To the Editor.— The review article by Risk et al ( Arch Neurol 35:494-502, 1978) seems to have overlooked substantial data regarding subacute sclerosing panencephalitis (SSPE) as it occurs in several Latin American countries. It is likely that they are unfamiliar with, or have no access to, the Latin American medical literature. In fact, we 1 have recently emphasized the high incidence of SSPE in South America based on the series from Sao Paulo, Brazil, 2 and the large number of cases from Colombia. 3 At the Fourth Pan-American Congress of Neurology, 4 a total of 110 cases of SSPE were collected from the joint Venezuelan, Peruvian, Mexican, and Colombian series. To our knowledge, this entity was first recognized in Colombia in 1966 by one of us (G.T.), and shortly thereafter, other cases were diagnosed in different areas of the country. A group of 22 patients was reported in 1970 to