John Crowell, 58, owner of a personal assistant service in Charlotte, NC, was just a boy when he began to notice that his hands trembled. He was teased when he tried to write on the blackboard at school, and the thought of reaching for a wafer or the juice cup at church communion services filled him with terror. "I was afraid I would send it flying," he says.

At the time nobody knew what was wrong. "Everybody thought it was nerves," Crowell says. It wasn't until he was in his thirties that he saw a neurologist and learned that the involuntary quivering of his hands had a name: essential tremor.

A Common Condition

Essential tremor is a neurologic disorder that affects approximately 7 million people in the United States, according to a 2014 study published in the journal Tremor and Other Hyperkinetic Movements. Prevalence of the disorder among all ages, including children, is between 0.4 and 3.9 percent. The incidence increases to between 1.3 and 5 percent in people older than 60, according to a 2017 study published in Movement Disorders Clinical Practice. These estimates vary, though, because the severity of essential tremor varies as well. In most cases, patients are mildly affected and may never be diagnosed.

The condition is characterized by involuntary shaking of the hands, and sometimes of the head, voice, or other body parts. When severe, this shaking can make it hard to perform everyday activities. People with the disorder can feel self-conscious or embarrassed.

No one is sure where essential tremor originates in the brain; some evidence suggests that it starts in the cerebellum. "The best we can tell is that it derives from an abnormality in a network that goes between the cortex, the cerebellum, and the thalamus," says Mark Hallett, MD, FAAN, senior investigator at the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH).

Different from Parkinson's

Essential tremor is often confused with Parkinson's disease, which also produces tremor. But that is the only symptom the conditions share. "With essential tremor, that is virtually the sole symptom," says Paul S. Fishman, MD, PhD, professor of neurology at the University of Maryland School of Medicine and chief of neurology at the Veterans Affairs Maryland Health Care System in Baltimore. "People with Parkinson's disease also experience slowing movement and muscular stiffness, which affects walking and dexterity, and it progresses over years."

Another difference: Essential tremor tends to interfere with purposeful movements such as eating, writing, sewing, and shaving, while the tremor of Parkinson's typically occurs at rest but not during activity, says Dr. Hallett. In addition, essential tremor doesn't usually respond to medications for Parkinson's disease.

A Difficult Diagnosis

"Essential tremor is a clinical diagnosis," says Howard I. Hurtig, MD, professor emeritus of neurology at the Perelman School of Medicine at the University of Pennsylvania. The diagnosis is tricky, though. Other causes of tremor need to be considered, including medication side effects and other metabolic or medical illnesses. "No simple tests exist," says Dr. Hurtig, "but the diagnosis is usually accurate when the examining physician is a neurologist."

If the diagnosis is unclear, a second opinion from a movement disorders specialist is often useful. In some situations, doctors may order SPECT imaging with DaTscan, a radioactivity-based brain imaging test that provides a map and measure of the activity of the brain's dopamine system. "In the brain of a patient with Parkinson's, the scan will show very low dopamine levels. In people with essential tremor, the levels will be normal," says Dr. Hurtig.

Genetic Component

"As far as we know, the main risk factor is genetic. Essential tremor has a strong prevalence in families," says Dr. Hallett. "The strange thing is that while we know there are important genetic factors, we can't seem to identify them. Unlike with Parkinson's disease and dystonia, where we can identify genetic factors relatively easily, we have not yet identified them in essential tremor."

John Crowell has since learned that his great-grandmother was affected by tremors. "By the time she died, she could no longer use her hands," he says.

While some people with the condition have a mild tremor that doesn't cause significant impairment, in others it becomes progressively disabling. Stress, fatigue, illness, and stimulants such as caffeine can worsen the disorder.

Medications May Help

No cure exists for essential tremor, and in many cases no treatment is necessary, says Dr. Hallett. "Many patients don't really need anything, and it's important to recognize that," he says. "Tremor needs to be treated only if a person believes it would be useful either for function or cosmetic reasons."

For those who do require treatment, Dr. Hallett says, the first option is medication such as propranolol, a nonselective beta-adrenergic antagonist (a drug that blocks nerve impulses to the muscles), or primidone, an anticonvulsant; they can both be taken orally.

A 2014 study in the Journal of Central Nervous System Disease shows that both propranolol—the only drug approved by the US Food and Drug Administration (FDA) for essential tremor—and primidone reduce tremor by about 50 percent. The two drugs may be prescribed together to improve effectiveness. Physicians monitor how well the drugs are working and observe patients for side effects. If necessary, physicians may adjust the dose.

If these medications don't help, doctors may try the beta blockers sotalol and atenolol; anti-seizure medications, including gabapentin and topiramate; and alprazolam or other benzodiazepines, which slow down the central nervous system, Dr. Hallett says. Benzodiazepines may be particularly useful for patients with associated anxiety. These drugs are not approved by the FDA for treating essential tremor, but Dr. Hallett says they are commonly prescribed for the condition.

Alprazolam is just one of the medications that Crowell has tried over the years without success. "It actually made me feel more wired," he says. Unfortunately, no drug has helped him long-term.

