Lee Ho Yun, Kim Jae Hyoung, Weon Young-Cheol, Lee Jung Seok, Kim Sang Yun, Youn Sung Won, Kim Sung Hyun
Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, 300 Gumi-Dong, Bundang-Gu, Seongnam-Si, South Korea.
Neuroradiology. 2007 Jun;49(6):481-7. doi: 10.1007/s00234-007-0213-5. Epub 2007 Feb 14.
Transient global amnesia (TGA) is characterized by a sudden onset of anterograde amnesia without alteration of consciousness or personal identity. Interestingly, recent studies have reported a high frequency of small high-signal abnormalities in the hippocampus with diffusion-weighted (DW) imaging, and ischemia has been proposed as an etiology of TGA. We hypothesized that TGA lesions occur preferentially in the CA1 region of the hippocampus, known to be susceptible to ischemia.
Over a 30-month period 34 patients with TGA underwent MRI including DW imaging within 4 days of symptom onset. Patients with high-signal abnormalities in the hippocampus on the initial DW images underwent subsequent DW and T2-weighted imaging in the coronal plane to identify the precise lesion locations.
Fourteen patients had small (1-3 mm) high-signal abnormalities in the hippocampus unilaterally on DW images. One of these patients had two lesions in one hippocampus and therefore in total 15 lesions were identified: four in the hippocampal head, and 11 in the body. Eleven lesions in ten patients with available coronal images were clearly demonstrated on both coronal DW and T2-weighted images and were localized to the lateral portion of the hippocampus, corresponding to the CA1 region.
Lesions associated with TGA were localized exclusively to the lateral portion of the hippocampus corresponding to the CA1 region. This finding supports the ischemic etiology of TGA; however, the pathophysiological mechanism involved requires further study.
短暂性全面性遗忘症（TGA）的特征是突然发作的顺行性遗忘，意识或个人身份无改变。有趣的是，最近的研究报告称，在扩散加权（DW）成像中，海马体出现小的高信号异常的频率很高，并且有人提出缺血是TGA的病因。我们假设TGA病变优先发生在已知易受缺血影响的海马体CA1区。
在30个月的时间里，34例TGA患者在症状发作后4天内接受了包括DW成像在内的MRI检查。初始DW图像上海马体有高信号异常的患者随后在冠状面进行了DW和T2加权成像，以确定精确的病变位置。
14例患者在DW图像上单侧海马体有小的（1-3毫米）高信号异常。其中1例患者在一个海马体中有两个病变，因此总共确定了15个病变：4个在海马头部，11个在体部。10例有冠状图像的患者中的11个病变在冠状面DW和T2加权图像上均清晰显示，且位于海马体外侧部分，对应于CA1区。
与TGA相关的病变仅局限于对应于CA1区的海马体外侧部分。这一发现支持了TGA的缺血病因；然而，所涉及的病理生理机制需要进一步研究。
