Tremor is a common presentation in old age. It would not be a new feature to geriatricians, neurologists, other physicians and GPs dealing with older people. It is an old but still interesting and sometimes challenging “puzzle” for all of us. It is defined as a rhythmic, oscillatory and involuntary movement of a body part.1 The extent of tremor can vary from a mild condition to a severe one. Any form of severe tremor may have a negative effect on activities of daily living, as well as quality of life in the elderly.1

It can have a profound psychological impact and contributes to social distress in older people. Tremor could be an important clue for an acute underlying pathology such as cerebellar stroke. Therefore, it is imperative to understand the different categories of tremor, conduct a systematic evaluation to explore a correct diagnosis, and to establish appropriate management.

Incidence and prevalence of tremor
Different types of tremor have different rates of incidence and prevalence in different older populations. Essential tremor is more common in Caucasian older people than African and Asian elderly.2 The incidence rate of essential tremor is approximately 616 in 100,000 people aged 65 and over.3 The prevalence rate is about 40 in 1,000 people aged 65 and over.2,4 In general, about 4% of the middle and old aged UK population (people aged 65 and over) have essential tremor.4

A Spanish epidemiological study for neurological disorders (NEDICES) highlighted that the prevalence of essential tremor was about 4.8% among Spanish older people.3 This study also noted that prevalence of essential tremor was directly proportionate to advanced ageing in older people.3

Similarly, the prevalence of tremor related to idiopathic Parkinson’s disease increases with advanced age.4 The prevalence of idiopathic Parkinson’s disease is about 100 to 190 per 100,000 people in the West.4 It is more common in males than females.4
Drug-related tremor is another common form of tremor in old age. It represents about 9% of Parkinsonism-type resting tremors.4

Classifications of tremor
Tremor can be classified as below:1,4,5
A. Resting tremor: a tremor commonly occurs at rest. Its common aetiologies include:

  • 1. Idiopathic Parkinson’s disease
  • 2. Secondary Parkinsonism (mainly drug-induced Parkinsonism, strokes, previous encephalitis, HIV infection, post-traumatic Parkinsonism, commonly seen in punch drunk boxers)
  • B. Postural tremor: a tremor occurs at certain positions such as with outstretched hands. Its common underlying causes are:
  • 1. Essential tremor
  • 2. Stress and anxiety-related 
  • 3. Alcohol withdrawal
  • 4.Drug-related (eg. inhaled bronchodilators, theophyllines)
  • 5.Endocrine causes (eg. hyperthyroidism, hypoglycaemia)
  • 6. Lifestyle-related (eg. excessive caffeine drinking)
  • C. Action tremor: a tremor is noted on action, such as during the finger-nose test. Its common aetiologies are: 
  • 1. Posterior circulatory strokes
  • 2. Cerebellar tumors (either primary or secondary)
  • 3. Other posterior fossa space occupied lesions (eg. brain abscess)
  • 3. Chronic alcohol excess (causing cerebellar atrophy)
  • 4. Multiple sclerosis (less common in the elderly)
  • D. Others
  • 1. Flapping tremor (a red flag sign of medical emergencies such as acute hepatic failure)
  • 2. Orthostatic tremor.
Different varieties of movement disorder
There are some movement disorders that should be differentiated from tremor when assessing an older person with a tremor. Occasionally, tremor and other movement disorders could co-exist and overlap. Such complex situations might cause “a diagnostic challenge” to clinicians. These movement disorders include:5, 6
  • Athetosis: slow, irregular, writhing, muscular distortions, commonly in hands and feet
  • Chorea: jerky, quasi-purposive and explosive movements (in the elderly common aetiologies for chorea are basal ganglia infarct, drugs such as phenytoin, alcohol excess)
  • Dyskinesia: restless, repetitive and involuntary movements mainly in face and neck (eg. lip-smacking)
  • Dystonia: sustained involuntary muscle contraction in some parts of the body
  • Hemiballismus: violent swinging movements in one side of the body (the main cause is contralateral sub-thalamic infarct or bleed)
  • Myoclonus: sudden involuntary jerking movements (in the elderly nocturnal myoclonus is a common one and normally is not pathological)
  • Tics: repetitive twitches around muscle groups of face and neck. These generally start from childhood and are not pathological.
Diagnostic workup in an older person with tremor

 

Relevant history taking
As with other clinical presentations, relevant and thorough history taking is essential in the diagnostic workup of tremor. For instance, people, having essential tremor, usually present with longer duration (over years) and similar conditions in immediate family members whereas people suffering idiopathic Parkinson’s disease have shorter duration (over months) and associated hypokinetic features such as bradykinesia.4,5,6 The other important clue in history, favouring an essential tremor, is that the severity or frequency of tremor becomes settled when people drink alcohol.6 However, history taking may be challenging in older people as circumstances such as: cognitive impairment; hearing deficits; speech disturbances; language barriers; and underlying learning difficulties could jeopardise the history taking. It can be important to seek collateral history or relevant information regarding tremor from families and caregivers. It is also important to focus on how tremor affects the patient’s daily activities, personal and social life.1 For example, an older person who enjoys drawing might be frustrated when they get tremor or their tremor is getting worse.1

