Evaluation of CNS-function in CAPD patients using magnetoencephalography (MEG): comparison with hemodialysis patients

In order to evaluate the CNS-function of uremic patients, the magnetic activity emitted from the brain of 20 pts (10 pts on CAPD and 10 on HD) was measured. MEG consisted of taking 32 consecutive records from the 32 equally spaced points chosen on the skull in uremic pts around our reference points T3, T4, P4, F3, F4 of the international 10-20 electrode placement point system. MEG data were converted using an AD-converter with sampling frequency 256 Hz and stored in a P/C. Our results showed significant differences between the two groups. In all HD pts there was abnormal magnetic brain activity with high spectral amplitudes (in the band 2-7 Hz) which was more prominent in pts in hemo for more than 4 years. The magnetic activity was within normal ranges in all CAPD pts. We conclude that: 1) There is high magnetic brain activity in HD pts, which in accordance with the EEG findings are signs of diffuse encephalopathy. 2) CAPD pts show a very low magnetic brain activity which must be interpreted as normal brain function, and 3) MEG can be useful in further measurement of adequacy of dialysis.