Sural nerve myelin thickness and axis cylinder caliber in human diabetes

The relationships of transverse axis cylinder area to number of myelin lamellae and index of circularity of myelinated fibers, and vice versa, were analyzed on electronmicrographs from 12 healthy subjects, 3 diabetic patients without symptomatic neuropathy, and 9 diabetic patients with neuropathy. The transverse axis cylinder area of surviving myelinated fibers of nerves from patients with or without neuropathy was not significantly smaller or more irregular than that of controls, but myelin sheaths of nerve fibers from patients with neuropathy had significantly fewer lamellae. These results do not provide evidence that axonal atrophy precedes segmental demyelination in human diabetic neuropathy.