Reversibility of electrophysiologic abnormalities in diabetic renal failure

Neurologic complications of diabetes predominantly involve the peripheral and autonomic nervous systems. Central nervous system (CNS) involvement, other than that resulting from vascular disease or acute metabolic derangement, has not been well documented. Neurologic complications of renal failure are similar to that of diabetes peripherally, but include a high incidence of encephalopathy. Abnormalities of the electroencephalogram, the visual and auditory, evoked potential occur in both groups leading to the speculation that diabetes and uremia may potentiate the CNS effects of each other. We have followed a group of 6 diabetic (ages 24 to 49, mean duration of diabetes 17 years) and 12 nondiabetic uremics (ages 15 to 52) through renal transplantation (RTX) using the visual-evoked potential (VEP). All subjects exhibited vision above 20/50 and normal neurological exam prior to study. VEPs were recorded to a checkerboard pattern with checks subtending 15, 31, and 63 minutes visual arc, reversing 1.9 times/sec. Two trials in each eye were performed. Signals were recorded from Oz referenced to Cz. All waves were replicated and measured at the peak of the first large negative component (N75) and the following positive wave (P100). All patients underwent VEP recording 24 to 48 hours prior to RTX and at least 24 hours after hemodialysis. Recovery VEPs were recorded between 50 and 80 days after RTX. Statistical analysis was performed on VEP data using the analysis of variance.