![]() ![]() Any sound above what we can hear is, by definition, ultrasound. The lowest sound most of us can hear is about 20 Hz the highest is about 20,000. With standard tuning, the low E string of a guitar vibrates back and forth about 82 times a second, or, in scientific notation, at 82 hertz. When those sound waves reach our ears, their mechanical energy vibrates the thin membrane of our eardrums at the same frequency as the guitar string, which our brain interprets as a musical note. This creates a mechanical wave of compression and decompression that ripples through the air. When a guitarist plucks a string, for example, its rapid back-and-forth movement is transmitted to the surrounding air molecules, which then relay the vibrations to more neighboring molecules, and so on. Vibrations in the air create nearly all the sounds that we hear. For people such as Aldrich, who are not helped by medication and have had no good surgical options available to them, the promise is enormous. ![]() Our institution is one of several participating in the first pivotal trial of focused ultrasound for essential tremor we expect to release results in 2016. In the U.S., the use of FUS in brain surgery is still confined to clinical trials. Focused ultrasound has been approved in Europe for treating essential tremor, tremor caused by Parkinson's disease, and neuropathic pain. Patients with cancers and movement disorders might avoid invasive procedures, radiation and lengthy hospital stays and instead be treated with relatively low risk, incision-free sonic surgeries. The accumulating evidence suggests that the technology could soon make painless, bloodless brain surgery a reality and revolutionize how many conditions are treated. In recent years growing numbers of researchers around the world have begun experimenting with focused ultrasound. So Aldrich went online and signed up to participate in a future study. The report said that results from early clinical trials at the University of Virginia were promising. Then, in 2013, Aldrich saw a news program on television about an experimental new tremor treatment called focused ultrasound, or FUS, that used sound waves to destroy the malfunctioning nerve cells responsible for her condition. The former helped for only a little while, and the latter involved side effects that Aldrich found intolerable, such as lethargy. Like many sufferers, Aldrich sought relief from several medications, including propranolol-more commonly used to treat high blood pressure and anxiety-and primidone, a first-line therapy for essential tremor that is also prescribed as an antiseizure medicine. Unfortunately, drug treatment fails to satisfactorily control essential tremor in up to 50 percent of all patients. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. If you're enjoying this article, consider supporting our award-winning journalism by subscribing. More than half of the people afflicted cannot find work, and one in three report withdrawing from social life. About one in four, according to a 1994 study by neurologists at what is now the University College London Institute of Neurology, have to change jobs or take early retirement. Although the disorder is sometimes called benign essential tremor, for many patients it is anything but benign: the vast majority, about 85 percent, say the tremor causes a significant change in their life. Her symptoms eventually shook her self-esteem, too. Within a decade it had advanced to her head. They most frequently affect the hands and head but can also strike other parts of the body and the voice they usually worsen with time.įor Aldrich, the trembling progressed to her left hand after about five years. Its hallmark tremors are typically small, rapid, back-and-forth movements-often oscillating more than five times a second. The cause of the condition is unknown, but it often runs in families. She visited her doctor who diagnosed essential tremor, which today is the most common movement disorder, found in about 5 percent of people older than 64 years worldwide. “After a while, it was with me all the time,” Aldrich says. Gradually, though, her shaking grew more persistent. “I just thought I had had too much coffee,” the mother of three recalls. At least initially, her tremor would come and go, leaving her sometimes unable to manage tiny screws and fragile settings. ![]() Working for an optometrist in Port Townsend, Wash., a picturesque town on the Olympic Peninsula, Aldrich routinely performed delicate work with her fingers-replacing broken eyeglass lenses and repairing frames. Carol Aldrich first noticed a slight tremor in her right hand when she was in her early 50s. ![]()
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