Drug Management in Cervical Dystonia

Currently, the prevalence of cervical dystonia in the US is estimated to be greater than 90,000. Other studies show that its prevalence differs among ethnic groups.^5–7 Claypool et al., in 1995, reported an incidence of 1.2 per 100,000, while an incidence of 5.4 per 100,000 was published in a practice-based survey of dystonia in Munich.⁷

Women are affected 1.3- to two-fold more often than men. CD can occur at any time of life, but most individuals experience their first symptoms in middle age. Chen et al. reviewed the clinical details of CD in 266 patients. In their study, the median age of onset was 41 years old, with a female to male ratio of 1.9 to 1. They found a familial history of dystonia in 12% of cases. Remission was achieved in 9.8% of patients.⁸

Pathophysiology
The pathophysiology of idiopathic CD is not well understood. Recent studies have explained the pathogenesis of CD at the peripheral and central nervous system (CNS) level. Although any muscle in the neck may be involved, the common muscles associated with abnormal head posture are well described.^9,10 CD, like other focal dystonias, is a syndrome of abnormality in central motor processing.

Clinical Manifestation
Head tremor and neck spasms are cardinal clinical features in patients with CD.^8,11 The majority of affected patients complain of pain, which is not common in other types of focal dystonia other than writer’s cramp. Hand and arm tremor may be seen in patients with torticollis.11–13 In certain cases, head, arm, or trunk tremor can be the initial presenting symptom and sometimes the isolated manifestation of torticollis.¹⁴

Most patients with torticollis find a sensory trick a useful tool to control or eliminate their symptoms. A sensory trick has been called a ‘geste antagoniste’ and is a unique feature of dystonia.Typically, placing the hand on the chin, the side of the face or the back of the neck reduces muscle contraction in CD without applying mechanical pressure. In some patients, thinking about a geste antagoniste eliminates or diminishes their symptoms just the same as actually performing the sensory trick.15 Although the use of a geste antagoniste is reported in more than 50% of patients with CD11, its mechanism of action is still unknown.