Objective: To determine whether difficulties in motor or perceptive anticipation are present in writer’s cramp and are specific to writing or also observed during other motor activities.

Background: The writer’s cramp is a « task specific dystonia »: the dystonia is not present in other actions but writing. Recent researches highlight a sensitive and proprioceptive deficit in writer’s cramp. Perceptive and motor anticipation require functional sensory and proprioceptive feedback which could be disturbed in writer’s cramp.

Methods: Fifteen patients with writer’s cramp, aged from 29 to 60 years old and ten healthy control participants, matched according to age, gender, socio-educational level and frequency of hand use, were enrolled. To evaluate perceptive and motor anticipation, they had to perform two types of tasks: (1) to write couples of letters (morphocinetic task), and (2) to point two spots (totocinetic task).

Results: We demonstrated motor and perceptive difficulties for morphocinetic tasks in the writers’cramp group when compared to controls. Topocinetic capacities were preserved on either perceptive and motor anticipation in all participants.

Conclusions: Our experiments suggest that writers’ cramp is associated to motor and perceptive anticipation difficulties. Despite such difficulties were found to be specific of writing in our patients, a causal link cannot be proved on the basis of these data. Anticipation and writing difficulties could rather involve a dysfunction of the same area, such as the premotor cortex.

Perception and proprioception in focal hand Dystonia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-writers-cramp-and-its-connections-with-sensory-deficits/