clinics, occurring in approximately 0.390% of the united states population in 2007 (390 per 100,000). worldwide, it has been reported that the incidence rate of spasmodic torticollis is at least 1.2 per 100,000 person years, and a prevalence rate of 57 per 1 million. the exact prevalence of the disorder is not known; several family and population studies show that as many as 25% of cervical dystonia patients have relatives that are undiagnosed. studies have shown that spasmodic torticollis is not diagnosed immediately; many patients are diagnosed well after a year of seeking medical attention. a survey of 59 patients diagnosed with spasmodic torticollis show that 43% of the patients visited at least four physicians before the diagnosis was made. there is a higher prevalence of spasmodic torticollis in females; females are 1.5 times more likely to develop spasmodic torticollis than males. the prevalence rate of spasmodic torticollis also increases with age, most patients show symptoms from ages 50–69. the average onset age of spasmodic torticollis is 41.