The primary aim of this study is to investigate improvements of dystonia severity in patients with cervical dystonia (CD) with (DYT-trick) and without sensory trick (DYT-no-trick) following 6 weeks of physiotherapy combined with botulinum toxin injection (BoNT).

The recruited patients will be divided into two groups according to the presence of an effective sensory trick (DYT trick and DYT no-trick groups).

The researchers analyzing clinical, neurophysiological and MRI data as well as the statistician will be blind about the allocation of subjects to the two groups. Considering the different clinical phenotypes of patients (DYT-trick and DYT-no-trick) clinical evaluators and physiotherapists cannot be blind.

All patients will perform the routinely BoNT injection and after 1 week they will start a multimodal physiotherapy program lasting 6 weeks, 3 times a week for 45 minutes each session. The physiotherapy treatment will include soft tissue mobilization of inoculated muscles, stretching exercises of the inoculated muscles, strengthening of antagonist muscles, and motor learning exercises (attentive strategies, feedback-based cervical active exercises). Exercises will be progressively difficult (increase of active range of motion -ROM) according to clinical improvements during the 6 weeks of treatment.

Clinical assessments will be performed at baseline (T0), after 6 weeks of treatment (W6) and before the next BoNT injection (about 12 weeks of follow-up, W12) to evaluate disease severity (TWSTRS), pain, active cervical range of motion, disability, quality of life and mood. Cervical movements during TWSTRS will be monitored using the Virtual Reality Rehabilitation System (VRRS), which includes the usage of magneto-inertial sensors to objectively assess joint positions and quality of movement. MRI evaluations will be performed at T0 and at W6 to investigate resting state functional Magnetic Resonance Imaging (fMRI) changes and fMRI changes of brain activation during the simulation and imagination of sensory trick.

SAI paradigm is obtained combing transcranial magnetic stimulation (TMS) with peripheral electrical stimulation techniques. It will be performed at baseline (before BoNT injection and physiotherapist training) and after week 6 of physiotherapist training.

A group of healthy subjects similar for age and sex to patients will be recruited to perform cognitive assessment and MRI at baseline.

Inclusion Criteria fo patients with Cervical Dystonia:

• Adult onset idiopathic CD according to established diagnostic criteria (Albanese et al., Eur J Neur, 2011) with and without an effective sensory trick will be eligible for the study

Exclusion Criteria for all participants

• presence of fixed postures because of skeletal neck deformity;
• history of (other) systemic, neurologic, psychiatric diseases, head injury, cardiovascular events, and cerebrovascular alterations visible at an MRI scan;
• alcohol and/or psychotropic drugs abuse;
• contraindication to perform MRI scan (cardiac pace-maker or other types of cardiac catheters, splinters or metallic shards, metallic prosthesis not compatible with magnetic field generated by MRI, claustrophobia).

The statistician will be blind about the characteristics of the two groups. Considering the different clinical phenotypes of patients (DYT-trick and DYT-no-trick) clinical evaluators and physiotherapists cannot be blinded.