Characterization of Manual Dexterity by Finger Force Manipuladum (FFM) in Patients With Writer's Cramp and in Control Subjects

Inclusion criteria for patients with writer's cramp * Patient with writer's cramp and writing speed \<140 letters / min * Writer's cramp focal dystonia specific to the task of writing * Patient treated or not with botulinum toxin injection * Person having attended school in French Non inclusion criteria for patients with writer's cramp * Patients whose writer's cramp has no impact on the handwriting and has kept a writing speed\> 140 letters per minute. * Tremor of writing * Neurological condition other than writer's cramp (eg Parkinson's syndrome) * Pain, trauma or pathology of the upper limb of the writing member other than the writer's cramp who required medical or surgical treatment in the last 6 months preceding the initial check-up Inclusion criteria for control subjects •\> 18 years old * Without writer's cramp * Person having attended school in French Non inclusion criteria for control subjects * Tremor of writing * Neurological condition other than writer's cramp (eg Parkinson's syndrome) * Pain, trauma or pathology of the upper limb of the writing member other than the writer's cramp who required medical or surgical treatment in the last 6 months preceding the initial check-up Matching criteria between cases and control patients * Age (± 5 years) * Gender * Hand writing