The prevalence estimates for primary dystonia range from two to 50 cases per million for early-onset dystonia and from 30 to 7320 cases per million for late-onset dystonia. From analysis of methodological information from 14 selected studies, we concluded that all studies on the basis of treatment settings or record-linkage systems, and two population-based surveys were probably flawed by incomplete ascertainment; the third population-based study provided the largest prevalence for late-onset dystonia but probably overestimated the prevalence of the disorder. Age and ethnic differences among study populations further biased comparisons of estimates. On the basis of methodologically more robust service-based studies and the likely percentage of underdiagnosis in a given area, more accurate prevalence estimates may be 111 per million for early-onset dystonia in Ashkenazi Jews from New York area, 600 per million for late-onset dystonia in northern England, and 3000 per million for late-onset dystonia in the Italian population over age 50 years.
BACKGROUND: Essential tremor (ET) is the most common adult tremor disorder and is characterized by postural and kinetic tremor. Symptoms are typically progressive and potentially disabling, often forcing patients to change jobs or seek early retirement. Proper treatment is contingent on a correct diagnosis, and other possible causes of tremor must be excluded.
REVIEW SUMMARY: Although primidone and propranolol have been regarded as the mainstays of pharmacologic therapy for ET, additional agents may be useful in reducing tremor. Surgical procedures are available that effectively ameliorate tremor that is refractory to medical management. This article reviews the epidemiology, pathophysiology, and treatment options for ET.
CONCLUSIONS: Despite a range of treatment options currently available, further research is necessary to manage this syndrome most effectively. Double-blind, controlled trials are needed to determine whether primidone, propranolol, or a combination of these medications is superior in the initial management of ET. Other pharmacologic agents have shown potential to reduce tremor and should be investigated further. Additional studies are also needed to determine the best treatment of head and voice tremor with pharmacologic and surgical interventions. With proper treatment, tremor is sufficiently reduced in the majority of patients.
The prevalence estimates for primary dystonia range from two to 50 cases per million for early-onset dystonia and from 30 to 7320 cases per million for late-onset dystonia. From analysis of methodological information from 14 selected studies, we concluded that all studies on the basis of treatment settings or record-linkage systems, and two population-based surveys were probably flawed by incomplete ascertainment; the third population-based study provided the largest prevalence for late-onset dystonia but probably overestimated the prevalence of the disorder. Age and ethnic differences among study populations further biased comparisons of estimates. On the basis of methodologically more robust service-based studies and the likely percentage of underdiagnosis in a given area, more accurate prevalence estimates may be 111 per million for early-onset dystonia in Ashkenazi Jews from New York area, 600 per million for late-onset dystonia in northern England, and 3000 per million for late-onset dystonia in the Italian population over age 50 years.
