F-waves in evaluating uremic polyneuropathy: a long-term study after the application of continuous ambulatory peritoneal dialysis

Electrophysiological parameters were studied in 8 patients with end-stage chronic renal failure (CRF). The patients had complete evaluations of the state of CRF, clinical neurological examinations and EMG studies, performed before starting continuous ambulatory peritoneal dialysis (CAPD) as well as 10 days, 2 months and 6 months after initiation of CAPD treatment. All the conventional electrophysiological parameters studied (motor and sensory conduction velocities, terminal latencies, muscle and nerve action potentials) had a tendency to shift towards normal values, the effect being more pronounced in the upper limbs. F-wave maximum and minimum latencies improved quickly in the upper limbs, but very slowly, if at all, in the lower limbs. F-wave frequency became normal in 82% of the median and ulnar nerves, in 75% of the tibial nerves and remained unchanged in the peroneal nerves. F-wave identically, as represented by the "test of multiplicity", showed a general improvement in all nerves, including the peroneal. Studies of F-wave parameters, in addition to improving the diagnostic results, provide a more sensitive method, whereby the effects of CAPD can be examined quantitatively.