Influence of end-stage renal failure and hemodialysis on event-related potentials

Chronic renal failure frequently causes uremic encephalopathy with impairme nt of different cognitive functions, but the pathophysiology of uremic ence phalopathy is still unknown. We measured visually evoked event-related pote ntials (ERPs) in 33 neurologically asymptomatic patients before and after t hey underwent hemodialysis and compared their data with those of a strictly age-matched healthy control group. Before hemodialysis. the patients' P3 l atency was significantly increased and P3 amplitude was significantly decre ased as compared with that of the healthy control group. After hemodialysis , P3 latency of the patients showed a significant decrease (457 +/- 56 befo re and 438 +/- 54 ms after hemodialysis) and the P3 latency habituation dur ing the ERP measurement was also significantly decreased. Patients with hig her levels of blood urea nitrogen (BUN), creatinine, and uric acid performe d better in ERP measurement than did patients with lower levels. Hemoglobin did not influence ERP latencies and amplitudes. Our data suggest that impa ired cognitive processing can be disclosed by ERP even in neurologically as ymptomatic chronic renal disease. Removal of uremic toxins by hemodialysis leads to an improvement in cognitive processing.