Cervical dystonia

[Luis Fok]

Cervical dystonia is characterized by involuntary tonic contractions or intermittent spasms of neck muscles. The cause is usually unknown. Diagnosis is clinical. Treatment can include physical therapy, drugs, and selective denervation of neck muscles with surgery or locally injected botulinum toxin.
(See also Overview of Movement and Cerebellar Disorders.)
In cervical dystonia, contraction of the neck muscles causes the neck to turn from its usual position. Cervical dystonia is the most common dystonia.
There are two forms of cervical dystonia:

Caput: When the most proximal cervical vertebrae (C1 or C2) are involved
Collis: When any of the lower cervical vertebrae (C3 to C7) are involved

The caput form (torticaput) involves muscles that move the skull or head joints; it is further described as anterocaput, laterocaput, or retrocaput. The collis form involves muscles that control the lower cervical vertebrae and is further described as anterocollis, laterocollis, retrocollis, or torticollis. Differentiating the two forms is important because it helps clinicians identify the correct muscles to inject with botulinum toxin.
Spasmodic adult-onset torticollis is the most common form of cervical dystonia. It is usually idiopathic. A few patients have a family history, and in some of them (eg, those with dystonia-6 [DYT6], dystonia-7 [DYT7], or dystonia-25 [DYT25; associated with the GNAL gene]), a genetic cause has been identified. Some of these patients have other dystonias (eg, of the eyelids, face, jaw, or hand).
Cervical dystonia can be

Congenital
Secondary to other conditions such as lesions of the brain stem or basal ganglia or use of dopamine -blocking drugs (eg, haloperidol )

Rarely, dystonia has a psychogenic cause. In this type of dystonia, pathophysiology is not well-understood; however, changes in brain function have been detected by functional neuroimaging. In many cases, an emotional stressor or an abnormal core of beliefs is identified as a trigger. In such cases, a multidisciplinary team, including a neurologist, psychiatrist, and psychologist, is necessary.