Somatosensory evoked potentials and central motor pathways conduction after magnetic stimulation of the brain in diabetes.

Somatosensory evoked potentials (SEPs) on stimulating median and posterior tibial nerves, and central and spinal conduction time of the motor pathways calculated by means of magnetic stimulation of the cortex were valuated in diabetic patients. The latencies L1-Cortex and L1-C7 were significantly larger in 54 diabetics than in controls. An increment in L1-C7 interval was found in 17 patients, and the latency L1-Cortex was increased in 20. No patients showed increase in C7-Cortex interval. The increased latency L1-C7 reflects a delayed conduction along afferent spinal pathways in some patients with diabetes in contrast with the normal C7-Cortex supraspinal segment. The central and spinal conduction time after magnetic stimulation of the cortex were normal in 14 out of 15 tested diabetics suggesting that central motor pathways were spared. These results are consistent with the existence of a central-peripheral sensory axonopathy in some diabetics.