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hi gang this isn't strictly 'new' but i thought it was interesting in light of the discussions on 'shakiness' and tremour frequency janet ------------------------------------------------------------------------ Muscle Sounds Change In Parkinson's Disease ------------------------------------------------------------------------ NEW YORK, Feb 27 (Reuters) -- The muscles of people with untreated Parkinson's disease produce sounds that are different from those found in healthy individuals, according to a new study. Listening with a stethoscope, researchers have found that the wrist muscles of Parkinson's patients produce vibrations at a much lower sound frequency than normal during strong and repeated activity. But when the patients receive their medication (Levodopa), normal muscle sounds are restored along with improved movement ability. "The vibrations produced by muscle activity can, with the aid of a stethoscope, tell us a great deal about the control of muscles by the brain, because the frequency of muscle sound reflects the pattern of (the brain's) motor-unit activation," says Dr. P. Brown, a research neurologist with the National Hospital for Neurology and Neurosurgery in London, England. According to the researcher, "one of the most interesting muscle sounds is a somewhat impure tone of around 40-50 hertz, commonly heard as the noise that accompanies a spontaneous yawn, or if the jaw is moved when the ear is blocked with soap suds." A hertz (Hz) is a unit of frequency equivalent to one cycle per second. It is this sound -- or range of frequencies -- Brown says, that was first identified by Hans Piper in 1912, and which since then is referred to as the "Piper-band sound." During forceful muscle contractions, which are difficult for Parkinson's patients, these are high-frequency, rhythmic bursts of sound, which represent the firing of many motor nerves. Brown says these "Piper-style rhythms are lost in untreated Parkinson's disease," and in their place are the lower frequency sounds of muscle fibers that are vibrating too slowly, thereby causing the slow movements and low muscle strength that typify people with the disease. SOURCE: The Lancet (1997;349:533-535) Copyright 1997 Reuters Limited. <http://www.reutershealth.com/news/rhdn/199702/1997022702.html> ------------------------------------------------------------------------ [log in to unmask]