Physical examination
It is important to assess the level that a patient can perform routine activities and functions.1,4. For example, ask the patient to write a sentence and check their handwriting or ask the patient to do a simple task such as checking the amount of water spilled while they are holding a cup of water.1,4,5 People having essential tremor, generally show shaky handwriting but people suffering idiopathic Parkinson’s disease, present with micrographia.6 Again tremor becomes noticeable when a person with an essential tremor, is asked to hold a cup. The time-up and go test (TUG) should be performed in order to assess gait, overall mobility and balance. In this test a patient is asked to stand up from a chair, walk about three metres, turn and return back to the chair. A normal older person can complete this simple task in less than 20 seconds.4,5

When TUG is performed, features such as lack of arm swing in one side, tremor prominent while walking, are indicative of idiopathic Parkinson’s disease and feature like a small stepping gait is suggestive of an atherosclerotic Parkinsonism.4 A cerebellar pathology should be considered when a patient’s gait demonstrates wide-based ataxic in nature.4 All these assessments are straightforward and can be conducted easily without having any special instruments. They can be applied in any clinical setting: either primary or secondary care. Information gained from these assessments is valuable clinically in differentiating a tremor. 

Full neurological examination (particularly other cerebellar signs, vertical gaze palsy), assessing for clinical features of hyperthyroidism and checking blood pressure in lying and standing positions (to rule out postural hypotension) should be undertaken.5,6 In addition to these, a capillary random blood glucose check should be done to exclude hypoglycaemia.5,6

Tremor and cognitive function assessment
Another key assessment is memory or cognitive function assessment.4,5 Serial ratings and records of cognitive function are needed in order to disclose undiagnosed cognitive impairment or to monitor any process of cognitive decline in older people with tremor.4,5 For example, an elderly person with Lewy body dementia can present with visual hallucinations, resting tremor and cognitive impairment.4 
There are many different cognitive function assessment scales available in current clinical practice. In a busy clinical setting AMTS (abbreviated mental test scale), MMSE (mini-mental state examination) or other rating scales should be used appropriately in line with local clinical guidance. The clock drawing test (ask the patient to put numerical numbers as a clock face in a circle) is a useful test for visuo-spatial function, but can be difficult to perform.4 Tremor might restrict the drawing ability of a patient and the patient’s literacy status might constrain him from completing this task. 

Laboratory and imaging tests
Blood tests such as thyroid function tests and radiological imaging such as computed tomogram (CT) brain scan or magnetic resonance imaging (MRI) brain scan could be considered accordingly based on the patient’s presentation.4,5,6 But requesting all available blood tests and imaging in a “tick the box” manner is not a good practice. In this particular group of patients, history and physical examination are more applicable than advanced investigations. The other radiological imaging is DaT-Scan.7 This nuclear imaging scan uses ioflupane (a radioactive isotope) uptake in caudate and putamen areas of the basal ganglia and is indicated to differentiate idiopathic Parkinson’s disease from essential tremor and drug-related secondary Parkinsonism.7 However it is not a single diagnostic tool in assessing older people with tremor.7 Three common causes of tremor in older people are idiopathic Parkinson’s disease, vascular Parkinsonism and essential tremor. History taking and examination can be targeted to help differentiate between these conditions.4,5,6

Managing tremor in older people is not always simple and straightforward. Older people have underlying multiple comorbidities and complex social circumstances. They usually take more than one regular medication. More importantly, most aetiologies causing tremor in older people are chronic conditions and can be progressive in nature.4,5 Therefore, integrated long-term management plans including the patient’s understanding and awareness, plus family support, are imperative in managing tremor.4,5

Non-pharmacological intervention
Integrated multi-disciplinary team involvement is essential in this step. Depending on the severity of tremor, its impact on the patient’s activities of daily living and specific social need, individualised multi-disciplinary team based assessments and care arrangements must be provided to the patient.7 This approach includes physiotherapy, occupational therapy, speech therapy, mental health assessment, nutritional assessment, medications review and long-term social care.7 Communication with patients and families is key and should cover the nature of tremor, possible underlying aetiology and management plans.7 All these management strategies are equally important as therapeutic interventions in managing older people with tremor.7

Therapeutic interventions
Pharmacological agents are utilised according the type of tremor:

For older people with resting tremor
The most clinically important cause of resting tremor is idiopathic Parkinson’s disease. If a person fulfills UK PDS Brain Bank Diagnostic Criteria of Parkinson’s disease (bradykinesia with one of three key symptoms: resting tremor, rigidity and postural instability), this person should be referred to a specialist movement disorder service without delay.4,7 The first line medications recommended in idiopathic Parkinson’s disease are levodopa, dopamine agonists such as ropinirole and monoamine-oxidase B inhibitors (MAOI) such as selegiline.7 Modified-release levodopa, catechol-o-methlytransferase inhibitor (COMT) such as entacapone, Amantadine (weak dopamine agonist), apomorphine (dopamine agonist acting on D1 and D2 receptors in intermittent subcutaneous injection or continuous subcutaneous infusion) are indicated as second-line treatment in idiopathic Parkinson’s disease.7

