Limb immobilization for the treatment of focal occupational dystonia.

BACKGROUND: Occupational focal upper-limb dystonia is characterized by involuntary muscle contractions that selectively interfere with the execution of specific motor tasks such as writing or playing a musical instrument. Occupational dystonias have a severe social impact, especially in certain professions. The available medical treatments offer little benefit.
METHODS: In eight patients with idiopathic occupational focal dystonia of the upper limb, the dystonic forearm and hand were immobilized with a plastic splint for mean (+/-SD) 4.5 +/- 0.75 weeks. Before splinting (base line) and at various intervals afterwards (4, 12, and 24 weeks), the authors assessed the severity of dystonia and the patients' motor performance objectively (Arm Dystonia Disability Scale and Tubiana and Chamagne Score) and subjectively (Self-Rating Score).
RESULTS: Assessment 4 weeks after splint removal, when patients had regained normal voluntary movements, showed that the severity of dystonia and the patients' performance of the impaired motor task had improved; the benefit persisted unchanged at later follow-up visits (Arm Dystonia Disability Scale: base line 20.6 +/- 30.2%; after 4 weeks 83.9 +/- 23.8%, p = 0.007; after 12 weeks 83.9 +/- 23.8%, p = 0.007; after 24 weeks 79.7 +/- 29.5%, p = 0.015. Tubiana and Chamagne Score: base line 28.6 +/- 22.7%; after 4 weeks 80.0 +/- 23.1%, p = 0.015; after 12 weeks 80.0 +/- 23.1%, p = 0.015; after 24 weeks 74.3 +/- 32.1%, p = 0.031. Self-Rating Score: base line 20.6 +/- 19.3%; after 4 weeks 63.7 +/- 25.2%, p = 0.015; after 12 weeks 66.9 +/- 28.1%, p = 0.015; after 24 weeks 70.6 +/- 31.8%, p = 0.015). At the 24-week visit the improvement disappeared in one patient, was moderate in three, and marked in four.
CONCLUSIONS: Limb immobilization can be a simple, effective, safe, and inexpensive treatment for focal occupational upper-limb dystonia.