Tremor is probably the most commonly encountered movement abnormality and is characterised by the rhythmic oscillation of a body part. An involuntary, rhythmic muscle contraction causes the shaking.
Most common in the hands, tremors can also occur in the arms, head, vocal cords, torso, and legs. Tremors can be intermittent, happening every so often, or constant. Sometimes tremors develop on their own, and other times they signal an underlying health issue. Shaky hands may lead to difficulty in writing and drawing. A person may also have trouble holding and using tools and utensils, such as cutlery.
There are two main categories of tremors:
- Resting tremors: These occur when the muscles are relaxed, such as when the hands are resting on the lap.
- Action tremors: The majority of tremors are action tremors. They happen when the muscles are contracted because of voluntary movement.
A very fast fine tremor (10-14 Hz) is either physiological (i.e. anxiety and stress-related) or postural (e.g. in thyrotoxicosis, substance withdrawal, low blood glucose, encephalopathy). A slower tremor (5-10 Hz) may be indicative of an essential tremor or senile tremor. A parkinsonian tremor is usually described as a coarse (3-7 Hz) ‘pill-rolling’ tremor present at rest.
Below is a list of some of the types of tremors that I have encountered at the clinic:
Essential tremor
For some people, this tremor is mild and remains stable for many years. The tremor usually appears on both sides of the body but is often noticed more in the dominant hand because it is an action tremor. The key feature of essential tremor is a tremor in both hands and arms, which is present during action and when standing still.
Psychogenic tremor
The symptoms often start abruptly. The tremor increases in times of stress and decreases or disappears when distracted. Many individuals with psychogenic tremor have an underlying psychiatric disorder such as anxiety, depression or post-traumatic stress disorder (PTSD).
Physiologic tremor
Physiologic tremor occurs in all healthy individuals. It is rarely visible to the eye and typically involves a fine shaking of both of the hands and also the fingers. It is not considered a disease but is a normal human phenomenon that is the result of physical properties in the body (for example, rhythmical activities such as heartbeat and muscle activation).
Enhanced physiologic tremor
Enhanced physiological tremor is a more noticeable case of physiologic tremor that can be easily seen. It is generally attributed to reactions to certain drugs, alcohol withdrawal, or medical conditions including an overactive thyroid and hypoglycemia. It is usually reversible once the cause is corrected.
Parkinsonian tremor
Parkinsonian tremor is a common symptom of Parkinson’s disease. Symptoms include shaking in one or both hands at rest. It may also affect the chin, lips, face, and legs. The tremor may initially appear in only one limb or on just one side of the body. As the disease progresses, it may spread to both sides of the body. The tremor is often made worse by stress or strong emotions. More than 25 per cent of people with Parkinson’s disease also have an associated action tremor.
Tremor as part of extrapyramidal side effects
Extrapyramidal side effects are a group of symptoms that can occur in people taking antipsychotic medications. They are more commonly caused by typical antipsychotics, but can and do occur with any type of antipsychotic. Antidepressants and other medications can sometimes cause extrapyramidal side effects as well.
Extrapyramidal function refers to our motor control and coordination, including being able to not make movements we do not want to make. Extrapyramidal side effects from medications are serious and may include Parkinsonism, which means you have the same symptoms as someone with Parkinson's disease, but your symptoms are caused by medications, not by the disease. These symptoms may include tremor, slower thought processes, slower movements, rigid muscles, difficulty speaking and facial stiffness.
The following health issues can also cause shaky hands:
- anxiety or panic
- depression or post-traumatic stress disorder
- inherited degenerative disorders, such as hereditary ataxia or fragile X syndrome
- alcohol abuse or withdrawal
- hyperthyroidism, or an overactive thyroid
- liver or kidney failure
Certain drugs can also cause hand tremors, such as:
- some asthma medicines
- amphetamines
- caffeine
- corticosteroids
- medicines used to treat certain psychiatric and neurological disorder
