Some Causes of Tremor
Cause | Suggestive Findings | Diagnostic Approach |
|---|---|---|
Action tremor* | ||
Alcohol or other substance withdrawal (eg, of benzodiazepines or opioids) | Agitation and fine tremor starting 24–72 hours after the last use of alcohol or a medication or substance (eg, a benzodiazepine) Sometimes hypertension, tachycardia, or fever, especially in hospitalized patients | Clinical evaluation |
Amelioration of tremor after stopping the medication or substance | ||
Endocrinologic, metabolic, and toxic abnormalities:
| Tremor plus altered level of consciousness (suggesting encephalopathy) and an obvious underlying disorder (eg, renal or hepatic failure) Sometimes multifocal myoclonus and negative myoclonus (asterixes) in metabolic causes of tremor Exophthalmos, hyperreflexia, tachycardia, heat intolerance (suggesting hyperthyroidism) Extreme, refractory hypertension (suggesting pheochromocytoma) | TSH level 24-hour urine collection to check for metanephrines Ammonia level, BUN, glucose level, and calcium and PTH levels Heavy metal testing |
Essential tremor | Progressively persistent tremor (4–12 Hz), usually symmetric and affecting both upper extremities and sometimes the head and voice, particularly in patients with a family history of tremor May be suppressed with low doses of alcohol or other sedatives | Clinical evaluation |
Physiologic tremor | Fine, rapid (8–13 Hz) tremor that occurs in otherwise healthy people and may be enhanced by certain medications or conditions (see above) May be suppressed with low doses of alcohol or other sedatives | Clinical evaluation |
Resting tremor | ||
History of using medications that block dopamine receptors or deplete dopamine reserves | Amelioration of tremor after stopping the medication | |
Low-frequency (3–6 Hz) alternating tremor, often of the thumb against the index finger (pill rolling) but sometimes also affecting the chin or a leg Usually accompanied by other symptoms, such as micrographia, bradykinesia (slow movement), cogwheel rigidity, and shuffling gait Often no family history of Parkinson tremor and no reduction in tremor after alcohol consumption | Specific clinical criteria Good response to empiric trial of dopaminergic medications | |
Intention tremor | ||
Cerebellar lesions:
| Low-frequency (< 4 Hz) tremor that usually occurs unilaterally with ataxia, dysmetria, dysdiadochokinesia (inability to perform rapid alternating movements), and dysarthria In some patients, family history of the disorder (eg, Friedreich ataxia) | MRI of the brain |
History of use of certain medications or other substances | Amelioration of tremor after stopping the medication or substance | |
Complex tremors | ||
Holmes tremor (midbrain, red nucleus, rubral, or thalamic tremor) | Irregular, low-frequency (< 4.5 Hz) tremor predominantly in the proximal limbs Combination of rest, postural, and intention tremors caused by midbrain lesions (eg, due to stroke or multiple sclerosis) near the red nucleus Sometimes signs of ataxia and weakness | MRI of the brain |
Neuropathic tremor: | Variable tremor type and frequency, usually postural and intention tremor in the affected extremities Other signs of peripheral neuropathy | Electromyography |
Functional (psychogenic) tremor | Abrupt onset and/or spontaneous remission of complex mixed-type tremor with changing characteristics Increased by attention and lessened by distraction of patient A key diagnostic hallmark of psychogenic tremor: Tremor entrainment, change or elimination of tremor as the patient performs a voluntary rhythmic movement with the unaffected limb | Clinical evaluation |
Variable tremor type (usually in the proximal arm) in children or young adults, often with signs of hepatic failure, rigidity, clumsy gait, dysarthria, inappropriate grinning, drooling, and neuropsychiatric signs | ||
* Classification of action tremors can be subdivided into postural and kinetic (which include simple kinetic and intention) tremors. Simple kinetic tremor occurs during voluntary movement and is about the same throughout the movement. Intention tremors occur during voluntary movement with a crescendo increase in tremor as the affected limb approaches a target. Postural tremors are maximal when a limb is maintained in a fixed position against gravity. | ||
BUN = blood urea nitrogen; Hz = hertz; PTH == thyroid-stimulating hormone. | ||