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(Stroke. 2009;40:e15.)
© 2009 American Heart Association, Inc.

Case Reports

Serial Diffusion Imaging in a Case of Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes

From Department of Neurology (C.T., L.A.B.), Haukeland University Hospital, Bergen Norway; Department of Clinical Medicine (C.T., L.A.B.), University of Bergen. Bergen, Norway.

Correspondence to Charalampos Tzoulis, Department of Neurology, Haukeland University Hospital, 5021, Bergen, Norway. E-mail chtzoulis{at}yahoo.com or tzou@helse-bergen.no

Background and Purpose— Most diffusion MRI studies of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode stroke-like lesions report high- or normal-apparent diffusion coefficient, and this has been used to differentiate stroke-like lesion from ischemic stroke. There are, however, 3 recent reports of restricted diffusion in the acute phase of the stroke-like lesions. The purpose of our study was to investigate this apparent paradox.

Methods— We performed 9 serial MRI covering 2 stroke-like episodes in a 36-year-old man with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode caused by the common mitochondrial DNA mutation 3243A>G.

Results— We found clear evidence of initial restricted diffusion in the stroke-like lesions, which gradually evolved to high-apparent diffusion coefficient as lesions aged. Evolution was, however, asynchronous with both high- and low-apparent diffusion coefficients temporally coexisting.

Conclusions— Our findings suggest that cytotoxic edema does occur early in the course of a stroke-like lesions and that its presence or, conversely, the absence of vasogenic edema, should not weaken the possibility of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode in favor of ischemic stroke.

Key Words: brain imaging • cerebral infarct • diffusion-weighted imaging • imaging • mitochondria