Dr. Mark Hallet responds: 

Once known as familial tremor, benign essential tremor (ET), or senile tremor, ET is a neurologic condition that causes a rhythmic trembling of the hands, head, voice, legs, or trunk. Early on, some people even feel an internal shake without a visible tremor. Its exact cause is unknown, although genetic factors are probably important. ET is often confused with Parkinson's disease, although it is eight times more common, affecting an estimated 10 million Americans and millions more worldwide.

Most drug therapies for ET focus on managing symptoms. These therapies may include propranolol or other beta-blockers and primidone, an anticonvulsant drug. Eliminating caffeine and other dietary triggers is often recommended. Physical and occupational therapy can sometimes help reduce tremor and improve coordination and muscle control.

ET that does not respond to drug treatment can be successfully treated with neurosurgical methods. One standard procedure, deep brain stimulation (DBS), provides excellent relief for approximately 90 percent of ET patients. DBS requires surgically placing electrodes into the thalamus—a structure deep in the brain that coordinates and controls muscle activity—and then stimulating them continuously from a pacemaker-like device implanted under the collarbone.

One benefit of DBS is that brain activity can be modulated bilaterally, so that the impulses that cause tremor can be blocked on both sides of the body. Some people experience side effects, though, such as uncomfortable sensations. When that happens, clinicians can reset the pacemaker to reduce the amount of stimulation. The device can also be tweaked to control the symptoms. While DBS has a high probability of success, it requires surgery and continuous care of the device under the collarbone. The presence of a foreign object in the body may increase the risk of infection, and surgery must be repeated every three to five years to replace the battery in the device.

Prior to treating patients with DBS, neurosurgeons would occasionally treat ET by creating lesions—in other words, they would destroy small areas of tissue in the thalamus. While that also worked to reduce tremor and did not require continuous care, it could only be done safely on one side. Because this type of surgery is limited and is a destructive procedure, DBS has become more popular.

Another technique, currently experimental, called focused ultrasound (FUS), creates lesions without requiring surgery. Ultrasound sends sound waves through brain tissue that are powerful enough to make a lesion. Studies have shown that the effect on tremor is immediate. A large, multicenter trial evaluating the procedure is currently ongoing in the US.

The technique appears promising for dealing with tremor on one side of the body. However, we will need results from a larger study to make a more informed decision about FUS. Presumably, when the results of the trial are known there will be a better sense of the benefits and risks of this experimental treatment. At this point, I would not recommend seeking this treatment outside of a clinical trial.

For more information about essential tremor. visit the National Institute of Neurological Disorders and Stroke's Essential Tremors Information Page. You can discover more about federally-funded clinical trials on essential tremor at ClinicalTrials.gov. Also, visit the International Essential Tremor Foundation.