Prevalence of primary Sjögren's syndrome in patients with multiple sclerosis.

Sixty-four consecutive patients with clinically or laboratory-supported definite multiple sclerosis (MS) were evaluated prospectively for evidence of primary Sjögren's syndrome (SS). This diagnosis was established when a patient had objective keratoconjunctivitis sicca, xerostomia, or both together with positive labial salivary gland biopsy. We found 2 patients (3.1%) with clinical evidence of primary SS. Whether this association is fortuitous or whether there is pathogenetic linkage between MS and primary SS remains to be established.