title: Contingent negative variation before and after hemodialysis among patients with end-stage renal disease.
abstract: OBJECTIVE
  To investigate changes in contingent negative variation (CNV) induced by uremia and to study the effects of hemodialysis.
  
  
  METHODS
  Fifteen right-handed healthy subjects and 12 patients with end-stage renal disease (ESRD) were studied. CNV was recorded from the Fz, Cz and Pz (using the International 10-20 System) referenced to linked ear lobes, using an S1 (click)-S2 (flashes)-key press paradigm. The amplitude of initial CNV (iCNV) was calculated as the average amplitude at 550-750 ms after S1. The amplitude of late CNV (lCNV) was the mean amplitude of the last 200 ms before S2. Testing was repeated for the patient group at pre- and post-hemodialysis observations. Neuropsychological measurements, a trail making test (TMT) and mini-mental state examination (MMSE), were conducted at each time.
  
  
  RESULTS
  The mean amplitudes of iCNV and lCNV at the vertex (Cz) were both significantly lower in the patient group than in the control group (P<0.05). TMT were also significantly different between patient and control groups (P<0.05)), however MMSE showed no significant difference. There were no significant correlations between the values of neuropsychological tests and the parameters of CNV. Both iCNV and lCNV were not significantly different between the pre- and post-dialysis tests.
  
  
  CONCLUSIONS
  CNV negativity in patients with ESRD reflects diffuse nonlocalizing neurological symptoms of uremia rather than a selective involvement of the frontal lobes. It is likely to reflect dysfunction in the frontal-subcortical circuit. In addition, hemodialysis seemed to have no significant effect on executive brain function in these patients with ESRD.
authors.affiliation: Department of Neurology, Inje University, College of Medicine, 633-165 Gaegeum-dong, Busanjin-gu, Busan 614-735, South Korea. neurobae@yahoo.co.kr
authors.forename: Jong Seok
authors.initials: JS
authors.lastname: Bae
authors.forename: Sung Sik
authors.initials: SS
authors.lastname: Park
mesh_terms: D001928:Brain Diseases, Metabolic / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D003265:Contingent Negative Variation / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials; D005625:Frontal Lobe / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy; D009434:Neural Pathways / Q000378:metabolism / Q000503:physiopathology; D009483:Neuropsychological Tests; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D006435:Renal Dialysis; D016896:Treatment Outcome; D014511:Uremia / Q000150:complications* / Q000628:therapy*