Essential tremor

What it is

Essential tremor is the most common form of tremor, and up to 5% of the population is affected. It is a benign form, hereditary, with a positive family history in 50-70% and autosomal dominant inheritance, or else sporadic. It sits among the action tremors, against the resting tremor of the basal ganglia and the coarse intention tremor of a cerebellar lesion.

How it presents

• It is fine, and mostly bilateral, with a frequency of 5-10 Hz.
• The localization is the hands and the head: hands more than arms, more than head, and far more than legs.
• It comes with certain sustained postures, such as the hands outstretched, and is worse with sustained voluntary movement, with stress or with an anxious state.
• It improves with alcohol.
• The neurological examination is otherwise normal.

It is an action tremor, with a postural part, as with the hands outstretched, and a kinetic part during movement, as on the finger-nose maneuver; one page adds that in essential tremor the amplitude of the kinetic tremor is more than that of the postural tremor. In advanced essential tremor there can be a resting tremor, more restricted to the arms.

It is not limited to the arm; neck tremor is seen in about 20% of patients, and head tremor is one of its features.