Essential Tremor: Symptoms, Risk Factors, and Treatments

Essential tremor, a disorder of the nervous system, causes involuntary shaking of the upper limbs, and sometimes affects the head, torso, voice, or other parts of the body. It is the most common neurologic tremor disorder, affecting about 7 million people in the United States.

What Are The Symptoms?

Essential tremor can affect both sides of the body, but it is usually more prominent on one side. The tremor is usually worse during movements and actions rather than when limbs are at rest. When more severe, the tremor can interfere with activities like eating, drinking, writing, or shaving. While tremors can affect the arms, hands, head, voice, and trunk, they rarely affect the lower limbs. Stress and anxiety can exacerbate the tremor. Moderate amounts of alcohol may improve tremor for some people, but the tremor may worsen once the effects of alcohol wear off and it is not considered a treatment for tremor.

What Are The Risk Factors?

Age increases the risk, although tremor can affect everyone, including children. About 30 to 70 percent of patients have a family history of tremor, and 80 percent of those who develop tremor before age 40 have a family history of the disorder. Men and women are affected at similar rates, but some studies suggest men may be at a slightly higher risk.

How Is It Diagnosed?

During a physical examination, neurologists look for three things: a tremor that affects both upper limbs and has persisted for several years; upper-limb tremor with or without tremor in other areas; and the absence of other neurologic symptoms. In general, the diagnosis is made based on careful history and neurologic examination. When the clinical diagnosis remains uncertain, physicians may order a type of single-photon emission computed tomography (SPECT) imaging called DaTscan that shows the activity of the brain's dopamine system, to rule out Parkinson’s disease as a cause of the tremor. Unlike those with Parkinson’s disease, people with essential tremor have normal dopamine levels.

How is Essential Tremor Treated?

First-line treatments include propranolol, a nonselective beta-adrenergic antagonist—a drug that blocks nerve impulses to the muscles—and primidone, an anticonvulsant. Both drugs may be prescribed together for more serious cases. Other beta blockers and seizure medications, as well as benzodiazepines, also may be used to quell tremor. Botulinum toxin injections may be helpful for head and voice tremor. For severe cases that do not respond to more conservative treatments, doctors may recommend surgical options such as deep brain stimulation (DBS) or focused ultrasound (FUS), both of which are FDA approved for treatment of essential tremor.

DBS is more established and involves implanting an electrode in the ventral intermediate (VIM) nucleus of the thalamus, a part of the brain that helps control movement. The electrode is connected to a battery-powered pulse stimulator, which is placed under the skin near the collarbone. Electrical stimulation delivered to the VIM area of the brain can suppress tremor on the opposite side of the body. MRI-guided FUS thalamotomy, a more recent treatment, uses high-energy ultrasound waves to create a lesion in the VIM nucleus of the thalamus.

What Research is Being Done?

Clinical trials exploring novel medications remain relatively few as standard medications have generally shown at least similar or better efficacy. More recent research has tended toward wearable devices, neuromodulation, and advances in existing surgical treatments. Devices include those that monitor tremor severity, dampen or suppress tremor activity with active or passive strategies, and electrical modulation of peripheral nerves.

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Where Can I Find More Information About Essential Tremor?

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