Motor neuron disease and past poliomyelitis. Geographic study in Hokkaido, the northern-most island of Japan. ALS Study Group.

We carried out a survey on the cases of motor neuron disease (MND) occurring in Hokkaido between 1980 and 1989 in order to establish whether there is a relationship between MND and poliomyelitis. Hokkaido, the northern-most island of Japan, was one of the most affected areas during the poliomyelitis epidemic of the late 1940s to 1950s. We ascertained 389 cases of MND for these 10 years and 2,171 cases of paralytic poliomyelitis for the period 1949-1958, and analysed their geographic distributions. No significant correlation was found between MND and poliomyelitis in their geographic distributions.