Natural course of idiopathic torsion dystonia among Jews.

The natural history of 51 idiopathic torsion dystonia cases identified in a nationwide survey in Israel was studied. In order to take advantage of all data regarding the evolution of the disease, independently of the length of follow-up, we have used a life table method of analysis. An estimate of the mean degree of generalization of the disease at different times from onset was calculated and a curve of the estimated temporal evolution was drawn. This analysis confirmed the heterogeneity of the disease course. The most rapid deterioration occurred in patients with juvenile onset in the lower limbs, particularly in the first 2 years following the onset. The rate of evolution was not influenced by gender or familiarity. The course of the disease seemed more deleterious in non-Ashkenazic Jews. The present statistical method of estimating the evolution in different patient groups should be useful especially for the evaluation of therapeutic interventions.