Movement disorders result from blocked, slowed or distorted communication between the central nervous system and the muscles. The cause of the communication interference may vary and include:

• Traumatic injury. Many parts of the brain are involved in processing and transmitting the nerve signals necessary for coordinating balance and movement. They are susceptible to damage from head injuries. Spinal cord injuries may also lead to movement disorders by blocking the transmission of nerve signals from the brain to muscles below the head.
  
  
• Stroke. Much like head injuries, stroke can also damage parts of the brain involved in movement. The lack of oxygen getting to nerves in the brain (neurons) can cause the cells to die.
  

  

• Genetic mutation. Genes provide the instructions for all of the body’s functions. While some mutations may occur with no apparent effects, others can cause nerve or muscle degeneration that result in a movement disorder. Mutations may occur spontaneously or may be inherited from a parent who may or may not have had the disorder.
  
  
• Medications. Several types of medications (e.g., for psychiatric, gastrointestinal and neurological disorders) may cause damage to the brain and nerve cells. Physicians will likely monitor the patient’s side effects while under these medications to prevent occurrence of tardive dyskinesia and other movement disorders.
  
  
• Infection. In rare cases, Streptococcus bacterial infections may lead to Sydenham’s chorea.

Certain factors put some populations at greater risk for developing movement disorders. They vary greatly among the many disorders and some groups who are at greater risk for one type may be at less risk for another. Risk factors for movement disorders may include:

• Age
• Gender
• Race
• Family history of disease