The aim of the study was assessment of visual (VEPs) and brain stem auditory evoked potentials (BAEPs) in patients dialysed due to chronic renal failure in order to evaluate the clinical usefulness of this method. In 50 patients (19 female, 31 male), aged 28-73 (mean 50) dialysed because of chronic renal failure, VEPs and BAEPs were performed. In 12 patients no abnormalities were found in neurologic examination; 23 displayed polyneuropathy of minor degree; 28 showed symptoms of minimal CNS lesions. VEPs were recorded over visual cortex, while right and left eye were stimulated subsequently with the reversal checkerboard pattern. Latency and amplitude of visual evoked response (P100) were estimated. BAEPs were recorded over the mastoid. Latencies of components I-V of brain stem auditory response and interpeak latencies I-III, III-V, I-V were estimated. The results were compared to the data obtained in 50 age-matched controls and statistically analysed by means of Student's t-test. Abnormal VEPs (mean latencies significantly longer in comparison with the control group) and/or BAEPs (significantly prolonged latencies of particular components and interlatencies I-III, III-V, I-V) were recorded in 32 cases (64%). The authors attribute this high percentage of abnormal evoked potentials in dialysed patients to the presence - apart from renal failure - of other diseases affecting CNS (diabetes, collagenoses, hypertension). Abnormal evoked potentials (EP) were found in patients with symptoms of CNS damage, as well as without them. No correlation was found between pathologic EPs and duration of dialysis, degree of anaemia and serum levels of urea and creatinin. Evoked potentials abnormalities did not depend on EEG changes. EP study in patients with chronic renal failure, especially without clinical symptoms of CNS damage may be helpful in prognosis and monitoring of the course of the disease and the results of treatment.

Keywords: chronic renal failure, Dialysis, brain stem auditory evoked potentials, visual evoked potentials