Tremors
A tremor is a repetitious, involuntary shaking movement produced by the alternate contraction of opposing groups of muscles. It usually disappears during sleep.
In Parkinson's disease (paralysis agitans) there is a slow motion tremor, most noticeable when the muscles are otherwise at rest, which involves the fingers (with a "pill rolling" gesture), the forearms, the head, and the tongue. A tremor which increases in the part of the body under immediate use is characteristic of multiple sclerosis. Tremor appears in many cases of advanced arteriosclerosis of the vessels of the brain, also in some brain tumors and brain abscesses.
A fine, rapid tremor of the fingers is present in many cases of over activity of the thyroid gland. Tremor occurs commonly in alcoholism and in drug poisoning. It may develop in anxiety states and hysteria.
