A quantitative electrophysiological study of uraemic neuropathy. Diabetic and renal neuropathies compared.

The numbers of functioning motor units and the parameters of the electrically evoked motor unit potentials in the extensor digitorum brevis muscles of 30 patients on chronic haemodialysis for renal failure were obtained using recently introduced quantitative electrophysiological techniques. Measurements of the distal motor latencies and motor nerve conduction velocities in the lateral popliteal nerves of the same patients are also presented. The results support the presence of a "dying back" type of neuropathy in uraemia, with a preferential involvement of the fastest conducting motor axons. Collateral reinnervation and compensatory increase in size of surviving motor units is relatively impaired in uraemic neuropathy in comparison with a similar study on diabetic neuropathy. The significance of paranodal and segmental demyelination in producing abnormalities of conduction velocity in these neuropathies is discussed.