Buy the Book PDA Download

Update Me E-mail alerts The Merck Manual Minute

Print This Topic Email This Topic

Tremors are rhythmic, alternating, or oscillatory movements. A tremor can be a normal exaggeration of movement, a primary disorder, or a symptom of a cerebellar disorder or Parkinson's disease. Diagnosis is usually clinical. Treatment varies by etiology.

Tremors must be differentiated from asterixis, which typically causes repetitive, nonrhythmic, nonoscillatory wrist flexion during attempted wrist extension.

Tremors include resting tremors, postural (sustention) tremors, and intention tremors. Resting tremors are maximal at rest and decrease with activity; they are usually a symptom of Parkinson's disease. Postural tremors are maximal when a limb is maintained in a fixed position against gravity; gradual onset suggests physiologic or essential tremor, and acute onset suggests a toxic or metabolic disorder. Intention tremors are maximal during movement toward a target, as in finger-to-nose testing; they suggest a cerebellar disorder but may result from multiple sclerosis or Wilson's disease. Tremors can be characterized by frequency of oscillation (usually 4 to 13 cycles/sec or Hz) and amplitude of movement (fine or coarse).

Physiologic tremor: Physiologic tremor is present normally but usually causes such small movements that it is noticeable only under certain conditions. It is predominantly a postural or intention tremor. The tremor is fine and rapid (8 to 13 Hz). It is most easily visible when hands are outstretched. Physiologic tremor may be enhanced (increased amplitude) by anxiety, stress, fatigue, metabolic disorders (eg, hyperadrenergic states such as alcohol or drug withdrawal or thyrotoxicosis), or certain drugs (eg, caffeine, other phosphodiesterase inhibitors, β-adrenergic agonists, corticosteroids). Alcohol and other sedatives usually suppress the tremor.

No treatment is necessary unless symptoms are bothersome. Physiologic tremors enhanced by alcohol withdrawal or thyrotoxicosis respond to treatment of the underlying condition. Oral benzodiazepines tid or qid (eg, diazepamSome Trade Names
VALIUM
Drug Information
2 to 10 mg, lorazepamSome Trade Names
ATIVAN
Drug Information
1 to 2 mg, oxazepamSome Trade Names
SERAX
Drug Information
10 to 30 mg) may be useful for people with tremor and chronic anxiety, but continuous use should be avoided. PropranololSome Trade Names
INDERAL
Drug Information
20 to 80 mg po qid (and other β-blockers) is often effective for tremor enhanced by drugs or acute anxiety (eg, stage fright). PrimidoneSome Trade Names
MYSOLINE
Drug Information
50 to 250 mg po tid may be tried if β-blockers are ineffective or poorly tolerated. For some patients, a small amount of alcohol is effective.

Essential tremor (benign hereditary tremor, senile tremor): The tremor is coarse or fine, slow (4 to 8 Hz), and usually bilateral; it can affect the hands, head, and voice. It tends to increase with age and may be incorrectly called senile tremor. In 50% of patients, inheritance is autosomal dominant. The tremor is minimal or absent at rest. It may be enhanced by any factor that enhances physiologic tremor, but it can occur without such factors, differentiating it from physiologic tremor, although the difference is not always obvious.

PropranololSome Trade Names
INDERAL
Drug Information
20 to 80 mg po qid (and other β-blockers) is often effective. PrimidoneSome Trade Names
MYSOLINE
Drug Information
50 to 250 mg po tid may be tried if β-blockers are ineffective or poorly tolerated.

Tremor of cerebellar disease: This tremor is an intention tremor. No effective drug is available; physical measures (eg, weighting the affected limbs or teaching patients to brace the proximal limb during activity) sometimes help.

Last full review/revision November 2005

Content last modified November 2005