The SEP (Somatosensory Evoked Potential) and EEG were studied with 19 patients undergoing hemodialysis (dialyzed group, 41~65 y. o.), consisted of non-diabetic group (13 patients with chronic gromerulonephritis) and diabetic group (6 patients with diabetic nephropathy), comparing with those of 20 healthy subjects (normal group, 38~66 y. o.). EEGs containing SEPs evoked by median nerve stimulation were recorded with 1024 msec of analysis time through the two derivations (1CH : C3'→F3' and 4CH : C3'→A1+2). The group-mean SEPs were obtained with each group, and compared with each other, and then the differences of latencies and peak-to-peak amplitudes of the components were tested statistically between the groups.
The EEGs were subjected to the quantitative frequency analysis. Correlation coefficients were tested between the latencies, peak-to-peak amplitudes and EEG power %, and between the latencies, peak-to-peak amplitudes and blood data. The following results were obtained.
1. The waveforms of group-mean SEP of normal group and non-diabetic group had hexaphasic contour, consisted of the components Pl~8, N1~8. But, in that of diabetic group the contour deteriorated at around the long latency components.
2. The latencies were longer in the ascending order normal group, non-diabetic group and diabetic group, and peak-to-peak amplitudes were larger in the ascending order diabetic group, normal group and non-diabetic group.
3. In the SEP of non-diabetic group, latencies were increased and amplitudes were decreased.
4. In the SEP of diabetic group, latencies were increased more than those of non-diabetic group, and amplitudes were decreased.
5. Quantitative frequency analysis of EEG, indicated decreased peak frequency of α waves in non-diabetic group, and decreased peak frequency of α waves and increased δ, θ waves in diabetic group, more than those in normal group.
6. The correlation coefficients of EEG power % between SEP-latencies indicated increased latencies due to decreased fast waves and increased slow waves, and those between SEP peak-to-peak amplitudes indicated increased amplitudes due to increased fast waves and decreased slow waves.
7. Between SEP-latencies, negative correlation was found with blood K, Ca, BUN, and positive correlation with dialyzed period (years), and between SEP-amplitudes, negative correlation with creatinin, Ca, hemogrobin, and positive correlation with BUN.
These results were attributed to more marked disturbances of GABA-inhibitory system in gray matter together with white matter in non-diabetics, and to severe disturbances of the central nervous system in both of gray and white matter in diabetics
