To determine if there is any difference in nerve conduction studies or sympathetic skin response (SSR) between patients on peritoneal dialysis and those on regular hemodialysis, we did a cross-sectional observational study. The study group consisted of 24 patients on peritoneal dialysis (PD) (12 men, aged 45 +/- 17 years) and 20 patients on hemodialysis (HD) (11 men, aged 50 +/- 22 years). All of these patients were in stable clinical condition, they were receiving adequate dialysis, and none of them had systemic diseases. Motor and sensory nerve conduction studies of the common and medial peroneal nerve and SSR were performed in all patients. There were no differences in motor and sensory nerve conduction velocities between PD and HD patients. All PD patients had detectable SSR. However, six patients on HD (30%) failed to show SSR (p < 0.05). Mean SSR amplitude was higher in PD patients than in HD patients (1233 +/- 843 vs. 605 +/- 771 microv, p < 0.05). There were no differences in mean SSR latency between PD and HD patients. PD modality (continuous ambulatory PD vs. automated PD) or the presence of residual renal function did not influence nerve conduction studies or SSR. In conclusion, using standard nerve conduction studies, no differences could be found between HD and PD. However, a higher proportion of patients on HD showed an impaired SSR, suggesting that subclinical neuropathy may be more common in HD than PD patients.

Sympathetic skin response (SSR) is a useful and simple test for unmyelinated axon function in peripheral sensorimotor neuropathies. SSR was tested on a group of patients undergoing chronic regular hemodialysis before and after a single dialysis session. Nineteen patients in hemodialysis for more than three months were included. Nine patients were on dialysis with cellulosic membranes (CA, 3 male and 6 female, aged 57.7 +/- 16.4 years) and ten ones were on dialysis with non-cellulosic membranes (NC, 4 male and 6 female, aged 50.2 +/- 15.9 years) were studied. There were no differences neither in Kt/V values (NC 1.37 +/- 0.34 vs. CA 1.22 +/- 0.27) nor in TAC ones (NC 41.5 +/- 18.2 vs. CA 41.3 +/- 14.1 mg/dL). After hemodialysis with NC amplitude significantly increased (994 +/- 1015 vs. 382 +/- 465 microv baseline, p < 0.05). Latency did not change (1.76 +/- 0.83 vs. 2.07 +/- 0.50 s baseline). After hemodialysis with CA neither amplitude changed (1368 +/- 1074 vs. 1240 +/- 1594 microv baseline), nor did latency (1.79 +/- 0.35 vs. 1.94 +/- 0.59 s baseline). Hemodialysis with non-cellulosic membranes (but not with cellulose acetate) yields a short-term improvement of sympathetic skin response. This effect is similar to those seen in nerve conduction velocities and it may be related to increased middle-molecules depuration.