Essential tremor is less well known than Parkinson's disease, but it's far more common.
For many, the late actress Katherine Hepburn provided an indelible public image of essential tremor. Her quavering voice and trembling hands unmistakably betrayed the disorder.
Essential tremor affects about 5% of people over age 50. The intensity of the shaking from essential tremor can be mild to very significant. Also the tremor can vary in location, being most prominent in the hands, head or voice.
For people with essential tremor, holding a coffee cup, writing a note, buttoning a sweater, and applying makeup can all be challenging and sources of frustration or embarrassment. When essential tremor interferes with independent living or holding a job, it can be devastating. Fortunately, there are medications that help control the essential tremor symptoms, and ways to make the tasks of daily living easier.
How does essential tremor develop?
Essential tremor symptoms often first appear in a person's 40s, when delicate movements such as threading a needle become difficult. But it's usually not until people reach their 50s or 60s that the tremor becomes troublesome — for example, making it difficult to use a fork, drink from a cup, or write a letter. Essential tremor progresses slowly. Though essential tremor may eventually affect the voice and head, many people find that their symptoms don't progress beyond mild hand and arm tremor. Tremors are usually absent during sleep.
We don't know the precise cause of essential tremor. Some experts believe that the problem lies in the cerebellum (the part of the brain that controls movement and balance) or its connections with the brainstem, which lies at the base of the brain. Essential tremor is a heritable condition. If you have essential tremor, your children will have a 50% chance of developing it as well.
Tremors, yes; Parkinson's disease, no
Essential tremor is often mistaken for Parkinson's disease, but the two conditions differ in several ways. Essential tremor is an action tremor, meaning that the involuntary shaking increases when you move and try to use your hands. In Parkinson's disease, tremors occur mainly at rest, and activity reduces the symptoms. Some people with essential tremor develop head nodding or shaking; few people with Parkinson's do. Balance problems and rigidity of the arms and legs are common features of Parkinson's disease but not of essential tremor. One of the hallmarks of essential tremor, useful in diagnosing the disorder, is that alcohol can temporarily ease symptoms; in Parkinson's, alcohol has little effect on the tremor.
Parkinson's disease is marked by a progressive loss of brain cells that produce dopamine, a chemical messenger that enables normal body movements. Essential tremor also appears to involve a disruption in the activity of motor pathways, but it's uncertain whether there is any loss of brain cells. Postmortem examinations of brain tissue taken from people with essential tremor reveal various abnormalities in the cerebellum and brainstem, including the loss of Purkinje cells, which produce an important neurotransmitter, called GABA. But the samples don't all show the same changes, so the import of these findings is uncertain.
Tips for surviving essential tremor
Here are some ways to minimize the effects of tremors on your daily life:
Managing essential tremor
There's no cure for essential tremor, but the symptoms can be managed in several ways, starting with practical measures such as those listed above in "Tips for surviving essential tremor."
Essential tremor treatments include medications and surgery.
Medications. Propranolol (Inderal) and primidone (Mysoline) are most effective in reducing tremors. Propranolol is a beta blocker, also used to treat high blood pressure and performance anxiety. Its side effects are mild to moderate and include slow heartbeat, fatigue, and shortness of breath. (People with asthma should not take propranolol.) Primidone is an antiseizure medication with mild to moderate side effects that include drowsiness, difficulty concentrating, nausea, and dizziness. Both of these drugs can reduce tremors by as much as 50%.
Several other drugs may be helpful in treating essential tremor, though the evidence for them isn't as strong. These include the beta blockers atenolol (Tenormin) and sotalol (Betapace); and the antiseizure drugs gabapentin (Neurontin) and topiramate (Topamax).
Surgery. If medications don't help essential tremor, surgery may. Surgery always carries risk, and the risk is especially great for operations involving the brain. The two best-studied surgical treatments for severe limb tremor that hasn't responded to medications are thalamotomy and deep brain stimulation (DBS). Both procedures can help reduce limb tremors; they are less useful for head shaking and a quavering voice.
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