Correlation between the number of epineurial and endoneurial blood vessels in diseased human sural nerves.

In a preceding study it was shown that changes in the number of epineurial blood vessels may be a prominent feature in angiopathic and other peripheral neuropathies, for instance in vasculitis, diabetes mellitus, or cerebral autosomal dominant angiopathy with multiple infarcts and leukoencephalopathy (CADASIL). Endoneurial blood vessels usually may also show significant structural alterations in a broad spectrum of neuropathic conditions, although these are not as prominent as in the epineurium. However, the relationship between changes in the number of epineurial and endoneurial blood vessels in diseased human sural nerves, and the impact of the loss of myelinated nerve fibers on the number of endoneurial blood vessels has thus far not been determined. Therefore, we investigated and compared the number of epineurial and endoneurial blood vessels in 50 human sural nerve biopsy specimens, representing a variety of peripheral neuropathies. We found that despite a significant increase of the number of epineurial blood vessels in cases with vasculitic neuropathy (P<0.05) and neuropathy with other types of microangiopathy (P<0.01), the number and density of the endoneurial blood vessels remained remarkably constant. In cases with an axonal type of neuropathy, severe neuropathic changes were associated with a decreased epineurial blood vessel number and a simultaneous, relative increase in the endoneurial blood vessel density. No significant correlation was found between (1) the number of epineurial and endoneurial blood vessels, and (2) the severity of the neuropathy and the number or density of epineurial and endoneurial blood vessels.