Dystonia is a movement neurological disorders due to chemical unbalance with resultant dysfunction in a part of the brain called Basal Ganglia. It leads to abnormal electrical input signals to the motor cortex in the brain and alters the muscle tone.
Dystonia is characterised by sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. The postures are typically not fixed and tend to be repetitive or patterned, consistently involving the same muscle groups. A Dystonia tremor may occur and involve the affected body past. It is jerky, irregular and typically worsens in particular positions.
Dystonia is aggravated by voluntary movement. When Dystonia is evinced by only with particular action, it is called Task Specific Dystonia such as ‘Writer’s Cramp’. Fatigue and emotional stress often exacerbate, while sleep and relaxation tends to decrease the abnormal movements. Improvement to some degree by touching is often successful in some patients (sensory tricks). Adult over Dystonia tends to be associated with disease related pain and depressive disorders.
There are three different ways of classifying Dystonia which are essential for diagnosis, prognosis, guiding therapy and genetic counselling.
- By Anatomical Distribution:
- Focal Dystonia– Abnormal body movements involve a single region only e.g. the hand in ‘Writer’s cramp’, where the patient shows abnormal postures affecting the hand while writing but not while performing other tasks.
- Segmental– Abnormal body movements affect two or more contiguous body regions.
- Hemidystonia – Affecting one side of body.
- Generalised– Include both legs, trunk plus one other body region.
- Age at Onset:
- Young Onset– less than 26 yrs.
- Adult Onset– more than 26 yrs.
- Underlying Causes:
- Primary– No identifiable cause present. Dystonia alone, no other part of Nervous system affected. No Secondary cause or degenerative disorder obvious due to genetic disorder.
- Dystonia Plus– Signs other than Dystonia are present e.g. Parkinsonism, myoclonus.
- Secondary– Clear acquired or exogenous cause present- e.g. Head injury, Stroke, Brain infection, drug exposure.
A detailed history (including family history, drug intake, childhood infections) while carefully observing the patient, making him walk forwards and backwards, followed by a thorough clinical examination by a experienced Neurologist, are the most helpful tools in the diagnosis of this difficult condition. Investigation including MRI of Brain, blood tests and genetic studies can be helpful in narrowing down the diagnosis.
Management depends on the type of Dystonia and the degree of disability. In some conditions such as Wilson’s disease, drug induced disease or Dopa responsive Dystonia and Writer’s cramp, the outcome is satisfactory. Most other conditions need prolonged treatment.
- Medication- Pacitane Levodopa, Baclofen and some other medications are used.
- ‘Botulinum Toxin’ injections given locally in affected muscles or muscle group guided by needle EMG.
- Deep Brain Stimulation Surgery in selected group of patients.