The term dystonia collectively refers to a heterogeneous group of movement disorders characterized by sustained involuntary muscle contractions that result from co-contracting antagonistic muscles and overflow into extraneous muscles. Focal dystonias are adult-onset forms that affect a specific area of the body, ie hand, neck, vocal cords. Most focal dystonias are primary. By primary it is meant that the dystonia is the only neurological symptom.
There is no one isolated cause of hand and limb dystonia. A variety of pathological conditions may lead to similar symptoms. As a child develops, he/she learns many different movements (such as walking, writing, or playing an instrument) that are stored in the brain as motor programs. Instances of hand dystonia that are highly task-specific have been described as a “computer virus” or “hard drive crash” in the sensory motor programs that are essential for playing music. However, additional factors, such as a genetic predisposition, are likely to play a significant role in the development of such a sensory-motor dysfunction. Why this “computer virus” cannot be easily overcome by establishing a new and improved sensory-movement pattern remains an important question for researchers.
Most affected persons describe symptoms in terms of their occupation terms. A musician may notice
- Subtle loss of control in fast passages
- Lack of precision
- Curling of fingers
- Fingers “sticking” to keys
- Involuntary flexion of bowing thumb in strings
- Deterioration in neatness or speed of writing or just clumsiness
- A cramp or aching in the hand on writing
- May report that the hand freezes up on attempting to write
- Difficulty in moving the pen across the page
- The pen commonly is held very tightly, with an exaggeration of the normal semiflexed posture of thumb, index and other fingers, and with hyperextension of the distal interphalangeal joint of the index finger. Occasionally, the hand suddenly stops and the paper is perforated, or it might dart across the page with a sudden jerk. The script produced is usually abnormal. Tremor is a common finding in all forms of writer’s cramp but it is usually not severe. (photo credit)
- Examination of the musician while playing reveals non-physiologic posture and gestures in most of the patients. Sometimes it is possible to identify involuntary dysfunction such as flexion, curling in one or two fingers, or involuntary extension of the “sticking fingers”. These may be difficult to detect, even with slow motion video.
There is no cure for dystonia at this time, and although treatment of the disorder may be challenging, there are several available options. The different causes of hand dystonia may warrant different treatments. Don't give up--see Leon Fleisher's story.
- Doses recommended of biperiden are 2 mg per oral two or three times a day and titration to 16 mg a day.
- Diazepam is another choice. However, it is rarely adequate when used as sole agent. Doses are 10mg per oral two or three times a day.
- Clonazepam can be useful for improvement of phasic symptoms in cases with myoclonus and/or tremor. Doses are 0.25 mg per oral twice a day, increasing to 0.125 to 0.25 mg every three days up to a dose of 4 mg/day.