Table of Contents
- Classification of Tremor
- Classification based on phenomenological parameters
- Tremor Frequency
- Amplitude of Tremor
- Anatomical Distribution
- Activation Pattern
- Etiological Classification of Tremor
- Classification based on Tremor Syndromes
- Isolated tremor syndromes
- Combined tremor syndromes
- Other tremor syndromes
- Further Reading
- Defined as an involuntary, rhythmic, and oscillatory movement of a body part.
- May occurs in healthy individuals as enhanced physiologic tremor.
- Induced by alternating or synchronous contractions of reciprocally innervated antagonist muscles.
- History and physical examination (position, posture, and activation pattern) aid in diagnosis.
- Clinical rating scales and electrophysiological measurements are utilized in evaluating the severity and therapeutic response.
- Enhanced physiologic tremor, essential tremor, and Parkinsonian tremor are more prevalent.
- Older people are more commonly affected as ~5% of the population over the age of 40 years have tremor.
- Tremors are classified and interpreted differently.
- Various tremor syndromes have overlapping features and etiologies.
- May differ in frequency and amplitude.
- Induced by physiological & psychological factors and drugs.
- A clinical and etiological classification strategy has been recommended by International Parkinson and Movement Disorder Society.
- Fundamental parameters utilized in tremor classification are:
- Phenomenology of tremor assists in classification and diagnosis.
- It includes clinical features manifested during history and physical assessment.
- The following parameters are valuable during examination:
- Anatomical distribution
- Activating conditions
- Frequency is the number of vibrations per second.
- Gauged by EMG or Accelerometers.
- Various disorders may have overlapping frequencies.
- Parkinsonian tremors, myorhythmia, and some palatal tremors have a frequency below 4 Hz.
- The frequency of primary orthostatic tremors is 13 to 18 Hz.
- Essential tremors and central neurogenic components of physiological tremors have a frequency of 5-10 Hz.
- A frequency of <4 Hz is observed in severe cerebellar tremors, but up to 10 Hz may be seen in mild distal cerebellar tremors.
(a) Low Frequency Tremor
Parkinsonian tremor, cerebellar tremor, holmes tremor, palatal tremor, drug-induced tremor. intention tremor.
(b) Intermediate Frequency Tremor
Physiological tremor, Essential tremor, Task-specific tremor, Dystonic tremor, Neuropathic tremor, Palatal tremor, Drug-induced tremor, Psychogenic tremor.
(c) High Frequency Tremor
Orthostatic tremor, Essential tremor, Physiological tremor.
(d) Very high frequency
Primary orthostatic tremor
(e) Variable frequency
- The extent of linear or angular displacement elicited about the fixed plane.
- Accurately scaled in millimetres or degrees by accelerometers or gyroscopes.
- Coarse tremor: have large amplitude and low irregular frequency, that includes parkinsonian and holmes tremors.
- Fine tremor: have low amplitude and high frequency, includes enhanced physiological and essential tremor.
- Tremors may be unifocal, multifocal, or generalized.
- May involve the head, face, jaw, vocal apparatus, tongue, trunk, or extremities.
(a) Focal tremor
Single body region is affected.
Voice tremor, Head tremor, Palatal tremor, Task-specific tremor,
(b) Segmental tremor
Two or more contiguous body parts in the upper or lower body are affected.
Cervical dystonia, Segmental tremulous dystonia,
One side of the body is affected.
Rest tremor combined with parkinsonism, Intention tremor, Myorhythmia, Holmes’ tremor,
(d) Generalized tremor
Effects the upper and lower body.
Cerebellar tremor, Enhanced physiological tremor, Psychogenic tremor, Orthostatic tremor, Essential tremor, Drug-induced tremor.
(e) Proximal tremor
Tremor affecting proximal limb musculature, has high amplitude and low frequency.
(f) Distal tremor
Low amplitude and high frequency tremors affecting distal limb muscles.
- Tremor is primarily classified based on its occurrence with a certain posture.
