Cerebellar and brainstem MRI alterations in primary brain calcification

Purpose: Primary Brain Calcification (PBC) is a neurodegenerative disorder with marked genetic, radiological, and clinical heterogeneity. Infratentorial changes are largely unknown, and MRI role is still underinvestigated. Methods: Fifty PBC patients underwent brain 3T-MRI (3D-FLAIR, 3D-T1, 3D-T2, SWI), genetic, and clinical-neuropsychological evaluation. 50 matched controls were enrolled. Qualitative signal abnormalities and quantitative measures of cerebellar and brainstem atrophy were correlated with genetic and clinical data. Results: PBC patients frequently showed abnormal cerebellar (86%) and brainstem (46%) findings. Compared to controls, patients showed more frequently brainstem vascular involvement, cerebellar and brainstem atrophy, T1 and SWI alterations in dentate nuclei and cerebellar cortex, and SWI changes in medullary corpora and middle cerebellar peduncles, with a dentate-to-peduncular gradient. Cerebellar and brainstem atrophy were associated with cerebellar cortex, medulla oblongata nuclei and middle cerebellar peduncles SWI-abnormalities, red nuclei T1-hyperintensity, and dentate nucleus hila FLAIR-hyperintensity. Voxel-based-morphometry demonstrated superior cerebellar peduncles decussation, red nuclei, and subthalamic nuclei atrophy; region-of-interest-based analysis showed cerebellar, pontine, and midbrain atrophy. Definite PBC showed a higher burden of qualitative MRI abnormalities than probable PBC and controls. Voxel-based-morphometry confirmed more extensive atrophy in definite PBC vs. controls, probable PBC did not differ from other subgroups. At multivariate analysis, brainstem atrophy was an independent predictor of freezing (p = 0.03) and oculomotor dysfunction (p = 0.01), brainstem vascular involvement of falls (p = 0.003), cerebellar atrophy of dysarthria (p = 0.002) and cerebellar signs (p = 0.04). Conclusions: Infratentorial qualitative and quantitative MRI abnormalities are common and clinically relevant in PBC, and identify neurodegenerative changes that improve our understanding of its clinical heterogeneity.