Peripheral nervous system involvement in HCV-related mixed cryoglobulinemia

In HCV-related mixed cryoglobulinemia (MC) a peripheral neuropathy (PN) may occur. To evaluate the prevalence and the characteristics of PN, 133 consecutive patients with HCV-MC (117 type II, 16 type III) were studied. Neurologic evaluation was performed according to the guidelines of Italian Group for the Study of Cryoglobulinemias, using a neurological disability score and a neurological symptom score. In 52/133 patients an electrophysiologic study (ENG) of ulnar, peroneal and sural nerves was performed. For 27/52 patients ENG data registered at different times (interval 12-96 months) were available. In 11 patients a sural nerve biopsy was obtained. An overt PN, mostly as sensory asymmetrical or symmetrical nerve impairement, was found in 107/133 patients (80.4%). ENG abnormalities-reduction or absence of sensory and sometimes of motor action potential, normal or slightly impaired nerve conduction velocity, consistent with axonal damage- were detected in 48/52 patients (92.3%). In 26 out of the 27 patients observed at different times an evolution of PN was found. Nerve biopsies showed a prevalent axonal damage, swollen endotelial cells in epi- and perineurial vessels and scarce mononuclear perivascular infiltrates. No leukocytoclastic vasculitis was observed. Immunoglobulins and complement in sub-perineurial vessel wall were detected. Conclusions. In HCV-MC a PN is frequent. It is mostly a sensory and progressively worsenig axonopathy. Different mechanisms may be involved in the pathogenesis of this disorder and a direct role of HCV cannot be excluded.