Participation of cryoglobulinaemia in the severe peripheral neuropathies of primary Sjögren's syndrome.

A peripheral neuropathy is encountered in 10 to 50% of patients with primary Sjögren's syndrome (pSS). The pathogenesis of this complication remains unknown, but severe cases of peripheral neuropathies seem to result from a vasculitis. Since about 20% of pSS are associated with a cryoglobulinaemia, we initiated a retrospective study to assess the participation of cryoglobulinaemia in the severe peripheral neuropathies (SPN) of pSS. We found 6 cases of SPN (presence of pain and/or muscle weakness) in a group of 115 pSS (5%): 3 polyneuropathies and 3 mononeuritis multiplex. In all cases, the involvement was sensoromotor and axonal. Four patients had a biopsy-documented cutaneous vasculitis, and 2 of them had also a muscular lymphocytic vasculitis. A cryoglobulinaemia was detected in sera of 5 patients. Although the research was negative in the remaining patient, the presence of an IgM monoclonal gammapathy and of an hypo-complementaemia suggested also the presence of a cryoglobulinaemia. Complement was activated in the 6 cases. Treatment was aggressive: oral corticosteroid (6 cases), methylprednisolone pulses (4 cases), chloraminophen (1 case), plasma exchanges (2 cases), intravenous immunoglobulins (1 case). A stabilization or a partial regression of the neuropathies were observed in 1 case and 5 cases, respectively. This was associated with a reduction of cryoglobulin level and complement activation in 5 cases and 6 cases, respectively. This study suggests that SPN of pSS result from a cryoglobulin-mediated vasculitis.