Dystonia is a movement disorder that causes a disruption in the regulation of muscle tone. This disruption causes the muscle to involuntarily contract and can cause progressive rigidity in different areas of the body. Dystonia can cause increased tone in opposing muscles of the affected area of the body that can hinder movement. If the increase in tone is not symmetrical it can cause abnormal posturing.
Dystonia can occur in patients as young as three, although it typically occurs just before puberty. When Dystonia occurs in younger patients it primarily impacts the legs and can hinder the patients ability to walk normally. Younger patients with dystonia tend to experience a more rapid progression of the issue.
If dystonia develops later in life, it can affect the trunk of the body and the neck as well as the legs. The issue can reach the point where the sufferer is rendered completely immobile. Death may occur as a result of secondary complications such as pneumonia.
There are multiple types of dystonia:
- Primary dystonia – Caused by gene mutation
- Secondary dystonia – Caused by an injury to the nervous system
- Generalized dystonia – Occurs throughout the body
- Focal dystonia – Occurs in a specific area of the body
- Segmental dystonia – Occurs in two adjoining body parts
The primary medical therapy for dystonia is targeted botulinum toxin injections. If botulinum toxin is ineffective, deep brain stimulation can be considered.
If deep brain stimulation is being considered, there are several factors that must be taken into consideration before surgery. These factors include the type of dystonia the patient suffers from, as deep brain stimulation is more effective in individuals with primary dystonia compared to secondary dystonia. Deep brain stimulation is also more effective in patients with general dystonia than it is in individuals who suffer from focal dystonia. Still, with increasing experience, patient with secondary dystonias and focal dystonias are still considered for treatment. Deep brain stimulation has been shown to effective in about 50% to 70% of patients. The effect of deep brain stimulation can take up to 6-12 months to become apparent. Throughout this time, close management and follow-up by a movement disorders neurologist is required.