273 Dystonia is associated with macro and microstructural abnormalities of the cerebellum: A nested case-control study

Abstract

OBJECTIVES/GOALS: Dystonia is a brain disorder which causes excessive muscle activation, manifesting as abnormal movements. Neuroimaging studies of dystonia have revealed changes in a network involving the cerebellum. We sought out to determine whether subjects with dystonia in the UK Biobank exhibit MRI-based cerebellar pathology. METHODS/STUDY POPULATION: This nested case-control study drew from the UK Biobank, a cohort of >500,000 subjects in the United Kingdom, aged 40-69, enrolled 2006-2010. Eligible subjects must have undergone diffusion-weighted brain MRI. Dystonia cases were ascertained using ICD10 codes. We selected controls without neurologic diagnoses, matched (1:3) on age, sex, imaging site, and medical comorbidities. Mean diffusivity, fractional anisotropy, intracellular and isotropic volume fractions, and orientation dispersion were extracted from four white-matter tracts (inferior, middle, superior cerebellar peduncles; superior thalamic radiations) along with cerebellum, basal ganglia, and whole-brain grey and white-matter volumes. Means were compared using two-tailed t-tests and the Benjamini-Hochberg procedure (FDR = 0.05). RESULTS/ANTICIPATED RESULTS: 23 cases of dystonia and 69 control subjects were selected and ascertained. After correcting for multiple-comparisons (40 volumetric and 35 diffusion-related), intracellular-volume-fraction (ICVF) of the middle- and superior-cerebellar peduncles was significantly lower in subjects with dystonia, suggesting reduced axon density. Volumetric analysis showed significantly reduced volumes of the motor cerebellum (lobules VI and VIII). There were no differences in basal ganglia, cortical, or whole-brain volumes. DISCUSSION/SIGNIFICANCE: These findings support the hypothesis that abnormalities of cerebellar networks contribute to dystonia. In future we will use similar techniques to assess these tracts in subjects with dystonia who are undergoing Deep Brain Stimulation, with the goal of guiding stimulation targeting, and predicting therapeutic outcomes.