Anticholinergics such as benzhexol are effective in controlling tremor but its administration is not popular in older people because of its side effects (such as confusion).4,5,7

In managing resting tremor due to secondary Parkinsonism the key approach is exploring underlying cause and optimising it appropriately.5,6 Common causes for secondary Parkinsonism in the elderly are drugs and stroke (multiple small infarcts).5,6 Antipsychotic agents such as chlorpromazine, haloperidol, risperidone, and olanzapine are notorious for causing secondary Parkinsonism.4,5,6 No specific management is available for drug- induced resting tremor. However rationalising antipsychotic drugs might reduce or control severity of drug-related resting tremor.5,6 

Patients with vascular Parkinsonism, (Parkinsonism mainly secondary to recurrent lacunar infarcts) present with legs stiffness, small-stepping gait rather than resting tremor.4 These patients might suffer early cognitive impairment, emotional lability and urinary incontinence.4 Anti-Parkinsonism drugs do not work well in vascular Parkinsonism.4 Similarly to secondary stroke preventive measures, its managements include anti-platelet agents such as aspirin, clopidrogel and controlling vascular risk factors such as lowering cholesterol and optimising blood pressure.4

For older people with postural tremor
In this group of patients the commonest cause is essential tremor. There are some therapeutic agents available for managing essential tremor. These include beta-blockers, topiramate primidone and gabapentin.4 Amongst these agents, a beta-blocker (propranolol) is the first-line agent.4,8 In the elderly propranolol should be commenced as starting from 10mg three times a day, then 40mg twice a day, then 80mg twice a day and 160mg twice a day as a maximal dose.8,9 The second-line agents: topiramate (from 25mg to 400mg per day), primidone (from 12.5mg to 750mg per day) should be considered only when propranolol has failed to work.

However, these therapeutic interventions should not be the first-line option in older people. They should be considered only when people feel uncomfortable with the tremor or are struggling to cope with it. It is important to make a careful clinical judgment prior to starting any of these medications and a “start low and go slow” approach must be applied.4,5 

After introducing medication, patients should be seen in the first four to six weeks to check the drug’s effectiveness and untoward effects. Regular follow up review, such as every six months, in the specialist service or general practice should be arranged appropriately.
The surgical intervention: deep brain stimulation (DBS) of the thalamic nuclei can be suggested to control a severe essential tremor.8 Again it should be considered only when the therapeutic interventions do not work well. It is not a favorable option in older people with essential tremor.

For older people with action tremor

Management of action (intention) tremor mainly relies on the underlying aetiology. Exploring the duration of tremor is clinically important. For example, posterior circulatory stroke should be excluded when an older person presents with acute onset intention tremor and other cerebellar signs. The “red flag” diagnoses of a space occupying lesion, such as secondary brain metastasis (more common in the elderly) should be considered, as well as alcohol use and brain abscess. These can be managed appropriately.5,6 Neurosyphilis is a rare but recognised cause of action tremor in older people.6

Creutzfeldt-Jakob disease (CJD), a rare but fatal neuro-degenerative disorder, could cause rapidly declining cognitive function, hallucinations, ataxia and intention tremor.6 Therefore broad consideration and systematic diagnostic workup are crucial in managing older people with action tremor.

For older people with other forms of tremor and movement disorders
Amongst these varieties “flapping tremor” is a solid sign of potential medical emergency. Certain conditions such as type II respiratory failure and hepatic encephalopathy must be considered, based on the patient’s presentation and other important clinical features.
Primary orthostatic tremor is a form that makes older people fearful of falls and increases psychological distress.10 It can be easy to misdiagnose. It is characterised by coarse shakiness of legs and feeling of instability in a standing position.10 These symptoms are generally relieved by walking and cease whilst sitting down.10 It is a rare form of benign tremor and might be seen in women aged 60 and over.10 The surface electromyogram (EMG) could demonstrate rhythmic oscillations of legs muscles at a frequency of 13-18 Hz per second.10 No specific therapeutic intervention is available but primidone, clonazepam or sodium valproate may give a positive response in some people.11
Multi-disciplinary team-based rehabilitation assessment plays an important role in managing the other forms of movement disorders.1,5 Some therapeutic options (ie regular botulinum toxin injections) could be considered in certain conditions such as cervical dystonia (spasmodic torticollis).6

We should all be aware that we cannot always elucidate the cause of a movement disorder and functional or non-organic causes should be considered within the spectrum of tremor in old age.

Conclusion
Older people can present with different forms of tremor. Thorough history taking, including a collateral history, functional assessments and clinical judgment are imperative in managing older people with tremor. A systematic and sensible clinical approach is far more important than sophisticated investigations. Patients’ lifestyles and personal interests should be taken into account in management plans.

Conflict of interest: none declared


References
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