Magnetic resonance spectroscopy in adult-onset citrullinemia: elevated glutamine levels in comatose patients.
BACKGROUND
Adult-onset type II citrullinemia is an inborn error of urea cycle metabolism that can lead to hyperammonemic encephalopathy and coma. However, type II citrullinemia is rare outside Japan, and diagnosis and treatment can be delayed. Magnetic resonance spectroscopy may be a useful adjunct to magnetic resonance imaging, and has been applied to noninvasively study chemical metabolism in the human brain.


METHODS
We describe 2 patients with type II citrullinemia who presented with episodic postprandial somnolence and coma. Diffusion-weighted magnetic resonance imaging showed bilaterally symmetrical signal abnormalities of the insular cortex and cingulate gyrus. On magnetic resonance spectroscopy, glutamine and glutamate levels were elevated, and choline and myo-inositol levels were decreased. The diagnosis of citrullinemia was confirmed based on elevated plasma ammonia and citrulline levels.


CONCLUSIONS
Characteristic features found at the time of magnetic resonance imaging and magnetic resonance spectroscopy may be helpful for early diagnosis of type II citrullinemia in adult patients who present with hyperammonemic encephalopathy and coma.
Wong
Yee-Choon
YC
Department of Neurology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Republic of Singapore.
Au
Wing Lok
WL
Xu
Maosheng
M
Ye
Jieru
J
Lim
C C Tchoyoson
CC
D000328:Adult; D000641:Ammonia / Q000097:blood; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology; D002794:Choline / Q000378:metabolism; D002956:Citrulline / Q000097:blood; D020159:Citrullinemia / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*; D003128:Coma / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D042241:Early Diagnosis; D017809:Fatal Outcome; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D006179:Gyrus Cinguli / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D022124:Hyperammonemia / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D008297:Male; D011237:Predictive Value of Tests
D015415:Biomarkers; D005973:Glutamine; D002956:Citrulline; D018698:Glutamic Acid; D007294:Inositol; D000641:Ammonia; D002794:Choline