A case of position dependent tremor.

A 79-year-old woman presented 3 years' history of hand shaking while drinking a cup of tea. The tremor was seen bilaterally, more predominantly on the left, and it also appeared when reading a book or writing. It was also induced by flexing the elbow to about 90 degrees or more without any specific task. Although there was no family history, the tremor in the present case was clinically diagnosed as essential tremor, because there were no other movement abnormalities, and other causes of tremor were excluded by laboratory tests. The tremor was dependent on the position of the involved extremity regardless of the kind of tasks. Position-specific tremor is discussed in relation to postural tremor.