Two patterns of results in polyneuropathies investigated with the H reflex. Correlation between proximal and distal conduction velocities.

The Hoffman (H) reflex of the soleus muscle has been used to study peripheral neurological disorders in 79 cases of chronic renal insufficiency prior to the initiation of haemodialysis, and in 94 cases of chronic alcoholism. In both groups, care was taken to ensure that the subjects examined could not be suspected of any other type of neuropathy. The results have been compared with those obtained in 42 normal subjects. The nerve conduction velocity in the reflex pathway was evaluated by an H index formula in which the conduction time (interval between M and H responses) is related to the length of the nervous pathway (a function of the subject's height). This method demonstrated a marked reduction in the conduction velocity of the proximal parts of the peripheral nerves, in both uraemic and alcoholic subjects. The maximal amplitude of the reflex response was evaluated in relation to the maximal amplitude of the direct motor response (H max/M max). It was shown that this ratio diminishes very greatly and very rapidly in the course of alcoholic polyneuritis, while, at comparable conduction velocities, the amplitude of the reflex response is much less changed in chronic renal insufficiency. These results prove that there is a noteworthy difference between uraemic and alcoholic polyneuropathy. Its significance is discussed in the context of currently knwon histopathological and electrophysiological data on the polyneuritides. From a practical point of view, the H reflex appears to be an effective tool for the investigation of peripheral neuropathy in man.