- Broadly categorized into rest tremor and action tremor.
- Generated by voluntary contraction of a muscle.
- Further divided into kinetic and isometric tremor.
Types of Tremor
Clinical features and Provocative maneuvers
Elicited by voluntary movement.
(a) Task-specific kinetic tremor while doing a specific task. (b) Simple-kinetic tremor non-specific to any activity (c) Intention tremor while performing goal-directed activities.
Finger-to-nose test, heel-to-shin test, reaching, writing, drawing, pouring water into a cup, eating with utensils, speaking, doing specific tasks for task specific tremor.
Evoked during sustained muscle contraction against a rigid stationary object.
Pushing against a wall, flexing the wrist against table, making a fist.
- Elicited in part that is not voluntarily activated.
- Assessed when the affected body part is relaxed and completely supported against gravity.
- Amplitude increases with mental stress, cognitive tasks, and the activity of another body part.
- Subsides with the activity of the affected limb.
- Emerges during voluntary maintenance of a specific posture held against gravity.
- Amplitude increases during the voluntary movement.
- Evaluated during upper limb extension, object pointing, sitting upright without support, standing, and tongue protrusion.
- Usually exhibits the frequency of 5-9 Hz.
- Comprises enhanced physiological, drug-induced, essential, and psychogenic tremors.
- Subdivided into a positional-dependent and positional-independent postural tremor.
- Tremor has marked etiological heterogeneity.
- Can be due to genetic, acquired, or idiopathic etiologies.
- Prognosis and specific treatment plans are determined by underlying etiology.
- Physiologic Tremor, is an 8-12 Hz normal variant that occurs during the maintenance of a posture.
- Physiologic tremor is increased by emotions, fatigue, stress, exercise, alcohol withdrawal, and drugs.
- Pathologic tremor is either idiopathic or occurs secondary to some disorders.
- Essential tremor and Parkinsonian tremor are the two most common types of pathologic tremor.
Emotions (fear, stress, anxiety), exercise, fatigue.
Parkinson’s disease, Multiple system atrophy, Corticobasal degeneration, Frontotemporal dementia with Parkinsonism, Spinocerebellar ataxias, Wilson’s disease, Lesch-Nyhan’s syndrome, Fragile X–associated tremor/ataxia syndrome, Spinal muscular atrophy.
Anticonvulsants (valproate, carbamazepine, phenytoin), Tetrabenazine, antidepressants, sympathomimetics, bronchodilators, beta-2 agonists, Lithium, Neuroleptics, metoclopramide, Amiodarone, Thyroid hormone replacement, Anticancer drugs (vincristine, cisplatin, paclitaxel, doxorubicin, cytosine arabinoside, ifosfamide, tacrolimus, 5-fluorouracil, methotrexate), Drug and alcohol withdrawal.
Mercury, Lead, Manganese, Arsenic, Cyanide, DDT, CO, Naphthalene, Toluene, Lindane
XYY, XXY (Klinefelter’s syndrome), and XXYY syndromes.
Mitochondrial genetic disorders
Leigh’s syndrome, Mitochondrial polymerase gamma mutations.
Infectious and other inflammatory diseases
Demyelinating diseases such as multiple sclerosis, Encephalitis lethargica, subacute sclerosing panencephalitis, HIV, Tuberculosis, syphilis, measles, typhus, neuroborreliosis, Bacterial or viral encephalitis, Antineuronal antibody disease.
Endocrine and metabolic disorders
Nephrotic or liver failure, hyperthyroidism. hypoglycemia
Neuropathies and spinal muscular atrophies
Kennedy’s syndrome, Guillain-Barre’s syndrome, Gammopathy-induced neuropathies.
Brain neoplasms, Brain injury (head trauma, brain surgery, and electrical injury), Vascular (ischemia, hemorrhage, and arteriovenous malformations), Anxiety and stress, Fatigue, Cooling, Trauma of peripheral tissues, HIV, human immunodeficiency virus.
- Categorization is based on associated neurological or systemic signs and symptoms.
