About dystonia Types of dystonia What are the causes? Dystonia is caused by incorrect signals from the brain to the affected body part but the causes for this are not yet fully understood. Simple writer’s cramp is thought to usually be caused by over-use of the hand, poor writing posture or poor pen hold. Dystonic writer’s cramp is thought to be affected by dystonia in other parts of the body. Musician’s dystonia is thought to be caused by the repetitive hand movements, which result in remapping of the receptive fields in the cortex of the brain.