A tremor is any involuntary shaking movement. Tremors most often affect the hands but can occur in any part of the body. They may be a sign of an underlying illness or they may be due to stress, fear, anger, fatigue or the ingestion of chemicals such as caffeine or nicotine. For tremors that do not go away or become severe enough to interfere with daily activities, it is important to determine the underlying cause.
Parkinson's Disease
Parkinson's disease, a disorder of the brain, affects approximately 1 million Americans and 4 million people worldwide, according to the Parkinson's Disease Foundation. It occurs when cells in the area of the brain known as the substantia nigra are destroyed. These cells are responsible for producing dopamine, a chemical that works within the central nervous system to produce smooth, controlled movements.
Parkinson's disease is a progressive disease, meaning it worsens over time; as more cells are destroyed, less dopamine is produced, resulting in more severe symptoms. Tremors are often the first noticeable symptom, occurring in 70 percent of patients in the early stages, the foundation reports. Parkinson's disease tremors occur in muscles at rest; therefore, they are called resting tremors and often subside once the patient begins to move.
Essential Tremor
Essential tremor, which affects approximately 10 million Americans, is the most common cause of tremor, according to the International Essential Tremor Foundation. Also called familiar tremor or hereditary tremor, it is genetic, which means that it is passed from parent to child. Essential tremor causes the rhythmic trembling of the hands, head, voice and legs and can result in debilitation. The exact mechanism in the brain is not yet understood, and many essential tremor patients are diagnosed mistakenly with Parkinson's disease.
Multiple Sclerosis
The National Multiple Sclerosis Society reports that there are approximately 400,000 Americans and 2.1 million people worldwide who suffer from multiple sclerosis (MS). This autoimmune disease is caused by the body's immune system attacking and breaking down myelin, the fatty tissue that surrounds and protects the nerves. When this breaks down, the nerve signals traveling to and from the brain are distorted or interrupted resulting in the symptoms.
The loss of myelin can cause tremors in multiple sclerosis patients. The tremors may affect the arms, legs, head or body and can interfere with speech and sexual function. The most common type of MS tremor is intention tremors, a type of action tremor that occurs when a person activates a muscle, such as reaching for something.
