Abstract
Sural nerve biopsies were performed on 5 male diabetic patients to investigate the relationshipbetween clinical features and patho-histological findings.
Light microscopic examinations revealed that the density of myelinated nerve fibers was reduced in all the diabetic patients. Histograms of the myelinated nerve fiber diameter showed a reduction in nerve fibers of large diameter and a relative increase in nerve fibers of small diameter. Clusters of regenerated myelinated fibers frequently appeared in patients with a longer duration of diabetes. Degeneration and destruction of myelin sheaths and axons were recognized in all the diabetic subjects. Thickening of the vascular wall (Vasa nervorum) was also apparent in all cases; however, the changes in the nerve fibers were not consistent with the vascular alterations.
Teased nerve fiber studies revealed that all the cases exhibited segmental demyelination (12-28%), and axonal degeneration (1-12%). Degenerated nerve fibers were more frequent in diabetics with poor diabetic control than diabetics with fair control. Sensory nerve conduction velocity could not be evoked in the patient with the most marked segmental demyelination. The internodal lengths of the myelinated nerve fibers were reduced in the diabetics and the serial internodal lengths of the nerve fibers (especially those of large diameter) were widely scattered.It is suggested that the evolution of nerve lesions in diabetic neuropathy may be affected by diabetic control of long duration, and that changes in nerve fibers and blood vessels (Vasa nervorum) tend to develop independently.
