Neuropathology and morphometry of dentate nucleus neurons in DYT1 brains: Cerebellar abnormalities in isolated dystonia

Brain lesions exclusive to dystonia, or specific forms of it, such as isolated dystonia, have been rarely described. While the identification of distinctive intra- or extraneuronal abnormalities in childhood-onset generalized dystonia (DYT1) brains remains lacking, recent stereology-based findings demonstrated hypertrophy of neurons in the substantia nigra (SN) of DYT1-carriers manifesting dystonia (DYT1-manif) versus DYT1-carriers nonmanifesting dystonia (DYT1-nonmanif), and age-matched control subjects (C). Because other brain regions including the cerebellum (CRB) have been implicated in the pathomechanisms of dystonia, we investigated neurons of the dentate nucleus (DN), the "door-out" nucleus of the CRB. We performed systematic neuropathologic assessments and stereology-based measurements of 7 DN from DYT1-carriers (DYT1-DN; 4 DYT1-manif and 3 DYT1-nonmanif), and 5 age-matched control (C-DN) subjects. Data demonstrated larger cell body (+14.1%), nuclear (+10.6%), and nucleolar (+48.3%) volumes of DYT1-DN versus C-DN neurons. No differences in intra- and extracellular pathological indicators (β-amyloid, pTau, α-synuclein, Torsin1A, Negri, Bunina, Hirano, Marinesco, Nissl bodies, Buscaino bodies, granulovacuolar degeneration, or cerebrovascular lesions) were detected in DYT1-DN versus C-DN. Astroglial reactivity (GFAP) and microglial activation (IBA1) were observed in some DYT1-DNs. These novel findings confirm involvement of the DN and CRB in the pathogenesis of DYT1 and perhaps of other forms of isolated dystonia.