Neurophysiological findings and serum aluminium in dialysis encephalopathy.

64 patients on hemodialysis were investigated. The mean duration of dialysis was 43 months. In all the patients, serum aluminium levels, systolic blood pressure (averaged over a period of 6 weeks) and the EEG were investigated. Psychological testing to assess the level of intelligence (IQ) was also performed. The serum aluminium levels have been assayed by flameless atomic absorption (Perkin-Elmer atomic absorption spectrophotometer model 420). In 6 patients, the diagnosis of dementia was made on the basis of psychological testing and clinical observations. The demented patients showed significantly (p less than 0.01) higher aluminium levels (mean 409 microgram/l, SD 235) than the 58 non-demented patients (mean 189 microgram/l, SD 152), whereas the age of the patients, duration of dialysis and blood pressure were the same in both groups. The EEG was abnormal in all 6 demented patients. Only in 23 of the 58 non-demented patients was the EEG pathological (p less than 0.05). A significant correlation was found between serum aluminium levels and the EEG data with regard to bilateral slow waves, focal slow waves and epileptic potentials (p less than 0.05). The EEG, age of the patients, duration of dialysis and blood pressure showed no correlation. Electromyography, nerve conduction velocity and latency showed no correlation with aluminium levels or dementia. It can be concluded from our findings that in dialyzed patients there is a correlation between serum aluminium levels and the appearance of dementia and EEG changes.