Relationship between cerebral perfusion in frontal-limbic-basal ganglia circuits and neuropsychologic impairment in patients with subclinical hepaticencephalopathy

Early detection of neuropsychologic impairment in cirrhotic patients with s ubclinical hepatic encephalopathy (SHE) is important for their prognosis an d quality of life. Abnormal MRI and MR spectroscopy (MRS) findings have bee n proposed as early markers of brain damage in these patients, but the role of functional neuroimaging in this field still has to be defined. In this study, the SPECT perfusion pattern in patients with SHE was investigated, a nd the relationship between regional cerebral blood flow (rCBF) and the MRI , MRS, neuropsychologic evaluation and biochemical data of these patients w as assessed. Methods: Data were obtained from 13 cirrhotic patients with SH E and 13 age-matched healthy volunteers. Fasting venous blood ammonia and m anganese sampling and a battery of standardized neuropsychologic tests rela ted to basal ganglia function and sensitive to the effects of liver disease were all performed on the same day. MRI and Tc-99m-hexamethyl propyleneami ne oxime SPECT were performed within 2 wk. Results: A pattern of decreased prefrontal rCBF was found in patients with SHE compared with healthy volunt eers. Basal ganglia and mesial temporal rCBF correlated inversely with perf ormance on motor tasks involving speed (Purdue pegboard test) and frontal p remotor function (Luria graphic alternances and Stroop tests). Thalamic rCB F correlated positively with T1-weighted MRI signal hyperintensity in the g lobus pallidus and with abnormal MRS findings. Neither the MRI signal inten sity of the globus pallidus nor MRS correlated with neuropsychologic test r esults. Conclusion: Cirrhotic patients with SHE show a SPECT pattern of imp aired prefrontal perfusion that does not seem to account for their neuropsy chologic deficits. On the other hand, perfusion in some parts of the limbic system and limbic-connected brain regions, such as the striatum and the me sial temporal regions, increased with neuropsychologic impairment. These fi ndings suggest that brain SPECT may be more sensitive than MRI in delineati ng cirrhotic patients requiring in-depth clinical testing to reveal basal g anglia-related neuropsychologic alterations.