OBSERVATIONS ON ESSENTIAL TREMOR

Abstract

Essential tremor is also known as familial or senile tremor while physiological tremor accompanies muscular activity in normal persons. Recordings of essential tremor in 30 patients showed its characteristic features and these were then related to physiological tremor. Essential tremor occurred most commonly in the upper limbs with additional involvement frequently seen in the head. Frequency varied from 4 to 12 cycles per sec. (c/s) with modes of a bimodal distribution curve at 10 and 6 c/s. There was no evidence that duration of tremor had an independent effect on frequency but when duration was held constant, there was a significant decrease of fre- quency with age. These observations suggest that essential tremor is basically physiological tremor which occurs at an increased amplitude due to an unknown deficit, possibly genetic in nature, in the nervous system.