[Evaluation of polyneuropathy severity in chronic renal failure patients on continuous ambulatory peritoneal dialysis or on maintenance hemodialysis].

UNLABELLED: The aim of the study was to assess severity of injury of the peripheral nervous system of chronic renal failure patients on continuous ambulatory peritoneal dialysis (CAPD) or on maintenance hemodialysis (HD) diagnosed based on the electrophysiological testing as well as to establish the effect of adequate dialysis dose on peripheral nerve functioning. The study was performed in 53 patients (21 males, 32 females) on CAPD for mean 16.9 +/- 14.4 months and 68 patients (46 males, 22 females) on HD for mean 47.5 +/- 46.5 months. Both groups were age matched (48.9 +/- 12.4 vs. 50.6 +/- 11.9 yrs; p= NS). Patients with co-existing diseases that could lead to disturbances in nerve conduction were excluded from the study group.

METHODS: Electrophysiological testing was performed using Medelec Shaphire 2ME equipment. Nerve conductivity testing was performed in motor and sensory fibres of right ulnar nerve, motor fibres of right fibular nerve and left tibial nerve as well as in sensory fibres of right calf nerve. In the sensory nerves there were assessed: amplitude of the evoked sensory response, latency of the response and conduction velocity. In the motor nerves there were analyzed amplitude of the compound muscle action potential, latency of the evoked response, F-wave minimal latency and conduction velocity. Polyneuropathy was diagnosed if abnormal results obtained in electrophysiological examination were found in at least two out of four tested nerves. To assess dialysis adequacy in the CAPD group weekly Kt/V (wKt/ V) and weekly creatinine clearance (WCrCI) were used and in the HD patients the following indices were measured: Kt/V, PRU, TAC and TAD.

RESULTS: Polyneuropathy diagnosed based on the above described criteria, was found in 59 (86.8%) HD patients and in 41 (77.4%) CAPD patients (p= NS). The results of motor conductivity testing showed significantly longer distal latency in HD patients in comparison to the CAPD patients in fibular nerve (4.9 +/- 0.9 vs. 4.5 +/- 0.8 ms; p< 0.05) and F-wave latency in ulnar nerve (29.3 +/- 3.1 vs. 27.3 +/- 2.5 ms; p< 0.05), in fibular nerve (52.4 +/- 6.4 vs. 48.5 +/- 7.94 ms; p< 0.05), in tibial nerve (54.8 +/- 7.8 vs. 50.6 +/- 7.12 ms; p< 0.05) and also significantly lower conduction velocity in ulnar nerve (51.9 +/- 5.9 vs. 55.6 +/- 6.99 m/s; p< 0.05), in fibular nerve (41.2 +/- 5.9 vs. 44.5 +/- 5.5 m/s; p< 0.05), in tibial nerve (40.1 +/- 5.81 vs. 42.7 +/- 4.6 m/s; p< 0.05). Mean value of sensory response amplitude evoked in ulnar nerve was significantly higher in the CAPD treated patients than in HD patients (21.2 +/- 14.8 vs. 15.1 +/- 11.4 microV; p< 0.05) and distal latency in calf nerve was significantly shorter (2.1 +/- 1.0 vs. 2.4 +/- 0.6 ms; p< 0.05). Analysing the effect of dialysis on peripheral nerve functioning in the group of CAPD patients a statistically significant relationship between the severity of peripheral nerve injury and WCrCl was demonstrated. Mean value of WCrCl in patients without features of neuropathy was significantly higher (83.3 +/- 28.98 l/week/ 1.73m2) in comparison with those with diagnosed polyneuropathy (59.9 +/- 15.9 l/week/1.73m2) (p< 0.01). Analyzing effect of WCrCl on conduction velocity in the tested nerves there was demonstrated that in patients with WCrCl value at least 60 l/week/1.73m2, mean velocity values were higher, and the statistically significant difference was found for sensory (p< 0.05) and motor (p< 0.01) fibers of ulnar nerve. Mean value of residual renal clearance in the CAPD treated patients without features of sensory and motor nerve injury was significantly higher (2.9 +/- 1.8 ml/min) when compared to the patients with diagnosed polyneuropathy (1.4 +/- 1.3 ml/min) (p= 0.006). In the hemodialyzed group no statistically significant relationship was found between conduction velocity in the tested nerves and indices of dialysis efficiency (Kt/V, PRU) as well as degree of exposure to uremic toxemia described by TAC and TAD.

CONCLUSIONS: Polyneuropathy is a common complication in patients with chronic renal failure independently of a kind of the therapy. Well preserved residual renal function in CAPD patients plays an important role in improving effectiveness of the dialytic treatment, in consequence influencing preservation of proper peripheral nerve function.