CNS involvement in primary Sjögren's syndrome: prevalence, clinical aspects, diagnostic assessment and therapeutic approach.

Among the systemic manifestations of primary Sjögren's syndrome, neurological involvement is still an intriguing and debated issue. Although peripheral nervous system abnormalities are a well documented occurrence with a reported prevalence ranging from 10 to 20%, opinions differ as to the prevalence of CNS disease, with suggestions from 'nonexistent' to 'very common'. The lack of agreement probably reflects the different populations selected, different inclusion criteria and lack of rigorous epidemiological studies. In our experience, CNS involvement was detected in 7 of 87 (8%) unselected consecutive patients observed over a period of 5 years. The spectrum of CNS involvement is wide, including focal, diffuse, neuropsychiatric and spinal cord symptoms, frequently characterised by insidious onset, remitting course and, sometimes, progressive evolution. The diagnostic approach enabling early recognition of this complication relies on careful clinical assessment using history and physical examination combined with neuropsychological testing and instrumental, laboratory and imaging investigations such as magnetic resonance imaging, single photon emission computed tomography, electrophysiological testing and CSF analysis. The clinical picture often shows spontaneous remission, but when overt neurological symptoms occur or become progressive, therapeutic interventions with high dose corticosteroids and cytotoxic agents, such as intravenous cyclophosphamide pulse therapy, may be indicated.