Essential tremor is one of the most common movement disorders. It is usually inherited. The tremor is not present when someone is relaxed but becomes evident when a body part assumes a posture or undertakes a specific action. The tremor is generally rhythmic and can vary from being only subtle to very severe and debilitating. The tremor affects the hands and arms and may affect the head and the voice.
Dystonic tremors are quite variable in their presentation and on some occasions can look like essential tremor. They are, however, seldom seen in isolation and usually are associated with dystonic body postures. The tremors are also sometimes somewhat more irregular than what is seen with essential tremor. Because essential tremor and dystonia tremor may look the same and both can be genetic, researchers have investigated whether patients with essential tremor might carry an abnormality in the DYT1 gene that is associated with early onset genetic dystonia. This has been found not to be the case although the actual gene for essential tremor has not been identified.