Extracellular Concentrations of Non–Transmitter Amino Acids in Peri-Infarct Tissue of Patients Predict Malignant Middle Cerebral Artery Infarction

Abstract

Background and Purpose-Space-occupying brain edema is a life-threatening complication in patients with large middle cerebral artery (MCA) infarction. To determine predictors of this detrimental process, we investigated alterations of extracellular non-transmitter amino acid concentrations in peri-infarct tissue. Methods-Thirty-one patients with infarctions covering Ͼ50% of the MCA territory in early cranial CT scans were included in the study. Probes for microdialysis, intracranial pressure, and tissue oxygen pressure were placed into the noninfarcted ipsilateral frontal lobe. Positron emission tomography imaging was performed in 16 of these patients to measure cerebral blood flow in the tissue around the neuromonitoring probes. Results-Fourteen of the 31 patients developed a malignant MCA infarction, and 17 did not. The patients in the malignant group had significantly lower extracellular concentrations of non-transmitter amino acids than those in the benign group in the first 12 hours of neuromonitoring. At this time, CBF values determined in regions of interest around the probes by positron emission tomography and tissue oxygen pressure showed that the monitored tissues were not yet infarcted, and no differences in transmitter amino acids concentrations were found between the 2 groups. Furthermore, extracellular concentrations of non-transmitter amino acids were negatively correlated with size of infarction. Conclusions-We

Identification and Clinical Impact of Impaired Cerebrovascular Autoregulation in Patients With Malignant Middle Cerebral Artery Infarction

“…In fact, edematous expansion of the extracellular space not detectable on CT scan seems to take place in the peri-infarct tissue of patients with malignant infarction. 21 We found the lactate-pyruvate ratio to be higher in patients with malignant infarction as early as 24 hours after stroke, and it was closely correlated with COR, supporting the assumption that tissue acidosis might be involved in the impairment of autoregulation in peri-infarct tissue. From our findings, we hypothesize a cascade-like, self-energizing sequela in patients with malignant MCA infarction: lactate and extracellular fluid from the vasogenic edema of the infarct core spread into peri-infarct tissue and impair autoregulation in this compartment.…”

Recommendations for the Management of Cerebral and Cerebellar Infarction With Swelling

“…29,61,62 Other descriptions include effacement of the ipsilateral sulci and lateral ventricle 63 and CT signs of elevated ICP. 64 Most commonly, the degree of midline shift is used as the benchmark for radiographic deterioration, either undefined 16,60,65 or specified as >5 mm at the level of septum pellucidum, 19,41,47,[66][67][68] >2 mm at the level of septum pellucidum or pineal gland, 69,70 or >10 mm.…”

“…Hemispheric stroke with marked blood pressure changes may be attributable to unusual circumstances such as an aortic dissection or myocardial infarction, and further diagnostic tests might be necessary. There is marked variation in set blood pressure goals in published studies 31,61 or avoidance of antihypertensive agents in the first days. 5 However, hypertension, defined as systolic blood pressure >220 mm Hg or diastolic pressure >105 mm Hg, increases the risk of hemorrhagic transformation.…”

In Vivo Regional Neurochemistry in Stroke: Clinical Applications, Limitations, and Future Directions

“…1 The authors should be commended on their elegant work with multi-modality monitoring in predicting "malignant" infarction with large middle cerebral artery ischemia. However, the technique of in vivo cerebral microdialysis utilized in this study deserves several comments that are generally applicable to similar studies.…”

“…We have to thank Dr. Bhardwaj for his valuable comments on our microdialysis study on patients suffering from hemispheric stroke, 1 and we would like to briefly respond. Cerebral in vivo microdialysis has become a common research technique in neuro critical care in recent years, [2][3][4][5] and one example is monitoring in severe stroke patients to predict and evaluate the further clinical course.…”