Bright basal ganglia in T1-weighted magnetic resonance images are frequent in patients with portal vein thrombosis without liver cirrhosis and not suggestive of hepatic encephalopathy

Background/Aims: Deposition of paramagnetic substances in basal ganglia, resulting in increased signals in T1-weighted magnetic resonance images (bright basal ganglia), is frequently seen in liver cirhrosis. The present study describes the prevalence of bright basal ganglia and its clinical significance in patients with long-standing portal vein thrombosis in the absence of liver cirrhosis. Methods: Six patients with angiographically proven complete portal vein thrombosis and cavernomatous transformation without signs of acute or chronic liver disease were studied by magnetic resonance imaging of the brain, neuropsychiatric evaluation, psychometric tests, electroencephalography, and determination of arterial ammonia levels and of serum manganese concentrations from peripheral venous blood. Results: Five out of six patients demonstrated increased signal intensity in the basal ganglia. Overt portal-systemic encephalopathy was not noted prior to or at the time of evaluation. Normal EEG results were recorded in all patients. Only one of the six patients had pathological results in at least two out of four psychometric tests. This latter patient had had a large right-sided brain infarction. Arterial ammonia concentrations were normal in four of the six patients; one patient with increased ammonia levels had concomitant renal insufficiency with azotemia. The other four patients had no relevant concomitant diseases. Serum manganese levels were non-significantly increased compared with control group (p=0.06), but they were significantly correlated to basal ganglia signal intensity (R=0.88; p=0.02). Conclusions: Our results demonstrate that bright basal ganglia primarily represent shunt-induced alterations. They are not directly associated with disturbed liver function nor with portal-systemic encephalopathy.