SUBACUTE MYELO-OPTICO-NEUROPATHY (S.M.O.N.) IN JAPAN: A Community Survey

Abstract

An epidemiological survey of subacute myelo-optico-neuropathy (S.M.O.N.) was made in Toda City (population 65,000) and Warabi City (population 76,000), Japan. In Toda City, after an outbreak in 1964, the occurrence was sporadic. In Warabi City the incidence was lower and less variable. The highest incidence was in middle-aged females; no cases were found in children. Out of 47 cases examined, 36 had been treated at 2 particular medical institutions (A and B) at the time of onset of neurological symptoms, although there were 52 medical institutions in the areas. The remaining 11 cases had been treated in other medical institutions inside and outside the areas. Review of the National Health Insurance returns from 30 medical institutions in Warabi City revealed that the highest dosage of clioquinol was used in medical institution B. No case of S.M.O.N was observed in 20 medical institutions which did not use clioquinol. In medical institution A, 17 out of 21 patients with confirmed S.M.O.N. (81%) had been given clioquinol before the onset of neurological symptoms. A comparative study showed that the dosage of clioquinol to S.M.O.N. patients had been heavier than to other patients with similar enteric symptoms.