What causes dystonia?

Dystonia is a central nervous system disorder so far as we know, usually coming from a dysfunction deep in the brain in the region called the basal ganglia, including its connections into the upper portion of the brainstem (the part of the brain that lies between the hemispheres of the brain and the spinal cord). There may be some spinal cord disorders, which may be affected in certain kinds of dystonia, but these appear to be in the minority. There are two categories of dystonic classification. Those that are primary or essential; that is they are not due to any injury to the brain like multiple sclerosis, stroke or other diseases, but rather are intrinsic to the way that nervous system operates. Secondary dystonia means the condition is due to some alteration of an otherwise normal nervous system due to an acquired disorder, changing the original functioning of the nervous system and producing over-activity in the muscles because of a brain or spinal cord relative over-activity and directing the muscles to be overactive. Most of the essential dystonias are thought to likely have some genetic mechanisms. But not all genetic disorders are multi-generational. That may be because of a new spontaneous genetic mutation that has occurred in that person or it may be that other family members may possess what is called a suppressor gene, which limits the expression of the dystonia gene. One of the nice things about essential dystonia, which appears at all ages but especially in adulthood and the most common form of dystonic mechanisms, is that it is almost always potentially reversible, since the brain is not dying (as occurs in Alzheimer's disease, where nerve cells are shrinking and dying off, as they also do in Parkinsonism). A spontaneous improvement or response to therapy improve the probabilities that dystonic symptoms will lessen. However, once dystonia has occurred and then goes away, the patient continues to be at risk to have their symptoms recur.

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