Dystonia is a neurological condition with a very broad range of manifestations. The basic underlying problem involves over-activity of the main muscles needed for a movement, extra activation of other muscles that are not needed for the movement, and simultaneous activation of muscles that work against each other. The final result is determined by the severity and distribution of muscles involved. In some cases, dystonic movements appear only as transient exaggerations of a normal movement. In other cases, dystonic movements appear slow, stiff, cramped, twisting or jerky. In extreme cases, dystonia manifests as odd postures that may become almost permanent.
Types of dystonia:
The many types of dystonia are divided into separate groups because of their implications for treatment and prognosis. The simplest method of grouping divides people based on the region that is affected, as shown below:
Focal Dystonia (isolated region):
Focal dystonia describes cases with involvement of isolated areas, such as the muscles of the neck in torticollis, the muscles around the eyes in blepharospasm, or the muscles of the hand in writer’s cramp.
- Blepharospasm – spasmodic winking from involuntary contraction of the periocular muscles
- Oromandibular – affecting the jaw, tongue or peri-oral
- Laryngeal – affecting the use of the voice
- Cervical – torticollis, retrocollis
- One limb – writer’s cramp or foot dystonia
Segmental Dystonia (two contiguous regions):
Segmental dystonia describes people with involvement of at least two adjacent regions, such as the eyes and mouth in Meige syndrome.
- Meige Syndrome – blepharospasm plus oromandibular dystonia
- Cervial Dystonia, plus one arm
- Hemidystonia – impacting the arm and leg on the same side of the body
- Diffuse – two or more non-contiguous body areas
Generalized (more extensive areas):
Generalized dystonia describes people with muscles affected throughout their bodies, although specific areas in individual people are typically more affected than others.
- Both legs, another region, which may or may not include the trunk
- One leg, another region and the trunk
How is dystonia diagnosed?
Dystonia is not rare. It is actually the third most common problem seen in movement disorder clinics. But because of its many different and very often unusual manifestations, it is frequently misdiagnosed. The diagnosis is usually based on clinical evaluation by an expert in movement disorders. Some tests, such as blood samples or brain scanning, are helpful for identifying a cause in some cases. The types of tests needed depend on the type of dystonia.
Treatment for dystonia
There are many treatment options in dystonia. The best treatments depend on the type of dystonia. For many focal dystonias, injection of botulinum toxin as a muscle relaxer is the treatment of choice. Botulinum toxin can virtually eliminate the jerky posturing of the head in torticollis or the eye spasms in blepharospasm. Some children with generalized dystonia known as DOPA-responsive dystonia respond dramatically to levodopa and related medications. For some people, neurosurgical options exist, such as selective denervation and deep brain stimulation.
There is a research team at Hopkins actively engaged in research devoted to understanding the causes for dystonia, better treatments for people with dystonia, and ultimately a cure. This research involves laboratory studies of animals with dystonia, studies of the brains of people with dystonia, and clinical trials of potential new therapies. Researchers at Hopkins were among the first to link dystonia with abnormal communication involving calcium among nerve cells. These studies then led to a clinical trial of medications that influence calcium signaling in people with dystonia. Researchers at Hopkins are also leading the way in understanding how different brain regions may contribute to the appearance of dystonia, and how these regions might be manipulated to control it.