- Examination of cranial nerves, speech, gait, balance, and muscle tone may assist in clinical diagnosis.
- This classification helps in clinical and research purposes.
- Helps in explaining new syndromes without etiological inferences.
- Preliminary classification may be altered with the manifestation of new clinical features.
- Multiple etiologies might be associated with a tremor syndrome
Isolated tremor syndromes
Essential tremor, Essential tremor plus, Voice tremor, Head tremor, Jaw tremor, Essential Palatal tremor, Face tremor, Primary orthostatic tremor, Pseudo orthostatic tremor, Task specific writing/musician’s/sport tremor.
Combined tremor syndromes
Dystonic tremor, Parkinsonism-associated tremor, Intention tremor (with cerebellar signs), Holmes tremor(with brainstem & cerebellar signs), Myorhythmia (with brainstem & cerebellar signs), Symptomatic palatal tremor.
Functional tremor, Indeterminate tremor.
- Tremor is the only clinical manifestation, without any other abnormal neurological or systemic signs.
- Bilateral upper limb action or postural tremor without additional neurological signs.
- High-frequency tremor with an increase in amplitude at the end of goal-directed activities.
- Bilateral upper limb action tremor, with additional neurological signs of uncertain significance.
- Tremor of vocal apparatus in the absence of dystonia or other neurological signs.
- Causes periodic fluctuations in pitch and loudness of voice with voice-less pauses.
- Head Tremor in the absence of any obvious cervical dystonia or tremor of other body parts.
- Causes shaking of the head in yes-yes, no-no, or variable directions.
- Isolated focal tremor of the soft palate, often with audible clicks.
- They have a frequency of 1-7 Hz and completely cease during sleep.
- Action tremor that occurs exclusively during writing.
- Causes low frequency and high amplitude supination-pronation movements limited to hands.
- Postural tremor of legs and trunks occurs exclusively while standing.
- Symptomatic, bilateral upper extremity action tremor with a frequency of 9-12 Hz
- Caused by fatigue, anxiety, stress, fear emotions, drugs, hypoglycemia, and thyrotoxicosis.
- Isolated resting tremor of arm resembling early PD that fails to evolve into more generalized PD over time.
- No evidence of nigrostriatal dopamine deficiency on imaging.
- Tremors with associated abnormal neurological or systemic signs (dystonia, rigidity, bradykinesia, myoclonus, Kayser-Fleischer ring, hepatosplenomegaly, or exophthalmos).
- Postural, task-specific, or rest tremor in a body part that is affected by dystonia.
- Irregular, jerky tremor that alleviates by maneuvers (sensory tick or geste antagoniste).
- Palatal tremor with coexisting neurological signs and symptoms.
- They have a lower frequency(1.5–3 Hz) and usually persist during sleep.
- Low-frequency action tremor in the presence of other cerebellar signs (ataxia, dysmetria, titubation).
- Increases in severity as the hand move closer to the target.
- Action tremor of arms/hands, in the presence of severe peripheral neuropathies.
- Frequency and amplitude vary greatly when associated with a proprioceptive deficit.
- Low amplitude pin-rolling resting tremor is a characteristic feature of Parkinson's disease.
- Occurs in a body part that is reposed, relaxed, and completely supported against gravity.
- A subtype of cerebellar tremor with high amplitude and low frequency occurring at rest.
- Persists unchanged or increases with postural change or goal-directed activity.
- Slow, rhythmic, repetitive jerky movements involving cranial and limb muscles.
- Associated with other neurological signs (dystonia, palatal tremor, and abnormal eye movements)
- They include syndromes that can not be categorized into either isolated or combined syndromes;
- Abrupt onset complex tremor with a static course, changeable features and spontaneous remission.
- Manifests variable tremor frequency and tremor entrainment with distraction maneuvers.
- Classic essential tremor with neurologic signs not sufficient to make a diagnosis of a recognizable neurologic disorder.
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Neurologist in Birmingham, Alabama.