Patients with focal dystonia have involuntary muscle contractions that can be painful in a single group of muscles. In comparison, patients with generalized dystonia have these muscle contractions that affect either most or all of their body.
There are several types of focal dystonia, which differ by the muscle group affected. One type of focal dystonia is focal dystonia of the hand, which is also called “writer’s cramp” or “pianist’s cramp,” as it affects people who perform repetitive hand movements. The Dystonia Medical Research Foundation noted that focal hand dystonia accounts for 5 percent of all focal dystonia cases.
The NYU Langone Medical Center stated that a dystonia can occur when dysfunction occurs in an area of the brain called the basal ganglia. This dysfunction affects proper signaling for muscle contractions. Inherited abnormalities may cause this dysfunction, as well as acquired conditions, such as a stroke, trauma, infection, vitamin B-12 deficiency or a reaction to medication.
With focal hand dystonia, there is not an identified specific cause. The Dystonia Medical Research Foundation noted that “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.”
In some cases of focal dystonia of the hand, patients may develop generalized dystonia or segmental dystonia, in which two or more adjacent body parts are affected.
Patients with focal hand dystonia may have curling of their fingers and a lack of precision. Musicians with this type of dystonia may have a subtle loss of control when playing pieces with faster parts or feel like their fingers are sticking to the keys. Many focal hand dystonia patients only have symptoms when performing certain tasks, according to the Dystonia Medical Research Foundation.
Some patients may experience tremors with the muscle spasms. Non-musicians with focal dystonia of the hand may have trouble writing — their handwriting becomes worse after they write a few lines.
While there is no cure for focal hand dystonia, several treatments are available. Medication options include anticholingeric drugs, which affect the neurotransmitter acetylcholine. When acetylcholine is released at the nerve endings, the body can have a muscle contraction. The anticholingeric drug interferes with this, reducing the involuntary muscle contractions.
Another option is botulinum toxin injections, which temporarily weaken the muscle affected by the involuntary muscle contraction. Research is also investigating new treatment for focal dystonia for the hand. For example, the National Institute of Neurological Disorders and Stroke sponsored a study to look at whether motor training can treat focal hand dystonia.
References
Dystonia Medical Research Foundation. Focal Hand Dystonia. Web. 14 November 2011.
http://www.dystonia-foundation.org/pages/focal_hand_dystonia/57.php
Cleveland Clinic. Dystonias. Web. 14 November 2011.
http://my.clevelandclinic.org/disorders/Dystonia/hic_Dystonias.aspx
NYU Langone Medical Center. Focal Dystonia. Web. 14 November 2011.
http://www.med.nyu.edu/content?ChunkIID=191761
ClinicalTrials.gov. Motor Training to Treat Hand Dystonia Web. 14 November 2011.
http://clinicaltrials.gov/show/NCT00021853
Reviewed November 14, 2011
by Michele Blacksberg RN
Edited by Jody Smith