Vespa P, Prins M, Ronne-Engstrom E, Caron M, Shalmon E, Hovda D A, Martin N A, Becker D P
Department of Surgery, University of California Los Angeles School of Medicine, 90024, USA.
J Neurosurg. 1998 Dec;89(6):971-82. doi: 10.3171/jns.1998.89.6.0971.
To determine the extent and duration of change in extracellular glutamate levels after human traumatic brain injury (TBI), 17 severely brain injured adults underwent implantation of a cerebral microdialysis probe and systematic sampling was conducted for 1 to 9 days postinjury.
A total of 772 hourly microdialysis samples were obtained in 17 patients (median Glasgow Coma Scale score 5+/-2.5, mean age 39.4+/-20.4 years). The mean (+/-standard deviation) glutamate levels in the dialysate were evaluated for 9 days, during which the mean peak concentration reached 25.4+/-13.7 microM on postinjury Day 3. In each patient transient elevations in glutamate were seen each day. However, these elevations were most commonly seen on Day 3. In all patients there was a mean of 4.5+/-2.5 transient elevations in glutamate lasting a mean duration of 4.4+/-4.9 hours. These increases were seen in conjunction with seizure activity. However, in many seizure-free patients the increase in extracellular glutamate occurred when cerebral perfusion pressure was less than 70 mm Hg (p < 0.001). Given the potential injury-induced uncoupling of cerebral blood flow and metabolism after TBI, these increases in extracellular glutamate may reflect a degree of enhanced cellular crisis, which in severe head injury in humans appears to last up to 9 days.
Extracellular neurochemical measurements of excitatory amino acids may provide a marker for secondary insults that can compound human TBI.
为了确定人类创伤性脑损伤（TBI）后细胞外谷氨酸水平变化的程度和持续时间，17名重度脑损伤成人接受了脑微透析探针植入，并在伤后1至9天进行了系统采样。
17名患者（格拉斯哥昏迷量表中位数评分5±2.5，平均年龄39.4±20.4岁）共获得772个每小时一次的微透析样本。对透析液中的谷氨酸平均（±标准差）水平进行了9天的评估，在此期间，平均峰值浓度在伤后第3天达到25.4±13.7微摩尔。在每名患者中，每天都可见谷氨酸的短暂升高。然而，这些升高最常见于第3天。所有患者谷氨酸平均有4.5±2.5次短暂升高，平均持续时间为4.4±4.9小时。这些升高与癫痫活动同时出现。然而，在许多无癫痫发作的患者中，当脑灌注压低于70毫米汞柱时，细胞外谷氨酸会升高（p<0.001）。鉴于创伤性脑损伤后可能由损伤引起的脑血流与代谢解偶联，这些细胞外谷氨酸的升高可能反映了一定程度的细胞危机加剧，在人类重度颅脑损伤中这种情况似乎可持续长达9天。
兴奋性氨基酸的细胞外神经化学测量可能为加重人类创伤性脑损伤的继发性损伤提供一个标志物。
