Tremor is an involuntary to-and-fro shaking movement, seen most often in the hands. Benign tremors, which are tremors that have no underlying medical cause, are very common and are often lifelong. The onset of tremors--often accompanied by other symptoms--may indicate an underlying medical problem.
Parkinson's Disease
Parkinson's disease causes a resting tremor. This can be very strong when the hand is at rest and become much milder or disappear altogether when the hand is moved. A patient's hands may shake severely. Then, a second later when she lifts a glass to drink, she's often able to do so smoothly, without any tremor and without spilling a drop. The tremor often starts in one hand and eventually progresses to the other hand. The tremor has a pill rolling appearance; it's as though the patient is rolling a pill between her fingers. The tremor of Parkinson's increases with anxiety and disappears during sleep.
Alcohol
Alcohol can cause tremors as a result of prolonged use and during detoxification from alcohol. As explained by "Adams and Victor's Principles of Neurology," alcohol damages neurons in the cerebellum, leading to an intention tremor--a tremor that appears when the patient is consciously moving his arm. For example, when the patient reaches out to touch an examiner's finger, he might miss the target. This tremor is coarse and very noticeable.
Alcohol withdrawal can cause mild postural tremors, which are more noticeable when the arm is held in one position. If the tremor becomes more severe, it can be one of the symptoms of delirium tremens, a potentially life-threatening state of severe alcohol withdrawal.
Stroke
The basal ganglia are deep structures in the brain that coordinate involuntary movement. Strokes that affect them, known as lacunar strokes, can cause tremors. More commonly, strokes cause tremor by damaging the cerebellum.
Multiple Sclerosis
Multiple Sclerosis, or MS, can cause loss of myelin anywhere in the central nervous system. If the cerebellum or any of its connections are affected, tremor is one of the resulting symptoms. As stated by a study published in "The Journal of Neurology," tremor is very common in MS, occurring in about one-quarter to two-thirds of patients. Most often, it's postural or intentional.
References
- National Institute of Neurological Disorders and Stroke: Tremor
- Merck.com: Tremor--Movement Disorders
- "Journal of Neurology"; Tremor in multiple sclerosis; Marcus Koch et. al.; Feb 2007
- "Adams and Victor's Principles of Neurology"; Maurice Victor and Allan Ropper; 2001
