Peripheral neuropathy in mixed cryoglobulinemia: clinical and electrophysiologic investigations.

Peripheral neuropathy has been described in different rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus and systemic vasculitis, but usually in limited numbers of patients. Nerve injury is more frequently reported in mixed cryoglobulinemia. In earlier studies generally performed in small series of patients, prevalence of peripheral neuropathy varied widely. We evaluated prevalence of peripheral neuropathy in 33 unselected patients with mixed cryoglobulinemia (25 women, 8 men, aged from 45-71 years). Neurologic involvement was detected using a complete clinical and electrophysiologic assessment, including sensory motor conduction velocities, F wave and H reflex. Neurologic examination revealed a neuropathy in 48% of subjects, while electrophysiologic variables were altered in 82%; a percentage similar to that of subjective symptoms (91%). Among electrophysiologic investigations, F wave was altered in 22/33 subjects (67%); therefore, this variable seems to be the most reliable for the detection of neurologic involvement. Cryocrit levels were significantly higher in patients with peripheral neuropathy: abnormal examination (p less than 0.01), sensory motor conduction (p less than 0.04), and F wave alterations (p less than 0.008). In addition, hemorheological abnormalities seem to contribute to the pathogenesis of nerve injury. Our results indicate that peripheral neuropathy, to a variable degree, is present in the majority of patients with mixed cryoglobulinemia, and a complete clinical and electrophysiologic investigation can be useful for an early and correct diagnosis.