Refractory period, sensory conduction velocity and visual evoked potentials before and after haemodialysis.

In 18 patients suffering from chronic renal failure (being haemodialysed three times weekly for 22.2 +/- 27.9 months), sensory conduction velocity and relative refractory period of the sural nerve were estimated immediately before and after dialysis. Before haemodialysis all but one patient had conduction velocities within the normal range (x +/- 2 SD), but 50% had prolonged refractory periods. After dialysis the refractory period decreased to become normal in all but one patient. Visual evoked potential latencies showed no systematic alterations. A membrane abnormality due to uraemic poisoning is assumed to cause the reversible prolongation of the refractory period.