Prevalence of focal dystonias in the western area of Tottori Prefecture in Japan

Bilateral segmental dystonia in a professional tennis player

Dystonias occur frequently as repetitive movements, persistent elevations of muscle tone, or tonic contortions, whereby the cause is assumed to be an impairment of basal ganglia function. Focal dystonias are especially known in musicians, although little is reported on focal dystonias in athletic stress. The present case report describes the case of a 34-yr-old professional tennis player with bilateral segmental dystonia. The symptoms were expressed in involuntary movements when he intended to hit the ball and in a progredient tremor, initially in one hand, later in both, making him unable to write. The altered mobility during athletic stress was confirmed by video analysis, the altered innervation with excessive, uncoordinated impulse influx by means of electromyography during sport-type specific stress, and writing incapacity during a writing test. The symptoms abated under therapy with trihexyphenidyl-HCL, so that the patient has been able to work as a tennis coach with improved athletic performance for the past 3 yr. It is concluded that the various forms of dystonia should be included in the differential diagnosis of impaired coordinative movements under athletic exercise, especially of the upper extremities.

Dystonia and dyskinesia

Dystonia is defined as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Tardive dyskinesia (TD), estimated to occur in 30% of patients treated with neuroleptics, encompasses a broad spectrum of hyperkinesias associated with exposure to these drugs. Dystonia is one of the most common expressions of tardive dyskinesia. This article aims to provide an overview of classification, phenomenology, epidemiology, genetics, pathophysiology, neuropsychologic aspects, and treatment of these two conditions.

Ethnic variation in the clinical expression of idiopathic torsion dystonia

Although childhood, limb-onset idiopathic torsion dystonia (ITD) is at increased prevalence among Jews, and Ashkenazi Jews with this form of ITD show linkage disequilibrium for a unique haplotype, little else is known about phenotypic or genetic variation in ITD among ethnic groups. We assessed clinical features in 786 ITD patients and determined the relative frequencies of various clinical forms of ITD in the major ethnic groups. Several differences in age-at-onset and site-at-onset distributions among groups were demonstrated. As expected, Ashkenazi Jews had an earlier age-at-onset distribution than did non-Jewish Caucasians. In the early-onset group, Jews were less likely to have cervical onset and more likely to have onset in the limbs than were non-Jewish Caucasians (p < 0.01). Among late-onset cases, Jews had less cervical onset and more cranial onset than did non-Jewish Caucasians (p < 0.01). African-Americans showed suggestive differences in both age at onset and site at onset as compared with the two caucasian groups, with an intermediate age at onset, a deficit of leg onset, and an excess of cranial and larynx onset. Subgroups of non-Jewish Caucasians showed no significant differences from each other. The observed ethnic variations in age at onset and site at onset of ITD suggest population differences in disease-causing alleles or loci. However, environmental influences on expression of ITD can not be excluded.

Pain perception in idiopathic cervical dystonia (spasmodic torticollis)

Cervical spinal pain is frequently found in conjunction with idiopathic cervical dystonia (ICD), a focal dystonia characterized by sustained deviation of the head. Since the perception of noxious stimuli has never been studied in ICD, we performed a controlled study to obtain more insight into the psychophysics of dystonia-related muscle pain by evaluating pressure-induced pain levels. In nine ICD patients and five gender- and age-matched asymptomatic control subjects, pain-pressure thresholds (PPTs) were determined in the sternocleidomastoid and upper trapezius muscles, both at resting activity and at maximal voluntary contraction (MVC). The masseter muscles served as non-pathological control regions. To determine the accuracy of PPT values, pain intensity and unpleasantness were rated at threshold on 100-mm visual analogue scales. Four replication measurements were obtained. The data were analyzed by multilevel procedures. For all muscles under investigation, average PPTs of the ICD patients were about two times lower than those of the control subjects (P < 0.001-0.0005) and showed a smaller intra-subject variance. Further, average PPTs at MVC were about two times higher than those at resting activity (P < 0.005). These results provide psychophysical evidence to suggest that, at controlled levels of muscle contraction, the threshold of pain perception is decreased in ICD. In addition, ICD patients seem to be better able to establish their own PPTs than control subjects, which might be due to a different setting of the discriminative aspect of pain in ICD. Surprisingly, lower intensity and unpleasantness scores were found in ICD patients with coinciding painful and deviated sides than in ICD patients for whom the painful side was opposite to the deviated one (P < 0.05). This finding might be of clinical importance for defining functional disability and predicting treatment outcome.