Primary cranial-cervical dystonia is managed mainly by repeated botulinum toxin injections.This study is to establish whether subthalamic nucleus neurostimulation could improve symptoms in patients not adequately responding to chemodenervation or oral drug treatment. Investigators compared this surgical treatment with sham stimulation in a randomized, controlled clinical trial.

In this randomised, sham-controlled trial, investigators will recruit forty patients with primary cranial-cervical dystonia to receive an implanted device for STN-DBS, and participants will be randomly assigned to receive either neurostimulation or sham stimulation for 3 months.The primary end point was the change from baseline to 3 months in the severity of symptoms, according to the Burke-Fahn-Marsden Dystonia Rating Scale. Two masked dystonia experts who unaware of treatment status will assess the severity of dystonia by reviewing standardised videos.Subsequently, all patients will receive open-label neurostimulation; blinded assessment will be repeated after 6 months of active treatment.

Inclusion Criteria:

1. Clinical diagnosis of primary cranial-cervical dystonia: blepharospasm combined with dystonia of the lower facial muscles. Cervical muscles can be involved but did not dominate the clinical picture.
2. Medical intractable：including various drugs and local botulinum toxin injections.
3. patients deteriorated in activities of daily living and showed social withdrawal during the course of their disease as they suffered from apparent hyperkinesia of facial muscles and functional blindness secondary to severe blepharospasm.

Exclusion Criteria:

1. All other topographical areas remained unaffected.
2. Secondary causes will be excluded by standard cranial magnetic resonance imaging (MRI) scans.
3. Cognitive impairment, dementia,severe psychiatric diseases as well as higher surgical risks due to comorbidities will also be exclusion criteria.