What is the relationship between Essential Tremor and dystonia?
Although tremor is frequently found in patients with dystonia, it is not always clear whether the oscillatory movement is a form of dystonia (hence, a dystonic tremor) or whether it represents coexistent Essential Tremor.
Postural hand tremor, phenomenologically identical to Essential Tremor, may either precede or be the initial manifestation of dystonia.
The lack of demographic and other differences between patients with Essential Tremor and Essential Tremor–dystonia supports the notion that Essential Tremor is a single disease entity with a clinical spectrum that often includes dystonia.
Some investigators argue, however, that the postural tremor in patients with dystonia has different clinical characteristics—such as irregularity and a broader range of frequencies, asymmetry of contractions, and associated myoclonus—that distinguish it from Essential Tremor.
