Q: Three years ago, at age 63, I developed a mild shaking of my hands that has gotten slowly worse. No other symptoms have occurred, but I am concerned because a shaking hand was the first symptom of Parkinson's disease in a friend. Is it likely that I have or will get Parkinson's disease? Although the shaking is only mildly troublesome, I wonder whether there is any effective treatment.
A: It is impossible to know whether you have Parkinson's disease without further information. There is a good chance, however, that you have a far less dangerous disorder called essential tremor. The shaking, or tremor, of this condition is most evident when writing or pouring water into a glass, while the tremor of Parkinson's disease tends to be most prominent when walking and when the hands are at rest.
Essential tremor is estimated to affect as many as 2 million to 3 million Americans. The disorder usually begins around age 50 and worsens as people grow older. Nearly half the time, essential tremor is inherited as a dominant trait, meaning that about half the children of an affected individual will develop the disease.
In addition to shakes of the hands, essential tremor often causes a "no-no" type of shaking of the head, as well as a quavering quality to the voice. The tremor is due to involuntary, rhythmic contractions of opposing muscle groups.
Benign tremor poses no risk to life or general health, and the symptoms improve in about 70 percent of patients with beta-blocking drugs such as propranolol or the anti-seizure medication primidone. In recent years, attempts have been made to control the tremor by injecting small amounts of botulinum toxin into the muscles of the forearm to treat the hand tremor or into the neck for the head tremor. One study that included no control group found significant improvement. A preliminary report of a better-controlled study was unable to verify a significant benefit of botulinum toxin on average, but three patients showed marked improvement compared with none in the control group. At present, botulinum toxin remains an experimental treatment.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.