Sural nerve bioptic findings in essential cryoglobulinemic patients with and without peripheral neuropathy

Peripheral neuropathy often occurs in cryoglobulinemia but the pathogenesis of the peripheral nerve involvement is not completely understood, so that the relation between the reported endoneural changes and neuropathy is not clear. In this study we compared the sural nerve biopsies of 6 cryoglobulinemic patients with or without signs of peripheral neuropathy and all affected by the essential mixed type II form (ECII) and, moreover, of 8 age-matched controls. We found that in all the patients with neuropathy, axonopathy occurred and it was invariably associated with endoneural vessel damage. Moreover, the fiber losses were patchily distributed within the nerve fascicles. On the contrary both nerve fibers and vessels were normal in the patients without clinical and neurophysiological evidence of neuropathy and in controls. Our results support the hypothesis that the endoneural damage observed during ECII is not simply coincidental, but is relevant in the pathogenesis of cryoglobulinemic neuropathy. They also favor the assumption that ischemic damage of the nerve fibers occurs during ECII.