Tremor is defined as a rhythmic involuntary movement of a body part, due to regular rhythmic muscle contractions. It is often categorized in three positions which are:
Static tremor occurs when a relaxed limb is fully supported at rest. This type of tremor is typically seen in patients of Parkinson’s disease
Postural tremor appears when a body part is maintained in a fixed position and may also persist during movement. This tremor is seen in patients of essential tremors/post stroke tremors etc.
Intention or action tremor occurs specifically during active voluntary movement of a body part. If the amplitude of such an action tremor increases as goal-directed movement approaches the target. This is seen in patients of spin cerebellar ataxia, multiple sclerosis, etc.
Psychogenic tremors are generally rare and typically are of sudden onset with a variable but rarely remitting clinical course and typically affect the trunk or limb with standing and/or using the limb respectively.
The amplitude, frequency and severity of the tremor vary from patient to patient, but at its worst, tremor can cause severe functional disability.