[Acute hyponatraemic encephalopathy in a patient on chronic hemodialysis program -- a case report].

By the end of a dialysis session the patient had a generalized convulsive seizure. Then meningeal syndrome, right-sided hemiparesis with central lesion of right facial nerve and bilaterally positive extensor plantar response were found. Because of the increase of blood pressure and then increased body temperature the diagnosis of acute hyponatraemic encephalopathy was not made only on the basis of the plasma ionogram (Na+ 110mEq/1) but also after excluding possible subarachnoid haemorrhage and acute cerebrospinal meningitis and encephalitis by cerebrospinal fluid examination. Hyponatraemia found in some patients suffering from chronic renal insufficiency is increased by haemodialysis session. Cerebral oedema which is proportional to natraemia is caused by urea disolation from intracellular to extracellular fluid. This process increases concentration gradient between intracellular and extracellular fluids. The perceptible neurological signs occur as natraemia declines below 120 mEq/l.