Approach to Tremor in Older Adults
This article will assist the clinician in defining and categorizing tremor, also suggesting key questions and physical examination techniques to facilitate a probable diagnosis in an older adult. The role of many drugs in the causation and exacerbation of tremor is discussed and the treatment of several specific tremor disorders is reviewed.
Key words: essential tremor, postural tremor, kinetic tremor, enhanced physiological tremor, parkinsonism.
Introduction
Tremor is an important and frequent symptom/clinical sign among older adults and requires a logical approach to diagnosis. There are many different causes of tremor, with postural/essential type tremor being the most common. Once an accurate diagnosis is made, specific treatment can be effective.
It is important for clinicians not to assume that tremor implies Parkinson’s disease (PD); each year this author encounters several older adults who have been erroneously diagnosed and treated for PD.
Prevalence
Movement disorders rank among the most common neurological diseases. In a study by Wenning et al.,1 28% of the individuals studied who were age 50-89 years had a movement disorder, a proportion that increased sharply with age to 51.3% among 80-89 year olds. Prevalence of tremor overall was 14.5%, followed by restless leg syndrome (10.8%) and parkinsonism (7%). Essential tremor (ET) is the most common movement disorder among older adults and has a reported prevalence of 4% in a community population above 65 years of age.2 Interestingly, > 70% of cases were previously undiagnosed.
Definitions
Tremor
Tremor may be defined as a rhythmic oscillatory type of involuntary movement produced by contraction of reciprocally innervated muscles. Among older adults, it must be distinguished from other disorders, including the following.
Asterixis
Asterixis or “flapping tremor,” is most readily demonstrated by asking the patient to hold arms outstretched with the hands dorsiflexed. First described with hepatic encephalopathy, asterixis also occurs with hypercapnia, uremia, and other metabolic encephalopathies.
Myoclonus
Myoclonus, which are brief, shock-like muscular contractions, may be benign (for example, occurring physiologically as we fall off to sleep or awaken) or may be more severe, due to underlying central nervous system pathology or a variety of drugs such as narcotics.
Dystonia
Sustained involuntary muscle contractions.
Chorea
Rapid, random flowing movements.
Akasthisia
Akasthisia is a subjective state of motor restlessness usually occurring among individuals taking certain neuroleptics (for example, haloperidol).
Tardive Dyskinesia
Tardive dyskinesia involves mouth, tongue, and chewing movements associated with at least three months of neuroleptic exposure.
Tremor may be further described based on amplitude (that is, fine, medium, or coarse) and frequency3 based on oscillations per second (see Table 1).
Categories of Tremor
The main classification3 of tremor includes two major types.
Rest Tremor
Rest tremor, typical of parkinsonism, has a frequency of 4-6 hertz, a coarse amplitude, and is classically referred to as the pill-rolling tremor of the hands. Rest tremor is best observed when the limb is in a fully supported position and the patient is encouraged to relax. The parkinsonian tremor is characteristically worse with anxiety or mental stress and usually disappears during sleep. The resting tremor of PD typically first appears in one hand, spreads to the ipsilateral leg, and then to the contralateral side. A rest tremor of the tongue, lips, and chin may also be present in PD. For a differential diagnosis of rest tremor, see Table 2.
Action Tremor