Background: Cervical dystonia is the most common form of focal dystonia. Most cases of cervical dystonia are idiopathic and generally it is a life-long disorder. In recent years, Botulinum toxin type A (BtA) has become the first line therapy. However, some patients are resistant to it. This problem leads to the study of the clinical forms of cervical dystonias with the help of CT and MRI.
Patients and methods: 78 patients with diagnosed primary cervical dystonia were examined. All underwent CT of the soft tissues of the neck with the aid of slices at the level of cervical vertebra 3 and 7. The cervical spine and the soft tissues of the neck were examined using magnetic resonance tomography in T 1 and T 2 with a slice thickness of 2 mm and in T 1 tilted towards the deep neck muscles. For comparison the MRT image data of 50 patients who had no cervical dystonia was analysed. The largest diameters were measured and the shape of all muscles captured in the neck region was described, including the small neck muscles.
Results: It was shown that in lateral flexion and in rotation, in 1 / 5 of patients the disorder affected only muscles which work on atlanto-occipital joints (latero- or torticaput), and in a further 1 / 5 it affected only muscles which work on the cervical spine (latero- or torticollis). 3 / 5 showed both disorders, but with a different degree of caput and collis involvement. Thus a ration of 1:1:3 was obtained in relation to this.
Conclusions: 1. In lateral tilt, differentiation between laterocollis and laterocaput is clinically possible. 2. Lateral shift always occurs when laterocollis is present on one side and laterocaput on the other. 3. In rotation, clinical differentiation between torticollis and torticaput is not always possible. In this case CT sections at levels C 3 and C 7 are recommended. By comparing the vertebral position at the two levels it is possible to differentiate reliably between torticollis and torticaput. 4. Anteflexion--differentiation between anterocollis and anterocaput--is analysed by lateral inspection of the angle between the cervical spine and the thoracic spine or between the cervical spine and the base of the skull. The same applies for the analysis of retroflexion, the differentiation between retrocollis and retrocaput. 5. A posteroanterior sagittal shift requires no further diagnosis: it is often caused by bilateral dystonic activity of the sternocleidomastoid muscles.