Essential tremor (ET) is a type of involuntary shaking movement in which no cause can be identified. Involuntary means you shake without trying to do so. Everyone has some tremor present, but the movements are often so small that they can’t be seen. In ET these movements can be seen.
Causes, incidence, and risk factors
ET is the most common type of tremor. Although the shaking can start at any age, essential tremor is most common in people older than 65.
The tremor is not caused by brain damage or substantial degeneration in the brain. ET is probably due to a kind of ‘short-circuit’ in the electrical systems in the brain that are responsible for movement. Shaking can also occur with other brain and nervous system problems, such as dystonia, parkinsonism, and certain nerve conditions passed down through families.
If an essential tremor occurs in more than one member of a family, it is called a familial tremor. This type of essential tremor is passed down through families (inherited), which suggests that genes play a role in its cause.
Familial tremor is usually a dominant trait, which means that you only need to get the gene from one parent to develop the tremor. It often starts in early middle age, but may be seen in people who are older or younger.
The shaking is more likely to be noticed in the hands, but may affect the arms, head, eyelids, voice and trunk. The tremor rarely affects the legs or feet. People with ET may have trouble holding or using small objects such as a pen.
Specific symptoms may include:
- Problems with writing, drawing, drinking from a cup, or using tools if the shaking affects the hands
- Head nodding
- Shaking or quivering sound to the voice if the tremor affects the voice box
The tremors may:
- Most often occur with movement (action-related tremor), and are less noticeable at rest
- Come and go, but often get worse as you age
- Get worse with stress, caffeine, and certain medications
- Not affect both sides of the body the same way
Signs and tests
Your doctor can make the diagnosis by performing a physical exam and asking questions about your medical and personal history.
A physical exam will show shaking with movement, usually small movements that are faster than 5 times per second. There are only sometimes problems with coordination and mental function.
Further tests may be needed to rule out other reasons for the tremors. Other causes include:
- Smoking and smokeless tobacco
- Overactive thyroid (hyperthyroidism)
- Too much caffeine
- Use of certain medications
Blood tests and imaging studies (such as a CT scan of the head, brain MRI, and x-rays) are usually normal and not performed.
Treatment may not be needed unless the tremors interfere with your daily activities or cause embarrassment.
For tremors made worse by stress, try techniques that help you relax. For tremors of any cause, avoid caffeine and get enough sleep.
Medicines may help relieve symptoms. The most commonly used drugs include:
- Propranolol, a beta blocker
- Primidone, a drug used to treat seizures
The drugs can have side effects.
- Propranolol may cause fatigue, stuffy nose, or slow heart beat, and may make asthma worse
- Primidone may cause drowsiness, problems concentrating, nausea, and problems with walking, balance, and coordination. At Neurology Network Melbourne we often start primidone only after prescribing phenobarbitone 30mg daily for one month to allow the body to learn to metabolise the primidone
Other medications that may reduce tremors include:
- Antiseizure drugs such as gabapentin and topiramate
In severe cases, deep brain stimulation surgery may be tried:
- Implanting a stimulating device with wirse in the brain in the area that controls movement
An essential tremor is not a dangerous problem, but some patients find the tremors annoying and embarrassing. In some cases, it may be dramatic enough to interfere with work, writing, eating, or drinking.
Sometimes the tremors affect the voice box, which occasionally leads to speech problems. There is a substantial association between essential tremor and cerebellar ataxia (imbalance) which can cause mild or moderate gait disturbance.
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