Gropen T I, Prohovnik I, Tatemichi T K, Hirano M
Department of Neurology, State University of New York, Health Science Center at Brooklyn.
Stroke. 1994 Sep;25(9):1873-6. doi: 10.1161/01.str.25.9.1873.
The pathophysiology of stroke-like episodes in MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) is uncertain.
We studied a 24-year-old man with MELAS who had fluent aphasia and right hemianopia. Magnetic resonance imaging and computed tomography showed a large infarction in the parietal, temporal, and occipital lobes. We performed serial planar 133Xe regional cerebral blood flow studies and single-photon emission computed tomography. Fifteen and 26 days after the stroke-like episode, there was generalized hyperperfusion, highest in infarcted areas. Four and 8 months after the stroke-like episode, the brain was still hyperemic, with highest flow in noninfarcted tissue. Reactivity to CO2 was less than normal within the infarct at 26 days but improved thereafter. In the noninfarcted region, vasomotor reactivity was impared at 4 months, when resting flows were at their peak.
We observed generalized cerebral hyperemia and fluctuating CO2 reactivity in MELAS, possibly a consequence of local lactic acid production. In addition, this case suggests that nonquantitative functional imaging may be misleading in MELAS.
线粒体脑肌病伴乳酸血症和卒中样发作（MELAS）中卒中样发作的病理生理学尚不确定。
我们研究了一名患有MELAS的24岁男性，他有流利性失语和右侧偏盲。磁共振成像和计算机断层扫描显示顶叶、颞叶和枕叶有大面积梗死。我们进行了系列平面133Xe局部脑血流研究和单光子发射计算机断层扫描。在卒中样发作后15天和26天，出现全身灌注过度，梗死区域最为明显。在卒中样发作后4个月和8个月，大脑仍处于充血状态，非梗死组织血流最高。在26天时梗死灶内对二氧化碳的反应性低于正常水平，但此后有所改善。在非梗死区域，4个月时当静息血流达到峰值时血管舒缩反应受损。
我们在MELAS中观察到全身脑充血和二氧化碳反应性波动，这可能是局部乳酸产生的结果。此外，该病例表明在MELAS中非定量功能成像可能会产生误导。
