The purpose of this study is to compare the cervical muscular force control , taking into account the proprioceptive signals, in patients with and without cervical dystonia.

Inclusion criteria:

• patients presenting focal or segmental cervical dystonia diagnosed by a neurologist expert in the diseases with abnormal movements
• having signed a consent for study participation

No Inclusion Criteria:

Neurological affection other than cervical dystonia (typical or atypical parkinsonism, other ...)

• Severe pain, trauma or disease of the cervical spine known or suspected other than cervical dystonia requiring treatment in the last 6 months
• Ongoing neuroleptic treatment
• Pregnancy or breastfeeding
• Lack of insurance coverage

For patients, are added the following no inclusion criteria are added:

• Trembling cervical dystonia
• Injection of botulinum toxin in the past three months