White matter water diffusion changes in primary Sjögren syndrome.

BACKGROUND AND
PURPOSE: Histopathologic studies have demonstrated WM damage in primary Sjögren syndrome. The purpose of this study was to evaluate WM microstructural changes by use of DTI-derived parameters in patients with primary Sjögren syndrome.
MATERIALS AND METHODS: DTI was performed in 19 patients with primary Sjögren syndrome (age, 64.73 ± 9.1 years; disease duration, 11.5 ± 7.56 years) and 16 age-matched control subjects. Exclusion criteria were a history of major metabolic, neurologic, or psychiatric disorder and high risk for cardiovascular disease. Data were analyzed by use of tract-based spatial statistics, for which the WM skeleton was created, and a permutation-based inference with 5000 permutations was used with a threshold of P < .01, corrected for multiple comparisons to enable identification of abnormalities in fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity.
RESULTS: Tract-based spatial statistics showed decreased fractional anisotropy in multiple areas in patients with primary Sjögren syndrome compared with control subjects, located mainly in the corticospinal tract, superior longitudinal fasciculus, anterior thalamic radiation, inferior fronto-occipital fasciculus, uncinate fasciculus, and inferior longitudinal fasciculus. Increased mean diffusivity and radial diffusivity and decreased axial diffusivity were observed in most of the fiber tracts of the brain in patients with primary Sjögren syndrome, compared with control subjects.
CONCLUSIONS: Patients with primary Sjögren syndrome show loss of WM microstructural integrity, probably related to both Wallerian degeneration and demyelination.