Can diffusion weighted magnetic resonance imaging help differentiate stroke from stroke-like events in MELAS?
The precise mechanism of neurological symptoms in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is still controversial. The diffusion weighted MR findings at the acute phase of a neurological event in MELAS are described and the pathophysiology of stroke-like lesion in the light of diffusion changes is discussed. Brain MRI was performed 2 days after the sudden onset of cortical blindness in a 25 year old patient with MELAS. Fluid attenuated inversion recovery (FLAIR) images showed multifocal cortical and subcortical hyperintensities located bilaterally in the frontobasal and the temporo-occipital lobes. Diffusion weighted images showed normal to increased apparent diffusion coefficient values in the acute left temporooccipital lesion and increased values in the older stroke-like lesions. These diffusion weighted findings support the metabolic rather than the ischaemic pathophysiological hypothesis for stroke-like episodes occurring in MELAS. Normal or increased apparent diffusion coefficient values within 48 hours of a neurological deficit of abrupt onset should raise the possibility of MELAS, especially if conventional MR images show infarct-like lesions.
Oppenheim
C
C
Department of Neuroradiology, Groupe Hospitalier Pitié-Salpêtrière, Paris VI University, 47 Boulevard de l'Hôpital, 75651 Paris, Cedex 13, France. catherine.oppenheim@psl.ap-hop-paris.fr
Galanaud
D
D
Samson
Y
Y
Sahel
M
M
Dormont
D
D
Wechsler
B
B
Marsault
C
C
D000328:Adult; D001037:Aphasia / Q000209:etiology; D019575:Blindness, Cortical / Q000209:etiology; D002533:Cerebral Angiography; D004272:DNA, Mitochondrial / Q000235:genetics; D003937:Diagnosis, Differential; D017352:Echo-Planar Imaging; D017809:Fatal Outcome; D005625:Frontal Lobe / Q000098:blood supply / Q000473:pathology; D006801:Humans; D017241:MELAS Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D018810:Magnetic Resonance Angiography; D008297:Male; D008931:Mitochondria, Muscle / Q000235:genetics; D018482:Muscle, Skeletal / Q000473:pathology; D009778:Occipital Lobe / Q000098:blood supply / Q000473:pathology; D012008:Recurrence; D020521:Stroke / Q000175:diagnosis*; D013702:Temporal Lobe / Q000098:blood supply / Q000473:pathology
D004272:DNA, Mitochondrial