Diffusion-weighted image and MR spectroscopic analysis of a case of MELAS with repeated attacks.
We report the clinical and MR manifestations of an 18 year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Recurrent status epilepticus caused reversible cytotoxic edema on diffusion-weighted images (DWI). Initial and one month follow-up MR spectroscopy, after seizure control, showed some discrepancies in the ratio of metabolites. N-acetylaspartate (NAA) partially recovered (NAA/creatine (Cr) ratio: 1.27-->1.84). This was because of a normalization of decreased NAA due to cellular dysfunction as a result of status epilepticus. A low ratio of NAA/Cr due to abnormal mitochondria remained in the decreased state. Reversible NAA/Cr ratios in the acute lesion suggested that NAA reflects the neuronal function as well as the level of neuronal structural damage. The altered NAA/Cr ratio better correlated with the abnormal signal intensity area of T2-weighted images (T2WI) and DWI than the lactate (Lac)/Cr ratio. With conservative treatment with anti-epileptics not accompanied by coenzyme Q or sodium dichloroacetate, lactate persistently increased (Lac/Cr ratio: 1.01-->1.21) because of the continued production of lactate in cells with respiratory deficiency, which is the main pathology of MELAS.
Kim
H S
HS
Department of Diagnostic Radiology, Yonsei University College of Medicine, Seoul, Korea.
Kim
D I
DI
Lee
B I
BI
Jeong
E K
EK
Choi
C
C
Lee
J D
JD
Yoon
P H
PH
Kim
E J
EJ
Kim
S H
SH
Yoon
Y K
YK
D000293:Adolescent; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004058:Diffusion; D005260:Female; D006801:Humans; D017241:MELAS Syndrome / Q000175:diagnosis* / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine