Peripheral nervous system involvement complicated due to vasculitis in cases of primary Sjögren's syndrome: case studies in a single hospital and a literature review

To determine the background features of peripheral nervous system (PNS) involvement in cases of primary Sjögren's syndrome (SS), we studied the nervous system involvement, mainly that of PNS, in patients with primary SS who were admitted to our hospital during a period of 19 years. Nine of 82 admitted patients with primary SS had PNS involvement and 12 had central nervous system (CNS) involvement. Among 182 secondary SS patients, 25 had CNS involvement, and none had PNS involvement. The nine patients with PNS involvement were older and their disease duration was shorter than those with CNS involvement and either primary or secondary SS. Four patients exhibiting active progression of PNS involvement had concomitant vasculopathy clinically that was confirmed by nerve or skin biopsy examination, with an increase in the serum C-reactive protein level. According to the literature, among 17 reported SS patients with PNS involvement, 13 had primary SS, and 13 had vasculitis as confirmed by biopsy examination. Nervous system involvement in cases of SS is not rare. PNS involvement was observed mostly in elderly patients with primary SS, and its active progression was concomitant with vasculopathy.