Most common movement disorder.
The most common tremulous diseases are essential tremor and Parkinson disease.
Defined as a rhythmic, involuntary, oscillating movement of a body part.
Can occur in isolated fashion or part of a syndrome.
Common types include resting , postural, kinetic, task-specific , and intention tremor.
Diagnosis is based on history and neurological examination.
History can elucidate when a tremor is due to a specific event such as a stroke, head injury or disease such as multiple sclerosis.
The onset of tremor that is asymmetrical in the thumb or finger often suggests Parkinson’s disease.
Bilateral and symmetrical tremor with activity suggests a systemic cause of the tremor such as a metabolic abnormality or medication effect.
Resting tremor refers to body part with tremor when it is at complete rest against gravity, and the amplitude of the tremor decreases with voluntary movement.
Postural tremor occurs during the maintaining of a position against gravity and increases with action.
Kinetic tremor occurs during voluntary movement.
Task-specific tremor occurs during a specific activity, such as writing.
Intention tremor refers to a marked increase in tremor amplitude during a terminal portion of targeted movement.
Tremor can be disabling and often begins as early as the second decade and can progress to affect employment.
Tremor can result in psychological trauma with emotional trauma that is more significant than physical disability, as patients may develop social embarrassment and depression.
Resting tremors are seen with Parkinson’s disease, drug induced Parkinsonism, long-standing essential tremor, and Wilson’s disease.
Postural and kinetic tremors are seen with essential tremor, metabolic disorders, drug-induced Parkinsonism, neuropathic tremor and thoise seen with exposure to toxins.
Prevalence varies by tremor type.
Essential tremor is the most freqent type ranging from 0.4-5.6% (Findley LJ).
Essential tremor estimated to affect 10-20,000,000 people in the US.
Essential tremor associated with an autosomal dominant inheritance and a family history is noted in 60% of cases.
Essental trmor has onset in childhood and elderly.
Essential tremor is mainly a postural or action type tremor.
Alcohol intake may temporarily decrease essential tremor.
Parkinson’s disease affects more than 1 million individuals in the US, with an estimated incidence of 1% for those with age 60 years or older.
Essential tremor may be associated with hearing loss, which may correlate with severity of the tremor.
Essential tremor is a slowly progressive process.
Essential tremor has no preventative management.
Essential tremor may require no therapy, pharmacological and even surgical management.
Essential tremor treatment usually begins with primidone or propranolol monotherapy.
Essential tremor patients treated with beta blocker propranalol will have a reductiuon in the amplitude of their tremor 60-70% of the time.
Essential tremor treatment with propranolol is most effective for upper extremity tremors compared to head or voice tremors, and other beta blockers are not as effective.
Primidone, an analogue of phenobarbital, can reduce essential tremor by 60-70%
Essential tremor treatment may include botulinin toxin injections for refractory patients.
Parkinson’s disease prevalence rates for whites in Europe and North America, the age-adjusted prevalence ratio ranges from 56 to 234 per 100,000 compared with a range of 14 to 148 per 100,000 in Asia.
Tremor
In physiologic tremor mechanic oscillations can occur at a particular joint.
Toxic tremors are associated with reflex oscillations of muscle spindle pathways.
Central oscillators are groups of cells in the central nervous system present in the thalamus, basal ganglia, and inferior olive and can and produce tremor.
Parkinsonian tremor may originate in the basal ganglia, and essential tremor may originate within the inferior olive and thalamus.
Abnormal functioning of the cerebellum can produce tremor.
Cerebellar activation is present in almost all forms of tremor.
Physiologic tremor is seen in normal individuals withmaintaing posture or movement, and it is barely visible with a low amplitude (6-12 Hz).
Physiologic tremor may be enhanced by drugs or toxins, resulting in a high-frequency but low ampltude tremor that is visible when a specific posture is maintained.
Parkinson’s tremor is a low-frequency rest tremor typically defined as a pill-rolling tremor.
In Parkinson’s tremor some patients also have postural and action tremors.
Parkinson’s tremor usually occurs in association with other symptoms, such as micrographia, bradykinesis and rigidity.
Parkinson’s tremor is not improvede by alcohol intake and there is no familty history.
Cerebeller tremor refers to a intention tremor of low frequency, <4 Hz, that is usually unilateral and is associated with cerebeller damage, stroke or multiple sclerosis.
Rubral tremor (Holmes’ tremor) refers to a tremor with a rest, postural and kinetic process related to a midbrian lesion near the red nucleus, with associated ataxia, and weakness seen with stroke or multiple sclerosis.
Systemic disease associated tremor usually occurs when the patient is moving or assumes a specific position and include thryotoxicosis, hepatic failure, delirium tremens, and drug withdrawal.
Psychogenic tremor usually involves the extremities and is of sudden onset associated with a a combination of postural, action, and resting tremors.
Examination should be done in all positions and during movement and rest to determine a rating and tremor frequency.
Each affected site can be rated as resting, kinetic or positional from 1-5 from no tremor to severe tremor with an excursion of 4 cm.