Dystonia · What Is It, Causes, Treatment, and More

Dystonia is a movement disorder that causes involuntary muscle spasms and contractions. Movement disorders are neurological disorders that occur when changes in the nervous system affect how the muscles contract. In dystonia, the areas of the brain associated with muscle movement, such as the basal ganglia which are responsible for muscle coordination, are affected. Dystonia is the third most common movement disorder in the United States, after essential tremor and Parkinson’s disease. 

Dystonia derives from the Latin phrase dys, which means impaired functioning, and Greek phrase tonos, which means partial contraction of muscle tissue. The term dystonia was first used by Herman Oppenheim in 1911. Prior to this term, many other descriptions, like epilepsy, apoplexy, and palsy were all used with little distinction.

There are several causes of dystonia, although the exact underlying pathology is not completely understood. The disorder can be further classified into four types of dystonia according to its specific cause: isolated focal dystonia, inherited dystonia, acquired dystonia, and idiopathic dystonia. 

Isolated focal dystonias occur most commonly, and affect only one part of the body beginning in adulthood. One example of an isolated focal dystonia is oromandibular dystonia, which affects muscle contraction of the face, jaw, or tongue. 

Inherited dystonias may be caused by a genetic mutation that is inherited in an autosomal recessive, autosomal dominant, X-linked recessive, or mitochondrial manner. Inherited disorders were previously classified as DYT followed by a number, such as DYT1 dystonia. However, many of these have been given new names based on concurrence with other movement disorders, or are named after the affected gene. For example, DYT11 is also referred to as myoclonus-dystonia or DYT-SGCE. Some of these disorders present primarily in childhood, such as DYT-THAP1 dystonia or paroxysmal kinesigenic dyskinesia. 

Acquired dystonias are primarily caused by environmental factors, such as hypoxic brain injury during or around an individual’s birth; certain infections, like meningitis and encephalitis; certain medicines, like neuroleptics, anti-emetics, and antidepressants; and vascular abnormalities, such as stroke. They may develop at any age depending on the exposure.

There are also some idiopathic dystonias where no clear cause is identified. Sometimes, however, there may be multiple causative factors.

In general, the involuntary contractions of dystonia will cause a slow or irregular muscle movement in the affected area that worsens with increased movement and may be accompanied by pain. Individuals with dystonia may have abnormal postures, such as having their head tilted to one side or one raised shoulder. Symptoms are often mild at first and only associated with specific activities. However, over time they may become more noticeable without any precursory stressor or exertion. General dystonia affects the whole body, while focal dystonias may only affect specific areas.

Dystonia is diagnosed based on a medical examination which includes assessment of the individual’s signs and symptoms, a review of the family history, and conduction of a neurological examination. When hereditary causes are suspected, genetic testing may be requested. Additional imaging, such as an MRI, may be performed to rule out other anatomical causes of the impaired movement. 

As there is currently no cure, the mainstay treatment of dystonia is focused on alleviating symptoms to improve the overall quality of life. Typically, dystonia is treated with certain medications based on the type of dystonia. The most common medication is botulinum toxin (i.e., botox) injections. Other medications include those that affect neurotransmitters (i.e., the chemical messengers between neurons), such as anticholinergic, GABAergic, or dopaminergic agents. Sometimes individuals may also receive physical therapy, with or without speech therapy, to improve muscle movements.

If the symptoms continue to worsen, surgery may be considered. The most common surgical procedure is deep brain stimulation (DBS), during which a battery-powered stimulator is placed on the brain to send electrical impulses to the part of the brain responsible for the muscle movement. A remote control is then used to adjust the impulses based on the individual’s specific needs. It often takes several weeks or months to see clinical improvement after DBS.

Dystonia is a type of neurological movement disorder that results in involuntary muscle movements. Dystonia is made up of two Latin phrases, -dys meaning ‘impaired functioning’ and -tonos which refers to partial muscle contraction. Causes of dystonia are varied and include inherited genetic mutations, environmental factors like infections or medications, or even no known cause. The primary sign and symptom of dystonias are irregular muscle movements, which may be accompanied by pain and may cause abnormal postures in an individual. The specific movements may vary depending on the affected muscle. Dystonia can be diagnosed through medical examination, genetic testing for hereditary causes, MRI scans, and potentially other tests to exclude specific diagnoses. Treatments for dystonia are focused on improving symptoms since there is no cure. These treatments may include medications, physical therapy, and, if necessary, surgery like deep brain stimulation.