Relationship between excitatory amino acid release and outcome after severe human head injury.
In previous studies, Katayama and our group have documented a massive increase in excitatory amino acid release following traumatic brain injury, in both rat fluid percussion, and humans [2,5]. To test the hypothesis that the magnitude of this "Excitotoxic Surge" plays a significant role in determining 6-month patient outcome. We have studied 83 consecutive severely head injured patients at the Medical College of Virginia for inclusion into this study. A microdialysis probe was placed within the cortex to continuously measure dialysate excitatory amino acids (Glutamate and Aspartate), along with several other analytes for approximately 5 days after injury. ICP, CPP, and MABP measurements were also time linked with each analyte measurement to create a neurochemical, clinical, and physiological "profile" for each patient. Outcome was determined by follow up using the Glasgow 6-Month outcome scale. A very strong correlation existed between the release of the EAA's glutamate and aspartate after TBI (p < 0.0001). Patients with significantly elevated mean glutamate values for the entire monitoring period were most likely to exhibit elevated levels of ICP. The magnitude of glutamate released significantly correlates with 6-month patient outcome (p = 0.0234). When patients were subdivided by the CT diagnosis of lesion type, we found that those patients with contusions displayed the highest overall of EAA's.
Division of Neurosurgery, Medical College of Virginia, Virginia Commonwealth University, Richmond, USA.
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Koura
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Doppenberg
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Marmarou
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Choi
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Young
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Bullock
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001925:Brain Damage, Chronic / Q000175:diagnosis* / Q000503:physiopathology; D001930:Brain Injuries / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000293:injuries / Q000503:physiopathology; D018846:Excitatory Amino Acids / Q000378:metabolism*; D015600:Glasgow Coma Scale; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D017551:Microdialysis; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D051381:Rats
D018846:Excitatory Amino Acids; D001224:Aspartic Acid; D018698:Glutamic Acid