Tremor is an involuntary rhythmic movement involving one or more parts of the body. It is one of the common movement disorders encountered in clinical practice. Tremor can involve any part of the body, and most commonly the hands are affected. When severe, tremor can be disabling and interfere with daily activities. It can also result in social embarrassment.
Tremor can develop spontaneously or it can result from another disorder, such as Parkinson's disease or dystonia. Tremors can sometimes run in families or can result from certain medications, such as steroids, stimulants or inhalers. In many cases, however, the cause is unknown.
Tremor can be present at rest (resting tremor) or more commonly when carrying out activities (action tremor). The most common cause of a resting tremor is Parkinson's disease. There are many causes for an action tremor.
Tremor conditions
The following are examples of the more common conditions movement disorder specialists see in their clinical practice:
Essential tremor
Essential tremor (ET) is one of the most common movement disorders. The condition can affect the hands, head, legs, trunk, and/or voice. The tremor tends to affect both sides of the body and is predominantly present when carrying out activities, such as writing or eating and drinking (action tremor), and less so when resting. Essential tremor can start at any age, even at a young age, and often runs in families.
Dystonic tremor
Dystonic tremor tends to occur in individuals who have dystonia. The tremor can affect both sides of the body, however, most commonly one side is affected more than the other. Although the tremor can sometimes mimic a Parkinsonian tremor, there are usually no additional features, such as slowness of movements.
Cerebellar (intention) tremor
Cerebellar tremor can result from damage to the coordination centre of the brain (cerebellum). This type of tremor is characterized by slow irregular clumsy movements in the hands, which tend to worsen as you get closer to the target, such as picking up a small coin or pressing a button.
Parkinsonian tremor
Parkinsonian tremor, is one of the hallmark features of Parkinson's disease. Unlike essential tremor, a Parkinsonian tremor tends to occur at rest and affects one side of the body initially. When severe, the tremor can also become present with action. This is also known as a re-emergent tremor.