BACKGROUND Dystonia and tremor share many commonalities. Isolated tremor is part of the phenomenological spectrum of isolated dystonia and of essential tremor. The occurrence of subtle features of dystonia may allow one to differentiate dystonic tremor from essential tremor. Diagnostic uncertainty is enhanced when no features of dystonia are found in patients with a tremor syndrome, raising the...

The occurrence of Parkinson's disease and of essential tremor was examined in the parents and siblings of 52 Parkinson's disease patients with onset before the age of 45 years. The expected numbers of cases with Parkinson's disease or essential tremor were calculated according to the age and sex specific incidence rates of Parkinson's disease and essential tremor in the general population. Amon...

Essential tremor (ET) is one of the most common movement disorders in the world, with prevalence rates in the general population ranging from 0.4% to 4.6%. The incidence of ET increases with age, with the average age at onset in mid-to-late 40s. ET is estimated to affect as many as 7 to 10 million Americans. Clinically, ET is characterized by bilateral, symmetric, postural tremor in hands and f...