While the exact cause of dystonia is unknown, it may result from a problem with nerve cells in various areas of the brain. Some types of dystonia may also be hereditary. Dystonia can also be a symptom of various diseases, including:

Parkinson's disease
Huntington's disease
Wilson's disease
Traumatic brain injury
Birth injury
Stroke
Tumors or paraneoplastic syndromes that develop in some people with cancer
Oxygen deprivation or carbon monoxide poisoning
Infections such as tuberculosis or encephalitis
Reactions to certain medications or heavy metal poisoning

Depending on the type of dystonia, it can cause several complications. It can impair daily activities or job performance, cause vision problems by affecting the eyelids, lead to impaired jaw movement, make swallowing and speaking difficult, cause muscle pain and fatigue, lead to depression, and cause social isolation.