ABSTRACT
Cervical dystonia (CD) is a focal dystonia of the cervical muscles that causes abnormal postures of the head, neck, and shoulders1 (Table 8.1). In the past, CD was considered a psychiatric disorder, and terms such as ‘torticollis mentalis’ were used to describe the condition.2 The reasons for this misconception arise from its unusual movements, worsening with certain actions or postures, enhancement by stress, improvement by touches or ‘tricks’ and the lack of anatomic, physiologic, and biochemical abnormalities.3 Patients were referred to psychiatrists, some receiving inpatient psychiatric treatment, counseling, and electroconvulsive therapy for ‘hysteria’.4 Subsequently, the neurologic basis of CD was recognized, it was redefined as a subtype of focal dystonia and is now referred to as cervical dystonia.3,5
CD is marked by deviation of the head around horizontal (torticollis), coronal (retrocollis, anterocollis), and vertical axis (laterocollis), often associated with reduced range of motion in the direction contralateral to the movement.6 CD has been categorized into three types associated with dystonic muscle activation: tonic, phasic, and tremulous.7 Horizontal rotation is the most common abnormal movement, present in approximately 80% of patients. Electromyography in superficial neck muscles showed that this posture typically arises from activity of the sternocleidomastoid muscle contralateral to the turn and splenius capitis muscle ipsilateral to the direction of turn. Deeper muscles, including the longissimus capitis, splenius cervices, longus capitis, and obliquus capitis, can also be involved. Laterocollis is seen in 10-20% of patients, and is associated with electromyographic activity in ipsilateral splenius, sternocleidomastoid, and levator scapulae muscles. Retrocollis and anterocollis are less frequent, and involve bilateral posterior and anterior muscles, respectively. In most patients, these movements are not present in pure form, with combinations of torticollis and laterocollis.
