Pathophysiology of dystonia

Abstract

In the past 18 months, several important studies in neuroimaging, epidemiology of dystonia and animal models have been published. Moreover, new advances in genetics have broadened the spectrum of dystonia. Here, we discuss these findings and their implication in the pathophysiology of dystonia. From neurophysiological studies and animal models, converging arguments support the role of combined corticostriatal, cerebellar and dopaminergic dysfunctions in the pathophysiology of dystonia. A large study in epidemiology identified several risk factors associated with writer's cramp (time spent handwriting each day and the additional burden of an abrupt increase in the writing time in the year before onset). Important studies on the abnormal structure-function relationship in hereditary and sporadic dystonia explored the relationship between genotype, phenotype and endophenotype. Different pathophysiological mechanisms may underlie similar phenotypes whereas different genotypes may share similar functional abnormalities. The respective roles of corticostriatal-cortical and cerebellar loops remain to be clarified as the original causative process (either degenerative or developmental) is accompanied by functional reorganization.