Categorizing dystonia by the cause is not a simple task and can easily get complicated. The DMRF often states in publications that we don’t know the cause of dystonia because scientists have not yet identified the precise biochemical process in the body that triggers the symptoms. This is often referred to as the “mechanism” of dystonia, and it is suspected that this mechanism is common to all forms of dystonia
On the other hand, we do know that dystonia can occur as a result of trauma, certain medications, and mutated genes. So, we may say that the mutated DYT1 gene or physical trauma cause dystonia, but these explanations do not address the true origin of the dystonia and what happens inside the body to produce the symptoms
When describing dystonia by the cause, it may be characterized as primary, secondary, or dystonia-plus
The cause(s) of dystonia are not yet known or understood, however, they are categorized as follows on a theoretical basis
Primary dystonia is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA (Gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions
The word primary describes a case in which the dystonia is the only neurological disorder that the person has. Primary dystonias include some genetic forms (such as DYT1 dystonia in which a gene has been identified) and forms for which a cause is not usually found - such as most focal dystonias
Genetic dystonias may be described using certain terms
Sporadic—A case of dystonia that is genetic or presumed to be genetic when the affected person does not have a history of dystonia in the family
Familial—Dystonia that is inherited and occurs in multiple members of an extended family
Inherited—Dystonia that is passed on genetically from parent or ancestor to a child
Before any of the dystonia genes were discovered, the word idiopathic was often used to describe the forms that were presumed to be genetic. By definition, idiopathic means “of unknown cause.” Today, if a person’s dystonia is described as idiopathic, that simply means that the cause is not known—it cannot be attributed to trauma, drug exposure, a gene mutation, or another disease or condition
Secondary dystonia refers to dystonia brought on by some identified cause, usually involving brain damage, or by some unidentified cause such as chemical imbalance. Some cases of (particularly focal) dystonia are brought on after trauma, are induced by certain drugs (tardive dystonia), or may be the result of diseases of the nervous system such as Wilson's disease
Secondary dystonias include insults to the brain caused by certain kinds of tumors, infections, stroke, metabolic conditions, and toxins
Dystonia-plus Sometimes dystonia occurs along with symptoms of other neurological disorders or has a particular quality that resembles another disorder. These forms may be put in a category called dystonia-plus. These forms include
Dopa-responsive dystonia, in which affected persons have symptoms that resemble the physical attributes of Parkinson’s disease, but do not have full-blown degenerative Parkinson’s disease
Myoclonic dystonia is included in this category because affected persons may have prominent symptoms that resemble a movement disorder called myoclonus
Rapid-onset dystonia-parkinsonism, in which affected persons may experience symptoms of both dystonia and parkinsonism, progresses quickly over the course of days or weeks
X-linked dystonia-parkinsonism is a unique form that affects males of Filipino descent almost exclusively and has many parkinsonian features
Specific gene mutations have been associated with each of above mentioned forms, which means that they are genetic and can be inherited
There appear to be higher incidents of dystonia and related movement disorders in some geographic areas (like East Texas) indicating the possibility of a contributing factor from the environment
