Classification and Etiology of Dystonia
The term “dystonia” was coined by Oppenheim in 19111 in his description of “dystonia musculorum deformans,” even though he was not the first to recognize this hyperkinetic movement disorder. The word dystonia, originally from modern Latin and then adapted from German dystonie, derived from dys- and the Greek term –tonos, which has a musical connotation, meaning stretching, tension raising of voice, pitch.2 The term “dystonia” is used to describe a hyperkinetic movement disorder manifested by repetitive muscle contractions causing abnormal, but patterned, movements, or postures.
Dystonias are classified by various criteria. Their distribution may be generalized, segmental, hemibody, multifocal, and focal. Dystonias may be primary (without any other neurological deficit), or secondary, in which case it may be accompanied by other neurological features such myoclonus or parkinsonism; the latter “dystonia plus” disorders are often caused by structural lesions involving the basal ganglia or may be associated with heredodegenerative disorders.3 The genetics and pathophysiology of dystonia are described in the preceding chapters in this volume, and in recent reviews.4
Clinical Assessment of Dystonia
Several clinical scales have been developed to aid in the objective assessment of dystonia and its response to therapeutic interventions. The Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS)5 is used most frequently. Other scales used chiefly for assessment of generalized dystonias include the Unified Dystonia Rating Scale (UDRS) designed by the Dystonia Study Group and the Global Dystonia Scale (GDS).6 These three scales showed excellent internal consistency and good to excellent correlation among raters.6 Toronto Western Spasmodic Torticolis Rating Scale (TWSTRS) was developed for assessment of cervical dystonia (CD). 7 The Jankovic Rating Scale (JRS), which assesses the severity and frequency of involuntary eyelid contractions in patients with blepharospasm and the self-rating response scale Blepharospasm Disability Index (BSDI) have been found to correlate well with each other.8
Medical Treatment of Dystonia
The treatment of dystonia is largely geared toward symptomatic relief as there is no cure or even neuroprotective strategies for dystonia to date. Strategies for treatment may be divided into pharmacological, botulinum neurotoxin (BoNT) chemodenervation, and surgery, either peripheral or central (stereotactic). Many patients are treated, at least initially, with pharmacological therapy, but it is important to note that the use of these medications are based largely on clinical experience and custom and that none of the pharmacological approaches are supported by strong clinical trial-based evidence for efficacy. There is, however, strong (Class I and Class II) evidence from randomized controlled trials for the efficacy of BoNT in forms of focal dystonia (Simpson, 2008).9
Adjuncts to Medical Treatment
In addition to medical treatment, physical and occupational therapy play an important role in the overall quality of life and disability of patients with dystonia. A range of motion exercises are important ...