ABOUT THE DISEASE
Among the various types of movement disorders, tremors are the most common type. Tremors represent an interesting physiological phenomenon, which is noted in all living organisms and can present as a symptom or as a disease in its own right.
The most commonly used tremor definition is: ‘Tremor denotes a rhythmic involuntary movement of one or several regions of the body` - defined by the Tremor Investigation Group.
These are broadly classified into rest tremors and action tremors. Rest tremor is defined as the ‘tremor that occurs in a body part that is not voluntarily activated and is completely supported against gravity`. The Action tremor is defined as ‘tremor produced by voluntary contraction of muscle, including postural, isometric and kinetic tremor and also includes intention tremor`.
SYMPTOMS
These include rhythmic shaking in different body parts like hands, arms, head, legs, etc; difficulty writing /drawing/ holding and controlling objects, shaky voice, etc.
Different types of tremors may present as:
Physiological and enhanced physiological tremor - present in every normal subject and every joint or muscle that is free to oscillate, in the absence of any underlying neurological disease.
Essential tremors: visible and persistent kinetic/postural tremor at least for 5 years with other secondary causes being ruled out. Commonly seen in hand (94%), followed by head tremors (33%), voice tremor (16%), jaw tremor (8%), facial tremor (3%), leg tremor (12%) and trunk tremor (3%).
Parkinsonian tremors: are associated with Parkinson`s disease. Among the parkinsonian tremors, the rest tremor is the most common form and accounts for about 90% of all patients.
Orthostatic tremors: subjective feeling of unsteadiness during stance but only in severe cases during gait; patients rarely fall.
Dystonic tremors : associated with dystonia.
Primary writing tremor: occurs only (or predominantly) during writing but not during other tasks in the active hand.
Psychogenic tremors: Psychogenic tremors, usually have an acute onset with remissions and is characterized by combinations of various types of tremor phenomenologies with varying amplitude and frequency.
CAUSES
The causes can be grouped based upon the type of underlying pathogenic mechanisms and precipitating factors:
1. Hereditary and degenerative : Parkinson`s disease, Multiple system atrophy, Wilson`s disease, Spasmodic torticollis, Essential tremor, Task specific tremors.
2. Cerebral diseases of varies etiologies including infections and space occupying lesions.
3. Metabolic causes: Hyperthyroidism, Hyperparathyroidism, Hypomagnesimia, Hypocalcaemia, Hyponatremia, Hypoglycaemia, hepatic encephalopathy, B12 deficiency.
4. Peripheral neuropathies: chronic demyelinating neuropathies, Guillian Barre syndrome, diabetic neuropathies, porphyria, spinal muscular atrophy, drug induced neuropathies (mercury, lead, carbon monoxide, arsenic, cyanide, naphthalene, alcohol).
5. Drugs: Neuroleptics, reserpine, tetrabenzine, antidepressants, metoclopramide, lithium, cocaine, alcohol, beta 2 agonists, theophylline, caffeine, dopamine.
6. Others: Emotions, fatigue, cooling, drug withdrawal, psychogenic.
DIAGNOSIS
- Physical neurological examination
- Blood tests
- CT/MRI
- Electromyogram
TREATMENT METHODS
- Medications, in different types, like Propranolol for Enhanced tremors; beta adrenergic antagonists, anticonvulsants, benzodiazepines, botulinum toxin, calcium channel antagonists,antidepressants for Essential tremors; Levodopa in Parkinsonian tremors; anticholinergics, tetrabenazine, benzodiazepines. Botulinum toxin for Dystonic tremors.
- Physical therapy
- Surgery, such as Thalamotomy and Deep Brain Stimulation
Contributed by:
Dr. Prashanth LK
DM (Neurology) Fellowship in Movement Disorders (Toronto))
Consultant Neurologist.
Specialist : Parkinson`s Disease & Other Movement Disorders
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