EFFICACY OF METHYLCOBALAMIN IN SUBCLINICAL UREMIC NEUROPATHY AS DETECTED BY MEASURING VIBRATION PERCEPTION THRESHOLDS

Vibration perception thresholds (VPT) were measured using a new machin e, the SMV-5 (Technolog Company, Tokyo, Japan) in 25 patients receivin g maintenance haemodialysis without overt uraemic neuropathy. Patients who had other medical complications such as diabetes mellitus, dialys is amyloidosis or central nervous system dysfunction or peripheral vas cular disease were excluded from this study. Forty per cent of the upp er extremity VPT and 68% of the lower extremity VPT of the dialysis pa tients were abnormal, which was defined as greater than 2 s.d. above t he mean of the normal subjects. The VPT of smokers (n = ) were signifi cantly higher than those of non-smokers (n = 18; P < 0.01). The VPT of the patients in the treated group (n = 13, including 4 smokers) impro ved 6 months following the initiation of methylcobalamin therapy (P < 0.05). The high incidence of subclinical uraemic neuropathy led us to consider that uraemic neuropathy should be detected at an early stage. The relationship between neurologic disorders and smoking, and the ef ficacy of methylcobalamin (analogue vitamin B12) in the treatment of u raemic neuropathy (and in the peripheral neuropathy noted in Leber's d isease) suggest that cyanide may be the uraemic toxin responsible for the neuropathy. Further studies of chronic cyanide exposure and the me tabolism of cyanide in patients with uraemia are necessary.