Feeling Shaky?

By Peter Galvin, MD

Essential tremor is a disorder that causes involuntary, rhythmic shaking movements of a body part that is in motion. It is among the most common movement disorders worldwide. It is estimated to affect about 7 million people in the U.S., although that number may be an underestimate because some individuals do not seek medical attention for the tremors. Essential tremor is an action tremor, defined as occurring during voluntary movements such as reaching for a glass of water. There is no tremor at rest, only during voluntary movement, unlike the tremors from Parkinson disease, which occur both at rest and during movement. Other features of Parkinson disease are also not found in essential tremor, such as reduced facial expression (called mask-like facies), hoarse voice, stiffness, slowed movement, and shuffling gait.

Essential tremor typically begins in one upper extremity and progresses to involve both hands and arms within several years. In some, it may also cause involuntary movements of the head, jaw, neck, and voice. It does not affect life expectancy, but it can make simple tasks like eating, drinking, and writing difficult and may cause social embarrassment. The risk of essential tremor increases with age, affecting 1.3% of the general population and 5.79% of those aged 65 years and older. Those with a family history of it may develop symptoms as early as age 40 years or younger. It can be diagnosed by having a patient hold a position against gravity, such as outstretching their arms, or by the finger-to-nose test in which the patient moves their index finger between their nose and the examiner’s finger or hand. If the tremor does not stop at rest, it can be suppressed by a mental task such as counting backward.

Treatment of mild tremor involves occupational therapy and assistive devices like weighted utensils, cups, and wrist weights. Lifestyle changes such as avoidance of caffeine and alcohol can decrease the tremor. First-line medications include propranolol and primidone, which can reduce tremor. Using both medications together may be more effective, although about 30% to 50% of patients do not respond to these medications. Topiramate, used to treat epilepsy and headaches, can decrease tremor but has multiple side effects such as difficulty concentrating, a “pins and needles” skin sensation, and nausea. Injection of botulinum toxin type A may decrease tremor that affects the jaw, chin, or voice. A surgical procedure may be considered for those with severe essential tremor who do not respond to medications. This procedure, called deep brain stimulation, involves implantation of electrodes in the thalamus, which processes movement, with an external (to the brain) stimulator placed in the chest. Lastly thalamotomy, which uses radiofrequency or ultrasound to target the thalamus, may be used as a last resort.

For more information go to the website of the National Institute of Neurological Disorders and Stroke at www.ninds.nih.gov

Please direct questions and comments to editor@rockawaytimes.com