In addition to medication, some people benefit from botulinum toxin injections. But when used for hand tremor, a side effect can be temporary botulinum toxin-induced muscle weakness. The treatment may be best for people with hard-to-manage tremors, particularly those of the head or voice, Dr. Hallett says.

Deep Brain Stimulation

If tremors respond poorly to drugs and are very disruptive, patients may consider surgery. The most common type is deep brain stimulation (DBS). "If it's a severe and disabling tremor, placing an electrode in the thalamus is extremely effective," says Daniel Tarsy, MD, FAAN, professor of neurology and director of the Parkinson's Disease Center at Beth Israel Deaconess Medical Center in Boston.

In DBS, electrical stimulation is delivered to the brain through electrodes implanted in the ventral intermediate nucleus (VIM) of the thalamus, which helps control movement. The thalamus is composed of two lobes, each of which controls tremors on the opposite side of the body. This stimulation interferes with the abnormal thalamic activity contributing to tremor. The electrode is connected to a battery-powered pulse stimulator, which is placed under the skin near the collarbone and adjusted to provide the right amount of stimulation to control the tremor. About 90 percent of patients experience a reduction in tremor, says Dr. Tarsy. Patients with tremor in both hands will have an electrode implanted in each lobe.

DBS Complications

In 2014, Crowell underwent DBS surgery as part of a trial at the NIH. At first, things seemed to go well, but then he developed problems with his speech and other adverse effects, including extreme fatigue.

After he once fell asleep while driving, he began to have doubts about the treatment and subsequently had the electrodes and battery pack removed. "As hard as it was to decide to do the surgery, it was harder to take everything out," he says. (For more about DBS, visit BrainLifeMag.org/StimulatingtheBrain.)

A Noninvasive Procedure

Another surgical option involves using focused ultrasound (FUS) to create a lesion in the VIM of the thalamus in order to stop abnormal brain activity that causes tremor. "That's a modification of an old treatment that is still being used, which is done by passing an electrode into the thalamus and burning a hole," says Dr. Hallett. "Now it can be done noninvasively with focused ultrasound." In a 2016 study in the New England Journal of Medicine, patients experienced a 40 percent improvement in hand tremor after receiving FUS.

Other Options

Researchers are studying the use of gamma knife surgery, which uses radiation to create a lesion in the thalamus. Scientists at the NINDS are also evaluating the effectiveness of 1-octanol, a substance similar to alcohol but less intoxicating, for treating essential tremor. Alcohol often can quell tremors temporarily, but there may be a rebound effect, with tremor being more pronounced the following day.

Crowell has found ways to accommodate his tremor, such as having his drinking glass filled halfway to reduce the risk of spills and keeping his hands in his pockets when speaking in front of others.

And he looks for the silver lining. "I have a voice coach who loves to work with me because my tremor shows up in my music," Crowell says. "I have an amazing vibrato."

3 Ways to Ease Life with Essential Tremor

1. Ask for practical help. An occupational therapist can teach techniques and suggest devices to make the condition more manageable, such as weighted utensils, writing instruments, and cups; a computer mouse that compensates for tremor; and voice recognition programs that reduce the need for typing or writing.
2. Reduce stress. Stress can exacerbate tremor, so consider listening to meditation tapes or taking a yoga class designed for people with essential tremor. Also, avoid caffeine and alcohol.
3. Seek social support. Support groups, such as those sponsored by the International Essential Tremor Foundation and HopeNET, can help people adjust to life with the condition. "In general, support groups are helpful to combat feelings of isolation," says Howard I. Hurtig, MD, professor emeritus of neurology at the Perelman School of Medicine at the University of Pennsylvania. "Belonging to a community encourages patients to share insights, stories, observations, and ideas for improved function in daily life."

Clinical Trials for Essential Tremor

For information about trials, visit ClinicalTrials.gov and type "essential tremor" in the search field. In the meantime, here are two sample trials.

Gamma Knife Radiosurgery for Treatment of Essential Tremor

What: The Swedish Medical Center is recruiting patients to study the effects (good and bad) of gamma knife radiosurgery-which creates a small lesion in the brain to suppress tremors-on essential tremor.

Where: Seattle

When: Ongoing

For more information: Email Mary Monahan at mary.monahan@swedish.org; 206-320-7129; clinicaltrials.gov

Deep Brain Stimulation (DBS) Therapy in Movement Disorders

What: The National Institute of Neurological Disorders and Stroke seeks patients to undergo DBS surgery. Researchers will record brain function and determine the efficacy of the surgery.

Where: NIH Clinical Center in Bethesda, MD

When: Ongoing

More information: Contact Irene Dustin, CRNP, at Id30d@nih.gov or 301-402-4479, or Debra Ehrlich, MD, at debra.ehrlich@nih.gov or 301-443-7888; clinicaltrials.gov

Essential Tremor Resources

• American Academy of Neurology: BrainandLife.org/EssentialTremor
• Focused Ultrasound Foundation: fusfoundation.org; 434-220-4993
• HopeNET: thehopenet.org; 703-543-8131
• International Essential Tremor Foundation: essentialtremor.org; 913-341-3880
• International Parkinson and Movement Disorder Society: movementdisorders.org; 414-276-2145