[Involvement of the central nervous system in hemolytic uremic syndrome/thrombotic thrombocytopenic purpura].

Cerebral involvement is typical for thrombotic microangiopathies like haemolytic uremic syndrome (HUS) and thrombotic-thrombopenic purpura (Moschcowitz disease or TTP). Symptoms are irritation, restless behaviour, disorientation, disturbance of consciousness, seizures, and focal neurological deficits. The lack of typical imaging changes or pathological observations may explain the unknown pathophysiological cascade leading to the neurological symptoms. We describe the development of HUS/ TTP in a 52-year-old woman after acute pneumonia caused by Diplococcus pneumoniae. The patient showed an increasing psycho-organic syndrome with disorientation, followed by severe loss of consciousness and coma. Initially, computed tomography showed slight diffuse brain oedema, which was not found in later follow-up images. Magnetic resonance imaging was normal. The TCD examination revealed general velocity increases and vasospasms (especially MCA, ACA and PCA bilateral and BA). The reduction in blood flow velocities in the basal arteries was accompanied by a marked clinical improvement. The development of vasospasms may be an explanation for the neurological deficits in HUS/TTP. The origin of the vasospasms may be found in disturbed prostacyclin production, increased serotonin or platelet factor IV release, and leucocyte activation with consecutive endothelial damage.