Hand tremors are unintentional rhythmic shaking of the hands. Some tremor in the hands is normal, according to Merck.com, an online medical library. This type of tremor is called physiological tremor, and occurs most often when the hand is outstretched. However, there are also several types of tremor that are caused by neurological diseases, some of which are progressive and get worse over time. These hand tremors differ based on the characteristics of the tremor.
Intention Tremor
This type of hand tremor causes rhythmic shaking during purposeful movement, such as pressing a button, states Merck.com. The frequency of intention tremors is usually quite slow. There are multiple possible causes of intention tremor, which include alcoholism or abuse of sedative or anticonvulsive drugs. Neurological disorders, such as stroke or multiple sclerosis, may also cause intention tremor. An inherited tremor disorder called essential tremor can also cause intention tremors, which can disrupt normal activities such as eating or shaving, according to the National Institute of Neurological Disorders and Stroke.
Resting Tremor
A resting tremor of the hands occurs when the hands and arms are resting, as the name indicates. The frequency of this type of tremor is often slow, according to Merck.com. The tremor associated with Parkinson's disease is a resting tremor. One of the first signs of Parkinson's disease is an asymmetric tremor, meaning the tremor affects only one side of the body. In 75 percent of cases of Parkinson's disease, the tremor subsides when the hand is moved purposefully. The resting tremor of Parkinson's disease also often causes rhythmic moving of the forefinger against the thumb in a back-and-forth motion. Because resting tremors usually subside during purposeful movement, they usually do not interfere with daily activities.
Postural Tremor
Postural tremors cause rhythmic shaking of the hands when they are held in one position for a length of time, according to the University of Maryland Medical Center. For example, holding a cup or holding a pen while writing can cause the hands to shake. Merck.com specifies that the tremor causes the hands to shake when they are held in a position against gravity. Essential tremor may also cause postural-type tremors. Though normal physiological tremor can cause the gradual development of a postural tremor, a sudden onset of this type of tremor may indicate ingestion of a toxin or hyperthyroidism, or accompany withdrawal from drugs and/or alcohol.
