Tremors are rhythmic shaking of a body part caused by muscle contraction.
‘Tremor denotes a rhythmic involuntary movement of one or several regions of the body’
- Classification of tremor:
The classification of tremors have been done on various clinical and syndromic aspects
- Classification based on phenomenology of tremor
- Classification based upon syndromic categories
The Classification based on phenomenology is based upon various clinical characteristics based upon topographic distribution of tremors, condition of activation, frequency and associated symptoms. These tremors 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’,
- Action tremor is defined as ‘tremor produced by voluntary contraction of muscle, including postural, isometric and kinetic tremor and also includes intention tremor’.
- Postural tremor, present while voluntarily maintaining a position against gravity
- Kinetic tremors, occurs during any voluntary movement
- Intention tremor, is the pronounced exacerbation of kinetic tremor at the end of a visually guided, goal oriented movement
- Isometric tremor, occurs when a voluntary muscle contraction is opposed by a rigid stationary object.
The classification based upon syndromic diagnosis is based upon phenomenology of tremors elements which could be combined into specific syndromes. This type of syndromic classification helps for diagnostic and therapeutic approaches.
- Aetiology of Tremors:
The aetiology of tremors is wide and varied and requires continuous updating. The causes can be grouped based upon the type of underlying pathogenic mechanisms and precipitating factors
- Hereditary and degenerative : Parkinson’s disease, Parkinson’s diseaseMultiple system atrophy, Wilson’s disease, Progressive pallidal atrophy, Huntington’sdisease, Benign hereditary chorea, Fahr’s disease, Paroxysmal dystonic choreoathetosis, Progressive myoclonic ataxia, Ataxia telangiectasia, Dystonia, Dopa responsive dystonia, Spasmodic torticollis, Meige syndrome, Essential tremor, Task specific tremors, Klienfelter’s syndrome.
- Cerebral diseases of varies etiologies including infections and space occupying lesions
- Metabolic causes: Hyperthyroidism, Hyperparathyroidism, Hypomagnesimia, Hypocalcaemia, Hyponatremia, Hypoglycaemia, chronic hepatocerebral degeneration, hepatic encephalopathy, kidney disturbances, and B12 deficiency.
- Peripheral neuropathies: Charcot-Marie-Tooth, Roussy levy syndrome, chronic demyelinating neuropathies, GuillianBarre syndrome, Gammopathies, mal-absorption neuropathy, diabetic neuropathies, porphyria, spinal muscular atrophy, drug induced neuropathies (nicotine, mercury, lead, carbon monoxide, manganese, arsenic, cyanide, naphthalene, alcohol, toluene, dioxins, kepone)
- Drugs: Neuroleptics, reserpine, tetrabenzine, metoclopramide, antidepressants, metoclopramide, lithium, cocaine, alcohol, beta 2 agonists, theophylline, caffeine, dopamine, steroids, valproate, perhexiline, antiarrrthymics, mexiletine, procainamide, calcitonin, thyroid hormones, cytostatics, immunosuppressant’s
- Others: Emotions, fatigue, cooling, drug withdrawal, psychogenic.