Diagnosis of extrapyramidal disorders is mainly a clinical one [10, 11]. The number of existing cases of primary dystonia in the population is not precisely known, but the condition is probably much more frequent than reported.
This study examined the prevalence of three extrapyramidal diseases (dystonia, chorea, and athetosis) among the whole population (33,285 persons) in Al Qusier City, Red Sea Governorate, Egypt. The prevalence of dystonia in this study is 39/100,000 while the result reported by El-Tallawy and his colleagues in Al Kharga District, Egypt, was (30.36/100,000) . This may be attributed to different environmental factors between east and west deserts in Egypt (mines are more common in east desert area including Al Quseir City). In our study, the most common focal dystonias were blepharospasm (56.4%), cervical dystonia (36.7%), limb dystonia (3.4%), oromandibular dystonia (2.9%) and laryngeal dystonia (0.6%). Males with primary dystonia were found to have an earlier age of onset. We assume that such finding may be attributed to the fact that exposure of males to all environmental factors is more than females especially when they start working outdoors early in their lives. A female predominance was noted for most of the primary dystonia, with men to women ratio (M:F) of 1:2.01.
Moreover, the prevalence of primary dystonia (9/100,000) is consistent with the results reported by Kandil who reported a prevalence of primary dystonia of 10/100,000 in Egypt . A total of 1993 patients with movement disorders, were assessed in Bangkok, Thailand, dystonia was diagnosed in 8.4% of them . On the other hand, the prevalence of primary dystonia in the current study is slightly lower than that reported by Defazio in Ashkenazi Jews. He found the prevalence of dystonia to be 11.1/100,000, which might be attributed to racial, and genetic factors as the Jewish community is closed .
In our study, seven patients of chorea were identified with total prevalence of 21/100,000. When taking in consideration etiology of chorea, cerebral palsy is the most common cause of chorea in our study as its prevalence is 12/100,000 which appears more prevalent than that of a study conducted in Saudi Arabia by Rajeh  who reported a prevalence of 5.3/100,000. This difference may be attributed to lack of perinatal care measures in Al Quseir City and also due to changes in socioeconomic level between the populations involved in the studies.
In our study, rheumatic chorea is the second most common cause of chorea (9/100,000). This is in agreement with that in case series from Tunisia, Brazil, and Turkey [16,17,18] that reported rheumatic chorea to be the commonest form of acquired chorea and it occurs in approximately one-third of children suffering from rheumatic fever. Actually, the prevalence of rheumatic chorea in Al Quseir City was comparable to that in Turkey (14/100,000) , Hawaii, USA (7/100,000) , and it looks lower than rates in India (18.8/100,000) . Comparing it with other studies in Egypt, it is quite similar to that recorded by Eltallawy  in Alkharga District, Egypt (8/100,000) and far lower than that recorded in Assiut, Egypt by Kandil  (62/100,000). This decrement in prevalence is consistent with international records that rheumatic chorea prevalence is decreasing mostly due to major advancement in antibiotic era and eradication of infections which is a major cause of the disease. In our study, age distribution shows that all patients of rheumatic chorea are children in school age (5 years, 6 years, and 9 years), it is consistent with the India study in which it was reported that all cases of their study are in school age with mean 9.4 years .
In this study, the prevalence of Athetosis was 15/100,000. This figure is comparable with results of Kandil  in Egypt who reported a prevalence of 12/100,000, but more than that stated by Tekle  in Ethiopia (5/100,000), and El-Tallawy  in Al Kharga District, Egypt (1.6/100,000). High prevalence of Athetosis in our study could be explained on etiological basis as all reported cases of athetosis were secondary type (one case has post-encephalitic etiology and four cases are due to cerebral palsy mixed type).