Task-specific focal dystonia

Task-specific focal dystonia is a movement disorder that interferes with the performance of particular tasks, such as writing, playing a musical instrument, or participating in a sport. Dystonias are a group of movement problems characterized by involuntary, sustained muscle contractions, tremors, and other uncontrolled movements. The term "focal" refers to a type of dystonia that affects a single part of the body, such as the hand or jaw.

Researchers have described several forms of task-specific focal dystonia. The most common is writer's cramp, in which muscle cramps or spasms in the hand, wrist, or forearm interfere with holding a pen or pencil. Writer's cramp begins in the hand used for writing (the dominant hand) and is usually limited to that task, but with time it can spread to the other hand and affect other fine-motor activities such as shaving or typing.

Musician's dystonia is a form of task-specific focal dystonia characterized by muscle cramps and spasms that occur while playing a musical instrument. This condition can affect amateur or professional musicians, and the location of the dystonia depends on the instrument. Some musicians (such as piano, guitar, and violin players) develop focal hand dystonia, which causes loss of fine-motor control in the hand and wrist muscles. This condition reduces finger coordination, speed, and endurance while playing. Musicians who play woodwind or brass instruments can develop what is known as embouchure dystonia. This condition causes muscle cramps or spasms involving the lips, tongue, or jaw, which prevents normal positioning of the mouth around the instrument's mouthpiece. Musician's dystonia often occurs only when playing a particular instrument. However, over time focal hand dystonia may impair other activities, and embouchure dystonia can worsen to affect eating and speech.

Task-specific focal dystonia can affect people who play sports and engage in other occupations involving repetitive, highly practiced movements. For example, some golfers experience involuntary jerking of the wrists during putting, a condition known informally as "the yips." Cramps and spasms of the hand and arm muscles can also affect tennis players, billiards players, dart throwers, and other athletes. Additionally, task-specific dystonia has been reported in tailors, shoemakers, hair stylists, and people who frequently type or use a computer mouse.

The abnormal movements associated with task-specific focal dystonia are usually painless, although they can cause anxiety when they interfere with musical performance and other activities. Severe cases can cause professional disability.