CT and MRI in haemolytic uraemic syndrome with central nervous system involvement: distribution of lesions and prognostic value of imaging findings

Background: Central nervous system (CNS) involvement is a common complication in haemolytic uraemic syndrome (HUS). Various imaging findings have been described, mostly as case reports. Although there are a few retrospective studies on larger patient groups there is no report that focuses on MRI. Objective: To analyse the CT and MRI studies of patients with neurological complications of HUS, to describe the typical imaging findings, and to evaluate their predictive character with regard to follow-up examinations and clinical outcome. Materials and methods: Of 57 patients with clinically proven HUS who were referred to our hospital between 1995 and 2003, 17 had signs of serious CNS involvement and 10 underwent neuroimaging. Nine MRI and seven CT studies were performed in the acute phase and five MRI and two CT studies were done for follow-up. Results: In six patients, pathological imaging findings were seen on CT or MRI performed in the acute phase of the disease whereas CT and MRI scans were completely normal in four patients. All patients with positive imaging findings had pathological changes within the basal ganglia. Additional findings were seen in the thalami (n=2), cerebellum (n=2) and brain stem (n=1). On follow-up imaging performed in five cases, the pathological imaging findings had resolved completely in two and partially in three patients. All patients had a good neurological outcome. Comparing the various MRI findings, a haemorrhagic component within an acute lesion was the most reliable parameter predicting residual pathologic findings on follow-up imaging. Conclusions: Basal ganglia involvement is a typical finding in patients with neurological complications of HUS. Even in patients with severe CNS involvement on acute imaging studies, prognosis was favourable for clinical outcome and resolution of pathological imaging findings.