Department of Radiology, Rudolf Magnus Institute for Neuroscience, University Medical Center, Utrecht, The Netherlands.
Cerebrovasc Dis. 2011;32(2):133-40. doi: 10.1159/000328244. Epub 2011 Jul 19.
Because the pathogenesis of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is unclear, we studied cerebral perfusion at different time points around the occurrence of DCI.
We prospectively enrolled 53 patients admitted to the University Medical Center Utrecht who underwent CT perfusion (CTP) scans on admission, and within 2 weeks after hemorrhage on 2 scheduled time points or during clinical deterioration. The occurrence of DCI was assessed according to predefined criteria by 2 neurological observers blinded to perfusion results. Clinically stable patients (no-DCI) served as reference, and patients with other causes of deterioration (n = 11) were excluded. In DCI patients, the day of DCI onset and in no-DCI patients the median day of DCI onset was taken as t = 0. Scans made before and after DCI were clustered into 5 additional time points. At each time point, cerebral blood volume (CBV) and flow (CBF), and mean transit time (MTT) were measured, and absolute and relative (interhemispheric asymmetry) values were compared between DCI and no-DCI patients.
Absolute CBF was lower and MTT was higher in the 18 DCI patients than in the 24 no-DCI patients before, during and after DCI. MTT asymmetry increased during DCI and partially recovered afterwards in DCI patients while it remained constant in no-DCI patients. Absolute and relative CBV remained constant in both groups.
Our findings suggest that DCI patients already have diffusely worse perfusion (absolute values) than no-DCI patients before focal worsening (increased asymmetry) occurs and becomes symptomatic. The partial recovery in the measured areas suggests that DCI can be partly reversible.
由于蛛网膜下腔出血（SAH）后迟发性脑缺血（DCI）的发病机制尚不清楚，我们研究了 DCI 发生前后不同时间点的脑灌注情况。
我们前瞻性纳入了 53 名入住乌得勒支大学医学中心的患者，这些患者在发病时以及出血后 2 周内的 2 个预定时间点或临床恶化时进行了 CT 灌注（CTP）扫描。DCI 的发生根据预先定义的标准由 2 名对灌注结果不知情的神经科观察者进行评估。临床稳定的患者（无 DCI）作为参考，排除了其他原因导致病情恶化的患者（n=11）。在 DCI 患者中，以 DCI 发病日为 t=0，在无 DCI 患者中，以 DCI 发病日的中位数为 t=0。将 DCI 前后的扫描分为 5 个额外的时间点。在每个时间点测量脑血容量（CBV）和流量（CBF）以及平均通过时间（MTT），并比较 DCI 和无 DCI 患者之间的绝对和相对（半球间不对称）值。
在 18 名 DCI 患者中，与 24 名无 DCI 患者相比，在 DCI 前、期间和之后，绝对 CBF 较低，MTT 较高。在 DCI 期间，MTT 不对称性增加，随后在 DCI 患者中部分恢复，而在无 DCI 患者中保持不变。在两组患者中，绝对和相对 CBV 均保持不变。
我们的研究结果表明，在局灶性恶化（增加的不对称性）发生并出现症状之前，DCI 患者的灌注已经普遍较差（绝对值）。在测量区域中观察到的部分恢复表明 DCI 可能部分可逆。
