Chen et al15 | 1960–1966 | Guam | 37975 | National Institute of Neurological Diseases and Blindness | Pure | AD/AR-HSP and sporadic | 7 | 18.4 |
Skre16 | 1960–1968 | Western Norway | 725000 | University hospital in Bergen | Pure and complicated | AD-HSP | 31 | 12.1 |
Werderlin 17 Werderlin and Keiding18 | 1961–1975 | Zealand (Denmark) | 1179000 | All hospitals in Zealand | Pure and complicated | AD/AR-HSP | 23 | 2 |
| | | Age 10 to 50 | | | | | |
Brignoli et al19 | 1945–1982 | Turin (Italy) | 2327996 | District and regional hospitals, nursing homes and disability centres | Not stated | AD-HSP | 31 | 0.7 |
Sridharan et al20 | 1984 | Benghazi (Libya) | 519000 | Polyclinics, disability centres and four university hospitals | Pure and complicated | AD/AR-HSP and sporadic | 11 | 2.1 |
Polo et al21 | 1974–1986 | Cantabria (Spain) | 510000 | Neurology department of the regional hospital | Pure | AD/AR-HSP | 49 | 9.6 |
FIlla et al22 | 1989 | Molise (Italy) | 335211 | Mail and phone survey of 847 hospital physicians and GPs | Pure and complicated | AD/AR-HSP | 9 | 2.7 |
Hirayama et al23 | 1988–1989 | Japan | 123000000 | Mail survey of hospitals with 200 plus beds | Pure and complicated | AD/AR-HSP and sporadic | 109 | 0.17 |
Leone et al24 | 1981–1991 | Valle d'Aosta (Italy) | 115270 | Departments in the regional hospital and local disability centres | Pure | AD-HSP and sporadic | 5 | 4.3 |
Silva et al25 | 1994 | Viano do Castelano (Portugal) | 250061 | District & regional hospitals, disability centres and GPs | Pure and complicated | AD/AR-HSP | 5 | 2 |
Current study | 1995–2000 | Ireland | 5436000 | Neurologists, geneticists, and hospital records. | Pure | AD-HSP | 69 | 1.27 |