If your hand routinely shakes when you hold a drink, sign your name or tap a number into your cellphone, you may fear that you’re experiencing signs of Parkinson’s disease. But what you’re more likely to have is essential tremor, a common neurological condition that causes an involuntary, rhythmic trembling of the hands during movement but can also affect the head, voice or legs. While it’s often confused with Parkinson’s, essential tremor is eight times more common and affects an estimated 10 million people in the U.S., according to the International Essential Tremor Foundation.
Unlike Parkinson’s, which is a degenerative disease that causes someone to lose brain cells, essential tremor is not a degenerative disorder, explains Dr. Michael Rezak, director of the Movement Disorders Center at Northwestern Medicine Central DuPage Hospital in Winfield, Illinois. “Essential tremor results from a malfunction of certain neurons, but you don’t lose brain cells, and you don’t lose gait or balance.”
Despite its prevalence, it wasn’t until 2013 that essential tremor was given its own specific diagnostic code, one that’s distinct from other tremors, in the 10th edition of the World Health Organization’s International Statistical Classification of Disease and Related Health Problems (ICD) code book. In medicine, the word “essential” means there’s no known underlying cause for a symptom, which is the case for essential tremor. “When people hear it’s essential tremor and not Parkinson’s, that usually puts them at ease,” Rezak says. “Essential tremor is the most common movement disorder out there, but we don’t usually see people until it gets really bad. Most patients just learn to live with it.”
Usually, the tremor that’s characteristic of essential tremor occurs while the person is performing a movement-oriented activity – such as eating, drinking, writing, typing or brushing teeth – or when the hand is in a still but outstretched position (called a postural tremor). The severity can range from a barely noticeable trembling that’s exacerbated by stress, anxiety, fatigue, excess caffeine or certain stimulant asthma medications to a severe, disabling tremor that has a significant impact on your ability to perform daily activities.
The late “actress Katharine Hepburn is an extreme example of advanced essential tremor – it affected her voice, head and arms, as well as her hands,” Rezak notes. Playwright Eugene O’Neill also suffered from essential tremor. So does rocker J. Roddy Walston, of J. Roddy Walston & The Business, who became increasingly vocal about his condition in the band’s 2013 LP “Essential Tremors.”
The disorder affects men and women equally, and it’s hereditary in more than 50 percent of people who have it. Though the average decade of onset is in the 40s, essential tremor can occur at any time, even in children. Debbie Lamb developed “the shakes” when she was in her late 20s but she didn’t have a name for them until her second child was diagnosed as a baby in 2004 with “benign familial essential tremors.” “It turned out that not only did I, her mother, have them, but my mother, sister, grandmother and niece all had them, too,” says Lamb, now 50, a marketing executive in Vallejo, California.
There aren’t blood or other medical tests that can definitively diagnose essential tremor. Instead, a neurologist makes the diagnosis on the basis of a detailed medical history and a neurological evaluation that’s designed partly to rule out other possible causes of the tremor. In tough cases, a relatively new diagnostic imaging technique called DaTscan allows doctors to distinguish between patients who have a loss of dopamine, the neurotransmitter that’s predominantly responsible for Parkinson’s symptoms, and those who don’t have a dopamine deficiency.
If your essential tremor is mild and doesn’t bother you, it doesn’t need to be treated. But you can take steps to mitigate the effects by avoiding caffeine and doing yoga or other relaxation techniques. Lamb relies on focused breathing exercises and meditation to reduce the severity of her tremors. A 2015 study from Australia found that doing resistance training also can reduce essential tremor and improve manual dexterity in those who have the condition.
It’s often referred to as benign essential tremor because it isn’t life-threatening, “but it’s not that benign when it starts interfering with one’s life and you can’t work or eat soup,” Rezak says. If it impairs your ability to function, the condition is usually treated with medications such as beta-blockers, anti-seizure drugs, anti-anxiety meds or Botox injections. There’s a lot of trial and error to find a medication that works well for any given patient; sometimes drug treatment helps sufficiently, and sometimes it doesn’t.
With or without medication, essential tremor is often a progressive condition. “As the tremor progresses, it can worsen or people can have breakthrough tremors on medication,” explains Dr. Joseph Neimat, an associate professor of neurosurgery at Vanderbilt University Medical Center in Nashville.
Elsie Hamilton, of Englewood, Colorado, discovered this firsthand when her tremors got so bad over a 20-year period that she had to give up her career as a landscape, still life and portrait painter. Besides struggling to hold a paintbrush steady for detail work, on some days she had trouble keeping the brush between her fingers at all. In her personal life, when she was the slightest bit nervous in social situations, she would shake when moving a fork to her mouth or lifting a glass to her lips. For the last six years, Hamilton has been taking a beta-blocker for a heart condition, which helps with her essential tremor but doesn’t eliminate it. “It can still be very embarrassing but I tell people up front and try to laugh it off,” says Hamilton, now 54, president of the Lilly Brush Co., which manufactures and sells special brushes that remove pet hair from clothing and furniture. “My siblings, in-laws and two sons cover for me and help whenever they can.”
For people with severe tremor that doesn’t respond to drugs, surgical therapies and other treatments are gaining traction. With deep brain stimulation, a probe is implanted in the thalamus, the part of the brain that causes tremors, and a wire runs from the probe to a pacemaker-like device implanted in the chest. “We use the pacemaker to jam the tremor signal inside the brain,” Neimat explains. “If the tremor gets worse, we can dial up the stimulation.”
By contrast, a noninvasive procedure called Gamma Knife thalamotomy uses cobalt beams to deliver a precise dose of radiation to the thalamus to control these involuntary movements. In a recent study published in Neurology , researchers from France found that the Gamma Knife procedure improved upper limb tremor by 54 percent and the ability to perform activities of daily living by 72 percent in 50 patients with tremor.
Meanwhile, a new noninvasive MRI-guided high-intensity ultrasound technique, which uses concentrated ultrasound waves to selectively damage the part of the brain that contributes to tremors, is showing preliminary promise. “It’s unique in that you don’t need to cut the skin or insert something into the brain – and it’s a one-time treatment,” says Dr. Ali Rezai, director of the Neurological Institute at The Ohio State University Wexner Medical Center, where a clinical trial is being conducted on the technique’s safety and effectiveness. “So far the results seem to be robust.” The study will conclude next year, and doctors are hoping the technique gains approval by the Food and Drug Administration in short order.