. We concluded that intracranial hypertension in associated with an anaerobic cerebral metabolism indicated cerebral ischemia in high grade SAH patients.
Subject(s)
Intracranial Hypertension/diagnosis , Intracranial Hypertension/metabolism , Neurotransmitter Agents/metabolism , Subarachnoid Hemorrhage/diagnosis , Subarachnoid Hemorrhage/metabolism , Brain/physiopathology , Female , Humans , Intracranial Hypertension/etiology , Intracranial Pressure , Male , Microdialysis/methods , Middle Aged , Reproducibility of Results , Sensitivity and Specificity , Severity of Illness Index , Statistics as Topic , Subarachnoid Hemorrhage/complicationsABSTRACT
OBJECTIVE: To compare microdialysis (MD) and positron emission tomography (PET) in the detection of ischemia in aneurysmal subarachnoid hemorrhage (SAH) patients. METHODS: 15 SAH patients (13F/2M, 48+/-13 years, WFNS Grade I-V) were prospectively included in the study. A MD-catheter was inserted into the brain parenchyma most likely to be affected by vasospasm directly after aneurysm clipping. Glucose, pyruvate, lactate, glutamate and glycerol were analyzed hourly (CMA 600). 15O-H2O-PET scans (n=10) and 18F-FDG-PET scans (n=13) were performed between the day 2 and 17 after SAH. 15O-H2O-PET data were merged with CT scans to provide quantification of rCBF within the MD-ROI (rCBFMD; Amira, ZIB Berlin, Germany). 18F-FDG-PET data were evaluated visually by visual analysis. RESULTS: Regions of glucose hypometabolism were observed in 10 patients with symptoms of ischemia. Their rCBF was lower compared to asymptomatic patients (p<0.05). The MD levels of glutamate, lactate, the L/P ratio and glycerol were significantly higher in symptomatic than asymptomatic patients (p<0.05). Out of all measured MD parameters, glutamate showed the closest correlation with rCBF (r=-0.66, p=0.014). Microdialysis parameters were well correlated with glucose hypometabolism (18F-FDG-PET) and symptoms of ischemia. However, the threshold for a metabolic derangement was above the limits of cerebral ischemia defined by PET. CONCLUSION: MD is a useful tool to monitor ischemia, especially in patients with high-grade SAH.
