[Hoffmann reflex elicited by magnetic stimulation of S1 nerve roots in the diagnosis of diabetic radiculopathy].

OBJECTIVE: To determine the incidence of radiculopathy in diabetic patients neurophysiologically. METHODS: The H-reflexes were elicited by magnetic stimulation to S1 nerve root at the first sacral foramen (S1 H-reflex) in 40 normal subjects and 41 diabetic patients. The action potentials of the H-reflex were recorded from the soleus muscle. For comparison, a popliteal H-reflex (stimulated at popliteal fossa), and a regular distal sensory and motor conduction of the tibial nerves were simultaneously evaluated. RESULTS: A significant correlation of the peak interval of H wave and M wave (HMI) of the S1 H-reflex with body height and age was confirmed by multiple regression analysis in the normal subjects. The simultaneous regression of the HMI adjusted on age and body height produced the formula as 0.02 x (age) + 0.03 x (height) + 0.92. At 95% normal limits of the significant test, 40.2% HMI and 53.7% amplitude of H waves of the S1 H-reflex, 54.9% latency and 46.3% amplitude of H waves of the popliteal H-reflex, 40.2% SCV and 40.2% amplitude of sensory action potentials were diagnosed as abnormal. CONCLUSIONS: A high incidence rate of diabetic radiculopathy was confirmed to be comparable to that of proximal neuropathy and distal symmetrical sensory polyneuropathy. This suggests that diabetic neuropathy may be related to metabolic and/or vascular disorders.