Tremor

Tremors are rhythmic, alternating, or oscillatory movements.

Geriatric Essentials

• Essential tremor becomes more common with aging; simple coping strategies and assistive devices may help maintain quality of life.
• Drugs may cause or increase tremors.
• Resting tremor usually indicates Parkinson's disease or parkinsonism secondary to drugs, often antipsychotics.
• Intention tremor usually indicates cerebellar disease.

Tremors result from rhythmic contractions of reciprocally innervated antagonistic muscles. Most tremors are absent during sleep. The most common tremor among the elderly is essential tremor (also called familial tremor because it commonly runs in families-see Table 46-2). Parkinsonism also causes tremor. Tremors may be secondary to drugs or to conditions other than parkinsonism (see Table 46-3).

Tremors may be characterized as resting or action tremors. Action tremors include postural (sustention) and kinetic tremors; kinetic tremors include intention tremors. Resting tremors occur when the body part is at rest and may decrease with action; they are usually caused by Parkinson's disease. Postural tremors occur when a limb is maintained in a fixed position against gravity. This type of tremor is sometimes caused by essential tremor or Parkinson's disease but may also occur in patients with metabolic disorders or other brain disorders. Simple kinetic tremor occurs during voluntary limb movement (eg, eating, writing, dressing); its most common cause is essential tremor. Intention tremor worsens as the limb approaches a target, as in finger-to-nose testing; it suggests a cerebellar disorder.

Tremors can also be characterized by frequency of oscillation, which can range from 4 to 13 cycles/sec (Hz), and may be described as fast or slow. Amplitude of movement is described as fine or coarse. Typically, an essential tremor is fast with low amplitude; a Parkinsonian tremor is slow with high amplitude; and an intention tremor is very slow with amplitude that becomes very high as the limb nears its target.

Asterixis, which typically is repetitive, nonrhythmic, nonoscillatory lapse of sustained position (eg, flexion of a hyperextended wrist), can simulate tremor. Asterixis usually results from metabolic (eg, hepatic) encephalopathy.

Essential Tremor

Essential tremor is characterized by a 4- to 12-Hz action or postural tremor and is particularly common among the elderly. Diagnosis is by history and physical examination. Treatment includes coping mechanisms, avoidance of conditions that predictably worsen symptoms, and, if symptoms impair function, drugs.

Some experts consider essential tremor a variation of physiologic tremor, which may affect people of all ages. Because the incidence of essential tremor increases markedly with aging, it was once called senile tremor. Essential tremor may have an autosomal dominant pattern of inheritance and thus has also been called familial tremor.

Symptoms and Signs

Essential tremor may be mild, moderate, or severe; rate of progression ranges from slow to quick. The tremor most often affects both arms (eg, affecting the ability to eat or carry objects), followed by the head (eg, making the head nod or shake when unsupported) and voice (eg, making speech unsteady). Essential tremor may be aggravated by metabolic disorders (eg, hyperadrenergic states such as thyrotoxicosis or withdrawal from alcohol or certain drugs) or by use of certain drugs (eg, caffeine, other phosphodiesterase inhibitors, -adrenergic agonists, corticosteroids). It may also be aggravated by nervousness, stress, fatigue, embarrassment (possibly because of the tremor), or assumption of an uncomfortable or a strained position to handle objects. If embarrassing or debilitating, essential tremor may lead to social isolation. Alcohol suppresses the tremor; as a result, some patients abuse alcohol.

Diagnosis

Essential tremor is diagnosed when neurologic examination detects no abnormalities other than the tremor and the tremor has no other causes. A family history of essential tremor and marked suppression of tremor by alcohol suggests the diagnosis.

Treatment

Patients with mild essential tremor do not need treatment. They should be advised to avoid caffeine (eg, in coffee, tea, and colas). To reduce embarrassment caused by the tremor, patients can hold objects close to the body so as not to drop them, place napkins between cups and saucers to keep them from rattling during use, avoid eating soup in public, and avoid uncomfortable or awkward positions. Specially designed utensils (eg, rocker knives, utensils with large handles) can help with activities of daily living. If tremor is very severe, straws, button hooks, Velcro fasteners, zipper pulls, and shoe horns can help.

Drugs are required if function is impaired. However, for most patients, tremor continues to be bothersome despite currently available treatment. Some patients control symptoms with small amounts of alcohol. -Blockers (eg, propranolol 20 to 80 mg po bid or tid, nadolol 20 to 80 mg po once/day) may help, but adverse effects (eg, fatigue, depression) may limit the dose. The anticonvulsant primidone (50 to 250 mg po once/day) may help but can cause drowsiness and confusion. Benzodiazepines (eg, clonazepam) may help some patients, especially if anxiety is present. Gabapentin (eg, 400 mg po tid) may also help some patients. Patients with head or voice tremor may respond to local IM injections of botulinum toxin.

Patients with severe, drug-resistant tremor may be candidates for thalamotomy or for high-frequency deep brain (thalamic) stimulation.

Cerebellar Tremor

Cerebellar tremor results from dysfunction of the cerebellum or its pathways and represents a problem with the force and timing of motion (ataxia) rather than a true regular tremor or oscillation.

Cerebellar tremor is an intention tremor because it tends to worsen when a finger approaches a target, as during finger-to-nose testing. The tremor is coarse and irregular; frequency is 3 to 5 Hz. Cerebellar tremor in the elderly is the same as that in any other age group.

Cerebellar tremors do not usually respond to drugs, but drugs used for essential tremor occasionally help.

This topic was last updated June 2006.