Peripheral nerve involvement in pernicious anaemia.

Impairment of nervous function and thiamine metabolism were studied in 40 patients suffering from pernicious anaemia, 20 of whom had not been treated and the other 20 were on hydroxocobalamin therapy. Of the untreated patients 13 (65%) showed signs of peripheral nerve dysfunction with reduced conduction velocities, as compared with only 1 (5%) of the treated patients. Reduced blood thiamine levels were found in 16 of the untreated patients (80%), 10 (60%) of whom showed biochemical signs of thiamine deficiency. In the treated group, 7 patients (30%) had reduced blood thiamine levels. Thus, peripheral nerve involvement in pernicious anaemia is much more frequent than would be expected from the literature, and thiamine deficiency was present in the majority of these cases.