A complementary approach for evaluating S1-root in diabetic neuropathic patients.

Diabetic neuropathy is one of the most common causes of peripheral neuropathy. Conventional electrodiagnostic evaluation or even magnetic resonance imaging (MRI) of lumbosacral vertebrae cannot confirm radiculopathy (e.g S1-root irritation) in diabetic neuropathic patients definitely. The purpose of the present study was to evaluate spinal nerve pathway of H-reflex in diabetic neuropathic patients by the central loop of H-reflex when its conventional pathway was impaired. No similar study, however, has been done on this subject. Forty two diabetic neuropathic patients with impaired conventional H-reflex were studied by the central loop of H-reflex bilaterally. The central loop of H-reflex was elicited by monopolar needle stimulation of S1 nerve root at the level of S1 foramen and recorded in the half way of the line from popliteal crease to the medial malleolus. In 82 out of 84 (97.6%) limbs with impaired conventional H-reflex, the central loop of H-reflex was measurable with latency less than 8 ms. Therefore the central loop of H-reflex was a more reliable approach for investigating S1-root in these patients with significant statistical difference (P < 0.001). The central loop of H-reflex latency in this study was 6.34 +/- 0.96 ms with the range of 4.3-7.85 ms. In conclusion the presence of central loop of H-reflex with latency less than 8 ms can be used as a complementary approach for assessment of S1-root sparing in diabetics.