Tremor is a rhythmic, involuntary, oscillatory movement of body parts. It is the most common movement disorder. There are several types of tremor with differing underlying physiologic or pathologic etiologies. Tremors may also be caused by alcohol and by numerous drugs, including amphetamines, beta-adrenergic agonists, caffeine, lithium, neuroleptic agents, steroids, and tricyclic antidepressants.
Current Diagnosis & Treatment Family Medicine 2nd Edition (McGraw-Hill) 2007