Cerebral oedema in minimal hepatic encephalopathy due to extrahepatic portal venous obstruction.
BACKGROUND
Minimal hepatic encephalopathy (MHE) has recently been reported in patients with extrahepatic portal venous obstruction (EHPVO).


OBJECTIVE
To evaluate brain changes by magnetic resonance studies in EHPVO patients.


METHODS
Blood ammonia level, critical flicker frequency (CFF), brain metabolites on 1H-magnetic resonance (MR) spectroscopy and brain water content on diffusion tensor imaging and magnetization transfer ratio (MTR) were studied in 31 EHPVO patients with and without MHE, as determined by neuropsychological tests. CFF and magnetic resonance imaging studies were also performed in 23 controls.


RESULTS
Fourteen patients (14/31, 45%) had MHE. Blood ammonia level was elevated in all, being significantly higher in the MHE than no MHE group. CFF was abnormal in 13% (4/31) with EHPVO and in 21% (3/14) with MHE. On 1H-MR spectroscopy, increased Glx/Cr, decreased mIns/Cr, and no change in Cho/Cr were noted in patients with MHE compared with controls. Significantly increased mean diffusivity (MD) and decreased (MTR) were observed in the MHE group, suggesting presence of interstitial cerebral oedema (ICE). MD correlated positively with blood ammonia level (r=0.65, P=0.003) and Glx (r=0.60, P=0.003).


CONCLUSIONS
MHE was detected in 45% of patients with EHPVO while CFF was abnormal in only 13%. ICE was present in 7/10 brain regions examined, particularly in those with MHE. Hyperammonaemia elevated cerebral Glx levels correlated well with ICE.


CONCLUSIONS
MHE was common in EHPVO; CFF could identify it only in a minority. ICE was present in EHPVO, particularly in those with MHE. It correlated with blood ammonia and Glx/Cr levels. Hyperammonaemia seems to contribute to ICE in EHPVO.
Department of Gastroenterology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
Amit
A
Goel
Santosh
S
Yadav
Vivek
V
Saraswat
Arti
A
Srivastava
M Albert
MA
Thomas
Chandra M
CM
Pandey
Ramkishore
R
Rathore
Rakesh
R
Gupta
D000293:Adolescent; D000328:Adult; D000641:Ammonia / Q000097:blood; D001921:Brain / Q000378:metabolism; D001929:Brain Edema / Q000175:diagnosis* / Q000209:etiology; D003251:Constriction, Pathologic / Q000150:complications / Q000473:pathology; D005260:Female; D005425:Flicker Fusion / Q000502:physiology; D006501:Hepatic Encephalopathy / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011169:Portal Vein / Q000473:pathology*
D000641:Ammonia