Schröder M L, Muizelaar J P, Kuta A J, Choi S C
Division of Neurosurgery, Medical College of Virginia, Richmond, USA.
J Neurotrauma. 1996 Jan;13(1):17-23. doi: 10.1089/neu.1996.13.17.
Cerebral ischemic insults in at least 30% of severely head injured patients at a very early stage following trauma and are associated with early death. To date, the threshold for ischemia of 18 mL/100g/min used in human head injury studies has been adopted from animal studies (by temporary occlusion of the middle cerebral artery). Since the traumatized brain becomes more susceptible to irreversible damage if accompanied by ischemia one may question whether the threshold for ischemic vulnerability is higher than 18 mL/100 g/min. Cerebral ischemia can cause atrophy. Therefore, the authors obtained computerized tomography (CT) scans in 33 comatose head-injured patients (Glasgow Coma Score of 8 or less) at least 3 months following injury and compared ventricle sizes (as a reflection of atrophy) with cerebral blood flow (CBF) obtained within 4 h (average 2.3 +/- 0.8 h) after injury. Ventricular measurements were performed in three fashions: the third ventricular size (cm), the bicaudate cerebral ventricular index (BCVI), and the hemispheric ventricular index (HCVI). No significant correlation was found between early CBF and any of the ventricule sizes. Applying a multiple correlation analysis with four independent parameters [CBF, CBF/time postinjury, CBF/(time postinjury)2, age], only age emerged as a significant indicator for predicting ventricle size (p < 0.001). We also compared CBF data, obtained within 4 h after trauma, from survivors at 3 months after injury (mean CBF of 32 mL/100 g/min) with CBF data from non-survivors (CBF 20 mL/100 g/min). The difference in CBF between survivors and nonsurvivors was significant at p < 0.001 (Wilcoxon rank-sum test). The proportion of patients with CBF less than or equal to 20 mL/100 g/min was 56% in the nonsurvivors and only 5% in survivors. The difference in the proportions was significant at p < 0.001 (chi-square test). We conclude that a measure of atrophy does not correlate with ultra-early CBF. However, based on the clear distinction between survivors and nonsurvivors, we suggest the threshold for ischemia after head injury be redefined as a CBF of 20 mL/100 g/min.
在创伤后极早期，至少30%的重度颅脑损伤患者会发生脑缺血性损伤，且与早期死亡相关。迄今为止，人类颅脑损伤研究中使用的18 mL/100g/min的缺血阈值是从动物研究（通过暂时阻断大脑中动脉）中采用的。由于创伤后的大脑如果伴有缺血会更容易受到不可逆损伤，所以有人可能会质疑缺血易损性的阈值是否高于18 mL/100 g/min。脑缺血会导致萎缩。因此，作者对33例昏迷的颅脑损伤患者（格拉斯哥昏迷评分8分及以下）在受伤至少3个月后进行了计算机断层扫描（CT），并将脑室大小（作为萎缩的反映）与受伤后4小时内（平均2.3±0.8小时）测得的脑血流量（CBF）进行了比较。脑室测量采用三种方式：第三脑室大小（厘米）、双尾状脑室指数（BCVI）和半球脑室指数（HCVI）。未发现早期CBF与任何脑室大小之间存在显著相关性。采用包含四个独立参数[CBF、受伤后时间的CBF、（受伤后时间）²的CBF、年龄]的多元相关分析，只有年龄成为预测脑室大小的显著指标（p<0.001）。我们还比较了受伤后4小时内获得的CBF数据，这些数据来自受伤3个月后的幸存者（平均CBF为32 mL/100 g/min）和非幸存者（CBF为20 mL/100 g/min）。幸存者和非幸存者之间的CBF差异在p<0.001时具有显著性（Wilcoxon秩和检验）。CBF小于或等于20 mL/100 g/min的患者比例在非幸存者中为56%，在幸存者中仅为5%。比例差异在p<0.001时具有显著性（卡方检验）。我们得出结论，萎缩程度与超早期CBF不相关。然而，基于幸存者和非幸存者之间的明显差异，我们建议将颅脑损伤后的缺血阈值重新定义为CBF 20 mL/100 g/min。
