Ohshita T, Oka M, Imon Y, Watanabe C, Katayama S, Yamaguchi S, Kajima T, Mimori Y, Nakamura S
Third Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Neuroradiology. 2000 Sep;42(9):651-6. doi: 10.1007/s002340000335.
Clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) resemble those of cerebral infarcts, but the pathogenesis of infarct-like lesions is not fully understood. To characterise these infarct-like lesions, we studied two patients with MELAS using diffusion-weighted (DWI) MRI before and after stroke-like episodes and measured the apparent diffusion coefficient (ADC) in the new infarct-like lesions. These gave high signal on DWI and had much higher ADC than normal-appearing regions. The ADC remained high even 30 days after a stroke-like episode then decreased in lesions, with or without abnormality as shown by conventional MRI. We speculate that early elevation of ADC in the acute or subacute phase reflects vasogenic rather than cytotoxic edema. The ADC of the lesions, which disappeared almost completely with clinical improvement, returned to normal levels, which may reflect tissue recovery without severe damage. To our knowledge, this is the first study of DWI in MELAS.
线粒体肌病、脑病、乳酸性酸中毒和卒中样发作（MELAS）的临床特征与脑梗死相似，但梗死样病变的发病机制尚未完全明确。为了明确这些梗死样病变的特征，我们对两名MELAS患者在卒中样发作前后进行了扩散加权（DWI）磁共振成像（MRI）检查，并测量了新出现的梗死样病变中的表观扩散系数（ADC）。这些病变在DWI上呈高信号，且ADC值比正常区域高得多。即使在卒中样发作30天后，ADC仍保持较高水平，随后病变中的ADC值下降，无论常规MRI显示有无异常。我们推测，急性期或亚急性期ADC的早期升高反映的是血管源性水肿而非细胞毒性水肿。随着临床症状改善，几乎完全消失的病变的ADC值恢复到正常水平，这可能反映了组织在未受到严重损伤的情况下得以恢复。据我们所知，这是首次对MELAS进行DWI研究。
