There are several forms of dystonia, and dystonia may be a symptom of many diseases and conditions. If you are new to dystonia, it can be a challenging disorder to understand. The words used to describe your specific diagnosis may be confusing. To accurately describe the form of dystonia that an individual has, at least four specific pieces of information must be accounted for:
- The age at which the symptoms started;
- How the body is affected;
- What is known about the cause;
- If the dystonia occurs with symptoms of additional neurological disorders
All of the above is required to set the best course for treatment, but for the sake of routine conversation, most people use the terms that describe the most prominent feature of the dystonia (for example, cervical dystonia for dystonia that affects the neck and shoulders; dopa-responsive dystonia for the form of childhood-onset dystonia that has characteristics that resemble parkinsonism.).
The age at which symptoms begin is referred to as age of onset. If an individual develops symptoms prior to approximately age 30, it may be referred to as early-onset or childhood-onset. (If the dystonia occurs during the teen years, the term adolescent-onset may be used.)
If symptoms develop after the age of 30, it is called late-onset or adult-onset.
These forms of dystonia are typically early-onset:
- DYT1 generalized dystonia
- Non-DYT1 generalized dystonia
- Paroxysmal dystonia & dyskinesias
- Dopa-responsive dystonia
- Myoclonic dystonia
- X-linked dystonia-parkinsonism
- These forms of dystonia are typically adult-onset:
- Cervical dystonia
- Embouchure dystonia
- Oromandibular dystonia
- Laryngeal dystonia (spasmodic dysphonia)
- Hand dystonia (writer’s cramp)
Secondary dystonia may be early- or adult-onset, depending on the underlying cause.
When dystonia affects only one part of the body, it is called focal dystonia.
Segmental dystonia affects two or more connected body areas (for example the neck, shoulder, and arm). If two or more areas in different parts of the body are affected, the dystonia is termed multifocal(for example the eyes and vocal cords).
Generalized dystonia refers to dystonia that may affect the limbs, trunk, and other major body areas simultaneously. The term axial dystonia describes dystonia that specifically affects the torso.
When dystonia only affects muscles on one side of the body, it is called hemidystonia
Certain dystonias are labeled task-specific which means that the symptoms occur only when the person is performing a specific task or movement. These forms often involve the fingers and hands or the mouth.
If symptoms only occur in “episodes” that last for minutes or hours, the terms paroxysmal dystonia and dyskinesias are used.
The word torsion is sometimes used, usually in reference to generalized, axial, or segmental dystonia. Torsion refers to the twisting element of dystonia. It describes muscles contracting against each other.
What is Known About the Cause
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.
Dystonia can be associated with numerous diseases and conditions. These include specific vascular conditions, infections, brain tumors, metabolic conditions, neurodenegerative disorders, demylianating disorders, and structural conditions.
The classifications above are necessary needed to set the best course for treatment, but for the sake of routine conversation, most people use the terms that describe the most prominent feature of the dystonia (for example, cervical dystonia for dystonia that affects the neck and shoulders; dopa-responsive dystonia for the form of childhood-onset dystonia that has characteristics that resemble parkinsonism.).