Concordant late onset of craniocervical dystonia in a pair of monozygotic twins

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Focal and segmental primary dystonia in north-western Germany--a clinico-genetic study

OBJECTIVES

To determine the frequency of familial focal and segmental dystonias in a large patient cohort with primary dystonia from north-western Germany.

MATERIALS AND METHODS

In this study, 130 patients with focal or segmental dystonia were examined and a family history was obtained. Whenever possible, affected relatives were examined (a total of 789 first-degree relatives). Data on disease duration, age at disease onset and age of the patients were investigated by Student's t-test and a segregation analysis was performed by Weinberg's proband method.

RESULTS

Age at onset of disease was significantly later in the blepharospasm group. Only in the writer's cramp group were women outnumbered by men. A positive family history was found in 15 of the 130 index patients (11.5%). None of 102 index patients tested carried the GAG deletion in the DYT1 gene.

CONCLUSIONS

In accordance with previous series our study provides evidence that primary focal dystonia may have a genetic etiology, most probably caused by an autosomal dominant trait with reduced penetrance.

Cervical dystonia in monozygotic twins: case report and review of the literature

We report on monozygotic male twins of German origin with early onset cervical dystonia. No other family members were affected. Although identical in age of onset and clinical course, there were phenotypic variations. While the second-born, more affected twin suffered from a symmetric retrocollis, the twin brother mainly presented with a spasmodic torticollis to the left. Dystonia remained focal in both siblings. A DYT1 gene deletion was excluded. Including our patients, hitherto only four twin pairs with idiopathic dystonia have been reported. Although dystonia in twins can be remarkably uniform in some cases, major differences in terms of disease progression, remissions, and disability may be found. These observations underline the role of inheritance in the pathogenesis of idiopathic dystonia but also indicate that some other factors contribute to the clinical presentation of dystonia.