What is a tremor?
Tremor is an unintentional (involuntary), rhythmical alternating movement that may affect the muscles of any part of the body. Tremor is caused by the rapid alternating contraction and relaxation of muscles and is a common symptom of
diseases of the nervous system (neurologic disease).
Tremor may occur as an isolated symptom and usually of unknown cause (essential tremor) or a part of the symptom constellation of another disorder (Parkinson's Disease). Tremors may occur at rest (Parkinson's disease), during voluntary movements (cerebellar lesions) or during excessive activity of muscles (essential tremor, hyperthyroidism). In Parkinson's disease, the tremor occurs when muscles are resting. For example, people with Parkinson's disease will watch their hands shake when they rest quietly in their lap, but when they reach out to grab or hold something, such as a cup of coffee, the shaking stops. Just the opposite happens in people with essential tremor. Their tremor begins when they use their hands, for example, when holding a pen or pencil. Essential tremor often begins in the dominant hand (the one used for writing).
Tremor often accompanies neurological disorders associated with aging. Although the disorder is not life-threatening, it can be responsible for functional disability and social embarrassment. Tremors may increase with anxiety and caffeine and cease during sleep. Medications are used only if tremor interferes with daily life activities. Some of the drugs that can be used are clonazepam, mysoline, and propranolol.