Schaefer P W, Buonanno F S, Gonzalez R G, Schwamm L H
Department of Radiology, Massachusetts General Hospital, Boston 02114, USA.
Stroke. 1997 May;28(5):1082-5. doi: 10.1161/01.str.28.5.1082.
The pathophysiology of eclampsia remains unclear. While the majority of patients develop reversible T2 hyperintense signal abnormalities on MR scans and reversible neurological deficits, some patients do develop infarctions (permanent T2 hyperintense abnormalities) and permanent neurological impairment. Routine MRI cannot prospectively differentiate between these two patient groups. Echo-planar diffusion-weighted imaging, however, is a new technique that clearly differentiates between cytotoxic and vasogenic edema.
A 30-year-old woman developed symptoms consistent with eclampsia 24 hours after delivering premature twins. An MRI demonstrated extensive, diffuse T2 hyperintense signal abnormalities involving subcortical white matter and adjacent gray matter with a posterior predominance, consistent with either infarction or hypertensive ischemic encephalopathy. Diffusion-weighted images demonstrated increased diffusion, consistent with vasogenic edema and hypertensive ischemic encephalopathy.
Unlike routine MRI, diffusion-weighted imaging reliably differentiates between vasogenic edema and cytotoxic edema. Consequently, in eclamptic patients diffusion-weighted imaging can afford clear differentiation between hypertensive ischemic encephalopathy and infarction, two very different entities with very different treatment protocols. Diffusion-weighted imaging should be performed in all eclamptic patients and should greatly affect their management.
子痫的病理生理学仍不清楚。虽然大多数患者在磁共振成像（MR）扫描上出现可逆的T2高信号异常和可逆的神经功能缺损，但有些患者确实会发生梗死（永久性T2高信号异常）和永久性神经损伤。常规MRI无法前瞻性地区分这两组患者。然而，回波平面扩散加权成像（Echo-planar diffusion-weighted imaging）是一种新技术，能清晰地区分细胞毒性水肿和血管源性水肿。
一名30岁女性在早产双胞胎24小时后出现与子痫相符的症状。MRI显示广泛、弥漫性T2高信号异常，累及皮质下白质和相邻灰质，以后部为主，符合梗死或高血压缺血性脑病表现。扩散加权图像显示扩散增加，符合血管源性水肿和高血压缺血性脑病表现。
与常规MRI不同，扩散加权成像能可靠地区分血管源性水肿和细胞毒性水肿。因此，对于子痫患者，扩散加权成像能清晰地区分高血压缺血性脑病和梗死，这是两种截然不同的疾病，治疗方案也大不相同。所有子痫患者均应进行扩散加权成像检查，这将对其治疗产生重大影响。
