If you hold your hands in front of your face and examine them closely, you can see them shake ever so slightly. That's normal. Everyone has some degree of this involuntary trembling, known as a tremor. But for some people, because of changes in the connections in the brain caused by aging, injury, stroke or other neurological disorders -- such as multiple sclerosis or Parkinson's disease -- the tremor can become so severe as to leave the person unable to function.
As a neurologist specializing in tremors, I hear from patients about how disabling (and embarrassing) this shaking can be. These patients might not be able to hold a fork, use a spoon, write with a pen, type, cut with scissors, zip their pants, button their shirts, take a picture, drive a car or keep their heads still. If their tremor extends to the trunk and legs, they cannot even balance to walk. And not only can the tremor cripple a person's ability to perform daily tasks, it can also prevent sufferers from holding down a job. This past summer, however, there was some promising news for these patients. In July, the U.S. Food and Drug Administration approved a new treatment for the most common type of tremor, a non-life-threatening movement disorder known as benign essential tremor.
Treating Essential Tremor
Several million Americans, most over the age of 40, have essential tremor, according to the National Institute of Neurological Disorders and Stroke. It typically affects the fingers, hands and arms, and the shaking occurs only when the patient is moving the affected body part. People with more advanced cases, such as Katharine Hepburn in her later years, also experience uncontrolled trembling in the head and voice.
There are long-standing treatments for essential tremor, but none are ideal. Doctors usually prescribe drugs: beta-blockers such as propranolol and anti-seizure medications like primidone. These medications often make people groggy, not everybody responds to them and the side effects of the medications can be as debilitating as the disease itself. Deep Brain Stimulation is a surgical option where electrodes are implanted deep in the brain into the thalamus, a structure that controls muscle movement and the tremor. The electrodes are connected to a pacemaker-like device implanted under the skin in the chest area; it contains a battery and generates the pulse. These electric pulses, delivered to the thalamus, block the tremor. DBS is effective, but it's also highly invasive (it is brain surgery, after all), and it comes with a risk of infection and requires surgical replacement of the battery every few years.
A Different Approach
The new FDA-approved treatment, a magnetic resonance-guided focused ultrasonography device, requires no incision, no electrodes and no anesthesia. Doctors use MRI to locate a tiny section of the thalamus called the ventralis intermedius, a cluster of cells only a few millimeters thick that is the source of tremor. Then they deliver focused ultrasound -- sound waves -- to heat and destroy it.
By zapping the VIM with focused ultrasonography, research physicians have been able to reduce tremor by 47 percent, according to a study published in the August 25 issue of the New England Journal of Medicine. That might not sound like enough, but a nearly 50 percent improvement can enable a person to eat a bowl of soup or sign his or her name. Moreover, the entire procedure takes only a couple of hours, and patients are awake throughout.
It is important to remember that this new treatment is a therapy, not a cure. It is also important to consider that every procedure has certain drawbacks and risks. Focused ultrasonography kills part of the brain, albeit a tiny one causing a problem; it alters part of the person's anatomy forever. Also, when the thalamus is altered, patients sometimes experience abnormal sensations in other parts of the body, especially in the face. It can also affect gait.
Possibilities for Parkinson's -- and More
So far, focused ultrasonography has been approved only for the treatment of essential tremor and is not widely available, but once clinical trials are completed, it may well be approved as a therapy for Parkinson's disease, too. Essential tremor is frequently mistaken for Parkinson's disease, but Parkinson's is very different. People with Parkinson's also experience the tremor, but only when they are at rest; tremor stops when they move their hands. The disease, which is caused when nerve cells in the brain that produce the chemical dopamine become damaged or die, also causes a stooped posture, slow movement and a shuffling gait (bradykinesia). While the new treatment could potentially impact tremor in people with Parkinson's, their additional symptoms would still need to be treated with drugs.
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